U.S. patent application number 13/762562 was filed with the patent office on 2013-10-17 for anti-fouling composition comprising an aerogel.
The applicant listed for this patent is CISMI, COATZYME APS, ENPRO APS. Invention is credited to Knud Allermann, Henrik Tofte Jespersen, Kjeld Schaumburg, Ib Schneider.
Application Number | 20130273116 13/762562 |
Document ID | / |
Family ID | 40638351 |
Filed Date | 2013-10-17 |
United States Patent
Application |
20130273116 |
Kind Code |
A1 |
Jespersen; Henrik Tofte ; et
al. |
October 17, 2013 |
ANTI-FOULING COMPOSITION COMPRISING AN AEROGEL
Abstract
The present invention also relates to an anti-fouling
composition comprising one or more aerogels. In one embodiment the
aerogel encapsulate one or more bioactive agents. The one or more
encapsulated bioactive agents can in one preferred embodiment be
released from the aerogel over time. In one embodiment the
encapsulated bioactive agents comprise one or more enzymes. In one
preferred embodiment the anti-fouling composition comprising one or
more aerogels is a coating composition.
Inventors: |
Jespersen; Henrik Tofte;
(Kirke Hyllinge, DK) ; Allermann; Knud; (Rungsted
Kyst, DK) ; Schneider; Ib; (Gentofte, DK) ;
Schaumburg; Kjeld; (Herlev, DK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
COATZYME APS;
ENPRO APS;
CISMI; |
|
|
US
US
US |
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|
Family ID: |
40638351 |
Appl. No.: |
13/762562 |
Filed: |
February 8, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12742464 |
Jun 28, 2010 |
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PCT/DK2008/050272 |
Nov 12, 2008 |
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13762562 |
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60987221 |
Nov 12, 2007 |
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61059353 |
Jun 6, 2008 |
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Current U.S.
Class: |
424/400 ;
424/94.1; 424/94.6; 424/94.61; 424/94.63; 424/94.64 |
Current CPC
Class: |
C09D 7/65 20180101; B01J
13/0091 20130101; C08K 3/22 20130101; C08K 3/34 20130101; C09D 7/61
20180101; C09D 5/1637 20130101; C09D 7/70 20180101; C09D 5/1687
20130101; A61K 9/48 20130101; A61K 38/482 20130101 |
Class at
Publication: |
424/400 ;
424/94.1; 424/94.61; 424/94.63; 424/94.6; 424/94.64 |
International
Class: |
A61K 9/48 20060101
A61K009/48; A61K 38/48 20060101 A61K038/48 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 12, 2007 |
DK |
PA200701594 |
Jun 6, 2008 |
EP |
08157766.0 |
Claims
1. An anti-fouling composition for reduction or prevention of
fouling of a surface coated with said composition, said
anti-fouling composition comprising one or more aerogel(s) and one
or more bioactive agent(s) encapsulated in said one or more
aerogel(s).
2. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the one or more aerogel(s) is one or
more organic aerogel(s).
3. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the one or more aerogel(s) is one or
more in-organic aerogel(s).
4. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the one or more aerogel(s) is one or
more silica aerogel(s).
5. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the one or more aerogel(s) is one or
more carbon aerogel(s).
6. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the one or more aerogel(s) is one or
more metal aerogel(s).
7. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the one or more aerogel(s) has a
density in the range from 0.05 to 1.0 g/mol.
8. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the one or more aerogel(s) has a
surface area in the range from 500 m.sup.2/g to 2000 m.sup.2/g.
9. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the one or more aerogel(s) has a pore
size in the range of from 1 to 25 nm.
10. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the one or more aerogel(s) comprises
a self-polishing effect.
11. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the one or more bioactive agent(s)
are released from the one or more aerogel(s) over time.
12. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the one or more bioactive agent(s)
comprises one or more protein(s).
13. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the one or more bioactive agent(s)
comprises one or more enzyme(s).
14. The anti-fouling composition comprising one or more aerogel(s)
according to claim 13, wherein the one or more enzymes comprises
one or more hemicellulolytically active enzyme(s).
15. The anti-fouling composition comprising one or more aerogel(s)
according to claim 13, wherein the one or more enzymes comprises
one or more amylolytically active enzyme(s).
16. The anti-fouling composition comprising one or more aerogel(s)
according to claim 13, wherein the one or more enzymes comprises
one or more cellulolytically active enzyme(s).
17. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the one or more bioactive agent(s)
comprises one or more endopeptidase(s).
18. The anti-fouling composition comprising one or more aerogel(s)
according to claim 17, wherein the one or more endopeptidase(s)
comprises a Subtilisin (EC 3.4.21.62).
19. The anti-fouling composition comprising one or more aerogel(s)
according to claim 14, wherein the one or more hemicellulolytically
active enzyme(s) is selected from the group consisting of
Endo-1,4-beta-xylanase (E.C. 3.2.1.8), Xylan
endo-1,3-beta-xylosidase (E.C. 3.2.1.32), Glucuronoarabinoxylan
endo-1,4-beta-xylanase (E.C. 3.2.1.136), Beta-mannosidase (E.C.
3.2.1.25), Mannan endo-1,4-beta-mannosidase (E.C. 3.2.1.78) and
Mannan endo-1,6-beta-mannosidase (E.C. 3.2.1.101).
20. The anti-fouling composition comprising one or more aerogel(s)
according to claim 14, wherein the one or more hemicellulolytically
active enzyme(s) comprises a xylanase.
21. The anti-fouling composition comprising one or more aerogel(s)
according to claim 15, wherein the one or more amylolytically
active enzyme(s) comprises an amylase.
22. The anti-fouling composition comprising one or more aerogel(s)
according to claim 13, wherein the one or more enzymes comprises
one or more lipase(s).
23. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the composition further comprises an
esterase.
24. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the composition further comprises a
protease.
25. The anti-fouling composition comprising one or more aerogel(s)
according to claim 24, wherein the protease is of the subtilisin
type.
26. The anti-fouling composition comprising one or more aerogel(s)
according to claim 24, wherein the protease is alcalase.
27. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the composition further comprises a
lipase.
28. The anti-fouling composition comprising one or more aerogel(s)
according to claim 13, wherein the one or more enzyme(s) comprises
one or more hydrolytic enzymes.
29. The anti-fouling composition comprising one or more aerogel(s)
according to claim 13, wherein the one or more enzyme(s) are
functionalized to be actively incorporated into the
three-dimensional structure of the one or more aerogel(s).
30. The anti-fouling composition comprising one or more aerogel(s)
according to claim 13, wherein the one or more enzyme(s) are
encapsulated in the one or more aerogel(s) together with one or
more other bioactive agent(s).
31. The anti-fouling composition comprising one or more aerogel(s)
according to claim 1, wherein the composition further comprises a
rosin.
32. A coating composition comprising the anti-fouling composition
comprising one or more aerogel(s) according to claim 1 and a
carrier.
33. The coating composition according to claim 32, wherein the
coating composition comprises one or more pigment(s).
34. The coating composition according to claim 32, wherein the
coating composition comprises one or more binder(s).
35. The coating composition according to claim 32, wherein the
coating composition comprises one or more vehicle(s).
36. A method for preventing or reducing fouling of a surface, said
method comprising the steps of contacting the surface with a
composition according to claim 1 with an effective amount of said
composition or coating composition or hygienic composition, wherein
said contacting results in preventing or reducing fouling of said
surface.
37. A method for preventing or reducing fouling of a surface, said
method comprising the steps of contacting the surface with a
composition according to claim 32 with an effective amount of said
composition or coating composition or hygienic composition, wherein
said contacting results in preventing or reducing fouling of said
surface.
38. A method for preventing or reducing fouling of a surface
according to claim 36, wherein the surface is a surface that is at
least occasionally immersed in water, wherein said water includes
fresh, salt or brackish water.
39. A method for preventing or reducing fouling of a surface
according to claim 37, wherein the surface is a surface that is at
least occasionally immersed in water, wherein said water includes
fresh, salt or brackish water.
40. A method for preventing or reducing fouling of a surface
according to claim 36, wherein the surface is selected from
surfaces of vessels including boats and ships, ship hulls,
off-shore equipment, pipes, substructures of bridges, piers and
aquacultural apparatuses including fish farming nets.
41. A method for preventing or reducing fouling of a surface
according to claim 37, wherein the surface is selected from
surfaces of vessels including boats and ships, ship hulls,
off-shore equipment, pipes, substructures of bridges, piers and
aquacultural apparatuses including fish farming nets.
42. Method for preparing the composition according to claim 1, said
method comprising the steps of providing at least one pigment and
at least one enzyme capable of acting on a compound, wherein said
action results in the formation of an antifouling species
comprising an antifouling activity.
43. Method for preparing the composition according to claim 32 said
method comprising the steps of providing at least one pigment and
at least one enzyme capable of acting on a compound, wherein said
action results in the formation of an antifouling species
comprising an antifouling activity, the method comprises further
providing a carrier for said at least one enzyme, and forming said
composition by contacting said at least one enzyme with said
carrier.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/742,464 filed Jun. 28, 2010, which is the
U.S. national phase of PCT/DK2008/050272 filed Nov. 12, 2008, which
claims priority of Danish Patent Application No. PA 2007 01594
filed Nov. 12, 2007; U.S. Provisional Application No. 60/987,221
filed Nov. 12, 2007; U.S. Provisional Application No. 61/059,353
filed Jun. 6, 2008; and European Patent Application No. 08157766.0
filed Jun. 6, 2008.
[0002] All patent and non-patent references cited in the
application, or in the present application, are also hereby
incorporated by reference in their entirety.
BACKGROUND OF THE INVENTION
[0003] Aerogels
[0004] Aerogel is a low-density solid-state material derived from
gel in which the liquid component of the gel has been replaced with
gas. The result is a low density solid with several characteristic
properties such as its effectiveness as an insulator.
[0005] Aerogel was first created by Steven Kistler in 1931.
Aerogels are in general produced by extracting the liquid component
of a gel through supercritical drying. This allows the liquid to be
slowly drawn off without causing the solid matrix in the gel to
collapse from capillary action, as would happen with conventional
evaporation. The first aerogels were produced from silica gels.
Aerogels based on alumina, chromia and tin oxide have also been
described. Carbon aerogels were developed in the early 1990s.
[0006] Anti-Fouling Agents
[0007] In order to minimize the impacts of foulers, many underwater
structures are protected by antifouling coatings. Coatings,
however, have been found to be toxic to marine organisms. For
example, extremely low concentrations of tributyltin moiety (TBT),
the mostly commonly used anti-fouling agent, cause defective shell
growth in the oyster Crassostrea gigas (at a concentration of 20
ng/l) and development of male characteristics in female genitalia
in the dog whelk Nucella lapillus (where gonocharacteristic change
is initiated at 1 ng/l). The ban of organotins such as TBT and
triphenyltin (TPT), and other toxic biocides in marine coatings is
a severe problem for the shipping industry; it presents a major
challenge for the producers of coatings to develop alternative
technologies to prevent fouling on ship hulls. Safer methods of
biofouling control are actively researched. Copper and derivative
compounds have successfully been used either in paints or as metal
sheeting (for example Muntz metal which was specifically made for
this purpose), though there is still debate as to the safety of
copper.
SUMMARY OF THE INVENTION
[0008] The present invention relates to an aerogel. The present
invention also relates to an anti-fouling composition comprising
one or more aerogels. In one embodiment the aerogel encapsulate one
or more bioactive agents. The one or more encapsulated bioactive
agents can in one preferred embodiment be released from the aerogel
over time. In one embodiment the encapsulated bioactive agents
comprises enzymes.
BRIEF DESCRIPTION OF THE DRAWING
[0009] FIG. 1 is a photograph showing a series of test panels which
were used to evaluate the coatings of the present invention.
DEFINITIONS
[0010] Aerogel is a low-density solid-state material derived from
gel in which the liquid component of the gel has been replaced with
gas.
[0011] Anti-fouling is the process of removing or inhibiting the
accumulation of biofouling.
[0012] Antifouling species: Any species exerting antifouling
effect. Species such as antimicrobial species, antibacterial
species, antifungal species, biocides, biorepellents, and the like.
Bioactive agents and antifouling species are used interchangeable
herein.
[0013] Bio-film: Habitation of microbial organisms on a solid or
semi-solid surface.
[0014] Biofouling or biological fouling is the undesirable
accumulation of microorganisms, plants, algae, and animals on
surfaces such as submerged structures like ships' hulls.
Subtilisins comprises a family of serine proteases isolated from
bacillus subtilis. Anti-fouling: The effect of controlling,
reducing and/or eliminating over time the number of undesirable
microorganisms in a bio-film.
[0015] Coating composition: Composition for coating an object, such
as a paint.
[0016] Co-factor: Additional factor required by an enzyme.
[0017] Compound: Substrate for an enzyme capable of catalysing said
compound, wherein said catalysis results in the formation of an
antimicrobial species comprising an antimicrobial activity.
[0018] Enzyme: Biomolecule comprising a plurality of amino acids
and capable of catalysing conversion of substrates into products.
The terms enzyme and precursor enzyme are used interchangably
unless otherwise indicated. An enzyme is acting on a compound as
defined herein when said action generates an antifouling species
having antifouling activity. A precursor enzyme is any enzyme
capable of providing to the enzyme, by means of degradation or
otherwise, a substrate for said enzyme in the form of said
compound.
[0019] Lipid or lipid composition: When used herein in connection
with modification and/or coating of enzymes, lipid means a compound
having a long-chain alkyl group, which is a hydrophobic group, and
a hydrophilic group.
[0020] Marine organism: Any organism capable of habitating in an
aqueous environment, including organisms capable of forming
undesirable bio-films.
[0021] Microbial organism: Any organism belonging to the classes of
prokaryotes and lower eukaryotes, including bacteria, yeasts,
fungal cells and slime molds.
[0022] Oxidase: Enzyme the activity of which results in an
oxidation, including an oxidation resulting in the formation of a
peroxide, including hydrogenperoxide.
[0023] Paint is any liquid, liquifiable, or mastic composition
which after application to a surface in a thin layer is converted
to an opaque solid film.
[0024] Painting is the application of paint.
[0025] Peroxide: Product resulting from a reaction involving an
oxidase.
[0026] Precursor compound: Precursor compounds are capable of being
catalysed by a precursor enzyme, wherein said catalysis results in
the formation of a compound capable of being catalysed by an enzyme
under the generation of an antifouling species, including an
antimicrobial species having an antimicrobial activity.
[0027] Secretion: Process of translocating a compound or precursor
compound across the outer membrane of a microbial species.
Secretion applies to compounds which remain membrane associated and
to compounds which are subsequently released into an external
environment.
[0028] Surface: Outer part of e.g. a microbial organism in contact
with the external environment.
[0029] Xerogel: A xerogel is a solid formed from a gel by drying
with unhindered shrinkage. Xerogel usually retains high porosity
(25%) and enormous surface area (150-900 m.sup.2/g), along with
very small pore size (1-10 nm). When solvent removal occurs under
hypercritical (supercritical) conditions, the network does not
shrink and a highly porous, low-density material known as an
aerogel is produced. Heat treatment of a xerogel at elevated
temperature produces viscous sintering and effectively transforms
the porous gel into a dense glass.
DETAILED DESCRIPTION OF THE INVENTION
[0030] The present invention in one embodiment relates to a
composition comprising a xerogel and at least one enzyme capable of
acting on a compound, wherein said action results in the formation
of an antifouling species comprising an antifouling activity. The
compound can form part of said composition, but it does not need to
form part of said composition. The latter is the case when the
compound is e.g. provided by an external environment in which the
composition is exerting an antifouling effect. The composition is
preferably has a self-polishing effect.
[0031] The present invention in another embodiment relates to a
composition comprising an aerogel and at least one enzyme capable
of acting on a compound, wherein said action results in the
formation of an antifouling species comprising an antifouling
activity. The compound can form part of said composition, but it
does not need to form part of said composition. The latter is the
case when the compound is e.g. provided by an external environment
in which the composition is exerting an antifouling effect. The
composition is preferably has a self-polishing effect.
[0032] The composition can be a coating composition further
comprising a pigment, or a hygienic composition further comprising
a fragrance, or a composition as stated herein above further
comprising both a pigment and a fragrance.
[0033] In another embodiment there is provided a method for
preparing such compositions, including a coating composition, as
well as uses of such a coating composition, including uses as
described in more detail herein below.
[0034] In yet another embodiment of the invention there is provided
a method for reducing marine corrosion comprising the step of
coating a marine surface with a marine antifouling composition,
whereby the composition forms at least one film that reduces
adsorption of corrosive molecules to the surface. Also disclosed is
a method wherein the composition impedes surface corrosion and
intergranular corrosion.
[0035] In a still further embodiment of the invention there is
provided a method for reducing marine corrosion comprising the step
of coating a marine surface with a marine antifouling paint,
whereby the paint forms at least one film that reduces adsorption
of corrosive molecules to the surface. In yet another embodiment of
the claimed invention, a method is disclosed, wherein the paint
impedes surface corrosion and intergranular corrosion.
[0036] In an even further embodiment of the invention there is
provided a method for limiting absorption of water by a marine
surface comprising the step of coating the surface with a marine
antifouling composition or marine antifouling paint, whereby the
composition or paint produces a film which in turn reduces the
porosity of the surface.
[0037] In still another embodiment of the invention, a method is
disclosed for reducing the coefficient of drag of a marine surface
comprising the step of coating the surface with a marine
antifouling composition or marine antifouling paint. The invention
is also directed to methods of using the marine antifouling
composition or marine antifouling paint wherein surfactants capable
of acting as wetting agents are produced by microorganisms in
contact with the composition or paint.
[0038] Yet another embodiment of the invention is directed to a
method for removing marine growth from a marine surface, comprising
the step of coating the surface with a marine antifouling
composition or marine antifouling paint. Another embodiment of the
invention is a method of using the marine antifouling composition
or marine antifouling paint wherein the marine growth is hard or
soft growth.
[0039] An even further embodiment of the invention is directed to a
method of using the marine antifouling composition or marine
antifouling paint, wherein e.g. hydrolytic enzymes attack exudates
of existing growths and causes release of hard and soft growth.
Types of Aerogels:
[0040] In one embodiment the present invention relates to silica
aerogels gels or carbon aerogels. Alternatively the aerogels are
based on alumina, chromia, tin and bromo oxide.
[0041] Metal-aerogel nanocomposites can be prepared by impregnating
the hydrogel with solution containing ions of the suitable noble or
transition metals. The impregnated hydrogel is then, in one
embodiment, irradiated with gamma rays, leading to precipitation of
nanoparticles of the metal. Such composites can be used as eg.
catalysts, sensors, electromagnetic shielding, and in waste
disposal. A prospective use of platinum-on-carbon catalysts is in
fuel cells.
[0042] Carbon aerogels are used in the construction of small
electrochemical double layer supercapacitors. Due to the high
surface area of the aerogel, these capacitors can be 2000 to 5000
times smaller than similarly rated electrolytic capacitors. Aerogel
supercapacitors can have a very low impedance compared to normal
supercapacitors and can absorb/produce very high peak currents.
Aerogel Composition:
[0043] The aerogel may be composed of any material used in prior
art or any combination thereof.
[0044] The aerogel may be prepared using various oxide units in
order to add properties required as additional to the storage and
release of proteins. The invention includes silicon/titania;
silicon/borate-; silicon/zirkonate but is not limited to these.
[0045] The aerogel may be adjusted by its composition to have
hydrophilic or hydrophobic properties by use of a combination of
silicate and dialkyl silicate units. The mixture can be in the
range 100:0 to 80:20 such as such as 98:2, for example 96:4, such
as 95:5, for example 94:6, such as 92:8, for example 90:10, such as
88:12, for example 86:14, such as 85:15, for example 84:16, such as
82:18. In one preferred embodiment the mixture can be in the range
95:5.
Production of Aerogels:
[0046] Silica aerogel is made by drying a hydrogel composed of
colloidal silica in an extreme environment. Specifically, the
process starts with a liquid alcohol like ethanol which is mixed
with a silicon alkoxide precursor to form a silicon dioxide sol gel
(silica gel). Then, through a process called supercritical drying,
the alcohol is removed from the gel. This is typically done by
exchanging the ethanol for liquid acetone, allowing a better
miscibility gradient, and then onto liquid carbon dioxide and then
bringing the carbon dioxide above its critical point. A variant on
this process involves the direct injection of supercritical carbon
dioxide into the pressure vessel containing the aerogel. The end
result removes all liquid from the gel and replaces it with gas,
without allowing the gel structure to collapse or lose volume.
[0047] Aerogel composites have been made using a variety of
continuous and discontinuous reinforcements. The high aspect ratio
of fibers such as fiberglass have been used to reinforce aerogel
composites with significantly improved mechanical properties.
[0048] Resorcinol-formaldehyde aerogel (RF aerogel) is made in a
way similar to production of silica aerogel.
[0049] Carbon aerogel is made from a resorcinol-formaldehyde
aerogel by its pyrolysis in inert gas atmosphere, leaving a matrix
of carbon. It is commercially available as solid shapes, powders,
or composite paper.
Physical and Chemical Properties of Aerogels:
[0050] In one preferred embodiment the density of the aerogel is in
the range from 0.05 to 1.0 g/mol such as 0.05 g/mol to 0.45 g/mol,
for example 0.05 g/mol to 0.4 g/mol, such as 0.05 g/mol to 0.35
g/mol, for example 0.05 g/mol to 0.3 g/mol, such as 0.05 g/mol to
0.35 g/mol, for example 0.05 g/mol to 0.3 g/mol, such as 0.05 g/mol
to 0.25 g/mol, for example 0.05 g/mol to 0.2 g/mol, such as 0.05
g/mol to 0.15 g/mol, for example 0.05 g/mol to 0.1 g/mol, such as
0.05 g/mol to 0.5 g/mol, for example 0.1 g/mol to 0.5 g/mol, such
as 0.15 g/mol to 0.5 g/mol, for example 0.2 g/mol to 0.5 g/mol,
such as 0.25 g/mol to 0.5 g/mol, for example 0.3 g/mol to 0.5
g/mol, such as 0.35 g/mol to 0.5 g/mol, for example 0.4 g/mol to
0.5 g/mol, such as 0.45 g/mol to 0.5 g/mol, for example 0.05 g/mol
to 1.0 g/mol, such as 0.05 g/mol to 0.95 g/mol, for example 0.05
g/mol to 0.9 g/mol, such as 0.05 g/mol to 0.85 g/mol, for example
0.05 g/mol to 0.8 g/mol, such as 0.05 g/mol to 0.75 g/mol, for
example 0.05 g/mol to 0.7 g/mol, such as 0.05 g/mol to 0.65 g/mol,
for example 0.05 g/mol to 0.6 g/mol, such as 0.05 g/mol to 0.55
g/mol, for example 0.05 g/mol to 0.5 g/mol, such as 0.05 g/mol to
0.45 g/mol, for example 0.05 g/mol to 0.4 g/mol, such as 0.05 g/mol
to 0.35 g/mol, for example 0.05 g/mol to 0.3 g/mol, such as 0.05
g/mol to 0.25 g/mol, for example 0.05 g/mol to 0.2 g/mol, such as
0.05 g/mol to 0.15 g/mol, for example 0.05 g/mol to 0.1 g/mol, such
as 0.1 g/mol to 1.0 g/mol, for example 0.15 g/mol to 1.0 g/mol,
such as 0.2 g/mol to 1.0 g/mol, for example 0.25 g/mol to 1.0
g/mol, such as 0.3 g/mol to 1.0 g/mol, for example 0.35 g/mol to
1.0 g/mol, such as 0.4 g/mol to 1.0 g/mol, for example 0.45 g/mol
to 1.0 g/mol, such as 0.5 g/mol to 1.0 g/mol, for example 0.55
g/mol to 1.0 g/mol, such as 0.6 g/mol to 1.0 g/mol, for example
0.65 g/mol to 1.0 g/mol, such as 0.7 g/mol to 1.0 g/mol, for
example 0.75 g/mol to 1.0 g/mol, such as 0.8 g/mol to 1.0 g/mol,
for example 0.85 g/mol to 1.0 g/mol, such as 0.9 g/mol to 1.0
g/mol, for example 0.95 g/mol to 1.0 g/mol, such as 0.15 g/mol to
0.3 g/mol, for example 0.16 g/mol to 0.3 g/mol, such as 0.17 g/mol
to 0.3 g/mol, for example 0.18 g/mol to 0.3 g/mol, such as 0.19
g/mol to 0.3 g/mol, for example 0.20 g/mol to 0.3 g/mol, such as
0.21 g/mol to 0.3 g/mol, for example 0.22 g/mol to 0.3 g/mol, such
as 0.23 g/mol to 0.3 g/mol, for example 0.24 g/mol to 0.3 g/mol,
such as 0.25 g/mol to 0.3 g/mol, for example 0.26 g/mol to 0.3
g/mol, such as 0.27 g/mol to 0.3 g/mol, for example 0.28 g/mol to
0.3 g/mol, such as 0.29 g/mol to 0.3 g/mol, such as 0.15 g/mol to
0.29 g/mol, such as 0.15 g/mol to 0.28 g/mol, such as 0.15 g/mol to
0.27 g/mol, such as 0.15 g/mol to 0.26 g/mol, such as 0.15 g/mol to
0.25 g/mol, such as 0.15 g/mol to 0.24 g/mol, such as 0.15 g/mol to
0.23 g/mol, such as 0.15 g/mol to 0.22 g/mol, such as 0.15 g/mol to
0.21 g/mol, such as 0.15 g/mol to 0.20 g/mol, such as 0.15 g/mol to
0.19 g/mol, such as 0.15 g/mol to 0.18 g/mol, such as 0.15 g/mol to
0.17 g/mol, such as 0.15 g/mol to 0.16 g/mol.
[0051] In one embodiment the aerogel typically has a density of
0.15 g/mol to 0.30 g/mol.
[0052] The surface area of the aerogel is in one preferred
embodiment in the range from 500 m.sup.2/g to 2000 m.sup.2/g such
as from 500 m.sup.2/g to 1950 m.sup.2/g, for example from 500
m.sup.2/g to 1900 m.sup.2/g, such as from 500 m.sup.2/g to 1850
m.sup.2/g, for example from 500 m.sup.2/g to 1800 m.sup.2/g, such
as from 500 m.sup.2/g to 1750 m.sup.2/g, for example from 500
m.sup.2/g to 1700 m.sup.2/g, such as from 500 m.sup.2/g to 1650
m.sup.2/g, for example from 500 m.sup.2/g to 1600 m.sup.2/g, such
as from 500 m.sup.2/g to 1550 m.sup.2/g, for example from 500
m.sup.2/g to 1500 m.sup.2/g, such as from 500 m.sup.2/g to 1450
m.sup.2/g, for example from 500 m.sup.2/g to 1400 m.sup.2/g, such
as from 500 m.sup.2/g to 1350 m.sup.2/g, for example from 500
m.sup.2/g to 1300 m.sup.2/g, such as from 500 m.sup.2/g to 1250
m.sup.2/g, for example from 500 m.sup.2/g to 1200 m.sup.2/g, such
as from 500 m.sup.2/g to 1150 m.sup.2/g, for example from 500
m.sup.2/g to 1100 m.sup.2/g, such as from 500 m.sup.2/g to 1050
m.sup.2/g, for example from 500 m.sup.2/g to 1000 m.sup.2/g, such
as from 500 m.sup.2/g to 950 m.sup.2/g, for example from 500
m.sup.2/g to 900 m.sup.2/g, such as from 500 m.sup.2/g to 850
m.sup.2/g, for example from 500 m.sup.2/g to 800 m.sup.2/g, such as
from 500 m.sup.2/g to 750 m.sup.2/g, for example from 500 m.sup.2/g
to 700 m.sup.2/g, such as from 500 m.sup.2/g to 650 m.sup.2/g, for
example from 500 m.sup.2/g to 600 m.sup.2/g, such as from 500
m.sup.2/g to 550 m.sup.2/g, for example from 500 m.sup.2/g to 2000
m.sup.2/g, such as from 550 m.sup.2/g to 2000 m.sup.2/g, for
example from 600 m.sup.2/g to 2000 m.sup.2/g, such as from 650
m.sup.2/g to 2000 m.sup.2/g, for example from 700 m.sup.2/g to 2000
m.sup.2/g, such as from 750 m.sup.2/g to 2000 m.sup.2/g, for
example from 800 m.sup.2/g to 2000 m.sup.2/g, such as from 850
m.sup.2/g to 2000 m.sup.2/g, for example from 900 m.sup.2/g to 2000
m.sup.2/g, such as from 950 m.sup.2/g to 2000 m.sup.2/g, for
example from 1000 m.sup.2/g to 2000 m.sup.2/g, such as from 1050
m.sup.2/g to 2000 m.sup.2/g, for example from 1100 m.sup.2/g to
2000 m.sup.2/g, such as from 1150 m.sup.2/g to 2000 m.sup.2/g, for
example from 1200 m.sup.2/g to 2000 m.sup.2/g, such as from 1250
m.sup.2/g to 2000 m.sup.2/g, for example from 1300 m.sup.2/g to
2000 m.sup.2/g, such as from 1350 m.sup.2/g to 2000 m.sup.2/g, for
example from 1400 m.sup.2/g to 2000 m.sup.2/g, such as from 1450
m.sup.2/g to 2000 m.sup.2/g, for example from 1500 m.sup.2/g to
2000 m.sup.2/g, such as from 1550 m.sup.2/g to 2000 m.sup.2/g, for
example from 1600 m.sup.2/g to 2000 m.sup.2/g, such as from 1650
m.sup.2/g to 2000 m.sup.2/g, for example from 1700 m.sup.2/g to
2000 m.sup.2/g, such as from 1750 m.sup.2/g to 2000 m.sup.2/g, for
example from 1800 m.sup.2/g to 2000 m.sup.2/g, such as from 1850
m.sup.2/g to 2000 m.sup.2/g, for example from 1900 m.sup.2/g to
2000 m.sup.2/g, such as from 1950 m.sup.2/g to 2000 m.sup.2/g, for
example from 800 m.sup.2/g to 1500 m.sup.2/g, such as from 850
m.sup.2/g to 1500 m.sup.2/g, for example from 900 m.sup.2/g to 1500
m.sup.2/g, such as from 950 m.sup.2/g to 1500 m.sup.2/g, for
example from 1000 m.sup.2/g to 1500 m.sup.2/g, such as from 1050
m.sup.2/g to 1500 m.sup.2/g, for example from 1100 m.sup.2/g to
1500 m.sup.2/g, such as from 1150 m.sup.2/g to 1500 m.sup.2/g, for
example from 1200 m.sup.2/g to 1500 m.sup.2/g, such as from 1250
m.sup.2/g to 1500 m.sup.2/g, for example from 1300 m.sup.2/g to
1500 m.sup.2/g, such as from 1350 m.sup.2/g to 1500 m.sup.2/g, for
example from 1400 m.sup.2/g to 1500 m.sup.2/g, such as from 1450
m.sup.2/g to 1500 m.sup.2/g, for example from 800 m.sup.2/g to 1450
m.sup.2/g, such as from 800 m.sup.2/g to 1400 m.sup.2/g, for
example from 800 m.sup.2/g to 1350 m.sup.2/g, such as from 800
m.sup.2/g to 1300 m.sup.2/g, for example from 800 m.sup.2/g to 1250
m.sup.2/g, such as from 800 m.sup.2/g to 1200 m.sup.2/g, for
example from 800 m.sup.2/g to 1150 m.sup.2/g, such as from 800
m.sup.2/g to 1100 m.sup.2/g, for example from 800 m.sup.2/g to 1050
m.sup.2/g, such as from 800 m.sup.2/g to 1000 m.sup.2/g, for
example from 800 m.sup.2/g to 950 m.sup.2/g, such as from 800
m.sup.2/g to 900 m.sup.2/g, for example from 800 m.sup.2/g to 850
m.sup.2/g.
[0053] The surface area of the aerogel is in one preferred
embodiment in the range from 800 to 1500 m.sup.2/g.
[0054] In one preferred embodiment the pore size of the aerogel is
in the range of from 1 to 25 nm such as from 1 to 24 nm, for
example from 1 to 22 nm, such as from 1 to 20 nm, for example from
1 to 18 nm, such as from 1 to 16 nm, for example from 1 to 14 nm,
such as from 1 to 12 nm, for example from 1 to 10 nm, such as from
1 to 8 nm, for example from 1 to 6 nm, such as from 1 to 4 nm, for
example from 1 to 2 nm, such as from 2 to 25 nm, for example from 4
to 25 nm, such as from 6 to 25 nm, for example from 8 to 25 nm,
such as from 10 to 25 nm, for example from 12 to 25 nm, such as
from 14 to 25 nm, for example from 16 to 25 nm, such as from 18 to
25 nm, for example from 20 to 25 nm, such as from 22 to 25 nm, for
example from 24 to 25 nm, such as from 1 to 5 nm, for example from
5 to 10 nm, such as from 10 to 15 nm, for example from 15 to 20 nm,
such as from 20 to 25 nm, for example from 2 to 10 nm, such as from
2 to 9 nm, for example from 2 to 8 nm, such as from 2 to 7 nm, for
example from 2 to 6 nm, such as from 2 to 5 nm, for example from 2
to 4 nm, such as from 2 to 3 nm, for example from 3 to 10 nm, such
as from 3 to 9 nm, for example from 3 to 8 nm, such as from 3 to 7
nm, for example from 3 to 6 nm, such as from 3 to 5 nm, for example
from 3 to 4 nm, such as from 4 to 10 nm, for example from 4 to 9
nm, such as from 4 to 8 nm, for example from 4 to 7 nm, such as
from 4 to 6 nm, for example from 4 to 5 nm, such as from 5 to 9 nm,
for example from 5 to 8 nm, such as from 5 to 7 nm, for example
from 5 to 6 nm, such as from 6 to 10 nm, for example from 6 to 9
nm, such as from 6 to 8 nm, for example from 6 to 7 nm, such as
from 7 to 10 nm, for example from 7 to 9 nm, such as from 7 to 8
nm, for example from 8 to 10 nm, such as from 8 to 9 nm, for
example from 9 to 10 nm.
[0055] The pore size of the aerogel is typically 2-5 nm.
[0056] The surface of the aerogels feel like a light but rigid
foam, something between Styrofoam and the green floral foam used
for arranging flowers. Aerogels are dry materials and do not
resemble a gel in their physical properties but a nanofoam.
Pressing softly on an aerogel typically does not leave a mark;
pressing more firmly will leave a permanent dimple. Pressing firmly
enough will cause a breakdown in the sparse structure, causing it
to shatter like glass. Despite the fact that it is prone to
shattering, it is very strong structurally. Its impressive load
bearing abilities are due to the dendritic microstructure, in which
spherical particles of average size 2-5 nm are fused together into
clusters. These clusters form a three-dimensional highly porous
structure of almost fractal chains, with pores smaller than 100 nm.
The average size and density of the pores can be controlled during
the manufacturing process.
[0057] Aerogels are remarkable thermal insulators because they
almost nullify three methods of heat transfer (convection,
conduction, and radiation). They are good convective inhibitors
because air cannot circulate throughout the lattice. Silica aerogel
is an especially good conductive insulator because silica is a poor
conductor of heat--a metallic aerogel, on the other hand, would be
a less effective insulator. Carbon aerogel is a good radiative
insulator because carbon absorbs the infrared radiation that
transfers heat.
[0058] Due to its hygroscopic nature, aerogel feels dry and acts as
a strong desiccant.
[0059] Aerogels appear semi-transparent because they, in one
preferred embodiment, consist of up to 99% air. The color it does
have is due to Rayleight scattering of the shorter wavelengths of
visible light by the nanosized dendritic structure. This causes it
to appear bluish against dark backgrounds and whitish against
bright backgrounds.
[0060] Aerogels by themselves are hydrophilic, but chemical
treatment can make them hydrophobic. If they absorb moisture they
usually suffer a structural change, such as contraction, and
deteriorate, but degradation can be prevented by making them
hydrophobic. Aerogels with hydrophobic interiors are less
susceptible to degradation than aerogels with only an outer
hydrophobic layer, even if a crack penetrates the surface.
Hydrophobic treatment facilitates processing because it allows the
use of a water jet cutter.
[0061] Aerogel can be used as drug delivery system due to its
biocompatibility. Due to its high surface area and porous
structure, drugs can be adsorbed from supercritical CO2. The
release rate of the drugs can be tailored based on the properties
of aerogel.
Alteration of the Surface Properties of Aerogels:
[0062] By means of functionalization, the surface properties of the
aerogel according to the present invention can be altered;
different functional groups can be used to change the properties of
aerogel from hydrophilic to hydrophobic range. Controlling the
surface coverage of the functional group as well as its type is one
of the goals of this study. In principle, functionalization can be
done by three basic methods: [0063] 1. Functionalization during the
preparation of the gel (sol-gel). [0064] 2. Liquid phase
functionalization (by placing the wet gel in functionalization
solution). [0065] 3. Gas phase functionalization (by placing the
aerogel in a gas stream of functionalization solution).
[0066] By optimizing the working conditions of each method, it is
possible to control the functionalization degree of the desired
functional group on the aerogel surface, and as a result the
loading as well as the release time of the active drug can be
tailored.
[0067] The hydrophobicity of the aerogel can in one preferred
embodiment be adjusted by use of monomers containing alkyl groups
on some silicium compositions.
Bioactive Agents Encapsulated by Aerogels:
[0068] The present invention relates to encapsulation of one or
more bioactive agents into an aerogel. The one or more bioactive
agents can be, but is not limited to, the group consisting of
proteins, peptides, enzymes, proteases, small organic or inorganic
molecules, polysaccharides, pharmaceutical compositions or any
combination thereof.
[0069] In one preferred embodiment one or more enzyme(s) are
encapsulated into one or more aerogel(s). In one embodiment
encapsulation of one or more enzymes into one or more aerogels
results in stability of the enzyme--such as unaltered activity over
time. In another embodiment the activity of the enzyme is increased
by encapsulation into the one or more aerogel(s).
[0070] In one embodiment one or more protease(s) are encapsulated
in the aerogel. Proteases are in general difficult to store in
solution because they digest each other. When proteases on the
other hand are encapsulated in an aerogel they are not in contact
with each other.
[0071] The present invention also relates to encapsulation of one
or more subtilisins in the aerogel. Subtilisins comprises a family
of serine proteases isolated from bacillus subtilis.
[0072] In another preferred embodiment the present invention
relates to encapsulation of one or more hydrolytic enzymes. These
hydrolytic enzymes comprises in one preferred embodiment hydrolytic
enzymes that degrades polysaccharides and/or lipids. In yet another
embodiment the aerogel encapsulates one or more oxidase(s). These
oxidases can in one embodiment result in production of
hydrogenperoxide. The present invention also relates to
incorporation of a combination of starch and/or amylase and one or
more oxidase(s) for generation of hydrogenperoxide.
[0073] In another embodiment the one or more enzymes are
functionalized so it is actively incorporated into the
three-dimensional structure of the aerogel. This leads to covalent
attachment of the enzyme to the three-dimensional structure of the
aerogel.
[0074] In one preferred embodiment a mixture of more than one
enzyme is encapsulated into the aerogel. In another embodiment one
or more enzymes and one or more other bioactive agent(s) are
encapsulated into the same aerogel. In yet another embodiment more
than one bioactive agent(s) are encapsulated into the same aerogel.
In one preferred embodiment an enzyme and its substrate are
encapsulated into the same aerogel.
[0075] In one preferred embodiment one or more bioactive agent(s)
are encapsulated into an aerogel in a way so the one or more
bioactive agent(s) are located in individual compartments in the
aerogel.
[0076] In one embodiment the one or more enzymes can be selected
from the group consisting of hemicellulolytically active enzymes,
amylolytically active enzyme and/or cellulolytically active
enzyme.
[0077] In another preferred embodiment the one or more bioactive
agent(s) comprises endopeptidases.
[0078] In one embodiment the endopeptidase(s) comprises a
Subtilisin (EC 3.4.21.62). The Subtilisin (EC 3.4.21.62) has the
following characteristics: (i) optimum activity at a pH in the
range of about 7-10, and (ii) optimum activity at a temperature in
the range of about 55-65.degree. C. The Subtilisin (EC 3.4.21.62)
is in one embodiment Alcalase.RTM..
[0079] In one embodiment the hemicellulolytically active enzyme(s)
is selected from the group consisting of Endo-1,4-beta-xylanase
(E.C. 3.2.1.8), Xylan endo-1,3-beta-xylosidase (E.C. 3.2.1.32).
Glucuronoarabinoxylan endo-1,4-beta-xylanase (E.C. 3.2.1.136),
Beta-mannosidase (E.C. 3.2.1.25), Mannan endo-1,4-beta-mannosidase
(E.C. 3.2.1.78) and Mannan endo-1,6-beta-mannosidase (E.C.
3.2.1.101). In another preferred embodiment the
hemicellulolytically active enzyme is a xylanase. In one embodiment
the xylanase is an endo-1,4-beta-xylanase (E.C. 3.2.1.8).
[0080] The amylolytically active enzyme(s) can in one preferred
embodiment be an amylase. In another embodiment the one or more
amylolytically active enzyme(s) is selected from the group
consisting of .alpha.- and .beta.-amylases, amyloglucosidases (E.C.
3.2.1.3), pullulanases, .alpha.-1,6-endoglucanases,
.alpha.-1,4-exoglucanases and isoamylases. The one or more
amylolytically active enzyme(s) can also be amyloglucosidase. In
one preferred embodiment the amyloglucosidase is an
1,4-alpha-glucosidase.
[0081] In one embodiment the anti-fouling composition agent
comprises one or more aerogel(s) and at least one xylanase and at
least one amyloglucosidase.
[0082] In another embodiment the anti-fouling composition agent
comprises one or more aerogel(s) and at least one
endo-1,4-beta-xylanase (E.C. 3.2.1.8) and at least one
1,4-alpha-glucosidase (E.C. 3.2.1.3).
[0083] In one embodiment The anti-fouling composition comprising
one or more aerogel(s) and from about 0.1-10% of bioactive agent(s)
by weight. In another preferred embodiment the anti-fouling
composition comprising one or more aerogel(s) and from about 0.2-5%
of bioactive agent(s) by weight. In yet another preferred
embodiment the anti-fouling composition comprising one or more
aerogel(s) and from about 0.5-1% of bioactive agent(s) by
weight.
[0084] One or more bioactive agents can be encapsulated into the
one or more aerogels. When two bioactive agents are encapsulated
the present invention relates in one embodiment to the combinations
illustrated in table 1 and 2.
TABLE-US-00001 TABLE 1 combination of bioactive agents for
encapsulation into one or more aerogels. Small organic Small
inorganic Pharmaceutical Proteins Peptides Enzymes Proteases
molecules molecules Polysaccharides compositions Proteins X X X X X
X X X Peptides X X X X X X X X Enzymes X X X X X X X X Proteases X
X X X X X X X Small organic X X X X X X X X molecules Small
inorganic X X X X X X X X molecules Polysaccharides X X X X X X X X
Pharmaceutical X X X X X X X X compositions
TABLE-US-00002 TABLE 2 combination of bioactive agents for
encapsulation into one or more aerogels. Hydrolytic
Hemicellulytically Amylolytically Cellulytically Oxidases
Endopeptidases Proteases Subtilisins enzymes active enzymes active
enzymes active enzymes Oxidases X X X X X X X X Endopeptidases X X
X X X X X X Proteases X X X X X X X X Subtilisins X X X X X X X X
Hydrolytic X X X X X X X X enzymes Hemicellulytically X X X X X X X
X active enzymes Amylolytically X X X X X X X X active enzymes
Cellulytically X X X X X X X X active enzymes
[0085] In one embodiment two bioactive agents of the same type can
be combined.
Antifouling Species Generated by Oxidase Enzymes
[0086] The composition according to the present invention
preferably comprises at least one enzyme. In one embodiment the
enzyme is an oxidase capable of acting on a compound, such as a
substrate for said oxidase, wherein said action results in the
formation of an antifouling species including an antimicrobial
species comprising an antimicrobial activity, and wherein said
compound does not form part of said coating composition.
[0087] In a more preferred embodiment the enzyme is an oxidase the
activity of which results in the formation of a peroxide.
[0088] The oxidase can be present in said coating composition in
combination with one or more additional enzymes including, but not
limited to, an esterase, including a lipase, an amidase, including
a protease, and a polysaccharide degrading enzyme, wherein said one
or more additional enzyme(s), alone or in any combination, can be
included in the presence or absence of one or more substrates for
one or more of said enzymes.
[0089] The antifouling species comprising an antifouling activity
is preferably generated when the at least one enzyme acts on a
compound, or a precursor thereof including a polymer, capable of
being secreted by a microbial organism. The compound can be a
degradation product of a precursor compound, including a polymer
secreted by and/or located on the surface of microbial organisms,
wherein said degradation product is provided by a precursor enzyme
acting on said precursor compound.
[0090] Further Antifouling Species and Enzymes Resulting in their
Production
[0091] The species of the invention having antifoulant or
antimicrobial activity can be any species capable of being produced
e.g. as the result of an enzyme-substrate reaction. As such, there
can be mentioned many species having antifouling activity, species
having antibacterial/antifungal activity, species having biocidal
activity, and species having biorepellent activity.
[0092] In one preferred embodiment the one or more aerogel(s)
comprises one or more enzymes and one or more biocides.
[0093] The species having antimicrobial activity is thus produced
by an enzymatic reaction between an enzyme and a substrate in the
form of a compound which is preferably secreted by a microbial
organism. Species having antimicrobial activity can be any species
obtained as the direct result of enzymatic reaction between the
enzyme and the compound, as well as any species formed from the
product of such enzymatic reaction through further enzymatic and/or
chemical reaction.
[0094] The compounds are not limited to microbial secretion
products. The compounds of the invention can be any non-toxic
compound supplied to a predetermined environment, such as a dock
harbouring a ship hull, and capable of being converted into an
antifouling species, including an antimicrobial species by the
action of the at least one enzyme, including an oxidase.
[0095] Furthermore, it is also envisaged that antifouling species,
including an antimicrobial species can be generated by a
combination of i) enzymatic action on secreted microbial products,
including polymers and degradation products thereof, and ii)
enzymatic action on exogenously added compounds or precursor
compounds, wherein said combination of enzymatic actions results in
the formation of one or more antifouling species, including an
antimicrobial species having an antimicrobial activity.
[0096] In accordance with the invention, the at least one enzyme,
preferably an oxidase the activity of which results in the
production of peroxide, including hydrogenperoxide, is comprised in
the coating composition according to the invention in an effective
amount to reduce or prevent fouling of a surface coated with the
composition. In the present context the term "an effective amount"
means an amount which is sufficient to control or eliminate or
reduce or at least substantially reduce the settling of microbial
organisms, plants and/or animals, including aquatic organisms such
as bacteria, protozoa, algae and invertebrates, on a surface coated
with the composition according to invention.
[0097] In order to test the amount of the at least one enzyme
required in order to sufficiently reduce or prevent fouling, any
type of standard or modified antifouling bioassay can be applied,
including settlement assays as described by Willemsen (1994). In
one presently preferred embodiment, the amount of the enzyme is in
the range of from about 0.1 to preferably less than 10% (w/w)
coating composition (dry weight), such as from about 0.1 to less
than 9% (w/w), for example from about 0.1 to less than 8% (w/w),
such as from about 0.1 to less than 7% (w/w), for example from
about 0.1 to less than 6% (w/w), such as from about 0.1 to less
than 5.5% (w/w), for example from about 0.1 to less than 5.0%
(w/w), such as from about 0.1 to less than 4.5% (w/w), for example
from about 0.1 to less than 4.0% (w/w), such as from about 0.1 to
less than 3.5% (w/w), for example from about 0.1 to less than 3.0%
(w/w), such as from about 0.1 to less than 2.5% (w/w), for example
from about 0.1 to less than about 2.0% (w/w), such as from about
0.1 to less than about 1.5% (w/w), for example from about 0.1 to
less than about 1.0% (w/w), such as from about 0.1 to less than
about 0.5% (w/w).
[0098] In another embodiment the amount of the enzyme is present in
the coating composition in the range of from about 0.2% (w/w) to
about 0.4% (w/w) coating composition (dry weight), such as from
about 0.4% (w/w) to about 0.6% (w/w), for example from about 0.6%
(w/w) to about 0.8% (w/w) coating composition, such as from about
0.8% (w/w) to about 1.0% (w/w), for example from about 1.0% (w/w)
to about 1.2% (w/w) coating composition, such as from about 1.2%
(w/w) to about 1.4% (w/w), for example from about 1.4% (w/w) to
about 1.6% (w/w) coating composition, such as from about 1.6% (w/w)
to about 1.8% (w/w), for example from about 1.8% (w/w) to about
2.0% (w/w) coating composition, such as from about 2.0% (w/w) to
about 2.5% (w/w), for example from about 2.5% (w/w) to about 3.0%
(w/w) coating composition, such as from about 3.0% (w/w) to about
3.5% (w/w), for example from about 3.5% (w/w) to about 4.0% (w/w)
coating composition, such as from about 4.0% (w/w) to about 4.5%
(w/w), for example from about 4.5% (w/w) to about 5.0% (w/w)
coating composition.
[0099] In a preferred embodiment the at least one enzyme is an
oxidase the activity of which results in the formation of a
peroxide, including hydrogen peroxide. The amount of hydrogen
peroxide generated in accordance with the present invention depends
on the amount of available compound on which the at least one
oxidase can act. It will be possible to determine the amount of
hydrogen peroxide generated by using the method of Janssen and
Ruelius disclosed in Biochem. Biophys. Acta (1968), vol. 151, pages
330-342.
[0100] The amount of hydrogen peroxide generated is in preferred
embodiments about or at least about 1 nmol/cm.sup.2/day, such as 2
nmol/cm.sup.2/day, for example 3 nmol/cm.sup.2/day, such as 4
nmol/cm.sup.2/day, for example 5 nmol/cm.sup.2/day, such as 2
nmol/cm.sup.2/day, for example 3 nmol/cm.sup.2/day, such as 4
nmol/cm.sup.2/day, for example 5 nmol/cm.sup.2/day, such as 6
nmol/cm.sup.2/day, for example 7 nmol/cm.sup.2/day, such as 8
nmol/cm.sup.2/day, for example 9 nmol/cm.sup.2/day, such as 10
nmol/cm.sup.2/day, for example 12 nmol/cm.sup.2/day, such as 14
nmol/cm.sup.2/day, for example 16 nmol/cm.sup.2/day, such as 18
nmol/cm.sup.2/day, for example 20 nmol/cm.sup.2/day, such as 22
nmol/cm.sup.2/day, for example 24 nmol/cm.sup.2/day, such as 26
nmol/cm.sup.2/day, for example 28 nmol/cm.sup.2/day, such as 30
nmol/cm.sup.2/day, for example 32 nmol/cm.sup.2/day, such as 34
nmol/cm.sup.2/day, for example 36 nmol/cm.sup.2/day, such as 38
nmol/cm.sup.2/day, for example 40 nmol/cm.sup.2/day, such as 42
nmol/cm.sup.2/day, for example 44 nmol/cm.sup.2/day, such as 46
nmol/cm.sup.2/day, for example 48 nmol/cm.sup.2/day, such as 50
nmol/cm.sup.2/day, for example 55 nmol/cm.sup.2/day, such as 60
nmol/cm.sup.2/day, for example 65 nmol/cm.sup.2/day, such as 70
nmol/cm.sup.2/day, for example 75 nmol/cm.sup.2/day, such as 80
nmol/cm.sup.2/day, for example 85 nmol/cm.sup.2/day, such as 90
nmol/cm.sup.2/day, for example 95 nmol/cm.sup.2/day, such as 100
nmol/cm.sup.2/day, for example 110 nmol/cm.sup.2/day, such as 120
nmol/cm.sup.2/day, for example 130 nmol/cm.sup.2/day, such as 140
nmol/cm.sup.2/day, for example 150 nmol/cm.sup.2/day, such as 160
nmol/cm.sup.2/day, for example 170 nmol/cm.sup.2/day, such as 180
nmol/cm.sup.2/day, for example 190 nmol/cm.sup.2/day, such as 200
nmol/cm.sup.2/day, for example 220 nmol/cm.sup.2/day, such as 240
nmol/cm.sup.2/day, for example 260 nmol/cm.sup.2/day, such as 280
nmol/cm.sup.2/day, for example 300 nmol/cm.sup.2/day, such as 320
nmol/cm.sup.2/day, for example 340 nmol/cm.sup.2/day, such as 360
nmol/cm.sup.2/day, for example 380 nmol/cm.sup.2/day, such as 400
nmol/cm.sup.2/day, for example 420 nmol/cm.sup.2/day, such as 440
nmol/cm.sup.2/day, for example 460 nmol/cm.sup.2/day, such as 480
nmol/cm.sup.2/day, for example 500 nmol/cm.sup.2/day, such as 520
nmol/cm.sup.2/day, for example 540 nmol/cm.sup.2/day, such as 560
nmol/cm.sup.2/day, for example 580 nmol/cm.sup.2/day, such as 600
nmol/cm.sup.2/day, for example 620 nmol/cm.sup.2/day, such as 640
nmol/cm.sup.2/day, for example 660 nmol/cm.sup.2/day, such as 680
nmol/cm.sup.2/day, for example 700 nmol/cm.sup.2/day, such as 720
nmol/cm.sup.2/day, for example 740 nmol/cm.sup.2/day, such as 760
nmol/cm.sup.2/day, for example 780 nmol/cm.sup.2/day, such as 800
nmol/cm.sup.2/day, for example 820 nmol/cm.sup.2/day, such as 840
nmol/cm.sup.2/day, for example 860 nmol/cm.sup.2/day, such as 880
nmol/cm.sup.2/day, for example 900 nmol/cm.sup.2/day, such as 920
nmol/cm.sup.2/day, for example 940 nmol/cm.sup.2/day, such as 960
nmol/cm.sup.2/day, for example 980 nmol/cm.sup.2/day, such as 1000
nmol/cm.sup.2/day.
[0101] Preferred oxidases include, but is not limited to, malate
oxidase; glucose oxidase; hexose oxidase; cholesterol oxidase;
arylalcohol oxidase: galactose oxidase; alcohol oxidase;
lathosterol oxidase; aspartate oxidase; L-amino-acid oxidase;
D-amino-acid oxidase; amine oxidase; D-glutamate oxidase;
ethanolamine oxidase; NADH oxidase; urate oxidase (uricase);
superoxide dismutase; and the like.
[0102] In one preferred embodiment the at least one enzyme is a
hexose oxidase, including, but not limited to any oxidoreductase of
class EC 1.1.3.5. Hexose oxidases are enzymes which in the presence
of oxygen is capable of oxidising D-glucose and several other
reducing sugars including maltose, lactose and cellobiose to their
corresponding lactones with subsequent hydrolysis to the respective
aldobionic acids. Hexose oxidase differs from another
oxidoreductase, glucose oxidase, which can only convert D-glucose,
in that the enzyme can utilise a broader range of sugar
substrates.
[0103] Hexose oxidase is produced naturally by several marine algal
species. Such species are found inter alia in the family
Gigartinaceae. In one preferred embodiment the hexose oxidase is
obtained from the marine algae Chondrus cripus. Reference is made
to EP 0 832 245. WO 96/40935 and WO 98/13478 also disclose the
cloning and expression in recombinant host organisms of a gene
encoding a protein with HOX activity.
[0104] In another preferred embodiment the compound and the enzyme,
respectively, is selected from glucose/hexose oxidase;
glucose/glucose oxidase; L amino acid/L amino acid oxidase;
galactose/galactose oxidase; lactose/beta-galacto sidase/hexose
oxidase; 2-deoxyglucose/glucose oxidase; pyranose/pyranose oxidase;
and mixtures thereof.
Precursor Enzymes
[0105] The antifouling species, including an antimicrobial species
can be generated directly by the action of the at least one enzyme,
optionally in combination with an initial action of one or more
precursor enzymes. In the latter case, the precursor enzyme(s) and
the precursor compound(s) are selected such that the precursor
enzyme(s) eventually generates the compound.
[0106] An example of a precursor enzyme is any polysaccharide
digesting enzyme, including amyloglucosidase, and an example of a
precursor compound is any polysaccharide.
[0107] Thus in one embodiment the coating composition can comprise
at least one oxidase such as e.g. hexose oxidase and at least one
amylolytically active enzyme, such as e.g. an amyloglucosidase,
and/or at least one hemicellulolytically active enzyme, such as
e.g. a xylanase, and/or at least one cellulolytically active
enzyme, such as e.g. a cellulase, including any combination of an
oxidase with the aforementioned polysaccharide degrading enzymes,
such as an oxidase and an amylolytically active enzyme, an oxidase
and a hemicellulolytically active enzyme, an oxidase and a
cellulolytically active enzyme, an oxidase and an amylolytically
active enzyme and a hemicellulolytically active enzyme, such as an
oxidase and an amylolytically active enzyme and a cellulolytically
active enzyme, and an oxidase and a hemicellulolytically active
enzyme and an cellulolytically active enzyme.
[0108] A number of other enzymes, as alternatives to an oxidase, or
in addition to oxidases, can be employed in accordance with the
present invention, either alone or in any combination, including a
combination wherein the at least one oxidase is also present.
Esterases and Lipases
[0109] Esterases and lipases are triacylglycerol hydrolysing
enzymes capable of splitting of fatty acids having short, medium
and long chain lengths. Esterases and lipases degrade cell wall
lipids and other lipid associated macromolecules at the surface of
microbial organisms.
[0110] Accordingly, in one embodiment the at least one enzyme is an
esterase and the compound is an ester bond-containing species.
Examples of esterases include, but is not limited to,
carboxylesterase, arylesterase, acetylesterase, and the like.
[0111] In yet another embodiment the at least one enzyme/precursor
enzyme is a lipase such as, but not limited to, triacylglycerol
lipase, lipoprotein lipase, and the like.
Proteases
[0112] Proteinaceous materials involved in fouling the surfaces are
subject to disruption by proteases. Families of proteolytic enzymes
are well known, as reviewed in Neurath, Science 224, 350-357, 1984.
Candidates for use in non-toxic anti-fouling coating compositions
can be drawn from these families, trypsin and subtilisn being an
example of serine proteases of type I and II, papain being an
example of a sulfhydryl protease, pepsin being an example of an
acid protease, carboxypeptidase A and B and thermolysin being
examples of metalloproteases of type I and II. Other protease
families of relevance are the aminopeptidases, the collagenases and
the calcium and ATP-activated proteases, each with numerous
examples.
[0113] Accordingly, in a still further embodiment the at least one
enzyme/precursor enzyme is a protease such as, but not limited to,
subtilisins, chymotrypsins, trypsins, elastases, cathepsins,
papains, chromopapains, pepsins, carboxypeptidase A,
carboxypeptidase B, thermolysins, calcium activated proteases,
ATP-activated proteases, exopeptidases such as aminopeptidases and
carboxypeptidases, endopeptidases, and the like.
[0114] One class of preferred enzymes are the subtilisins.
Subtilisins are serine endopeptidases. Examples include subtilisin
BPN' (also known as subtilisin B, subtilopeptidase B,
subtilopeptidase C, Nagarse, Nagarse proteinase, subtilisin Novo,
bacterial proteinase Novo) and subtilisin Carlsberg (subtilisin A,
subtilopeptidase A, alcalase Novo). Now grouped under IUBMB enzyme
nomenclature EC 3.4.21.62, formerly EC 3.4.4.16 and included in EC
3.4.21.14. Subtilisin enzymes are produced by various Bacillus
subtilis strains and other Bacillus species.
[0115] Further examples of subtilisins include, but is not limited
to, e.g. alcalase; alcalase 0.6 L; alcalase 2.5 L; ALK-enzyme;
bacillopeptidase A; bacillopeptidase B; Bacillus subtilis alkaline
proteinase bioprase; bioprase AL 15; bioprase APL 30; colistinase;
(see also comments); subtilisin J; subtilisin S41; subtilisin
Sendai; subtilisin GX; subtilisin E; subtilisin BL; genenase I;
esperase; maxatase; alcalase; thermoase PC 10; protease XXVII;
thermoase; superase; subtilisin DY; subtilopeptidase; SP 266;
savinase 8.0 L; savinase 4.0T; kazusase; protease VIII; opticlean;
Bacillus subtilis alkaline proteinase; protein A 3 L; savinase;
savinase 16.0 L; savinase 32.0 L EX; orientase 10B; protease S.
[0116] Accordingly, one particularly preferred protease is
endopeptidases of the subtilisin type (EC 3.4.21.62). Subtilisin
type proteases can be applied in the form of a commercially
available enzyme preparations such as Alcalase.RTM.. Alcalase.RTM.
is a serine-type protease characterised by a good performance at
elevated temperatures and moderate alkalinity. In a presently
preferred embodiment the enzyme preparation Alcalase 2.5 L, Type
DX.RTM. is applied. However it is also contemplated that other
Alcalase.RTM. products, including Alcalase 2.0 T.RTM., Alcalase 3.0
T.RTM. and Alcalase 2.5 L, Type DX.RTM., can be applied in
accordance with the present invention. Such Alcalase.RTM. enzyme
preparations are available from Novozymes (Novozymes, Novo Alle,
2880 Bagsvaerd, Denmark).
[0117] However, it is also within the scope of the invention that
other proteases having essentially the same characteristics as the
protease of Alcalase.RTM. can be successfully applied in accordance
with the invention. Thus, it is contemplated that other proteases,
such as subtilisins, having essentially the same temperature and pH
profiles as the Alcalase, can be utilised. The temperature and pH
profiles of the Alcalase can be found on the product sheet from
Novozyme A/S (B259f-GB).
[0118] Accordingly, it is within the scope of the invention that a
subtilisin type protease (EC 3.4.21.62) having the following
characteristics: (i) optimum activity at a pH in the range of about
7 to 10, such as from more than 7.5 to about 10; and (ii) optimum
activity at a temperature in the range of from about or more than
55 to about 65.degree. C., may advantageously be applied.
Polysaccharide Degrading Enzymes
[0119] Enzymes/precursor enzymes capable of degrading
polysaccharides are generally desirable in combination with an
oxidase the activity of which results in the production of
peroxide. The reason is that polysaccharide digesting enzymes can
break down a polysaccharide component of a microbial adhesive
structure and/or degrade important structural polysaccharides of
microorganisms into building blocks of preferably mono- and/or
disaccharides. Such compounds and precursors thereof are substrates
for oxidases and their formation thus enhances the subsequent
production of peroxides. Additionally, the polysaccharide digesting
enzymes of the present invention can prevent or interfere with the
attachment process or the subsequent growth, metamorphosis or
replication of the fouling organisms in question.
[0120] Accordingly, in a still further embodiment the at least one
enzyme/precursor enzyme is a polysaccharide digesting enzyme, such
as, but not limited to, alpha-amylase, beta-amylase,
beta-glucosidase, glucosidase, glycosidase, cellulase, pectinase,
hyaluonidase, beta-glucuronidase.
[0121] The enzymes beta-amylase, beta-glucosidase, and glycosidase
all belong to the group of enzymes that can degrade
polysaccharides. Pectinase and cellulase are enzymes which break
down pectin and cellulose, respectively, two ubiquitous structural
polymers of the plant cell wall and cell wall connective tissue
matrix. Lysozyme and achromopeptidase can also break cell walls,
the latter having an exceptional range of activity against
microorganisms. Hyaluronic acid and collagen have analogous
structural roles in animals and are degraded by hyaluronidase and
collagenase, respectively. Beta-Glucuronidase will also break down
hyaluronic acid.
[0122] Additionally preferred polysaccharide degrading enzymes are
"hemicellulolytically active" enzymes, "cellulolytically active"
enzymes, and "amylolytically active" enzymes. The first group
belong enzymes such as xylanases, which have the capability to
degrade at least one substance belonging to the group of compounds
and precursor compounds generally referred to as hemicellulose,
including xylans and mannans, such as Endo-1,4-beta-xylanase (E.C.
3.2.1.8), Xylan endo-1,3-beta-xylosidase (E.C. 3.2.1.32),
Glucuronoarabinoxylan endo-1,4-beta-xylanase (E.C. 3.2.1.136),
Beta-mannosidase (E.C. 3.2.1.25), Mannan endo-1,4-beta-mannosidase
(E.C. 3.2.1.78) and Mannan endo-1,6-beta-mannosidase (E.C.
3.2.1.101).
[0123] Enzymes having "cellulolytic activity" are also generally
referred to as cellulases and is used herein to designate any
cellulose hydrolysing enzyme.
[0124] "Amylolytically active" enzymes includes, in the present
context, amylases, such as .alpha.-amylases and .beta.-amylases,
amyloglucosidases, pullulanases, .alpha.-1,6-endoglucanases,
.alpha.-1,4-exoglucanases and isoamylases.
[0125] The above-mentioned enzymes occur in preferred embodiments
in combination with at least one oxidase. Accordingly, when the
coating composition e.g. comprises an aerogel which comprises an
oxidase capable of acting on a compound, wherein said action
results in the formation of an antimicrobial species, the aerogel
and/or coating composition can in further embodiments comprise one
or more of
[0126] at least one esterase from the above group, optionally in
the absence of a substrate for said esterase, and/or
[0127] at least one lipase from the above group, optionally in the
absence of a substrate for said lipase, and/or
[0128] at least one protease from the above group, optionally in
the absence of a substrate for said protease, and/or
[0129] at least one polysaccharide degrading enzyme from the above
group, optionally in the absence of a substrate for said
enzyme.
[0130] Preferred combinations of the above enzymes in combination
with the at least one oxidase include
[0131] a coating composition comprising at least one oxidase in the
absence of a substrate for said oxidase and at least one hydrolytic
enzyme, optionally in the absence of a substrate for such a
hydrolytic enzyme,
[0132] a coating composition comprising at least one oxidase in the
absence of a substrate for said oxidase and at least one
esterase,
[0133] a coating composition comprising at least one oxidase in the
absence of a substrate for said oxidase and at least one
lipase,
[0134] a coating composition comprising at least one oxidase in the
absence of a substrate for said oxidase and at least one
protease,
[0135] a coating composition comprising at least one oxidase in the
absence of a substrate for said oxidase and at least one
polysaccharide digesting enzyme,
[0136] a coating composition comprising at least one oxidase in the
absence of a substrate for said oxidase and at least one esterase
and at least one lipase,
[0137] a coating composition comprising at least one oxidase in the
absence of a substrate for said oxidase and at least one esterase
and at least one protease,
[0138] a coating composition comprising at least one oxidase in the
absence of a substrate for said oxidase and at least one esterase
and at least one polysaccharide digesting enzyme,
[0139] a coating composition comprising at least one oxidase in the
absence of a substrate for said oxidase and at least one esterase
and at least one lipase and at least one protease,
[0140] a coating composition comprising at least one oxidase in the
absence of a substrate for said oxidase and at least one esterase
and at least one lipase and at least one polysaccharide digesting
enzyme,
[0141] a coating composition comprising at least one oxidase in the
absence of a substrate for said oxidase and at least one esterase
and at least one lipase and at least one protease and at least one
polysaccharide digesting enzyme,
[0142] a coating composition comprising at least one oxidase in the
absence of a substrate for said oxidase and at least one lipase and
at least one protease,
[0143] a coating composition comprising at least one oxidase in the
absence of a substrate for said oxidase and at least one lipase and
at least one protease and at least one polysaccharide digesting
enzyme, and
[0144] a coating composition comprising at least one oxidase in the
absence of a substrate for said oxidase and at least one protease
and at least one polysaccharide digesting enzyme.
[0145] Accordingly, it will be understood that the substrate for
the one or more enzymes can be present or not present in the
coating composition and/or the aerogel.
[0146] In various embodiments, the above coating compositions
comprising an aerogel do not comprise a substrate for the one or
more enzyme(s) and/or the one or more precursor enzyme(s) employed.
Accordingly, there are provided embodiments wherein any one of the
above-mentioned coating compositions i) does not comprise any
substrate for the at least one esterase, when an esterase is
present, ii) does not comprise any substrate for the at least one
lipase, when a lipase is present, iii) does not comprise any
substrate for the at least one protease, when a protease is
present, and iv) does not comprise any substrate for the at least
one polysaccharide digesting enzyme, when a polysaccharide
digesting enzyme is present, v) does not comprise the substrate for
the precursor enzyme.
[0147] In further embodiments the above coating compositions
according to the invention i) do not comprise a substrate for an
esterase and a lipase, when at least an esterase and a lipase are
present, optionally in combination with further enzymes ii) do not
comprise a substrate for an esterase and a protease, when at least
an esterase and a protease are present, optionally in combination
with further enzymes, iii) do not comprise a substrate for an
esterase and a polysaccharide digesting enzyme, when at least an
esterase and a polysaccharide digesting enzyme are present,
optionally in combination with further enzymes, iv) do not comprise
a substrate for an lipase and a protease, when at least a lipase
and a protease are present, optionally in combination with further
enzymes, v) do not comprise a substrate for a lipase and a
polysaccharide digesting enzyme, when at least a lipase and a
polysaccharide digesting enzyme are present, optionally in
combination with further enzymes, and vi) do not comprise a
substrate for a protease and a polysaccharide digesting enzyme,
when at least a protease and a polysaccharide digesting enzyme are
present, optionally in combination with further enzymes.
[0148] In the present invention, the at least one enzyme comprised
in the coating composition can be any one or more of a purified
enzyme or a crude enzyme. The source of the enzyme includes
microorganisms, plants, and animals. When incorporating an enzyme
into the coating composition, the enzyme may be directly
incorporated or it can be used after modification with another
species, or in the form of an immobilized enzyme. Immobilization
includes enzymes entrapped in reverse micelles; enzymes modified
with lipids or surfactants; enzymes modified with polyethylene
glycol; and enzymes immobilized on polymer matrices, among other
forms.
Rosins
[0149] It is in one embodiment preferred to include into a coating
composition of the invention at least one rosin. Rosins are solid
materials that e.g. occur naturally in the oleo rosin of pine trees
and is typically derived from the oleo resinous exudate of the
living tree, from aged stumps and from tall oil produced as a
by-product of kraft paper manufacture.
[0150] Rosin compounds have a number of highly desirable properties
for use as binders in antifouling paints such as e.g. being fairly
non-toxic to humans, being compatible with a large number of other
binders and being relatively inexpensive and readily available from
natural resources.
[0151] Thus, rosins are used in paints as binders, and thereby
provide a rather non-toxic alternative to synthetic and more toxic
binders such as e.g. polymeric binder components as epoxy,
polyvinylacetate, polyvinylbutyrate and polyvinylchloride
acetate.
[0152] Rosin is typically classed as gum rosin, wood rosin, or as
tall oil rosin which indicates its source. The rosin materials can
be used unmodified, in the form of esters of polyhydric alcohols,
in the form of rosins polymerised through the inherent unsaturation
of the molecules or in the form of hydrogenated rosin. Thus, rosin
can be further treated by e.g. hydrogenation, dehydrogenation,
polymerisation, esterification, and other post treatment processes.
Additionally, rosin with e.g. free carboxylic acid groups are
capable of reacting with metals and thereby forming rosin metal
salts.
[0153] Accordingly, the rosin compound of the antifouling paint
composition of the present invention is at least one selected from
rosins, rosin derivatives, and rosin metal salts. Examples of
rosins include tall rosin, gum rosin, and wood rosin. Examples of
rosin derivatives include hydrogenated rosins, modified rosins
obtained by reacting rosins with maleic anhydride, formylated
rosins, and polymerised rosins. Examples of rosin metal salts
include zinc rosinates, calcium rosinates, copper rosinates,
magnesium rosinates, and products of the reaction of rosins with
compounds of other metals.
[0154] Rosins of natural origin have the beneficial effect that
when used in combination with enzymes, the activity of said enzymes
are not substantially affected by the rosins as compared to enzymes
in paint compositions prepared with synthetic binders of
non-natural origin. Accordingly, it was found that no enzyme
activity was present in paint compositions comprising protease and
synthetic binders of non-natural origin.
[0155] The rosins are furthermore believed to have an immobilising
effect on the enzymes and thus preventing the enzymes from being
released from the paint composition into the environment.
[0156] The composition according to invention comprises a rosin
compound wherein the content of the rosin compound is in the range
of from about 5 to about 60% by weight. It is preferred that the
amount of rosin compound is higher than about 10% such as up to
about 20% by weight. However, it is also contemplated that the
amount of rosin compound in the composition can be up to about 30%,
such as up to about 40%, up to about 50% and up to about 55%. Thus,
a pigmented composition according to the invention could
advantageously comprise an amount of rosin compound in the range of
about 10-30% by weight, and a lacquer composition could comprise up
to about 60% of rosin compound by weight.
Resins
[0157] As an alternative to rosin compounds, any suitable resin
compound can be employed, such as the resins described below.
[0158] The resin produced by most plants is a viscous liquid,
typically composed mainly of volatile fluid terpenes, with lesser
components of dissolved non-volatile solids which make resin thick
and sticky. The most common terpenes in resin are the bicyclic
terpenes alpha-pinene, beta-pinene, delta-3 carene and sabinene,
the monocyclic terpenes limonene and terpinolene, and smaller
amounts of the tricyclic sesquiterpenes longifolene, caryophyllene
and delta-cadinene. Some resins also contain a high proportion of
resin acids. The individual components of resin can be separated by
fractional distillation
[0159] A few plants produce resins with different compositions,
most notably Jeffrey Pine and Gray Pine, the volatile components of
which are largely pure n-heptane with little or no terpenes. The
exceptional purity of the n-heptane distilled from Jeffrey Pine
resin, unmixed with other isomers of heptane, led to its being used
as the defining zero point on the octane rating scale of petrol
quality. Because heptane is highly flammable, distillation of
resins containing it is very dangerous. Some resin distilleries in
California exploded because they mistook Jeffrey Pine for the
similar but terpene-producing Ponderosa Pine.
[0160] Some resins when soft are known as oleo-resins, and when
containing benzoic acid or cinnamic acid they are called balsams.
Other resinous products in their natural condition are a mix with
gum or mucilaginous substances and known as gum resins. Many
compound resins have distinct and characteristic odors, from their
admixture with essential oils.
[0161] Certain resins are obtained in a fossilized condition, amber
being the most notable instance of this class; African copal and
the kauri gum of New Zealand are also procured in a semi-fossil
condition.
[0162] Solidified resin from which the volatile terpene components
have been removed by distillation is known as rosin. Typical rosin
is a transparent or translucent mass, with a vitreous fracture and
a faintly yellow or brown colour, non-odorous or having only a
slight turpentine odour and taste.
[0163] 1) It is insoluble in water, mostly soluble in alcohol,
essential oils, ether and hot fatty oils, 2) softens and melts
under the influence of heat, is not capable of sublimation, and
burns with a bright but smoky flame.
[0164] This comprises a complex mixture of different substances
including organic acids named the resin acids. These are closely
related to the terpenes, and derive from them through partial
oxidation. Resin acids can be dissolved in alkalis to form resin
soaps, from which the purified resin acids are regenerated by
treatment with acids. Examples of resin acids are abietic acid
(sylvic acid), C.sub.20H.sub.30O.sub.2, plicatic acid contained in
cedar, and pimaric acid, C.sub.20H.sub.35O.sub.2, a constituent of
gallipot resin. Abietic acid can also be extracted from rosin by
means of hot alcohol; it crystallizes in leaflets, and on oxidation
yields trimellitic acid, isophthalic acid and terebic acid. Pimaric
acid closely resembles abietic acid into which it passes when
distilled in a vacuum; it has been supposed to consist of three
isomers.
[0165] Synthetic resins are materials with similar properties to
natural resins--viscous liquids capable of hardening. They are
typically manufactured by esterification or soaping of organic
compounds. The classic variety is epoxy resin, manufactured through
polymerization-poly addition or polycondensation reactions, used as
a thermoset polymer for adhesives and composites. One more
category, which constitutes 75% of resins used, is unsaturated
polyester resin. Ion exchange resin is another important class with
application in water purification and catalysis of organic
reactions. Other examples of resin includes AT-10 Resin and
melamine resin.
Repellents
[0166] In addition to the at least one enzyme capable of producing
an antifouling species, including an antimicrobial species and
means for immobilization thereof, including rosins, as described
above, the coating composition of the invention can also comprise
additional agents useful for preventing fouling, particularly
macrofouling. One such group of agents is termed repellents of the
macrofouling organisms. Repellents belong to a group of
biologically active compounds which repel rather than attract
microbial organisms.
[0167] Repellents according to the invention include molecules that
are customarily associated with some inimicable material formed by
a predator (or other non-compatible organism) of the macrofouling
organism. An example is the material customarily excreted by
starfish that causes such prey organism as scallops to immediately
react to the material and try to escape therefrom. When affixed to
a surface as described herein, the repellent would not freely
diffuse but would act to elicit the escape response when the
organism contacted the surface being protected. An example of this
would be a purified chemical repellent or an impure suspension
containing the active chemical repellent that is obtained by
grinding and partially fractionating a coral or algae preparation.
The repellents of choice are those natural products used by corals,
seaweeds and other aquatic organisms to avoid fouling of their
surfaces.
Surfactants
[0168] In addition to natural products that can act as repellents,
the surface protection can also be brought about by affixing a
surfactant. Some repellents will be surfactants and vice versa, but
as surfactants are generally not regarded as repellents in all
senses of the word, they are considered as a separate class of
bioactive agents having a useful effect in combination with enzymes
and/or repellents of this invention.
[0169] A surfactant can have an inhibitory effect on attachment of
organisms to a surface even when immobilized on or within a coating
composition of the invention. Specific examples of immobilized
surfactants are cationic, anionic and non-ionic surfactants such as
quaternary ammonium ions, dipalmitoyl phosphatidyl choline, aralkyl
sulfonates and sucrose esters, respectively. Other examples are set
forth in the Kirk-Othmer Encyclopedia of Chemical Technology, Vol.
22, pages 332-432, John Wiley & Sons, New York, 1983.
Tannic Acids
[0170] Yet another example of a compound capable of being
incorporated into coating compositions according to the invention
is tannic acid, a representative compound of the tannins, a family
of compounds secreted by certain species of marine brown algae
(e.g. Sargassum), which appear to restrict bacterial colonization
of the frond surface (Sieburth and Conover (1965) Nature 208 52).
This is exemplary of the class of compounds, useful in non-toxic
anti-fouling coatings, that act by interference with enzymatic
reactions necessary for attachment of macro- or micro-organisms.
Candidate compounds in this category include kojic acid and similar
inhibitors of polyphenol oxidase. These inhibitors will interfere
with the cross-linking of cement-forming materials. of similar
value are glucosyl transferase inhibitors which will prevent the
formation of polysaccharide adhesives used in adhesion, mutastein,
ribocitrin, 1-deoxynojirimycin, acarbose, and
N-methyldeoxynojirimycin being exemplary of these.
Function of Encapsulation
[0171] In one preferred embodiment one or more bioactive agent(s)
are encapsulated into an aerogel to stabilize the one or more
bioactive agent(s).
[0172] In one preferred embodiment one or more bioactive agent(s)
are encapsulated into an aerogel to retain or improve the activity
of the one or more bioactive agent(s).
[0173] In one preferred embodiment one or more bioactive agent(s)
are encapsulated into an aerogel to retain or improve the heat
stability of the one or more bioactive agent(s).
Degradation of Aerogels
[0174] Aerogels are degraded over time. Aerogels comprises a
self-polishing effect. The one or more encapsulated bioactive
agents will be exposed to the surface over time. In one embodiment
the one or more encapsulated bioactive agents will be released from
the one or more aerogel(s) by controlled release.
[0175] In one embodiment hydrolysis of the hydrolysable moieties of
the coating composition generates a self-polishing effect. Being
submerged in water the hydrolysable moieties will slowly hydrolyse
at the interface between the coating composition and the water
phase. When sufficient hydrophilic groups have been formed, the
coating composition becomes water-soluble and dissolves leading to
a "self-polishing" effect.
[0176] In one preferred embodiment the self-polishing effect
comprises a true self-polishing effect. In another embodiment the
self-polishing effect comprises a simple self-polishing effect
[0177] The leaching of the one or more encapsulated bioactive
agent(s) is slow or absent when the aerogel is exposed to water or
another liquid over periods of hours. The leaching will be 0 to 2%
per hour at 37.degree. C. calculated based on total encapsulated
protein.
[0178] The leaching of the one or more encapsulated bioactive
agent(s) from the aerogel can be modified by alteration of the
aerogel composition and/or by annealing.
Use of Aerogels for Anti-Fouling:
[0179] In one embodiment the fouling organisms comprises aquatic
organisms selected from the group consisting of bacteria, protozoa,
fungus, algae and invertebrates. In one preferred embodiment the
aquatic organism is selected from barnacles and mussels. In another
embodiment the aquatic organism are of the Cirripedia subclass
including Balanus galeatus, Balanus amphitrite, Elminius modestus,
Balanus improvisus and Balanus balanoides.
[0180] In one preferred embodiment the aerogel which comprises one
or more encapsulated bioactive agents has an anti-fouling effect
and or anti-epibiosis effect. Anti-fouling is the process of
removing or inhibiting the accumulation of biofouling.
[0181] Biofouling or biological fouling is the undesirable
accumulation of microorganisms, plants, algae, and animals on
surfaces such as submerged structures like ships' hulls. Biofouling
also occurs on the surfaces of living marine organisms, when it is
known as epibiosis. Biofouling is also found in membrane systems,
such as membrane bioreactors and reverse osmosis spiral wound
membranes. In the same manner it is found as fouling in cooling
water cycles of large industrial equipments and power stations.
[0182] Biofouling is divided into microfouling--biofilm formation
and bacterial adhesion--and macrofouling--attachment of larger
organisms, of which the main culprits are barnacles, mussels,
polychaete worms, bryozoans, and seaweed. Together, these organisms
form a fouling community.
[0183] Individually small, accumulated biofoulers can form enormous
masses that severely diminish ships' maneuverability and carrying
capacity. Fouling causes huge material and economic costs in
maintenance of marineculture, shipping industries, naval vessels,
and seawater pipelines.
[0184] Biofouling can occur on any surface submerged in water such
as for example on ships. Other examples of surfaces that can be
exposed to biofouling are any installations, membranes, nets,
measuring equipment or other equipment in aquaculture.
[0185] Biofouling can also occur in groundwater wells where buildup
can limit recovery flow rates, and in the exterior and interior of
ocean-laying pipes. In the latter case it has been shown to retard
the seawater flow through the pipe and has to be removed with the
tube cleaning process.
[0186] In one preferred embodiment the surface for application of
the anti-fouling composition is a surface that is at least
occasionally immersed in water, wherein said water includes fresh,
salt or brackish water. The surface can be selected from the group
consisting of the surfaces of vessels including boats and ships,
ship hulls, off-shore equipment, pipes, substructures of bridges,
piers and aquacultural apparatuses including fish farming nets.
[0187] In another preferred embodiment the aerogel which comprises
one or more encapsulated bioactive agents has an anti-bacterial
effect. The aerogel with the anti-bacterial effect can in one
preferred embodiment be employed in food production such as in the
dairy industry. In another embodiment the aerogel with the
anti-bacterial effect can be used in hospitals such as in an
operating room.
Antimicrobial Effects of the Coating Composition
[0188] The coating compositions of the invention are capable of
reducing and/or eliminating fouling in the form of microbial growth
and/or the formation of bio-film on objects coated with the
composition. The microbial organisms can be e.g. bacteria, vira,
fungal cells and slime molds. For aquatic environments, the
microbial organisms are marine organisms.
[0189] In selecting the at least one enzyme of the coating
composition one must take into consideration--among other
things--the type of surface being protected, the environment in
which the surface is found, and the organism against which
protection is being sought.
[0190] The general principle underlying the choice of enzyme to be
immobilized is that the abundance of a particular type of enzyme
should be proportional to the probable frequency of surface contact
with the target organism against which the antifouling species,
including an antimicrobial species generated by the enzyme has
anti-fouling efficacy.
Marine Antifouling Effects
[0191] As an example, a short-term protection against settling
organisms in a marine environment can focus on deterring the
formation of films that are deposited by the settlement and growth
of marine algae and bacteria. In this case, the bioactive materials
to be incorporated on the surface can be distributed equally
between a bactericide and an algaecide.
[0192] Accordingly, the antimicrobial effects of the compositions
according to the invention are directed to--among others--the
following groups of microbial organisms: Bacteria, fungi, algae,
protozoa, porifera, coelenterata, platyhelminthes, nemertea,
rotifera, bryozoa, brachiopoda, annelida, arthropoda, mollusca,
echinodermata and chordata.
[0193] One interesting case is that of preventing growth and/or
attachment to a surface of Vibrio species in an aquatic
environment. Vibrio species often cluster together due to the
presence of an extracellular polysaccharide (slime) that they
synthesize. The best-known species of Vibrio is V. cholerae which
causes cholera, a severe diarrhoeal disease resulting from a toxin
produced by bacterial growth in the gut. Accordingly, the present
invention in one preferred embodiment also relates to preventing
and/or reducing the risk of cholera outbreaks in environments
wherein V. cholerae is present. The method includes the step of
coating pipes, filters, tanks and the like with a composition
according to the invention comprising at least one oxidase and a
polysaccharide degrading enzyme capable of degrading
polysaccharides secreted by Vibrio species including V.
cholerae.
[0194] The development of an antifouling species, including an
antimicrobial species which could eliminate only, for example,
barnacles in an aqueous environment would be solving only part of
the fouling problem. Studies on the temporal development of a
fouling community have revealed that bacteria are usually the first
organisms to colonize a submerged surface. Attached bacteria
produce a secondary extracellular polymeric adhesive, and
eventually the surface of the substratum becomes coated with
bacteria embedded within this extracellular matrix (collectively
referred to as a bacterial film).
[0195] The rate of subsequent colonization by other microorganisms,
and by marine invertebrate larvae, is often dependent upon the
initial formation of a bacterial film. Consequently, the
development of a coating composition capable of reducing and/or
eliminating the process of bacterial film formation can be expected
also to have a significant anti-fouling effect.
[0196] A small number of proteins and carbohydrates constitute the
important structural elements of the cell wall of a wide range of
microbial organisms. Collagen, cellulose, and chitin are three
abundant structural polymers. Chitin, for example, is an important
constituent of the shell matrix of the inarticulate Brachipoda, the
exoskeleton of the Ectoprocta (e.g. Bryozoa), the walls of sponge
gemmules (the dispersal stage of the sponge life cycle), the
perisarc (the outer layer of the integument) of hydrozoan
coelenterates, the cell wall of fungi, and the cuticle of all
arthropods. Additional relevant polysaccharides are mannans,
galactomannans, alginates, laminarins, carregeenans (iota and
kappa), and agars.
[0197] Any enzyme capable of degrading any one or more of the above
polymers, including collagen and/or cellulose and/or chitin can
therefore be included into the coating composition of the
invention, optionally in the absence of a substrate for such an
enzyme, and preferably in combination with an oxidase, in the
absence of a substrate for said oxidase.
[0198] The integument of most fouling organisms is the principal
organ of permanent post-metamorphic attachment and adhesion.
Interference with the synthesis of an important biochemical
constituent of the cell wall or integument, or any degradation of
such structural elements or interference with the enzymatic
processes involved in adhesion would therefore exert a strong
anti-fouling action.
[0199] As the bacterial and algae film production can well be a
prerequisite for most macrofouling, this term refers to the
attachment of organisms larger than unicellular organisms to an
aquatic surface. Should this be the case, little or no enzyme or
other chemical antifoulant capable of disrupting the attachment
process of macrofouling organisms may need to be included as
microfouling does not take place.
[0200] However, in a region that is heavily populated with barnacle
larvae, enzymes which specifically retard the settlement of the
barnacle larva would be more important and should be incorporated
on a surface, preferably in larger proportion.
[0201] The coating compositions according to the invention in one
embodiment result in the formation of essentially one or more
monolayers of enzymes located on the surface of an object. For
example, an enzyme having a molecular weight of approximately
50,000 daltons would give a monolayer when spaced on a surface with
a distance of approximately 40 angstroms between the centers of
adjacent molecules. This spacing assumes a Stokes radius of
approximately 20 angstroms. However, it is not essential that a
complete monolayer is present. A desirable activity can be
maintained with the spacing of bioactive compounds over greater
distances. A spacing of no more than 1,000 angstroms and more
preferably no more than 100 angstroms is preferred in order to
insure that a biologically active chemical is available for
reaction with a fouling organism at each point of initial
contact.
[0202] The coating compositions of the invention can be used in all
types of environments, including non-aquatic as well as aquatic
environments, including sea-water, estuary, and fresh water
environments. In addition to natural environments (i.e., those
which are in free contact with and freely exchange material with
other parts of the biosphere without human intervention), the term
"aquatic environments" as used herein also includes cooling towers,
fresh and salt water piping systems, desalination and other
filtration systems containing membrane "surfaces" subject to
protection, and other aquatic environments which rely upon the
intervention of human beings for their creation and
maintenance.
[0203] As used herein, the term "natural environment" includes
ponds, lakes, dredged channels and harbors, and other bodies of
water which were initially produced by the action of human beings
but which do not rely upon human intervention for the supply of
water into and out of such environments.
[0204] While many fouling organisms, such as barnacles and algae,
are well known to the general public, those skilled in the art will
recognize that the term fouling organism as used herein refers to
any living organism which is capable of attaching to a surface in
an aquatic environment.
[0205] The group of algae are very diverse and probably not related
to one another. There are 6 divisions of algae, some unicellular
and some multicellular. In some taxonomic schemes, the last three
divisions are included in the Kingdom Protista which includes all
eukaryotic, unicellular organisms, regardless of their mode of
nutrition.
[0206] Algae can be characterised with respect to e.g.: [0207] 1.
Photosynthetic pigments. Some pigments mask the chlorophylls and
give their name to the common name of the division--Brown algae.
The accessory pigments participate with the PS II reaction center.
[0208] 2. Food storage chemistry is an important distinguishing
feature. Not all organisms store energy in the form of starch as do
most plants. There are unique storage chemicals for the various
division. [0209] 3. Flagella structure is a good distinguishing
feature for those division that have flagellated cell. The number
of flagella, morphology of the flagellum and its orientation
characterize divisions. [0210] 4. Cell wall chemistry is another
distinguishing feature. [0211] 5. Sometimes the habitat for members
of the division can be important.
[0212] Rhodophyta are the red algae: [0213] 1. Pigments--the
phycobolins, phycoerythrin and phycocyaninare_the pigments that
usually mask the chlorophyll a that is common to all algae and the
green plants. [0214] 2. Food storage materials--Floridean starch is
a polysaccharide material. [0215] 3. Cell wall materials--The red
algae possess a microfibrillar network of polysaccharide material
(cellulose or some other) embedded within a mucilaginous matrix
such as agar. Some marine forms may produce CaCO.sub.3 in their
walls to give them a rigid structure. [0216] 4. Types and number of
flagella--The red algae never produce motile cells. Not only do
they not produce motile cells, it appears that they may never have
had motile cells. [0217] 5. Habitat--The red algae are mostly
marine organisms but a few freshwater types do exist. [0218] 6. The
life cycles of red algae are complicated by the presence of a third
generation type in addition the sporophyte and gametophyte.
[0219] Phaeophyta are the brown algae. This group includes the
kelps and rockweeds: [0220] 1. Pigments--The Brown algae have
fucoxanthin as an accessory pigment to mask the chlorophyll a and
c, giving them the brownish color. [0221] 2. Food storage
materials--Lamanarin is a polysaccharide food storage material
unique to the brown algae. [0222] 3. Cell wall materials include a
mucilaginous material called algin that is harvested from kelps.
[0223] 4. Types and number of flagella--The brown algae have
heterokont flagellated cells. One is an anteriorly-oriented
tinsel-type flagellum and the other flagellum is a
posteriorly-oriented whiplash type. [0224] 5. Habitat--The brown
algae are all marine organisms. [0225] 6. Several life cycle types
are exemplified by the brown algae. [0226] Ectocarpus is a
filamentous alga that has an isomorphic alternation of generations.
[0227] Laminaria is a kelp that has a heteromorphic alternation of
generations. The gametophyte is microscopic, whereas the sporophyte
is macroscopic. [0228] Fucus is a rockweed that has gametic
meiosis. There is no alternation of generations for this organism.
The gametangia, antheridia and oogonia, are produced within a
conceptacle. Many conceptacles are located on a receptical at the
end of the dichotomously branched thallus. Meiosis occurs in the
production of the gametes.
[0229] Chlorophyta are the green algae. Because of the similarity
in pigmentation, cell division, and food storage materials, the
land plants are thought to be derived from the Chlorophyta: [0230]
1. Pigments--Chlorophyll b is the accessory pigment. [0231] 2. Food
storage materials are starch. [0232] 3. Cell wall materials--are
primarily cellulose but some marine forms may add CaCO.sub.3.
[0233] 4. Types and number of flagella of the chlorophyta are
isokonts with whiplash flagella. [0234] 5. Habitat of chlorophyta
is freshwater and marine. [0235] 6. Taxonomy of the chlorophyta is
divided into three classes based on method of cell division,
insertion of flagella and internal cell structure. [0236] Method of
cell division refers to the production of a phragmoplast. or a phy
phycoplast. [0237] Insertion of flagella are either apical or
subapical. [0238] Internal cell structure refers to the possession
of a system of microtubules found near the flagella apparatus. Also
the possession of peroxisomes involved in photoresiration. [0239]
7. Classes of Chlorophyta [0240] Charophyceae are the group most
like the land plants. They undergo mitosis by formation of a
phragmoplast, possess the microtubular system characteristic of
land plants, and have subapically inserted flagella. Example
organisms in this group are Spyrogyra, the desmids and Coleochaeta.
[0241] The Ulvaphyceae are mostly marine organisms that have an
alternation of generation. The life cycle of Ulva has an isomorphic
alternation of generations with sporic meiosis. These organisms
produce a phycoplast when undergoing cell division and the nuclear
envelope persists during division. [0242] Chlorophyceae produce a
phycoplast when undergoing cell division and the nuclear envelope
persists during division. There are many forms that have zygotic
meiosis like Chlamydamonas.
[0243] Chrysophyta are unicellular algae: [0244] 1. Characteristics
of the Chrysophyta indicate a similarity with the brown algae.
There are three classes of chrysophyta. [0245] Pigments include
chlorophyll a and chlorophyll c. These are usually masked by an
abundance of a brownish pigment, fucoxanthin. [0246] Food reserve
in the Chrysophyta is called chrysolaminarin--a carbohydrate.
[0247] The cell of chrysophytes may be naked or they may have cell
walls of cellulose. Some members have silica scales or shells.
[0248] 2. Classes of Chrysophyta [0249] Chrysophyceae are primarily
freshwater planktonic organisms. They lack a clearly defined cell
wall but have silica scales. Many of these organisms have flagella.
[0250] Bacillariophyceae are the diatoms. These are important
phytoplanktonic organisms in freshwater and marine environments.
They are characterized by the presence of silica cell walls with
intricate markings. They have chlorophyll a and c and fucoxanthin
which gives them a brownish color. When they undergo sexual
reproduction, the only flagellated cell appears, a males sperm
cell. It has two flagella, one whiplash and one tinsel type. [0251]
Xanthophyceae are the yellow green algae because they lack
fucoxanthin and the greenish colors show. Vaucheria, which you saw
in lab belongs to this class.
[0252] Pyrrophyta are important phytoplanktonic organisms in
freshwater and marine habitats: [0253] 1. Characteristics of
Pyrrophyta [0254] The dinoflagellates contain chlorophyll a and c
and a brownish pigment called peridinin. [0255] The food storage
material of the pyrrophyta is starch. [0256] The cell walls of
those that possess them are in the form of cellulosic plates and
hence the name armored dinoflagellates given to some members of the
phylum. [0257] The pyrrophyta have two flagella. One flagellum
encircles the cell like a belt. The other flagellum trails behind
the cell. [0258] 2. Features of the dinoflagellates [0259] Some of
these organisms are responsible for the poisonous red tide. [0260]
Some of these organisms are capable of bioluminescence.
[0261] Euglenophyta are unicellular algae that lack a cell wall:
[0262] 1. Characteristics of the Euglenophyta [0263] The euglenoids
posses chlorophyll a and b and carotenoids. They have the same
grass green color as the green algae. [0264] The food storage
material of the euglenoids is paramylon, a polysaccharide material
[0265] The euglenophyta lack cell walls. Instead they have a
proteinaceous coating called the pellicle. They are capable of
changing shape because they lack the cell wall. [0266] The
euglenoids have two flagella but only one flagellum emerges from a
gullet at the tip of the cell. The other short flagellum is
basically nonfunctional as a swimming aid.
[0267] Prevention and/or elimination or at least substantial
reduction of microfouling by all or some of the above algae is
within the scope of the present invention.
[0268] The term microfouling is used to denote the attachment of
unicellular organisms, such as bacteria and algae, to the submerged
surface. These microfouling organisms can, in some cases, secrete
chemical signals which attract further organism to the surface,
thereby increasing the rate of fouling. Macrofoulers, such as
barnacles, become attached to the surface after the formation of
the initial microfouling layer.
[0269] As microfouling may occur before the macrofouling, any
process which interferes with the attachment of microbial organisms
to aquatic surfaces would decrease the total amount of fouling
which takes place. Thus, an active ingredient capable of preventing
the attachment of barnacles operates at the end of the fouling
chain while an active species which operates to prevent the
attachment of unicellular organisms such as bacteria operates at
the beginning of the fouling chain. Accordingly, species which
prevent microfouling may have some inhibitory effect against
settlement of all types of fouling. One such particularly preferred
antifouling species, including an antimicrobial species is
peroxides, such as hydrogen peroxide, produced by oxidases.
[0270] Additional antifouling organisms the growth of which is
capable of being controlled by the means of the present invention
as described herein includes, but is not limited to crustaceans and
other marine hard growth, such as:
Tube Worms: polychaetes; phylum Annelida; subclass Eunicea; family
Serpulidae Mussels: bivalves; phylum Mollusca; subclass
Pteriomorphia; family Mytilidae Clams: bivalves; phylum Mollusca;
subclass Hterodonta; family Veneridae Bryozoans: bryozoans; phylum
Bryozoa; suborder Anasca and Ascophora; genus Schizoporella
Barnacles: crustaceans; phylum Arthropoda; subphylum Crustacea
[0271] However, as is clear from the description herein above, the
invention also has utility against soft growth, which can impede
e.g. the efficiency of hull forms, damage substrates of marine
structures, generally shorten the viable life span of equipment,
and escalate the cost of operation. Examples of these soft growth
forms include:
Algae (Botanus): Padina, and Codium
Bryozoans (Animal): Bugula Neretina
Hydroids (Animal): Obelia
Sabellids (Animal):
Delaya Marina (Marine Bacteria): Zibria
[0272] The compositions, coatings and/or paints according to the
present invention may also function by direct attack on the surface
film, disrupting its polymeric structure through e.g. hydrolysis of
the proteins and polysaccharides of the film. This would interrupt
the chain of events that ultimately leads to the accumulation of
large amounts of marine organisms (including bacteria, fungi,
barnacles, etc.) on e.g. the hull of the ship.
[0273] Such attack may be accomplished by the use of extracellular
enzymes that disrupt the polysaccharides and proteins that make up
the surface film. Key hydrolytic enzymes in this respect are
proteases, alpha-amylases, amyloglycosidases and xylanases.
Alternatively, the coatings and/or paints may function by modifying
the surface tension of the marine surface to which the coatings
and/or paints have been applied. Such a change in the surface
tension may disrupt the colonization of the surface by undesirable
marine organisms.
[0274] The methods and compositions disclosed herein may be used on
a variety of surfaces, including but not limited to boat hulls,
marine markers, bulkheads, pilings, water inlets, floors, roofs,
and shingles. For example, the methods and compositions may be used
to minimize fouling of marine markers. Such markers constitute a
large category of floating objects and are greatly impaired by the
accumulation of marine growth.
[0275] Similarly, the methods and compositions may be used on
marine bulkheads. The accumulation of marine growth on bulkhead
structures is detrimental to the bulkhead structure over the long
term. Furthermore, the growth causes significant short term effects
that are aesthetically displeasing and dangerous. Moreover, the
harsh abrasive characteristics of the hard growth can result in
major damage to vessels.
[0276] Similarly, the present invention can be used to minimize
blockages due to fouling by marine growth of heat exchangers,
evaporators, condensers and fire and flushing systems, thus
resulting in significant decreases in maintenance costs for all
categories of marine structures.
[0277] Compositions and/or paints according to the invention may
include various hydrolytic enzymes, although it is possible to
practice the invention without such hydrolytic enzymes. Examples of
suitable enzymes include proteases, including subtilisins such as
e.g. alcalase, amylases, amyloglycosidases, xylanases and other
hydrolytic enzymes known in the art. The hydrolytic enzymes
selected should act to prevent or reduce attachment by unwanted or
undesirable marine organisms. The hydrolytic enzymes chosen should
be able to survive and flourish in the marine environment to which
they will be exposed.
[0278] Compositions and/or paints according to the invention
include the above-mentioned enzymes in an amount effective to
reduce the growth of unwanted or undesirable microorganisms. Such
compositions and/or paints may be in a variety of forms, including
paints, lacquers, pastes, laminates, epoxies, resins, waxes, gels,
and glues in addition to other forms known to one of skill in the
art.
[0279] The compositions and/or paints may be polymeric, oligomeric,
monomeric, and may contain cross-linkers or cure promoters as
needed. Such compositions and/or paints may contain other
additives, in addition to those mentioned above, to accomplish
purposes known to one of skill in the art. Such other additives
include preservatives, pigments, dyes, fillers, surfactants, and
other additives known to one of skill in the art.
Selected Antifouling Species
[0280] Peroxides in general constitute one much preferred group of
antifouling species, including an antimicrobial species according
to the invention. Hydrogen peroxide is an example of a presently
most preferred antifouling species, including an antimicrobial
species.
[0281] Any enzyme-compound combination capable of producing
hydrogen peroxide can be used, including a combination wherein the
enzyme is an oxidase and the compound can be oxidized by said
oxidase.
[0282] A combination of said oxidase with said compounds to be
oxidized thereby includes such combinations as (enzyme-substrate)
malate oxidase-malic acid; glucose oxidase-glucose; hexose
oxidase-glucose; cholesterol oxidase-cholesterol; arylalcohol
oxidase-arylalcohol: galactose oxidase-galactose; alcohol
oxidase-alcohol; lathosterol oxidase-lathosterol; aspartate
oxidase-aspartic acid; L-amino-acid oxidase-L-amino acid;
D-amino-acid oxidase-D-amino acid; amine oxidase-amine; D-glutamate
oxidase-glutamine; ethanolamine oxidase-ethanolamine; NADH
oxidase-NADH; urate oxidase (uricase)-uric acid; superoxide
dismutase-superoxide radical; and so forth.
[0283] The enzymatic reaction between said oxidase and the compound
yields hydrogen peroxide. The enzymatic reaction can proceed when
either oxygen or oxygen and water are present in an external
environment contacting the coating composition according to the
invention.
[0284] The above-mentioned oxygen is supplied not only from
atmospheric air but also from e.g. seawater containing dissolved
oxygen. The enzymatic reaction of the invention occurs in an
external environment including seawater with the result that
hydrogen peroxide is produced in said environment.
[0285] Additional preferred species having antimicrobial activity
includes, but is not limited to, carboxyl group-containing species,
hydroxyl group-containing species, amino group-containing species,
aldehyde group-containing species, and decomposition products of
chitosan.
[0286] The carboxyl group-containing species includes a variety of
organic acid species, e.g. aliphatic acids such as formic acid,
acetic acid, propionic acid, butyric acid, caproic acid, caprylic
acid, capric acid, lauric acid, myristic acid, palmitic acid, oleic
acid, linoleic acid, linolenic acid, monochloroacetic acid,
monofluoroacetic acid, sorbic acid, undecylenic acid, etc.; dibasic
acids such as oxalic acid etc.; aromatic carboxylic acids such as
benzoic acid, p-chlorobenzoic acid, p-hydroxybenzoic acid,
salicylic acid, cinnamic acid, etc.; and their derivatives and
halides. Any enzyme-compound combination capable of producing a
carboxyl group-containing species can be applied.
[0287] The ester bond-containing species mentioned above is not
particularly restricted in kind but includes, among others, esters
of any of said carboxyl group-containing species with aliphatic
alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol,
butyl alcohol, pentyl alcohol, caproyl alcohol, caprylyl alcohol,
capryl alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol,
oleyl alcohol, etc.; esters of any of said carboxyl
group-containing species with aromatic alcohols such as phenol,
benzyl alcohol, etc.; esters of any of said carboxyl
group-containing species with polyhydric alcohols such as ethylene
glycol, glycerol, etc.; and esters of any of said carboxyl
group-containing species with derivatives or halides of said
aliphatic alcohols, aromatic alcohols, or polyhydric alcohols.
[0288] The ester bond-containing species mentioned above is
hydrolyzed by said esterase in the above-mentioned coating
composition to produce said carboxylic group-containing species.
This enzymatic reaction can proceed when water is present in the
reaction system, as follows.
R.sub.1COOR.sub.2+H.sub.2O=>R.sub.1COOH+R.sub.2OH
[0289] In the above reaction scheme, R.sub.1 represents carboxylic
residue and R.sub.2 represents an alcohol residue.
[0290] When the above coating composition is applied to an object,
the antimicrobial effect is achieved when e.g. moisture from the
atmosphere is provided to the reaction resulting in the production
of an antifouling species, including an antimicrobial species. When
the coating composition is applied to an object to be placed in an
aqueous environment e.g. in water such as seawater, the reaction
resulting in the production of antifouling species, including an
antimicrobial species takes place in said water.
[0291] The amide bond-containing species mentioned above includes,
but is not limited to, amides of any of said carboxyl
group-containing species with aliphatic amines such as butylamine,
hexylamine, octylamine, decylamine, laurylamine, stearylamine,
oleylamine, etc.; and amides of any said carboxyl group-containing
species with aromatic amines such as aniline, toluidine, xylidine,
and alkylanilines such as hexylaniline, octylaniline, nonylaniline,
dodecylaniline, and so forth.
[0292] The hydroxyl group-containing species mentioned above
includes, but is not limited to, aliphatic alcohols such as methyl
alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl
alcohol, isobutyl alcohol, pentyl alcohol, isopentyl alcohol, hexyl
alcohol, etc.; aromatic alcohols such as phenol, chlorophenol, and
alkylphenols such as cresol, xylenol, etc., resorcinol, benzyl
alcohol, etc.; and the derivatives and halides of said aliphatic or
aromatic alcohols.
[0293] Any enzyme-compound combination capable of producing the
hydroxyl group-containing species can be applied. In one
embodiment, the enzyme is an esterase and the compound is an ester
bond-containing species. The esterase and the ester bond-containing
species includes the species mentioned hereinbefore, but is not
limited to these species.
[0294] The amino group-containing species mentioned above includes,
but is not limited to aliphatic amines such as butylamine,
hexylamine, octylamine, decylamine, laurylamine, stearylamine,
oleylamine, cyclohexylamine, etc.; and aromatic amines such as
aniline, toluidine, xylidine, p-n-hexylaniline, p-n-octylaniline,
p-nonylaniline, p-dodecylaniline, and so forth.
[0295] Any enzyme-compound combination capable of producing said
amino group-containing species can be used. Preferred is the case
in which the enzyme is an amidase including a protease, and the
compound is an amide bond-containing species including
apolypeptide. The amidase and the amide bond-containing species
includes the species mentioned hereinbefore, but is not limited to
these species.
[0296] The aldehyde group-containing species includes, but is not
limited to aliphatic aldehydes such as formaldehyde, glyoxal,
succinaldehyde, glutaraldehyde, capronaldehyde, caprylaldehyde,
caprinaldehyde, laurinaldehyde, stearinaldehyde, oleinaldehyde,
etc.; benzaldehyde and its derivatives such as
p-n-hexylbenzaldehyde, p-octylbenzaldehyde, p-oleylbenzaldehyde,
vaniline, piperonal, etc.; salicylaldehyde, cinnamaldehyde, and so
forth.
[0297] Any enzyme-compound combination capable of producing said
aldehyde group-containing species can be used, including the case
in which the enzyme is alcohol dehydrogenase and the compound is an
aliphatic alcohol, e.g. methanol, ethanol, etc.; the case in which
the enzyme is alcohol oxidase and the compound is an aliphatic
alcohol such as methanol, ethanol, etc.; the case in which the
enzyme is arylalcohol dehydrogenase and the compound is an aromatic
alcohol such as phenol, cresol, etc.; and the case in which the
enzyme is amine oxidase and the compound is an aliphatic amine such
as butylamine, hexylamine, and so forth.
[0298] Any enzyme-compound combination capable of producing a
decomposition product of chitosan can be applied. Preferred is the
case in which the enzyme is a chitosan-decomposing enzyme and the
compound is chitosan.
Enzyme Concentrations
[0299] In one preferred embodiment the aerogel comprises from 1 to
90 weight % enzyme, such as from 1 to 85 weight %, for example from
1 to 80 weight %, such as from 1 to 75 weight %, for example from 1
to 70 weight %, such as from 1 to 65 weight %, for example from 1
to 60 weight %, such as from 1 to 55 weight %, for example from 1
to 50 weight %, such as from 1 to 45 weight %, for example from 1
to 40 weight %, such as from 1 to 35 weight %, for example from 1
to 30 weight %, such as from 1 to 25 weight %, for example from 1
to 20 weight %, such as from 1 to 25 weight %, for example from 1
to 20 weight %, such as from 1 to 15 weight %, for example from 1
to 10 weight %, such as from 1 to 5 weight %, for example from 1 to
4 weight %, such as from 1 to 4 weight %, for example from 1 to 3
weight %, such as from 1 to 2 weight %, for example from 5 to 90
weight %, such as from 10 to 90 weight %, for example from 15 to 90
weight %, such as from 20 to 90 weight %, for example from 25 to 90
weight %, such as from 30 to 90 weight %, for example from 35 to 90
weight %, such as from 40 to 90 weight %, for example from 45 to 90
weight %, such as from 50 to 90 weight %, for example from 55 to 90
weight %, such as from 60 to 90 weight %, for example from 65 to 90
weight %, such as from 70 to 90 weight %, for example from 75 to 90
weight %, such as from 80 to 90 weight %, for example from 85 to 90
weight %, such as from 1 to 5 weight %, for example from 5 to 10
weight %, such as from 10 to 15 weight %, for example from 15 to 20
weight %, such as from 20 to 25 weight %, for example from 25 to 30
weight %, such as from 30 to 35 weight %, for example from 35 to 40
weight %, such as from 40 to 45 weight %, for example from 45 to 50
weight %, such as from 50 to 55 weight %, for example from 55 to 60
weight %, such as from 60 to 65 weight %, for example from 65 to 70
weight %, such as from 70 to 75 weight %, for example from 75 to 80
weight %, such as from 80 to 85 weight %, for example from 85 to 90
weight %.
[0300] The present invention relates in one preferred embodiment to
a method for increasing the amount of a bioactive agent in a
coating composition comprising an organic solvent, said method
comprising the steps of: [0301] a) providing a coating composition
comprising an organic solvent, [0302] b) providing an aerogel
comprising one or more biologically active enzymes entrapped
therein, [0303] c) mixing the coating composition provided in step
a) with the aerogel comprising one or more biologicaly enzymes
entrapped therein as provided in step b), thereby [0304] d)
obtaining a coating composition comprising an organic solvent and
an aerogel comprising one or more biologically active enzymes
entrapped therein, wherein said one or more biologically active
enzymes are present in a higher concentration and/or possesses a
higher biological activity than would have been the case had said
one or more enzymes not been entrapped in said aerogel
structure
Additional Components of Coating Compositions of the Invention
[0305] In one preferred embodiment the anti-fouling composition
comprising an aerogel further comprises at least one algicide,
herbicide, fungicide, molluscicide or other compound exhibiting
anti-fouling activity.
[0306] In one preferred embodiment the anti-fouling composition
comprising an aerogel further comprises a binder component,
suitable for marine applications and a pigment.
[0307] The coating compositions of the invention described herein
above can further comprise a binder to immobilise at least one of
the constituents, optionally to immobilise the enzymes.
[0308] The coating compositions of the present invention can be
formulated as coatings, lacquers, stains, enamels and the like,
hereinafter referred to generically as "coating(s)".
[0309] Preferably, the coating composition is formulated for
treatment of a surface selected from outdoor wood work, external
surface of a central heating system, and a hull vehicle should not
interfere with the activity of the at least one enzyme(s) and/or
any additional antifoulant compound.
[0310] Suitable solvents for coating compositions are disclosed
e.g. in U.S. Pat. No. 5,071,479 and include water and organic
solvents including aliphatic hydrocarbons, aromatic hydrocarbons,
such as xylene, toluene, mixtures of aliphatic and aromatic
hydrocarbons having boiling points between 100.degree. C. and
320.degree. C., preferably between 150.degree. C. and 230.degree.
C.; high aromatic petroleum distillates, e.g., solvent naptha,
distilled tar oil and mixtures thereof; alcohols such as butanol,
octanol and glycols; vegetable and mineral oils; ketones such as
acetone; petroleum fractions such as mineral spirits and kerosene,
chlorinated hydrocarbons, glycol esters, glycol ester ethers,
derivatives and mixtures thereof.
[0311] The solvent may be apolar or polar, such as water,
optionally in admixture with an oily or oil-like low-volatility
organic solvent, such as the mixture of aromatic and aliphatic
solvents found in white spirits, also commonly called mineral
spirits.
[0312] The solvent may typically contain at least one of a diluent,
an emulsifier, a wetting agent, a dispersing agent or other surface
bioactive agent. Examples of suitable emulsifiers are disclosed in
U.S. Pat. No. 5,071,479 and include nonylphenol-ethylene oxide
ethers, polyoxyethylene sorbitol esters or polyoxyethylene sorbitan
esters of fatty acids, derivatives and mixtures thereof.
[0313] Any suitable surface coating material may be incorporated in
the composition and/or coating of the present invention. Examples
of trade-recognized coating materials are polyvinyl chloride resins
in a solvent based system, chlorinated rubbers in a solvent based
system, acrylic resins and methacrylate resins in solvent based or
aqueous systems, vinyl chloride-vinyl acetate copolymer systems as
aqueous dispersions or solvent based systems, butadiene copolymers
such as butadiene-styrene rubbers, butadiene-acrylonitrile rubbers,
and butadiene-styrene-acrylonitrile rubbers, drying oils such as
linseed oil, alkyd resins, asphalt, epoxy resins, urethane resins,
polyester resins, phenolic resins, derivatives and mixtures
thereof.
[0314] The composition and/or coating of the present invention may
contain pigments selected from inorganic pigments, such as titanium
dioxide, ferric oxide, silica, talc, or china clay, organic
pigments such as carbon black or dyes insoluble in sea water,
derivatives and mixtures thereof.
[0315] The coating composition of the present invention can also
contain plasticisers, rheology characteristic modifiers, other
conventional ingredients and mixtures thereof.
[0316] The coating composition of the present invention optionally
further comprise an adjuvant conventionally employed in
compositions used for protecting materials exposed to an aquatic
environment. These adjuvants may be selected from additional
fungicides, auxiliary solvents, processing additives such as
defoamers, fixatives, plasticisers, UV-stabilizers or stability
enhancers, water soluble or water insoluble dyes, color pigments,
siccatives, corrosion inhibitors, thickeners or antisettlement
agents such as carboxymethyl cellulose, polyacrylic acid or
polymethacrylic acid, anti-skinning agents, derivatives and
mixtures thereof.
[0317] In one embodiment the present invention provides a marine
anti-foulant comprising the coating composition as described above.
Preferably, the anti-foulant is self-polishable.
[0318] In one embodiment of the present invention, the enzyme is
preferably encapsulated, such as encapsulated by a semi-permeable
membrane. One type of enzymes may be encapsulated individually
independently of other types of enzymes, or the enzymes may be
encapsulated together. The encapsulating material may be selected
such that on contact with a foulant, the enzyme may be released. In
this way, a composition may be provided which only provides an
anti-foulant species or increases provision of an anti-foulant
compound when contacted with a foulant. Alternating layers of
anti-foulant species and encapsulation material ensures a
sequential release of enzymes.
[0319] The composition of the present invention can be provided as
a ready-for-use product or as a concentrate. The ready-for-use
product may be in the form of an aqueous solution, aqueous
dispersion, oil solution, oil dispersion, emulsion, or an aerosol
preparation. The concentrate can be used, for example, as an
additive for coating, or can be diluted prior to use with
additional solvents or suspending agents.
[0320] An aerosol preparation according to the invention may be
obtained in the usual manner by incorporating the composition of
the present invention comprising or dissolved or suspended in, a
suitable solvent, in a volatile liquid suitable for use as a
propellant.
[0321] As discussed in U.S. Pat. No. 5,071,479, the coating
composition of the present invention can also include additional
ingredients known to be useful in preservatives and/or coatings.
Such ingredients include fixatives such as carboxymethylcellulose,
polyvinyl alcohol, paraffin, co-solvents, such as ethylglycol
acetate and methoxypropyl acetate, plasticisers such as benzoic
acid esters and phthlates, e.g., dibutyl phthalate, dioctyl
phthalate and didodecyl phthalate, derivatives and mixtures
thereof. Optionally dyes, color pigments, corrosion inhibitors,
chemical stabilizers or siccatives (dryers) such as cobalt octate
and cobalt naphthenate, may also be included depending on specific
applications.
[0322] The composition and/or coating of the present invention can
be applied by any of the techniques known in the art including
brushing, spraying, roll coating, dipping and combinations
thereof.
[0323] Compositions of the present invention can be prepared simply
by mixing the various ingredients at a temperature at which they
are not adversely affected. Preparation conditions are not
critical. Equipment and methods conventionally employed in the
manufacture of coating and similar compositions can be
advantageously employed.
Paint
[0324] In another embodiment the aerogel comprising one or more
bioactive agents is used as an agent in a paint or any other
preservation for protection of any type of surface such as wood,
metal, stone, bricks, concrete and plastic. The present invention
e.g. relates to house painting and wood or metal protection.
[0325] In one preferred embodiment the paint or other type of
coating composition comprises aerogel particles.
[0326] In one preferred embodiment the paint or other type of
coating composition comprises one or more premade aerogel(s). After
mixing of the one or more aerogels with the paint or other type of
coating composition the physical and chemical properties of the one
or more aerogels may be affected.
[0327] In one preferred embodiment an antifouling paint composition
comprises at least one subtilisin (EC 3.4.21.62), said subtilisin
having the following characteristics: (i) optimum activity at a pH
in the range of about 7-10, and (ii) optimum activity at a
temperature in the range of about 55-65.degree. C. In another
embodiment the antifouling paint composition comprises the
subtilisin Alcalase.RTM.. In one preferred embodiment the
antifouling paint composition comprises the Alcalase.RTM. Alcalase
2.5 L, Type DX.RTM..
[0328] Paint is any liquid, liquifiable, or mastic composition
which after application to a surface in a thin layer is converted
to an opaque solid film.
[0329] The paint or preservative is used to protect, decorate (such
as adding color), or add functionality to an object or surface by
covering it with a pigmented coating. An example of protection is
to retard corrosion of metal. An example of decoration is to add
festive trim to a room interior. An example of added functionality
is to modify light reflection or heat radiation of a surface.
Another example of functionality would be the use of color to
identify hazards or function of equipment and pipelines.
[0330] Paint can be applied to almost any kind of object. It is
used, among many other uses, in the production of art, in
industrial coating, as a driving aid (road surface marking), or as
a barrier to prevent corrosion or water damage. Paint is a
semifinished product, or intermediate good as the final product is
the painted article itself.
[0331] Paint can also be mixed with glaze to create various
textures and patterns. This process is referred to as faux
finish.
[0332] The present invention also relates to in-can preservation of
paint.
Components of Paint
[0333] There are three primary components to a paint:
1) Pigments;
[0334] 2) Binder, also known as non-volatile vehicle or resin and
3) Vehicle, also known as volatile vehicle, also called
solvent.
Pigment
[0335] Pigments impart such qualities as color and opacity, and
influence properties such as gloss, film flow, and protective
abilities. Pigment can generally be categorized into two main
types: Prime or hiding pigments and Inert or extender pigments.
[0336] The main modern white hiding pigment is Titanium dioxide.
Zinc oxide is a weaker white pigment with some important usages.
Color hiding pigments fall also into two main categories, those
being Inorganic, mostly duller earth tone colors, and Organic,
generally brighter but more expensive colors.
[0337] Inert pigments break down into natural or synthetic types.
Natural pigments include various clays, calcium carbonate, mica,
silicas, and talcs. Synthetics would include calcined clays, blanc
fix, precipitated calcium carbonate, and synthetic silicas.
[0338] Hiding pigments, in making paint opaque, also protect the
substrate from the harmful effects of ultraviolet light.
[0339] Some pigments are toxic, such as the lead pigments that are
used in lead paint. Paint manufacturers began replacing white lead
pigments with the less toxic substitute, which can even be used to
color food, titanium white (titanium dioxide), even before lead was
functionally banned in paint for residential use in 1978 by the
U.S. Consumer Product Safety Commission.
[0340] Titanium dioxide was first used in paints in the 19th
century. The titanium dioxide used in most paints today is often
coated with silicon or aluminum oxides for various reasons such as
better exterior durability, or better hiding performance (opacity)
via better efficiency promoted by more optimal spacing within the
paint film. Opacity is also improved by optimal sizing of the
titanium dioxide particles.
[0341] The present invention relates to an antifouling coating
composition comprising one or more aerogels, and one or more
bioactive agents and further comprising any pigment described in
the prior art or any combination thereof.
Binder
[0342] The binder, or resin, is the actual film forming component
of paint. It imparts adhesion, binds the pigments together, and
strongly influences such properties as gloss potential, exterior
durability, flexibility, and toughness.
[0343] Binders include synthetic or natural resins such as
acrylics, polyurethanes, polyesters, melamine resins, epoxy, or
oils.
[0344] Binders can be categorized according to drying, or curing,
mechanism. The four most common are simple solvent evaporation,
oxidative crosslinking, catalyzed polymerization, and
coalescence.
[0345] Note that drying and curing are two different processes.
Drying generally refers to evaporation of vehicle, whereas curing
refers to polymerization of the binder. Depending on chemistry and
composition, any particular paint may undergo either, or both
processes. Thus, there are paints that dry only, those that dry
then cure, and those that do not depend on drying for curing.
[0346] Paints that dry by simple solvent evaporation contain a
solid binder dissolved in a solvent; this forms a solid film when
the solvent evaporates, and the film can re-dissolve in the solvent
again. Classic nitrocellulose lacquers fall into this category, as
do non-grain raising stains composed of dyes dissolved in
solvent.
[0347] Paints that cure by oxidative crosslinking are generally
single package coatings that when applied, the exposure to oxygen
in the air starts a process that crosslinks and polymerizes the
binder component. Classic alkyd enamels would fall into this
category.
[0348] Paints that cure by catalyzed polymerization are generally
two package coatings that polymerize by way of a chemical reaction
initiated by mixing resin and hardener, and which cure by forming a
hard plastic structure. Depending on composition they may need to
dry first, by evaporation of solvent. Classic two package epoxies
or polyurethanes would fall into this category.
[0349] Latex paints cure by a process called coalescence where
first the water, and then the trace, or coalescing, solvent,
evaporate and draw together and soften the latex binder particles
together and fuse them together into irreversibly bound networked
structures, so that the paint will not redissolve in the
solvent/water that originally carried it.
[0350] Recent environmental requirements restrict the use of
Volatile Organic Compounds (VOCs), and alternative means of curing
have been developed, particularly for industrial purposes. In UV
curing paints, the solvent is evaporated first, and hardening is
then initiated by ultraviolet light. In powder coatings there is
little or no solvent, and flow and cure are produced by heating of
the substrate after application of the dry powder.
[0351] The present invention relates to an antifouling coating
composition comprising one or more aerogels, and one or more
bioactive agents and further comprising any binder described in the
prior art or any combination thereof.
Vehicle, or Solvent
[0352] The main purpose of the vehicle is to adjust the viscosity
of the paint. It is volatile and does not become part of the paint
film. It can also control flow and application properties. Its main
function is as the carrier for the non volatile components.
[0353] Water is the main vehicle for water based paints.
[0354] Solvent based, sometimes called oil based, paints can have
various combinations of solvents as the vehicle, including
aliphatics, aromatics, alcohols, and ketones. These include organic
solvents such as petroleum distillate, alcohols, ketones, esters,
glycol ethers, and the like. Sometimes volatile low-molecular
weight synthetic resins also serve as diluents.
[0355] The present invention relates to an antifouling coating
composition comprising one or more aerogels, and one or more
bioactive agents and further comprising any vehicle or solvent
described in the prior art or any combination thereof.
Additives
[0356] Besides the three main categories of ingredients, paint can
have a wide variety of miscellaneous additives, usually added in
very small amounts. Some examples include additives to improve wet
edge, improve pigment stability, impart antifreeze properties,
control foaming, control skinning, etc. Other additives might be
thickeners, coalescent solvents, or biocides to fight bacterial
growth.
[0357] The present invention relates to an antifouling coating
composition comprising one or more aerogels, and one or more
bioactive agents and further comprising any coating composition
additives described in the prior art or any combination
thereof.
[0358] Fillers serve to thicken the film, support its structure and
simply increase the volume of the paint. Not all paints include
fillers. Pigments that also function as fillers are called simply
"pigments"; "fillers" are generally color-neutral and opaque. It is
necessary to adjust the resulting off-white color with pigments to
give the desired color. Common fillers are cheap and inert, such as
talc, lime, baryte, clay, etc. Depending on the paint, most of the
paint film may consist of pigment/filler and binder, the rest being
other additives.
[0359] Besides pigments and dyes, other types of additives include
catalysts, thickeners, stabilizers, emulsifiers, texturizers,
adhesion promoters, flatteners (de-glossing agents), and the
like.
[0360] After application, the paint solidifies and becomes
tack-free. Depending on the type of binder, this hardening may be a
result of curing (polymerization), evaporation, or even phase
change brought about by cooling. In oil-based paint, curing takes
the form of oxidation, for example oxidation of linseed oil to form
linoxin to create a varnish. Other common cured films are prepared
from crosslinkers, such as polyurethane or melamine resins, reacted
with acrylic polyester or polyurethane resins, often in the
presence of a catalyst which serves to make the curing reaction
proceed more quickly or under milder conditions. These cured-film
paints can be either solvent-borne or waterborne.
[0361] Latex paint is a water-based dispersion of sub-micron
polymer particles. The term "latex" in the context of paint simply
means an aqueous dispersion; latex rubber (the sap of the rubber
tree that has historically been called latex) is not an ingredient.
These dispersions are prepared by emulsion polymerization. When the
water evaporates, the polymer particles coalesce to form a solid
film. The polymer itself resists water (and typically some other
solvents). Residual surfactants in the paint as well as hydrolytic
effects with some polymers cause the paint to remain susceptible to
softening and, over time, degradation by water.
[0362] Still other films are formed by cooling of the binder. For
example, encaustic or wax paints are liquid when warm, and harden
upon cooling.
[0363] The present invention relates to an antifouling coating
composition comprising one or more aerogels, and one or more
bioactive agents and further comprising any miscellaneous coating
composition agent described in the prior art or any combination
thereof.
Product Variants
[0364] Primer is a preparatory coating put on materials before
painting. Priming ensures better adhesion of paint to the surface,
increases paint durability, and provides additional protection for
the material being painted. [0365] Varnish and shellac provide a
protective coating without changing the color. They are paints
without pigment. [0366] Wood stain is a type of paint that is very
"thin," that is, low in viscosity, and formulated so that the
pigment penetrates the surface rather than remaining in a film on
top of the surface. Stain is predominantly pigment or dye and
solvent with little binder, designed primarily to add color without
providing a surface coating. [0367] Lacquer is usually a
fast-drying solvent-based paint or varnish that produces an
especially hard, durable finish. [0368] An enamel paint is a paint
that dries to an especially hard, usually glossy, finish. Enamel
can be made by adding varnish to oil-based paint. [0369] A Glaze is
an additive used with paint to slow drying time and increase
translucency, as in Faux Painting and Art Painting. [0370] A Roof
coating is a fluid applied membrane which has elastic properties
that allows it to stretch and return to their original shape
without damage. It provides UV protection to polyurethane foam and
is widely used as part of a roof restoration system. [0371]
Fingerpaint [0372] Inks are similar to paints, except they are
typically made using dyes exclusively (no pigments), and are
designed so as not to leave a thick film of binder. [0373] Titanium
dioxide is extensively used for both house paint and artist's
paint, because it is permanent and has good covering power.
Titanium oxide pigment accounts for the largest use of the element.
Titanium paint is an excellent reflector of infrared, and is
extensively used in solar observatories where heat causes poor
seeing conditions. [0374] Anti-Graffiti paints are used to defeat
the marking of surfaces by graffiti artists. There are two
categories, sacrificial and non-bonding. Sacrificial coatings are
clear coatings that allow the removal of graffiti, usually by
pressure washing the surface with high-pressure water, removing the
graffiti, and the coating (hence, sacrificed.) They must be
re-applied afterward for continued protection. This is most
commonly used on natural-looking masonry surfaces, such as statuary
and marble walls, and on rougher surfaces that are difficult to
clean. Non-bonding coatings are clear, high-performance coatings,
usually catalyzed polyurethanes, that allow the graffiti very
little to bond to. After the graffiti is discovered, it can be
removed with the use of a solvent wash, without damaging the
underlying substrate or protective coating. These work best when
used on smoother surfaces, and especially over other painted
surfaces, including murals. [0375] Anti-climb paint is a non-drying
paint that appears normal while still being extremely slippery. It
is usually used on drainpipes and ledges to deter burglars and
vandals from climbing them, and is found in many public places.
When a person attempts to climb objects coated with the paint, it
rubs off onto the climber, as well as making it hard for them to
climb. [0376] No-VOC paints, which are solvent-free paints that do
not contain volatile organic compounds, have been available since
the late 1980s. Low VOC paints, which typically contain anywhere
between 0.3%-5.0% VOCs as coalescent, or coalescing solvent have
been available since the 1960s.
Preferred Methods and Uses of the Invention
[0377] Preferred uses of the present invention include the
following methods, but is not limited thereto:
[0378] Method for treating a surface contacted by fouling
organisms, or a surface at risk of such contact, said method
comprising the steps of contacting the surface with a composition
according to the invention with an effective amount of said
composition or coating composition, wherein said contacting results
in eliminating said fouling or at least reducing said fouling.
[0379] Method for preventing or reducing fouling of a surface, said
method comprising the steps of contacting the surface with a
composition according to the invention with an effective amount of
said composition or coating composition or hygienic composition,
wherein said contacting results in preventing or reducing fouling
of said surface.
[0380] Method for treating a surface contacted by a fluid
composition comprising fouling organisms, said method comprising
the steps of contacting the surface with a composition according to
the invention with an effective amount of said composition or
coating composition, wherein said contacting prevents fouling of
said surface, or results in a reduced fouling of said surface.
[0381] The above-mentioned surfaces can be at least partly
submerged in seawater, or they can be interior or exterior surfaces
of a pipe for ventilation, or interior walls in a building.
[0382] Additional methods in accordance with the present invention
are:
[0383] Method for disinfecting a surface, said method comprising
the steps of contacting the surface with a composition according to
the invention with an effective amount of said composition or
coating composition or hygienic composition, wherein said
contacting results in a disinfection of said surface.
[0384] Method for removing microbial organisms from a surface, said
method comprising the steps of contacting the surface with a
composition according to the invention with an effective amount of
said composition or coating composition or hygienic composition,
wherein said contacting results in removing microbial organisms
from said surface.
[0385] Method for coating an object, said method comprising the
steps of contacting the surface with a composition according to the
invention with an effective amount of said composition or coating
composition or hygienic composition, wherein said contacting
results in coating said object.
[0386] Method for sealing a surface, said method comprising the
steps of contacting the surface with a composition according to the
invention with an effective amount of said composition or coating
composition or hygienic composition, wherein said contacting
results in sealing said surface from an external environment.
[0387] Method for reducing or eliminating marine corrosion, said
method comprising the steps of contacting the surface with a
composition according to the invention with an effective amount of
said composition or coating composition or hygienic composition,
wherein said contacting results in reducing or eliminating marine
corrosion.
[0388] Method for preserving a surface, said method comprising the
steps of contacting the surface with a composition according to the
invention with an effective amount of said composition or coating
composition or hygienic composition, wherein said contacting
results in preserving said surface.
[0389] Method for killing undesirable microbial cells, said method
comprising the steps of contacting the surface with a composition
according to the invention with an effective amount of said
composition or coating composition or hygienic composition, wherein
said contacting results in killing undesirable microbial cells.
[0390] Method for generating an antifouling species, said method
comprising the steps of providing a composition comprising at least
one enzyme capable of acting on a compound, wherein said action
results in the formation of an antifouling species comprising an
antifouling activity, wherein said compound does not form part of
said composition, further providing said compound, and forming said
antifouling species by contacting said at least one enzyme with
said compound.
[0391] Method for preparing a painting composition according to the
invention, said method comprising the steps of providing at least
one pigment and at least one enzyme capable of acting on a
compound, wherein said action results in the formation of an
antifouling species comprising an antifouling activity, wherein
said compound does not form part of said composition, further
providing a carrier for said at least one enzyme, and forming said
composition by contacting said at least one enzyme with said
carrier.
[0392] Preferred uses of the invention include, but is not limited
to:
[0393] Use of at least one enzyme comprising an oxidase activity in
the manufacture of a coating composition, wherein said coating
composition does not comprise any substrate for said oxidase
activity.
[0394] Use of at least one enzyme comprising an oxidase activity in
a cleaning in place system, wherein said system does not comprise
any substrate for said oxidase.
[0395] The aerogel may be used at the vehicle to distribute
proteins in a hydrophobic phase in a molecular disperse
distribution not achievable by other means.
[0396] The aerogel may be used to influence the rate of polishing
for a film prepared from the mixture
[0397] The aerogel can be used to influence the viscosity of the
film forming mixture to optimize film formation
[0398] In another preferred embodiment the aerogel material
described in the present invention is used for thermal insulation
material.
[0399] In another embodiment the aerogel according to this
invention is used as a chemical absorber for cleaning up spills.
The aerogel can also be used as a catalyst or a catalyst
carrier.
[0400] In another embodiment the aerogel is used as an agent in
cosmetics.
[0401] Resorcinol-formaldehyde aerogels (polymers chemically
similar to phenol formaldehyde resins) are mostly used as
precursors for manufacture of carbon aerogels, or when an organic
insulator with large surface is desired. They come as high-density
material, with surface area about 600 m.sup.2/g.
[0402] In an embodiment the invention concerns an antifouling
coating composition, for instance a painting composition, for use
in the prevention, reduction or removal of fouling of a surface or
material. In an embodiment said surface or material has been
submerged in water, such as sea water or fresh water, and has been
fouled by fouling organisms during said submersion in water. In an
embodiment the composition comprises an aerogel. In a further
embodiment said aerogel comprises at least one enzyme, such as
esterase.
[0403] The methods of the present invention may in an embodiment be
employed in the removal, reduction or prevention of fouling
resulting from submersion of a material in water, such as seawater
or fresh water.
[0404] The methods and composition of the present invention are in
an embodiment particularly suitable for use in the reduction,
prevention or removal of fouling of materials or surfaces having
been submerged in seawater or fresh water, such as for instance
ship hulls, buoys or other structures being exposed to water.
[0405] It is a particular advantage of the present invention that
the compositions and methods of the invention are capable of
effectively preventing fouling without the use of toxic
substances.
EXAMPLES
Example 1
[0406] The aerogel comprises siliciumoxid. The aerogel is obtained
by hydrolysis of tetraalkoxysiloxane dissolved in alcohol. The
alcohol is subsequently removed from the generated network by
exchange with supercritical CO2. This solvent can be evaporated
without collaps of the aerogel.
[0407] The aerogel is obtained by drying of a wet gel. During this
process the liquid is removed from the nanopores in the gel. The
drying is performed in the presence of supercritical CO2 or another
supercritical solvent. It is important to go directly from the
liquid phase to a supercritical phase and subsequently directly
from the supercritical phase to a gas phase. An alternative to the
supercritic drying is use of DCCA (Drying Control Chemical
Additives), ambient pressure drying and freeze drying.
[0408] The wet gel is obtained by a SOL-GEL process. The SOL-GEL
process is typically performed at temperatures lower than
100.degree. C. For preparation of in-organic gells, typically
metaloxides, the reaction typically occur by condensation of
metalhydroxides in solution such as they are obtained by hydrolysis
of one or more metalalkoxides. In the first step (referred to as
SOL) small independent more or less cross-linked colloid particles
are performed in a colloid suspension. In the second step (referred
to as GEL) these colloid particles bind to each other. This
three-dimensional network is known as GEL. If the three-dimensional
network is generated from linear polymer chains from the precursor
solution, without a preference for individual particles, a polymer
gel is obtained.
Example 2
[0409] The aerogel is obtained as described in example 1. The
aerogel further comprises one or more enzymes and/or one or more
other bioactive agents. The one or more enzymes and/or the one or
more other bioactive agents are added to the alcohol during the
generation of the network. This process results in encapsulation of
the one or more enzymes and/or the one or more other bioactive
agents in the aerogel. The process described in example 1 may be
interrupted after preparation of colloid particles containing an
enzyme as described in example 2. Completion of the network may be
performed under addition of one or more different active
components. Hereby the control of spatically distributed active
compounds can be obtained
Example 3
[0410] The aerogel is obtained as described in example 1 or 2. The
aerogel further comprises 1-10% dimethyldialkoxysiloxane to adjust
the hydrophobicity of the aerogel. Other alkoxysiloxanes may me
used to obtain similar adjustments in hydrophobicity.
Example 4
[0411] The aerogel is obtained as describes in example 1, 2 or 3.
Si is completely or partly replaced with Ti, Al or Boron. This
replacement affects the stability of the aerogel. The replacement
can be introduced statistically. It is possible by preparation of
colloid particles to obtain a spatically inhomogeneous aerogel.
Example 5
[0412] The aerogel is obtained as describes in example 1, 2, 3 or
4. The one or more enzymes and/or proteins are modified on amino
groups (NH2) and/or on thiol groups (SH) and/or on OH groups. With
succinimid, glutaraldehyde or isocyanat groups a desired group can
be fixed to the protein and/or enzyme. In one preferred embodiment
polyethylenglycol (PEG) is used as substituent. An alternative to
PEG is PEG linked to long alkyl chain and/or acryl and/or vinyl
groups.
Example 6
[0413] Esperase has been encapsulated in an aerogel. Tetrapeptide
staining has demonstrated that Esperase retain its activity after
encapsulation into the aerogel. Heating of the aerogel
encapsulating Esperase to 80.degree. C. for 24 hour shows that the
enzyme activity is retained after the heating. Heating of the
aerogel encapsulating Esperase in water to 80.degree. C. for 24
hour shows that the enzyme activity is decreased. This demonstrate
that Esperase is stabilised by encapsulation into the aerogel.
Example 7
[0414] Two different self-polishing solvent based paints have been
formulated with aerogels containing two different proteases. Panels
with the paints have been immersed in sea water in Elsinore
Harbour, Denmark, for a period of 6 months (May-October inclusive).
No fouling was observed after the period, or a very thin layer of
algal slime was detected compared to controls.
Example 8
[0415] Test fields were applied with same kind of formulation
containing aerogel and protease on both sides of the rudder of a
sailing boat based in Ishoj Harbour, Denmark. Inspection after the
sailing season 6 months later showed very thin algal slime and of
the same fouling degree as the conventional cupper based
antifouling paint.
Example 9
[0416] The aerogel is obtained as in examples 1, 2, 3 and 4. The
one or more enzymes/and or proteins are modified on amino groups
(NH2) and/or on thiol groups (SH) and or on hydroxyl groups (OH).
The substituent include a s SiR1R2R3R4 group where R1 links the Si
to the enzyme and R2R3 and R4 are chosen among Cl, Br, I and OR5
where R5 is an alkyl group. A preferred embodiment R5=CH3 and
R2=R3=R4=OR5. Hereby the enzyme can be chemically linked into the
gel network modifying its lifetime on gel surfaces exposed to
water.
Example 10
TABLE-US-00003 [0417] Enzyme Example of Silicagel, preparation,
preparations weight-% weight-% AP29 83.9 16.1 AP34 61.1 38.9 AP35
44.9 55.1 AP32 25.4 74.6
Example 11
[0418] Compositions according to the invention were applied to
well-defined panels on a raft and the raft was submerged in water
at Elsinore harbour, Denmark. The raft was submerged for a period
of 6 months before the results were evaluated. Also included on the
raft were panels with conventional paints and controls. The panels
of the reafts were treated as indicated in the following table:
TABLE-US-00004 Panels of the test raft Panel 1 Panel 2 Panel 3
Panel 4 Sigma MPT7-Z-AP MPT3-Z-AE MPT7-Z-AE Panel 5 Panel 6 Panel 7
Panel 8 MPT7-Z-A MPT3-Z-AE MPT3-ZS-AP SE-ZS-AE Panel 9 Panel 10
Panel 11 Panel 12 MPT3-Z-A MPT7-Z-AP MPT7-Z-AE Mille Xtra
[0419] The compositions applied to the raft as indicated in the
above table contained the following components:
MPT3: Base paint (the figure "3" refers to the amount of rosin in
relation to harpiks extender) MPT7: Base paint (the figure "7"
refers to the amount of rosin in relation to harpiks extender) SE:
Solvent epoxy paint
Z: Zink
S: Sulphide
A: Aerogel
P: Polarzyme
E: Esperase
[0420] Sigma: Positive control (conventional antifouling paint,
Sigma cupper based product+a biocide) Mille Xtra Positive control
(conventional antifouling paint, Hempel self-polishing cupper based
product)
[0421] At the end of the test period of 6 months, the fouling of
each panel on the raft was evaluated by using a score from 0 to 5,
where 0 is no fouling growth and 5 is complete coverage of the
panel by fouling growth. The results were as indicated in the table
below. A picture of the raft after the experiment is included as
FIG. 1. The quantifications of the below table were based on the
picture of FIG. 1.
TABLE-US-00005 Quantification of the growth on the panels of the
test raft Panel 1 Panel 2 Panel 3 Panel 4 0-1 1-2 2 0 Panel 5 Panel
6 Panel 7 Panel 8 2-3 2 5 5 Panel 9 Panel 10 Panel 11 Panel 12 3
1-2 0-1 2
[0422] A conclusion of the test was that the MPT7-Z-AE panels
(panels 4 and 11) were least fouled at the end of the test. These
panels had been treated with the base paint MPT7 comprising
aerogel, esperase enzyme and zinc. The MPT7-Z-AE panels proved to
be at least as good or possibly even slightly better than the
conventional Sigma cupper-based paint. This result was unexpectedly
positive and supports the advantageous effect of the present
invention. Also, it was evident that the compositions comprising
both aerogel and enzyme (panels 2, 3, 4, 6, 10, and 11) were
generally better at preventing fouling than the panels comprising
aerogel without enzyme (panels 5 and 9).
Example 12
[0423] The rudder from the yacht Erica was painted with 9 different
coatings as indicated in the table herein below. The results were
evaluated after a sailing a season (5 Months) in Danish seawater.
The evaluation is a quantification of the growth using a score from
0 to 5, where 0 is no fouling growth and 5 is complete coverage of
the panel by fouling growth.
TABLE-US-00006 Starbord side of rudder Port side of rudder Torm G
Solv 6 Solv 10 Solv 14 Solv 17 Solv 4 Solv 7 Solv 9 Solv 17 Solv 7
Solv 9 Solv 8 Sovl 8 Solv 4 Solv 14 Solv 10 Torm G Solv 6
Evaluation of the test 1 1-2 4 4 5 1 5 5 5 5 5 1 2-3 3 5 5 1 2
TABLE-US-00007 Aerogel with PVC Rosin/ esperase enzyme Activ
retarder SOLV 4 0.8 32.8 .sup. 03:01 SOLV 6 0.2 16.3 7.5:1 SOLV 7
1.1 16.4 .sup. 03:01 SOLV 8 0.2 freeze- 32.7 .sup. 03:01 dried
esperase SOLV 9 0.4 15.2 7.6:1 Comprises silver SOLV 10 0.8 16.5
.sup. 03:01 Comprises silver SOLV 14 0.6 21.4 3.9:1 SOLV 17 0.8
18.9 3.4:1 TORM G 0.4 27.4 5.4:1
* * * * *