U.S. patent number RE45,848 [Application Number 13/922,022] was granted by the patent office on 2016-01-19 for composite nanoparticles, nanoparticles and methods for producing same.
This patent grant is currently assigned to Vive Crop Protection Inc.. The grantee listed for this patent is Vive Crop Protection Inc. Invention is credited to Jose Amado Dinglasan, Cynthia M. Goh, Jane B. Goh, Richard Loo, Emina Veletanlic.
United States Patent |
RE45,848 |
Goh , et al. |
January 19, 2016 |
Composite nanoparticles, nanoparticles and methods for producing
same
Abstract
In various aspects provided are methods for producing a
nanoparticle within a cross-linked, collapsed polymeric material,
said method including (a) providing a polymeric solution comprising
a polymeric material; (b) collapsing at least a portion of the
polymeric material about one or more precursor moieties; (c)
cross-linking the polymeric material; (d) modifying at least a
portion of said precursor moieties to form one or more
nanoparticles and thereby forming a composite nanoparticle. In
various embodiments, a non-confined nanoparticle can be produced by
complete pyrolysis of the confined nanoparticle, and a
carbon-coated nanoparticle by incomplete pyrolysis of the confined
nanoparticle.
Inventors: |
Goh; Cynthia M. (Toronto,
CA), Dinglasan; Jose Amado (Toronto, CA),
Goh; Jane B. (Toronto, CA), Loo; Richard
(Toronto, CA), Veletanlic; Emina (Toronto,
CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Vive Crop Protection Inc |
Toronto |
N/A |
CA |
|
|
Assignee: |
Vive Crop Protection Inc.
(Toronto, CA)
|
Family
ID: |
37942273 |
Appl.
No.: |
13/922,022 |
Filed: |
June 19, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCT/CA2006/001686 |
Oct 13, 2006 |
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60726184 |
Oct 14, 2005 |
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Reissue of: |
11745377 |
May 7, 2007 |
7964277 |
Jun 21, 2011 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08J
3/215 (20130101); C09D 7/70 (20180101); C08J
3/14 (20130101); C09D 7/67 (20180101); C09D
7/65 (20180101); C08J 3/24 (20130101); C08J
3/128 (20130101); C08J 3/28 (20130101); C09D
7/62 (20180101); Y10T 428/2982 (20150115); Y10T
428/25 (20150115); Y10T 428/2991 (20150115); Y10T
428/2995 (20150115); Y10T 428/2996 (20150115); Y10T
428/2998 (20150115); Y10T 428/2993 (20150115) |
Current International
Class: |
B32B
5/16 (20060101); C08J 3/24 (20060101); C08J
3/28 (20060101); C08J 3/215 (20060101); C08J
3/12 (20060101); C09D 7/12 (20060101) |
Field of
Search: |
;428/403,404,405,406,407
;427/212 ;528/481 ;75/343 |
References Cited
[Referenced By]
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|
Primary Examiner: Torres Velazquez; Norca L
Attorney, Agent or Firm: Choate, Hall & Stewart LLP
Lyon; Charles E.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application .Iadd.is a broadening reissue application
of U.S. application Ser. No. 11/745,377, filed May 7, 2007, now
U.S. Pat. No. 7,964,277, issued Jun. 21, 2011, which
.Iaddend.claims the benefit of and priority to International Patent
Application No. PCT/CA2006/001686 filed Oct. 13, 2006, which claims
the benefit of and priority to U.S. Provisional Patent Application
No. 60/726,184 filed Oct. 14, 2005, the entire contents of both of
which are herein incorporated by reference.
Claims
What is claimed is:
.[.1. A method for producing a nanoparticle material, comprising
the steps of: a) providing a polymeric solution comprising a
polyelectrolyte polymer material and a solvent; b) collapsing at
least a portion of the polymeric material about one or more
precursor moieties to form a composite precursor moiety; c)
cross-linking the polymeric material of said composite precursor
moiety; and d) modifying at least a portion of said precursor
moieties of said composite precursor moiety to form one or more
nanoparticles having a mean diameter in the range between about 1
nm and about 100 nm and thereby forming a composite nanoparticle;
and e) pyrolysing said composite nanoparticle to form a
nanoparticle material..].
.[.2. The method of claim 1, wherein the pyrolysis substantially
removes the polymeric material from the composite
nanoparticle..].
.[.3. The method of claim 1, wherein the pyrolysis conditions are
controlled such that the nanoparticle material formed comprises at
least a partially carbon-coated nanoparticle, wherein the carbon is
in an amorphous form..].
.[.4. A composite nanoparticle made by the method as claimed in
claim 1..].
.[.5. An at least partially carbon-coated nanoparticle made by the
method as claimed in claim 3..].
6. A composite nanoparticle having a mean diameter in the range
between about 1 nm and about 100 nm, the composite nanoparticle
comprising a nanoparticle substantially confined within a
collapsed, internally cross-linked polyelectrolyte polymer material
wherein said nanoparticle comprises a metal alloy.
7. The composite nanoparticle of claim 6, wherein said metal alloy
comprises two or more of Cd, Zn, Cu, Pb, Ag, Mn, Ni, Au, Mg, Fe,
Hg, and Pt.
8. A composite nanoparticle having a mean diameter in the range
between about 1 nm and about 100 nm, the composite nanoparticle
comprising a nanoparticle substantially confined within a
collapsed, internally cross-linked polyelectrolyte polymer material
wherein said nanoparticle comprises a metal species-containing
compound.
9. The composite nanoparticle of claim 8, wherein said metal
species-containing compound comprises one or more .[.of a.]. of a
sulphide, selenide, telluride, chloride, bromide, iodide, oxide,
hydroxide, phosphate, carbonate, sulphate, chromate and a
combination thereof.
10. The composite nanoparticle of claim 8, wherein said
nanoparticle is capable of emitting electromagnetic radiation after
the absorption of energy.
11. A composite nanoparticle having a mean diameter in the range
between about 1 nm and about 100 nm, the composite nanoparticle
comprising a nanoparticle substantially confined within an
internally cross-linked polyelectrolyte polymer material wherein
said nanoparticle comprises an elemental metal.
12. The composite nanoparticle of claim 11, wherein said elemental
metal comprises Cd, Zn, Cu, Pb, Ag, Mn, Ni, Au, Mg, Fe, Hg, or
Pt.
13. A method for producing a substrate coated with a material
comprising nanoparticles, comprising the steps of: a) i) providing
a first solution comprising a first polymeric material and a first
solvent; ii) collapsing at least a portion of the first polymeric
material about one or more first precursor moieties to form a first
composite precursor moiety having a mean diameter in the range
between about 1 nm and about 100 nm; iii) cross-linking the first
polymeric material of said first composite precursor moiety; iv)
modifying at least a portion of said first precursor moieties of
said first composite precursor moiety to form one or more first
nanoparticles and thereby forming a first composite nanoparticle
material in the first solution; b) i) providing a second solution
comprising a second polymeric material and a second solvent; ii)
collapsing at least a portion of the second polymeric material
about one or more second precursor moieties to form a second
composite precursor moiety having a mean diameter in the range
between about 1 nm and about 100 nm; iii) cross-linking the second
polymeric material of said second composite precursor moiety; iv)
modifying at least a portion of said second precursor moieties of
said second composite precursor moiety to form one or more second
nanoparticles and thereby forming a second composite nanoparticle
material in the second solution; c) contacting a substrate with at
least a portion of the first composite nanoparticle material to
form a first layer on at least a portion of the substrate; d)
contacting at least a portion of the first layer with solution
containing a first charged compound to form a second layer, the
charged compound having a charge substantially opposite to that of
the first composite nanoparticle material; and e) contacting a
substrate with at least a portion of the second composite
nanoparticle material to form a third layer on at least a portion
of the second layer.
14. The method of claim 13, wherein the first solution and the
second solution are the same solution.
15. The method of claim 13, wherein the substrate is a thin
film.
.[.16. The method of claim 13, wherein at least one of the
composite nanoparticle materials comprises CdS/PAA and at least one
of the charged compounds is poly(allylamine)..].
17. The method of claim 13, wherein one or more of the layers on
the substrate form an optically active material.
18. A method for producing a composite nanoparticle of a
nanoparticle confined within a cross-linked, collapsed
polyelectrolyte polymer material, said method comprising a)
providing said polymeric material in a suitable solvent at a
suitable concentration; b) providing an entity or a precursor
thereof said nanoparticle in said solvent; c) treating said
polymeric material in said solvent with at least one collapsing
agent to collapse said polymeric material, d) cross-linking said
collapsed polymeric material; and e) treating said entity or
precursor thereof with suitable production means to produce said
composite nanoparticle.
19. A method as claimed in claim 18 wherein said entity or a
precursor thereof said nanoparticle is said at least one collapsing
agent.
20. A method as claimed in claim 18 .[.or claim 19.]. wherein said
at least one collapsing agent comprises at least one ionic
species.
21. A method as claimed in claim 20 wherein said at least one ionic
species is said entity or a precursor thereof of said
nanoparticle.
22. A method as claimed in claim 20 wherein said collapsing agent
comprises said ionic species that is provided by a salt selected
from the group consisting of inorganic salts, organic salts, and a
combination of inorganic and organic salts.
23. A method as claimed in claim 18 wherein said production means
comprises a radiation step.
24. A method as claimed in claim 18 wherein said production means
comprises suitable chemical treatment.
25. A method as claimed in claim 24 wherein said chemical treatment
comprises a reduction or oxidation step.
26. A method as claimed in claim 24 wherein said chemical treatment
comprises addition of a suitable counter ion or precursor of said
counter ion to effect formation of said nanoparticle.
27. A method as claimed in claim 18 wherein said solvent is an
aqueous solution.
28. A method as claimed in claim 18 .[.or claim 19.]. wherein said
entity or precursor is a metal cation, complexed metal cation or
complexed metal anion and said production means comprises treating
said cation or complexed anion with radiation or an agent selected
from a reducing agent or an oxidizing agent to effect production of
said nanoparticle comprising elemental said metal.
29. A method as claimed in claim 28 wherein said precursor entity
comprises ions selected from a cation or complexed metal anions of
a plurality of metals and said production means comprises treating
said cations or complexed anions with radiation or an agent
selected from a reducing agent or an oxidizing agent to effect
production of said nanoparticle comprising an alloy of elemental
said metals.
30. A method as claimed in claim 18 wherein said polymeric material
comprises linear or branched segments comprising polyions selected
from anions, cations or combinations thereof.
31. A method as claimed in claim 18 wherein said polymeric material
comprises linear or branched segments comprising one or more
functional groups.
.[.32. A method as claimed in claim 18, wherein said polymeric
material is conjugated to molecules capable of binding to
complementary binding partners to form affinity-binding
pairs..].
.[.33. A method as claimed in claim 32, wherein the
affinity-binding pair is selected from the group consisting of
protein-protein, protein-DNA, enzyme-substrate, antigen-antibody,
DNA-DNA, DNA-RNA, biotin-avidin, hapten-antihapten and combinations
thereof..].
.[.34. A method as claimed in claim 32, wherein the molecules are
selected from the group consisting of protein, DNA ligand,
oligonucleotide, aptamer, their nanoparticles and combinations
thereof..].
.[.35. A method for producing a nanoparticle, said method
comprising pyrolysing said composite nanoparticle prepared by a
method as claimed in claim 18, wherein said nanoparticle is an
elemental metal, alloy thereof, or a metal species-containing
compound, at an effective temperature to effectively remove said
polymeric material..].
.[.36. A method for producing a wholly or partially carbon-coated
nanoparticle said method comprising incompletely pyrolysing said
composite nanoparticle prepared by a method as claimed in claim 18,
wherein said nanoparticle is selected from the group consisting of
an elemental metal, alloy thereof and a metal species-containing
compound, at an effective temperature to effect production of said
wholly or partially carbon-coated nanoparticle..].
37. A composite nanoparticle when made by a process as claimed in
claim 18.
.[.38. A nanoparticle when made by a method as claimed in claim
35..].
.[.39. A wholly or partially carbon-coated nanoparticle when made
by a method as claimed in claim 36..].
40. A composite nanoparticle comprising a nanoparticle confined
within a cross-linked collapsed polyelectrolyte polymer material
wherein said nanoparticle is selected from the group consisting of
an elemental metal, an alloy comprising .[.said.]. .Iadd.a
.Iaddend.metal with at least one other metal, and a compound
containing a metal .Iadd.or metalloid .Iaddend.species.
41. A composite nanoparticle as claimed in claim 40 wherein said
nanoparticle is selected from the group consisting of an alloy
comprising .[.said.]. .Iadd.a .Iaddend.metal with at least one
other metal, and a compound containing .[.said.]. .Iadd.a
.Iaddend.metal .Iadd.or metalloid .Iaddend.species.
42. A composite nanoparticle as claimed in claim 41 wherein said
compound containing said metal species comprises a compound
selected from the group consisting of a sulphide, selenide,
telluride, chloride, bromide, iodide, oxide, hydroxide, phosphate,
carbonate, sulphate, chromate and a combination thereof.
43. A composite nanoparticle as claimed in .[.any one of claims 40
to 42.]. .Iadd.claim 40 .Iaddend.wherein said .[.metal is selected
from Cd, Zn, Cu, Pb, Ag, Mn, Ni, Au, Mg, Fe, Hg, Pt and a
combination thereof.]. .Iadd.nanoparticle is a compound containing
a metalloid species.Iaddend..
.[.44. A composite nanoparticle as claimed in any one of claims 37
to 43, wherein said nanoparticle is capable of emitting light after
the absorption of light energy..].
.[.45. A coated substrate having a plurality of layers of composite
nanoparticles as claimed in claim 37 interspersed between adjacent
layers of oppositely charged compounds..].
.[.46. A coated substrate as claimed in claim 45 wherein said
substrate is a film..].
.[.47. A coated substrate as claimed in claim 45 wherein said
composite nanoparticle is CdS/PAA and said oppositely charged
compound is poly(allylamine)..].
.Iadd.48. A composite nanoparticle having a mean diameter in the
range between about 1 nm and about 100 nm, the composite
nanoparticle comprising a precursor moiety substantially confined
within an internally cross-linked polyelectrolyte polymer material
wherein said precursor moiety comprises an inorganic
ion..Iaddend.
.Iadd.49. The composite nanoparticle of claim 48, wherein the
inorganic ion is selected from the group consisting of copper,
iron, magnesium, manganese, molybdenum, zinc, and chlorine ions and
combinations thereof..Iaddend.
.Iadd.50. The composite nanoparticle of claim 48, wherein the
inorganic ion is a metal ion..Iaddend.
.Iadd.51. The composite nanoparticle of claim 50 wherein the metal
ion is selected from the group consisting of copper, iron,
magnesium, manganese, molybdenum, and zinc ions and combinations
thereof..Iaddend.
.Iadd.52. A composite nanoparticle having a mean diameter in the
range between about 1 nm and about 100 nm, the composite precursor
moiety comprising a precursor moiety substantially confined within
an internally cross-linked polyelectrolyte polymer material wherein
said precursor moiety comprises a chloride or sulphide and the
polyelectrolyte polymer material comprises a cationic
polymer..Iaddend.
.Iadd.53. The composite nanoparticle of claim 52 wherein the
cationic polymer is selected from the group consisting of
poly(allylamine), poly(ethyleneimine), poly(diallyldimethylammonium
chloride), poly(lysine), co-polymers thereof and combinations
thereof..Iaddend.
.Iadd.54. The method of claim 21, wherein the ionic species is an
inorganic ion..Iaddend.
.Iadd.55. The method of claim 21, wherein the ionic species is
selected from the group consisting of chloride, sulphate and
sulphide..Iaddend.
.Iadd.56. The method of claim 21, wherein the ionic species is
chloride..Iaddend.
.Iadd.57. The method of claim 54, wherein the inorganic ion is a
metal ion..Iaddend.
.Iadd.58. The method of claim 57, wherein the wherein the metal ion
is selected from the group consisting of copper, iron, magnesium,
manganese, molybdenum, and zinc ions and combinations
thereof..Iaddend.
.Iadd.59. A method for producing a cross-linked composite
nanoparticle, comprising the steps of: a) providing a polymeric
solution comprising a polyelectrolyte polymer material and a
solvent; b) providing a precursor moiety in the solvent; c)
collapsing at least a portion of the polyelectrolyte polymer
material about the precursor moiety to form a composite precursor
moiety; and d) cross-linking the polyelectrolyte polymeric material
of said composite nanoparticle..Iaddend.
.Iadd.60. The method of claim 59, wherein the collapsing is caused
by a collapsing agent..Iaddend.
.Iadd.61. The method of claim 60, wherein the collapsing agent
comprises at least one ionic species..Iaddend.
.Iadd.62. The method of claim 61, wherein said at least one ionic
species is the precursor moiety..Iaddend.
.Iadd.63. The method of claim 61, wherein the at least one ionic
species is an inorganic ion..Iaddend.
.Iadd.64. The method of claim 61, wherein the at least one ionic
species is selected from the group consisting of chloride, sulphate
and sulphide..Iaddend.
.Iadd.65. The method of claim 61, wherein the at least one ionic
species is chloride..Iaddend.
.Iadd.66. The method of claim 63, wherein the inorganic ion is a
metal ion..Iaddend.
.Iadd.67. The method of claim 66, wherein the metal ion is selected
from the group consisting of copper, iron, magnesium, manganese,
molybdenum, and zinc ions and combinations thereof..Iaddend.
Description
BACKGROUND OF THE INVENTION
Nanoparticles are nanometer-sized materials e.g., metals,
semiconductors, polymers, and the like, possessing unique
characteristics because of their small size. Nanoparticles in both
aqueous and non-aqueous solvents can be synthesized using a variety
of methods.
The conformation of a polymer in solution is dictated by various
conditions of the solution, including its interaction with the
solvent, its concentration, and the concentration of other species
that may be present. The polymer can undergo conformational changes
depending on the pH, ionic strength, cross-linking agents,
temperature and concentration. For polyelectrolytes, at high charge
density, e.g., when "monomer" units of the polymer are fully
charged, an extended conformation is adopted due to electrostatic
repulsion between similarly charged monomer units. Decreasing the
charge density of the polymer, either through addition of salts or
a change of pH, can result in a transition of extended polymer
chains to a more tightly-packed globular i.e. collapsed
conformation. The collapse transition is driven by attractive
interactions between the polymer segments that override the
electrostatic repulsion forces at sufficiently small charge
densities. A similar transition can be induced by changing the
solvent environment of the polymer. This collapsed polymer is
itself of nanoscale dimensions and is, itself, a nanoparticle. In
this specification and claims the term "collapsed polymer" refers
to an approximately globular form, generally as a spheroid, but
also as an elongate or multi-lobed conformation collapsed polymer
having nanometer dimensions. This collapsed conformation can be
rendered irreversible by the formation of intramolecular chemical
bonds between segments of the collapsed polymer, i.e. by
cross-linking.
Macromolecules, i.e. polymers with the appropriate functional
groups can undergo inter- or intra-molecular cross-linking
reactions to produce new materials or new molecules with distinct
properties, such as for example, shape, solubility, thermal
stability, and density. These reactions are important in making new
materials and various schemes for chemical reactions leading to
cross-linking are described in the literature. For example, U.S.
Pat. No. 5,783,626--Taylor et al, issued Jul. 21, 1998, describes a
chemical method to cross-link allyl-functional polymers in the form
of latexes, containing enamine moieties and pendant methacrylate
groups via a free-radical cross-linking reaction during film
formation producing coatings with superior solvent resistance and
increased thermal stability. Polymer cross-linking has also been
used to stabilize semiconductor and metal nanoparticles. U.S. Pat.
No. 6,872,450--Liu et al, issued Mar. 29, 2005, teaches a method
for stabilizing surface-coated semiconductor nanoparticles by self
assembling diblock polymers on the surface coating and
cross-linking the functional groups on the diblock polymer.
Similarly, U.S. Pat. No. 6,649,138--Adams et al, issued Nov. 18,
2003, describes how branched amphipathic dispersants coated onto
hydrophobic nanoparticles can also be cross-linked to form a
permanent cohesive over coating around the nanoparticle.
Chemical means of cross-linking can be through radical reactions of
pendant groups containing unsaturated bonds as described in
aforesaid U.S. Pat. No. 5,783,626. Another method is through the
use of molecules having multifunctional groups than can react with
the functional groups of the polymer as described in aforesaid U.S.
Pat. Nos. 6,649,138 and 6,872,450. Alternatively, cross-linking can
be achieved though high energy radiation, such as gamma
radiation.
The most common method of preparing chalcogenide semiconductor
nanocrystals is the TOP/TOPO synthesis (C. B. Murray, D. J. Norris,
and M. G. Bawendi, "Synthesis and Characterization of Nearly
Monodisperse CdE (E=S, Se, Te) Semiconductor Nanocrystallites," J.
Am. Chem. Soc., 115:8706-8715, 1993). However, this method again
involves multiple chemical steps and large volumes of expensive and
toxic organometallic metal precursors and organic solvents.
Furthermore, such nanoparticles need to be chemically modified in
order to render them soluble in aqueous solution, which is
important for a number of applications. Chalcogenide nanoparticles
have also been synthesized in aqueous solution at low temperature
using water-soluble thiols as stabilizing agents ((a) Rajh, O. L.
Mi i , and A. J. Nozik, "Synthesis and Characterization of
Surface-Modified Colloidal CdTe Quantum Dots," J. Phys. Chem., 97:
11999-12003, 1993. (b) A. L. Rogach, L. Ktsikas, A. Kornowski, D.
Su. A. Eychmuller, and H. Weller, "Synthesis and Characterization
of Thiol-Stabilized CdTe Nanocrystals," Ber. Bunsenges. Phys.
Chem., 100(11): 1772-1778, 1996. (c) A. Rogach, S. Kershaw, M.
Burt, M. Harrison, A. Komowski, A. Eychmuller, and H. Weller,
"Colloidally Prepared HgTe Nanocrystals with Strong
Room-Temperature Infrared Luminescence," Adv. Mater. 11:552-555,
1999. (d) Gaponik, N., D. V. Talapin, A. L. Rogach, K. Hoppe, E. V.
Shevchencko, A. Kornowski, A. Eychmuller, H. Weller, "Thiol-capping
of CdTe nanocrystals: an alternative to organometallic synthetic
routes," Journal of Physical Chemistry B, 2002, vol. 106, iss. 39,
p. 7177-7185. (e) A. L. Rogach, A. Kornowski, M. Gao, A.
Eychmuller, and H. Weller, "Synthesis and Characterization of a
Size Series of Extremely Small Thiol-Stabilized CdSe Nanocrystals,"
J. Phys. Chem. B. 103:3065-3069, 1999). However, this method
generally requires the use of an inert atmosphere with multiple
processing steps and production of precursor gases. Another
water-based synthesis involves the formation of undesirable
by-products that must first be removed before semiconductor
particles can be obtained (H. Zhnag, Z. Hou, B. Yang, and M. Gao,
"The Influence of Carboxyl Groups on the Photoluminescence of
Mercaptocarboxylic Acid-Stabilized Nanoparticles," J. Phys. Chem.
B, 107:8-13, 2003).
CdTe nanocrystals are known to have tunable luminescence from green
to red and have shown tremendous potential in light-emitting thin
films (A. A. Mamedov, A. Belov, M. Giersig, N. N. Mamedova, and N.
A. Kotov, "Nanorainbows: Graded Semiconductor Films from Quantum
Dots," J. Am. Chem. Soc., 123: 7738-7739, 2001), photonic crystals
(A. Rogach, A. Susha, F. Caruso, G. Sukhoukov, A. Kornowski, S.
Kershaw, H. Mohwald, A. Eychmuller, and H. Weller, "Nano- and
Microengineering: Three-Dimensional Colloidal Photonic Crystals
Prepared from Submicrometer-Sized Polystyrene Latex Spheres
Pre-Coated with Luminescent Polyelectrolyte/Nanocrystal Shells,"
Adv. Mater. 12:333-337, 2000), and biological applications (N. N.
Memedova and N. A. Kotov, "Albumin-CdTe Nanoparticle Bioconjugates:
Preparation, Structure, and Interunit Energy Transfer with Antenna
Effect," Nano Lett., 1(6):281-286, 2001). PbTe and HgTe materials
exhibit tunable emission in the infrared and look promising in the
telecommunications industry. HgTe nanoparticles have been
incorporated into more sophisticated assemblies, particularly as
components in thin-film electroluminescent devices ((a) A. L.
Rogach, D. S. Koktysh, M. Harrison, and N. A. Kotov,
"Layer-by-Layer Assembled Films of HgTe Nanocrystals with Strong
Infrared Emission," Chem. Mater., 12:1526-1528, 2000. (b) E.
O'Conno, A. O'Riordan, H. Doyle, S. Moynihan, a. Cuddihy, and G.
Redmond, "Near-Infrared Electroluminescent Devices Based on
Colloidal HgTe Quantum Dot Arrays," Appl. Phys. Lett., 86:
201114-1-20114-3, 2005. (c) M. V. Kovalenko, E. Kaufmann, D.
Pachinger, J. Roither, M. Huber, J. Stang, G. Hesser, F. Schaffler,
and W. Heiss, "Colloidal HgTe Nanocrystals with Widely Tunable
Narrow Band Gap Energies: From Telecommunications to Molecular
Vibrations," J. Am. Chem. Soc., 128:3516-3517, 2006) or solar cells
(S. Gunes, H. Neugebauer, N. S. Sariiciftci, J. Roither, M.
Kovalenko, G. Pillwein, and W. Heiss, "Hybrid Solar Cells Using
HgTe Nanocrystals and Nanoporous TiO.sub.2 Electrodes," Adv. Funct.
Mater. 16:1095-1099, 2006). PbTe, on the other hand, can be grown
in a variety of glasses at high temperatures to produce composite
materials for applications in optoelectronic devices ((a) A. F.
Craievich, O. L. Alves, and L. C. Barbosa, "Formation and Growth of
Semiconductor PbTe Nanocrystals in a Borosilicate Glass Matrix," J.
Appl. Cryst., 30:623-627, 1997. (b) V. C. S. Reynoso, A. M. de
Paula, R. F. Cuevas, J. A. Medeiros Neto, O. L. Alves, C. L. Cesar,
and L. C. Barbosa, "PbTe Quantum Dot Doped Glasses with Absorption
Edge in the 1.5 .mu.m Wavelength Region,"Electron. Lett.,
31(12):1013-1015, 1995).
Doping of CdTe with Hg results in the formation of CdHgTe composite
nanocrystals. Red shifts in absorbance/photoluminescence spectra
and enhanced PL are observed with increasing Hg content (A. L.
Rogach, M. T. Harrison, S. V. Kershaw, A. Kornowski, M. G. Burt, A.
Eychmuller, and H. Weller, "Colloidally Prepared CdHgTe and HgTe
Quantum Dots with Strong Near-Infrared Luminescence," phys. stat.
sol., 224(1):153-158, 2001). Cd.sub.1-xHg.sub.xTe alloys are
popular components in devices used for near-IR detector technology.
A variety of methods have been developed to create these materials.
U.S. Pat. No. 7,026,228--Hails et al, issued Apr. 11, 2006,
describes an approach to fabricating devices and semiconductor
layers of HgCdTe in a metal organic vapour phase epitaxy (MOVPE)
process with mercury vapor and volatile organotelluride and
organocadmium compounds. In a different approach, U.S. Pat. No.
7,060,243--Bawendi et al, issued Jun. 13, 2006, describes the
synthesis of tellurium-containing nanocrystals (CdTe, ZnTe, MgTe,
HgTe and their alloys) by the injection of organometallic precursor
materials into organic solvents (TOP/TOPO) at high temperatures.
U.S. Pat. No. 6,126,740--Schulz, issued Oct. 3, 2000, discloses
another non-aqueous method of preparing mixed-semiconductor
nanoparticles from the reaction between a metal salt and
chalcogenide salt in an organic solvent in the presence of a
volatile capping agent.
Mixtures of CdTe and PbTe have also been investigated for IR
detection in the spectral range of 3 to 5 .mu.m. However, because
these materials have such fundamentally different structures and
properties (S. Movchan, F. Sizov, V. Tetyorkin. "Photosensitive
Heterostructures CdTe--PbTe Prepared by Hot-Wall Technique,"
Semiconductor Physics, Quantum Electronics & Optoelectronics.
2:84-87, 1999. V), the preparation of the alloy is extremely
difficult. U.S. Pat. No. 5,448,098--Shinohara et al, issued Sep. 5,
1995, describes a super-conductive device based on photo-conductive
ternary semiconductors such as PbCdTe or PbSnTe. Doping of
telluride quantum dots, e.g. CdTe, with transition metals, e.g. Mn
offers the possibility of combining optical and magnetic properties
in one single nanoparticle ((a) S. Mackowski, T. Gurung, H. E.
Jackson, L. M. Smith, G. Karczewski, and J. Kossut,
"Exciton-Controlled Magnetization in Single Magnetic Quantum Dots,"
Appl. Phys. Lett. 87: 072502-1-072502-3, 2005. (b) T. Kummel, G.
Bacher, M. K. Welsch, D. Eisert, A. Forchel, B. Konig, Ch. Becker,
W. Ossau, and G. Landwehr, "Semimagnetic (Cd,Mn)Te Single Quantum
Dots--Technological Access and Optical Spectroscopy," J. Cryst.
Growth, 214/215:150-153, 2000). Unfortunately, these materials are
mostly fabricated using thin-film technologies such as molecular
beam epitaxy or chemical vapour deposition and the necessity for a
very controlled environment during growth makes these materials
inaccessible. Some mixed-metal tellurides such as CdHgTe (S. V.
Kershaw, M. Burt, M. Harrison, A. Rogach, H. Weller, and A.
Eychmuller, "Colloidal CdTe/HgTe Quantum Dots with High
Photoluminescnece quantum Efficiency at Room Temperature," Appl.
Phys. Lett., 75: 1694-1696, 1999); and CdMnTe (N. Y. Morgan, S.
English, W. Chen, V. Chemornordik, A. Russ, P. D. Smith, A.
Gandjbakhche, "Real Time In Vivo Non-Invasive Optical Imaging Using
Near-Infrared Fluorescent Quantum Dots," Acad. Radiol, 12(3):
313-323, 2005) quantum dots have been prepared in aqueous solution
which is an adaptation of the synthetic technique outlined in supra
Rajh, O. L. et al. However, all of the aforementioned methods
involve many processing steps, sophisticated equipment or large
volumes of expensive and toxic organometallic metal precursors and
organic solvents.
A simple tellurite reduction method to prepare cadmium telluride
materials has been used using sodium tellurite (Na.sub.2TEO.sub.3)
as a tellurium precursor salt with a suitable reducing agent, such
as NaBH.sub.4 with M.sup.y+ cations (H. Bao, E. Wang, and S. Dong,
"One-Pot Synthesis of CdTe Nanocrytals and Shape Control of
Luminescent CdTe-Cystine Nanocomposites," small, 2(4):476-480,
2006).
Accordingly, there is a need in the art for an environmentally
friendly, "one-pot", cost-effective, and generalizable method of
directly producing metallic, metallic alloyed, semiconductor,
oxide, and other forms of nanocomposite particles having effective
functionality in a multitude of scientific disciplines.
SUMMARY OF THE INVENTION
In various aspects, the present invention provides methods of
producing a composite nanoparticle comprising a nanoparticle
confined within a cross-linked collapsed polymeric material, which
is itself a nanoparticle.
The term "composite nanoparticle" in this specification, means a
nanoparticle substantially confined within a cross-linked,
polymeric material.
In various aspects, the present invention provides said composite
nanoparticles when made by the methods of the present
inventions.
In various aspects, the present invention provides methods for
providing non-encapsulated nanoparticles from the aforesaid
composite nanoparticles.
In various aspects, the present invention provides methods for
producing wholly or partially carbon-coated nanoparticles from said
composite nanoparticles.
In various embodiments, the present inventions teach the ability to
make a wider variety of composite nanoparticles, including oxide,
semiconductor, and more complex composite nanoparticles.
In various aspects, the present inventions provide methods for
producing a composite nanoparticle comprising the steps of:
a) providing a polymeric solution comprising a polymeric material
and a solvent;
b) collapsing at least a portion of the polymeric material about
one or more precursor moieties to form a composite precursor moiety
having a mean diameter in the range between about 1 nm and about
100 nm;
c) cross-linking the polymeric material of said composite precursor
moiety; and
d) modifying at least a portion of said precursor moieties of said
composite precursor moiety to form one or more nanoparticles and
thereby forming a composite nanoparticle.
"Confined" in this specification means that the nanoparticle is
substantially within the limits of the collapsed polymer's
dimensions and includes, but is not limited to, the situation
wherein portions of the polymer may be strongly interacting with
the nanoparticle within the polymer dimensions.
As used herein, the term "precursor moiety" refers to a compound or
entity at least a portion of which is a component of the eventual
nanoparticle formed and includes nanoparticle precursors.
A polymeric material of use in the practice of the present
inventions can be any molecule capable of collapse that contains
units of monomers, that can be synthetic or naturally occurring and
can be linear, branched, hyperbranched, or dendrimeric.
Non-limiting examples of suitable polymeric materials are discussed
in the various examples, which include, but are not limited to,
poly(diallyldimethylammonium chloride) (PDDA), and polyacrylic acid
(PAA), poly(styrene sulfonic acid) (PSS),
It also can be any polymer containing ionized or ionizable moieties
along its length and is of sufficient length such that the
collapsed form has nanometer dimensions. The collapsed form can be
of different morphologies, such as, for example, spherical,
elongated, or multi-lobed. The dimensions in any direction are
anywhere from 0.1 to 100 nm, and preferably 1-50 nm.
A wide variety of solvents can be used to form a polymeric solution
of use in the present inventions. In various embodiments, the
polymeric solution is preferably an aqueous solution.
In preferred embodiments of the present inventions, a chosen
polymer is dissolved in a suitable solvent to form a solution of
the polymer. The solvent can be water, an organic solvent or a
mixture of two or more such solvents. The addition to the solution
of the collapsing agent induces a collapse of the polymer which
substantially surrounds, e.g., confines, a precursor moiety. The
collapsing agent can itself be the precursor moiety. The chosen
confined agent, for example a precursor moiety, can be, e.g., an
organic or inorganic charged ion or a combination thereof. For
example, the confined agent can be an ion from an organic salt, an
inorganic salt, or an inorganic salt that is water soluble where
the water soluble inorganic salt is of the form M.sub.xA.sub.y
where M is a metal cation belonging to Groups I to IV of the
Periodic Table possessing a charge +y and A is the counter ion to M
with a charge -x or a combination thereof. The confined agent could
further comprise a mixture of ions from at least two inorganic
salts.
Collapsing agents are usually water-soluble inorganic salts, most
preferably, those that contain metal cations and their
corresponding anions, both of which are known to induce a
collapse-transition for certain polymeric materials. Non-limiting
examples are Cd(NO.sub.3).sub.2, Zn(NO.sub.3).sub.2, Cu(SO.sub.4),
Pb(NO.sub.3).sub.2, Pb(CH.sub.3COO).sub.2, Ag(NO.sub.3),
Mn(SO.sub.4), Ni(NO.sub.3).sub.2.
A variety of techniques can be used to collapse the polymeric
material around a precursor moiety. For example, in various
embodiments a collapsing agent such as a different solvent, an
ionic species (e.g., a salt); or combinations thereof can be used.
In various embodiments, it is preferred that the precursor moiety
itself serve as a collapsing agent. Multiple collapsing agents can
be used.
In various embodiments the at least one collapsing agent preferably
comprises at least one ionic species. Preferably, in various
embodiments, the at least one ionic species is a precursor
moiety.
In various embodiments, the precursor moiety comprises at least one
metal cation, complexed metal cation, or complexed metal anion. In
various embodiments where the precursor moiety comprises a metal
cation, complexed metal cation, or complexed metal anion, the
modifying step (production means) comprises treating the cation,
complexed cation, or complexed anion with .gamma.-radiation or an
agent selected from a reducing agent or an oxidizing agent to
effect production of the nanoparticle comprising elemental metal
confined within the cross-linked, collapsed polymeric material.
In various embodiments, the precursor moiety comprises two or more
different metals. In various embodiments where the precursor moiety
comprises two or more different metals, the modifying step
comprises forming an alloy of two or more of the two or more
metals.
In various embodiments, the precursor moiety comprises ions
selected from a cation, complexed cations, or complexed metal
anions of a plurality of metals and the modifying step comprises
treating the cations or complexed anions with radiation, for
example, .gamma.-radiation, or an agent selected from a reducing
agent or an oxidizing agent to effect production of the
nanoparticle comprising an alloy of said metals, confined within
the cross-linked collapsed polymeric material.
In various embodiments, the precursor moiety comprises a metal
species-containing compound.
By the term "metal species-containing compound" is meant a compound
containing a metal or metalloid in any valence state.
In various embodiments of the present inventions having an
elemental metal, alloy comprising a metal, or a metal
species-containing compound, the metal is preferably Cd, Zn, Cu,
Pb, Ag, Mn, Ni, Au, Mg, Fe, Hg, Pt or a combination thereof.
In various embodiments of the present inventions having a metal
species-containing compound, said compound containing said metal
species preferably comprises one or more of a sulphide, selenide,
telluride, chloride, bromide, iodide, oxide, hydroxide, phosphate,
carbonate, sulphate, chromate and a combination thereof.
In various embodiments, a composite precursor moiety formed by a
method of the present inventions has a mean diameter in the range
between about 1 nanometer (nm) to about 100 nm. In various
embodiments, the composite precursor moiety has a mean diameter in
one or more of the ranges between: (a) about 1 nm to about 10 nm;
(b) about 10 nm to about 30 nm; (c) about 15 nm to about 50 nm; and
(d) about 50 nm to about 100 nm). It is to be understood that the
term "mean diameter" is not meant to imply any sort of specific
symmetry (e.g., spherical, ellipsoidal, etc.) of a composite
precursor moiety. Rather, the composite precursor moiety could be
highly irregular and asymmetric.
The formation of intra-molecular covalent bonds that effects the
cross-linking of the polymeric material can be induced either by
chemical means or by irradiation. Chemical means of cross-linking
can also be achieved through the use of multi-dentate molecules as
cross-linkers. These molecules contain multiple functional groups
that are complementary to, and, therefore, can form covalent bonds
with the functional groups on the polyelectrolyte polymeric
material. These molecules can be linear, branched, or dendrimeric.
For example, a molecule containing multiple amine groups, such as
2,2'-ethylenedioxydiethylamine can effect the intramolecular
cross-linking of collapsed poly(acrylic acid). The cross-linking
reaction in this case is promoted by the addition of an activating
agent, typically used for amide bond formation, such as a
carbodiimide.
The chemical cross-linking can be carried out to derivatize the
polymer, such that a fraction of the ionizable groups are converted
to groups that can be cross-linked through free-radical reactions.
An example is to convert some of the carboxylic acid groups of
poly(acrylic acid) to allyl esters. The allyl groups can then be
reacted to form intramolecular bonds through radical chemistry.
Cross-linking by irradiation can be effected by exposing a solution
of the collapsed polymer to an electromagnetic radiation source.
The radiation source can be, for example, an excimer laser, a
mercury arc lamp, a light emitting diode, UV germicidal lamp
radiation or gamma rays.
A variety of techniques can be used in the present inventions to
modify at least a portion of said precursor moieties of said
composite precursor moiety to form one or more nanoparticles and
thereby form a composite nanoparticle. These techniques are also
referred to as "production means" herein since they are used in the
production of the nanoparticle.
Suitable techniques for modifying a precursor moiety to form the
desired nanoparticle include, but are not limited to, exposure to
electromagnetic radiation, chemical treatment, and combinations
thereof. Examples of suitable electromagnetic radiation exposure,
include, for example .gamma.-radiation, ultraviolet radiation,
infrared radiation, etc. In various embodiments, the
electromagnetic radiation is coherent radiation, such as provided,
e.g., by a laser, in others it is incoherent, such as provided,
e.g., by a lamp. Examples of chemical treatments include, but are
not limited to, contacting with an oxidizing agent, contacting with
a reducing agent, addition of at least one counter ion, a compound
containing the counter ion, or a precursor to the counter ion,
where the counter ion is a counter ion with respect to the
precursor moiety or a portion thereof. Generally, modification of
the precursor moiety results in the formation of a nanoparticle
that is no longer soluble within the solvent of the polymeric
solution.
Reaction either by reduction or oxidation of the ions, ionic
precursor moieties, within the cross-linked polymeric material to
form the composite nanoparticles can be effected through chemical,
electrochemical, or photochemical means.
The resultant nanoparticles can be, for example, semiconductor
crystals, including, but not limited, to CdS, CdSe, CdTe, ZnS,
ZnSe, ZnTe, PbS, PbSe, PbTe, CuI, HgS, HgSe, and HgTe. The
nanoparticles can also be metal alloys.
In various embodiments, a composite nanoparticle formed by a method
of the present inventions has a mean diameter in the range between
about 1 nanometer (nm) to about 100 nm. In various embodiments, the
composite nanoparticle has a mean diameter in one or more of the
ranges between: (a) about 1 nm to about 10 nm; (b) about 10 nm to
about 30 nm; (c) about 15 nm to about 50 nm; and (d) about 50 nm to
about 100 nm). It is to be understood that the term "mean diameter"
is not meant to imply any sort of specific symmetry (e.g.,
spherical, ellipsoidal, etc.) of a composite nanoparticle. Rather,
the composite nanoparticle could be highly irregular and
asymmetric.
In various embodiments, the nanoparticle, formed from a precursor
moiety, comprises an alloy of two or more different metals. In
various embodiments where the precursor moiety comprises two or
more different metals, the modifying step comprises forming an
alloy of two or more of the two or more metals.
In various embodiments, the nanoparticle, formed from a precursor
moiety, comprises a metal species-containing compound. By the term
"metal species-containing compound" is meant a compound containing
a metal or metalloid in any valence state.
In various embodiments of the present inventions having an
elemental metal, alloy comprising a metal, or a metal
species-containing compound, the metal is preferably Cd, Zn, Cu,
Pb, Ag, Mn, Ni, Au, Mg, Fe, Hg, Pt or a combination thereof.
In various embodiments of the present inventions having a metal
species-containing compound, said compound containing said metal
species preferably comprises one or more of a sulphide, selenide,
telluride, chloride, bromide, iodide, oxide, hydroxide, phosphate,
carbonate, sulphate, chromate and a combination thereof.
In various aspects, the present inventions provide methods for
producing a nanoparticle material, comprising the steps of: (a)
providing a polymeric solution comprising a polymeric material and
a solvent; (b) collapsing at least a portion of the polymeric
material about one or more precursor moieties to form a composite
precursor moiety; (c) cross-linking the polymeric material of said
composite precursor moiety; and (d) modifying at least a portion of
said precursor moieties of said composite precursor moiety to form
one or more nanoparticles having a mean diameter in the range
between about 1 nm and about 100 nm and thereby forming a composite
nanoparticle; and (e) pyrolysing said composite nanoparticle to
form a nanoparticle material. In various embodiments, the pyrolysis
conditions are controlled such that the nanoparticle material
formed comprises at least a partially carbon-coated
nanoparticle
In various embodiments, the present inventions provide methods for
producing a metal nanoparticle, comprising pyrolysing the composite
nanoparticle prepared by a method of the present inventions
described herein, wherein the metal nanoparticle is an elemental
metal, an alloy comprising the metal with at least one other metal,
or a metal species-containing compound, at a temperature to
effective to substantially remove the polymeric material.
In various embodiments, the present inventions provide methods for
producing a carbon-coated metal nanoparticle comprising
incompletely pyrolysing the composite nanoparticle prepared by a
method of the present inventions described herein, wherein the
metal nanoparticle is selected from an elemental metal, an alloy
comprising the metal with at least one other metal, and a metal
species-containing compound, at a temperature to effect production
of the carbon-coated metal nanoparticle.
In various aspects, the present inventions provide composite
nanoparticles when made by a method or process of one of the
inventions described herein.
In various aspects, the present inventions provide non-confined and
wholly or partially carbon-coated metal nanoparticles when made by
methods of the present inventions described herein.
Various embodiments of the present inventions can be of value in
the production of semiconductor nanoparticles, including, for
example, quantum dots such as CdSe, CdS, CdTe, and others. Various
embodiments of the present inventions can be of value in the
production of complex salts, such as LiFePO.sub.4, and oxide
particles, such as Fe.sub.2O.sub.3.
Accordingly, in an various embodiments, the precursor moiety
comprises at least one metal cation, complexed metal cation, or
complexed metal anion, and the production means (modifying step)
comprises treating the metal cation, complexed cation, or complexed
anion with a suitable counterion or precursor thereof to effect
production of the composite nanoparticle comprising a metal
species-containing compound.
In various embodiments, the precursor moeity comprises an anion,
and the modifying step (production means) comprises treating the
anion with a suitable metal counterion or precursor thereof to
effect production of the composite nanoparticle comprising a metal
species-containing compound.
In various aspects, the modifying step comprises use of a suitable
counterion or precursor thereof to effect production of a
semiconductor nanoparticle or composite nanoparticle.
In a various aspects, the modifying step comprises use of a
suitable counterion or precursor thereof to effect production of a
composite nanoparticle comprising a complex salt.
In a various aspects, modifying step comprises use of a suitable
counterion or precursor thereof to effect production of a
nanoparticle comprising a hydroxide. In a preferred aspect, the
hydroxide may be subsequently heated to convert the hydroxide to an
oxide.
The aforesaid composite nanoparticles comprising a metal
species-containing compound, a complex salt, hydroxide, or oxide, a
semiconductor entity, can be, in various embodiments, effectively
pyrolysed to substantially remove the polymeric material, or to
only partially remove the polymeric material to produce, for
example, a wholly or partially carbon-coated nanoparticle.
Thus, various embodiments of the present inventions relate to
methods of making composite nanoparticles and nanoparticles that
may have a wide variety of applications in a variety of sectors,
including, but not limited to, biology, analytical and
combinatorial chemistry, catalysis, energy and diagnostics. By
utilizing starting materials that are readily soluble in water, the
present inventions, in various embodiments, can provide
nanoparticles and composite nanoparticles having unique
characteristics applicable in the aforesaid sectors, which
nanoparticles may be water soluble.
The synthesis routes of various embodiments of the present
inventions, include, but are not limited to, synthesis in a "one
pot" system in an aqueous medium. The particle size can be
controlled, for example, by varying the molecular weight of the
polymer, the degree of internal cross-linking, solution conditions
and the amount of collapsing agent added. The polymer coat can be
chosen to have desirable functional groups that can impart
desirable properties, for example, having the capability for
attachment to molecules, such as proteins or to enhance or decrease
the sticking to substrates.
In various embodiments, the present inventions provide methods for
making water-dispersable composite nanoparticles with inherent
chemical functional groups that can be reacted with complementary
functional groups on other molecules. Water-dispersable, in this
context, refers to the formation of composite nanoparticles that
can be prevented from aggregation in aqueous solution through
adjustment of solution conditions.
In various embodiments, the methods of the present inventions
provide a composite nanoparticle having at least one confined agent
substantially surrounded by a polymeric material which polymer can
be either a linear or branched polyanion or polycation or a
combination thereof.
In preferred embodiments of the present inventions, a chosen
polymer is dissolved in a suitable solvent to form a solution of
the polymer. The solvent can be water, an organic solvent or a
mixture of two or more such solvents. The addition to the solution
of the collapsing agent induces a collapse of the polymer which
substantially surrounds, e.g., confines the agent therein. The
chosen confined agent can be an organic or inorganic charged ion or
a combination thereof. For example, the confined agent can be an
ion from an organic salt, an inorganic salt, or an inorganic salt
that is water soluble where the water soluble inorganic salt is of
the form M.sub.xA.sub.y where M is a metal cation belonging to
Groups I to IV of the Periodic Table possessing a charge +y and A
is the counter ion to M with a charge -x or a combination thereof.
The confined agent could further comprise a mixture of ions from at
least two inorganic salts.
In various embodiments, to retain the conformation of the collapsed
polymer, cross-linking of the collapsed polymer is achieved by
exposing the polymer to .gamma.-radiation or UV radiation.
Preferably, the UV radiation is UV laser radiation or UV arc lamp
radiation. In various embodiments, the intra-molecular cross-links
of the intra-molecular cross-linking process are chemically
produced, for example, with carbodiimide chemistry with a
multifunctional cross-linker.
One preferred embodiment of the present inventions involves the
formation of composite nanoparticles by the addition of ions that
induce precipitate formation of the confined agent within the
collapsed polymeric material, wherein the collapsed polymer is
intra-molecularly cross-linked. As used herein, "precipitation" of
a confined ion refers to modification of the ion to a compound that
is substantially insoluble in the solvent of the polymeric
solution.
Various preferred embodiments of the aspects of the present
inventions include, but are not limited to, using polymers
dissolved in a solvent, usually water, so as to make a dilute
solution. Polymers with ionizable groups, for example, NH.sub.2,
RNH, and COOH can be chosen because of their water-solubility under
appropriate solution conditions and their ability to undergo a
collapse transition when exposed to certain concentrations of ions
in solution, usually through addition of an inorganic salt. The
collapse of the polymer brings about the confinement of some of the
ions within a collapsed polymeric structure. In order to make the
collapsed conformation of the polymers permanent,
intra-macromolecular bond formation is facilitated either through
radiation exposure, through the use of chemical cross-linkers, or
both. In various embodiments, the collapsed intra-molecular,
cross-linked polymer have some of the ions from an inorganic salt
confined within the collapsed structure as the basis for the
formation of the composite nanoparticle. The confined ions, for
example, can be reduced, oxidized, and/or reacted (e.g. by
precipitation with an external agent), which results in the
formation of the composite nanoparticle of the inner nanoparticle
confined within the collapsed intra-molecular cross-linked
polymeric material. Un-reacted ionizable groups, for example, can
serve as future sites for further chemical modification, dictate
the particles solubility in different media, or both.
An ionizable moiety or group is any chemical functional group that
can be rendered charged by adjusting solution conditions, while
ionized moieties refers to chemical functional groups that are
charged regardless of solution conditions. The ionized or ionizable
moiety or group can be either cationic or anionic, and can be
continuous along an entire chain as in the case of regular
polymers, or can be interrupted by blocks containing different
functional groups, as in the case of block polymers.
In various embodiments, a preferred cationic group is the amino
group and preferred anionic groups are carboxylic acid, sulfonic
acid, phosphates, and the like. For cationic polymers, examples are
poly(allylamine), poly(ethyleneimine) poly(diallyldimethylammonium
chloride, and poly(lysine). For anionic polymers, examples are
poly(acrylic acid), poly(styrene sulfonic acid), poly(glutamic
acid), etc. Block polymers are made up of blocks of polymers having
different functional groups. The block polymers can be made up of
blocks of any of the mentioned anionic and cationic polymers and
another polymer that imparts a specific desirable property to the
block polymer.
In various embodiments, functional groups of the polymeric material
can be used for conjugating the composite nanoparticles to other
molecules containing complementary functional groups. These
molecules can be any member of affinity-binding pairs such as
antigen-antibody, DNA-protein, DNA-DNA, DNA-RNA, biotin-avidin,
hapten-antihapten, protein-protein, enzyme-substrate and
combinations thereof. These molecules can also be protein, ligand,
oligonucleotide, aptamer, carbohydrate, lipid, or other
nanoparticles. An example is the conjugation of poly(acrylic
acid)-encased nanoparticles to proteins through amide bond
formation between amine groups on proteins and the carboxylic acid
groups on poly acrylic acid (PAA).
A fraction of the functional groups of the polyelectrolyte polymer
can also be modified to convert them to other functional groups
that can be used for conjugation. For example, a hetero
bi-functional molecule containing an amine group and a latent thiol
group can be reacted with poly(acrylic acid)-encased nanoparticles
through amide bond formation thereby converting the carboxylic acid
to a thiol group. The thiol group can be used for conjugation to
other molecules containing thiol-reactive groups.
The wide variety of potential applications for the composite
nanoparticles and nanoparticles, produced by the methods of the
present invention include, but are not limited to, the absorption
of light energy selected from the group consisting of UV, visible,
and IR light, wherein the composite nanoparticle or nanoparticle
are used as pigments or are incorporated into an optical device. In
various embodiments, after absorbing light energy the composite
nanoparticle may be capable of emitting light.
In various embodiments of the present inventions, provided are
methods wherein the polymeric material is conjugated to molecules
containing functional groups for binding to complementary binding
partners to form an affinity-binding pair selected from the group
having an enzyme-substrate, antigen-antibody, DNA-DNA, DNA-RNA,
biotin-avidin, hapten-antihapten and combinations thereof.
Preferably, the molecules are selected from the group consisting of
protein, ligand, oligonucleotide, aptamer, and other
nanoparticles.
In various embodiments, a composite nanoparticle of the present
inventions may be used, e.g., to enhance spectroscopic techniques,
including vibrational spectroscopy.
In various embodiments, provided are methods wherein the composite
nanoparticles are further assembled on a surface of a substrate
using layer-by-layer assembly or further aggregated into
three-dimensional systems of composite nanoparticles, whereby the
three-dimensional systems are created on a surface. In various
embodiments this substrate is a film.
Accordingly, in various aspects the present inventions provide a
coated substrate having a plurality of layers of composite
nanoparticles as herein a described interspersed between adjacent
layers of oppositely charged compounds.
In various embodiments, a coated substrate as herein described is
preferably coated, with a composite nanoparticle of CdS/PAA and the
oppositely charged compound is poly(allylamine) hydrochloride
(PAH).
In various embodiments, the present inventions provide use of a
composite nanoparticle as herein described in the production of a
multi-layered coated substrate. This substrate could be of value,
for example, as one or more of: (a) a solid substrate comprising
catalytic or otherwise reactive nanoparticles; and (b) an optical
filter or as an element in an optical device where the incorporated
composite nanoparticles have useful properties.
In various embodiments, the compounds according to the present
inventions could be of value as semiconductor materials, for
example, as quantum dots.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other aspects, embodiments, objects, features and
advantages of the present inventions can be more fully understood
from the following description in conjunction with the accompanying
drawings. In the drawings, like reference characters generally
refer to like features and structural elements throughout the
various figures. The drawings are not necessarily to scale,
emphasis instead being placed upon illustrating the principles of
the present inventions, wherein.
FIG. 1 represents UV-Vis absorption spectra of CdS/PAA composite
nanoparticles prepared according to Example 13;
FIG. 2 represents emission spectra of different CdS/PAA composite
nanoparticles prepared according to Example 13;
FIG. 3 represents STEM image of CdS/PAA composite nanoparticles
prepared according to Example 13;
FIG. 4 represents uv-vis absorption and emission spectra of
CdSe/PAA composite nanoparticles prepared according to Example
14;
FIG. 5 represents uv-vis absorption and emission spectra of
(CdSe--CdS)/PAA composite nanoparticles prepared according to
Example 15;
FIG. 6 represents uv-vis absorption and emission spectra of
CdTe/PAA composite nanoparticles prepared according to Example
16;
FIG. 7 represents uv-vis absorption and emission spectra of
(CdTe--ZnS)/PAA composite nanoparticles produced according to
Example 17;
FIGS. 8(a)-8(c) represent STEM with EDX analysis of
LiFePO.sub.4/PAA composite nanoparticles produced according Example
18;
FIG. 9 represents a XRD pattern of LiFePO.sub.4/PAA composite
nanoparticles produced according Example 18;
FIGS. 10(a)-10(c) represents STEM with EDX analysis of
Fe.sub.2O.sub.3/PAA composite nanoparticles produced according
Example 19;
FIG. 11 represents an XRD x-ray diffraction pattern of
Fe.sub.2O.sub.3/PAA composite nanoparticles produced according to
Example 19;
FIG. 12 represents STEM image of ZnO/PAA composite nanoparticles
made according to Example 20;
FIG. 13 represents uv-vis absorbance and emission spectra of
ZnO/PAA composite nanoparticles made according to Example 20;
FIG. 14 represents emission spectra of both CdS/PAA composite
nanoparticles coated and non-coated polystyrene prepared according
to Example 21;
FIG. 15 represents uv-vis absorption spectra of Ag/PAA composite
nanoparticles produced according to Example 22;
FIG. 16 represents a STEM image of Ag/PAA composite nanoparticles
produced according to Example 22;
FIG. 17 represents uv-vis absorption spectra of Au/PAA composite
nanoparticles produced according to Example 23;
FIG. 18 represents STEM image of Au/PAA composite nanoparticles
produced according to Example 23;
FIG. 19 represents uv-vis spectra of (Au, Ag)/PAA composite
nanoparticles produced according to Example 24;
FIGS. 20(a)-20(c) represent STEM with EDX analysis image of (Au,
Ag)/PAA composite nanoparticles produced according to Example
24;
FIG. 21 represents uv-vis and emission spectra of CdS/PSS composite
nanoparticles produced according to Example 27;
FIG. 22 represents uv-vis and emission spectra of CdS/PDDA
composite nanoparticles produced according to Example 28; and
FIG. 23 represents absorbance and emission spectra of CdPbTe/PAA
composite nanoparticles produced according to Example 36 according
to the present invention;
FIG. 24 absorbance and emission spectra of CdZnTe/PAA composite
nanoparticles produced according to Example 37 according to the
invention; and
FIG. 25 absorbance and emission spectra of CdMnTe/PAA composite
nanoparticles produced according to Example 38 according to the
present invention.
DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS
Examples
In the following examples, the term
(a) "M.sup.y+/polymer refers to the collapsed polymeric material
with the metal cation M.sup.y+, wherein M is the stated metal in
the example; and
(b) A.sup.x-/polymer refers to the collapsed polymeric material
collapsed with the anion A.sup.x-.
In the case of multiple cations or anions used to collapse a single
polymer, the different metal cations and anions will be separated
by a comma "," as in the case (M.sub.1.sup.y1+, M.sub.2.sup.y2, etc
. . . )/Polymer and (A.sub.1.sup.x1-, A.sub.2.sup.x2-, etc . . .
)/Polymer (e.g. Cd.sup.2+/PAA, Cl.sup.-/PDDA, etc.). Nanoparticles
formed from the metal ions will be designated as M.sub.1 x1 A.sub.1
y1/Polymer (e.g. CdS/PAA, (CdS, PbS)/PAA, etc). Nanoparticles
formed from the metal ions that have been treated with another
agent to form a different material will be designated by a "-" as
in (M.sub.1 x1 A.sub.1 y1-M.sub.2 y2 A.sub.2 y2)/Polymer (e.g.
(CdSe--CdS)/PAA, (CdTe--ZnS)/PAA, etc).
Example 1
Polycation Collapse with (-1) Anion
In a plastic 400.0 ml beaker, 3.0 ml of
poly(diallyldimethylammonium chloride) (PDDA) [Sigma, Average
M.sub.w 400-500K, 20 wt % in water] was diluted to 300 ml with
deionized water. The solution was stirred for 10 minutes. 5.0 ml
aliquots were obtained, and placed in 20 ml scintillation vials. To
each was added dropwise with vigorous stirring 5.0 ml of aqueous
NaCl solutions of different concentrations (2 mM-60 mM) yielding 10
mL of Cl.sup.-/PDDA solutions with different [Cl.sup.-] between 1
and 50 mM and a final PDDA concentration of 1 mg/ml. The relative
viscosity of each solution was measured with an Ostwald viscometer.
The viscosity as a function of NaCl concentration changed suddenly
at approximately 10 mM; this was taken as the PDDA collapse point
with Cl.sup.-, such that at lower concentrations, the PDDA is
primarily in an extended configuration.
Example 2
Polycation Collapse with (-2) Anion
In a plastic 400.0 ml beaker, 3.0 ml of
poly(diallyldimethylammonium chloride) (PDDA) [Sigma, Average
M.sub.w 400-500K, 20 wt % in water] was diluted to 300 ml with
deionized water. The solution was stirred for 10 minutes. 5.0 ml
aliquots were obtained, and placed in 20 ml scintillation vials. To
each was added dropwise with vigorous stirring 5.0 ml of aqueous
Na.sub.2SO.sub.4 solutions of different concentrations (2 mM-20 mM)
yielding 10 mL of SO.sub.4.sup.2-/PDDA solutions with different
[SO.sub.4.sup.2-] between 1 and 10 mM and a final PDDA
concentration of 1 mg/ml. The relative viscosity of each solution
was measured with an Ostwald viscometer. The viscosity as a
function of Na.sub.2SO.sub.4 concentration changed suddenly at
approximately 3 mM; this was taken as the PDDA collapse point with
SO.sub.4.sup.2-, such that at lower concentrations, the PDDA is
primarily in an extended configuration.
Example 3
Polycation Collapse with (-3) Anion
In a plastic 400.0 ml beaker, 15 ml of poly(diallyldimethylammonium
chloride) (PDDA) [Sigma, Average M.sub.w 400-500K, 20 wt % in
water] was diluted to 300 ml with deionized water. The solution was
stirred for 10 minutes. 5.0 ml aliquots were obtained, and placed
in 20 ml scintillation vials. To each was added dropwise with
vigorous stirring 5.0 ml of aqueous Na.sub.3PO.sub.4 solutions of
different concentrations (2 mM-50 mM) yielding 10 mL of
PO.sub.4.sup.3-/PDDA solutions with different [PO.sub.4.sup.3-]
between 1 and 25 mM and a final PDDA concentration of 5 mg/ml. The
relative viscosity of each solution was measured with an Ostwald
viscometer. The viscosity as a function of Na.sub.2SO.sub.4
concentration changed suddenly at approximately 2 mM; this was
taken as the PDDA collapse point with PO.sub.4.sup.3-, such that at
lower concentrations, the PDDA is primarily in an extended
configuration.
Example 4
Polyanion Collapse with (+1) Cation
In a 400 ml plastic beaker, 400.0 mg of (PAA) (Sigma, Average Mv
1.2 million) was dissolved in 200 ml deionized water. The plastic
beaker was immersed in a hot water bath (approximately
80-90.degree. C.) and was stirred vigorously for at least 30
minutes or until all of the solid PAA has dissolved. Once the
solution has cooled to room temperature, the pH was adjusted to 6.8
using 0.1 M NaOH. pH measurements were done using narrow range pH
paper. 5 ml aliquots of the pH adjusted PAA were obtained and to
each was added 5.0 ml aliquots were obtained, and placed in 20 ml
scintillation vials. To each was added dropwise with vigorous
stirring 5.0 ml of aqueous NaCl solutions of different
concentrations (0.2 mM-10.0 mM) yielding 10 mL of Na.sup.+/PDDA
solutions with different [Na.sup.+] between 0.1 mM and 5.0 mM and a
final PAA concentration of 1 mg/ml. The relative viscosity of each
solution was measured with an Ostwald viscometer. The viscosity as
a function of NaCl concentration changed suddenly at approximately
2 mM; this was taken as the PAA collapse point with Na.sup.+, such
that at lower concentrations, the PAA is primarily in an extended
configuration.
Example 5
Polyanion Collapse with (+2) Cation
In a 400 ml plastic beaker, 400.0 mg of PAA (Sigma, Average M.sub.w
1.2 million) was dissolved in 200 ml deionized water. The plastic
beaker was immersed in a hot water bath (approximately
80-90.degree. C.) and was stirred vigorously for at least 30
minutes or until all of the solid PAA has dissolved. Once the
solution has cooled to room temperature, the pH was adjusted to 6.8
using 0.1 M NaOH. pH measurements were done using narrow range pH
paper. 5 ml aliquots of the pH adjusted PAA were obtained and to
each was added 5.0 ml aliquots were obtained, and placed in 20 ml
scintillation vials. To each was added dropwise with vigorous
stirring 5.0 ml of aqueous Cd(NO.sub.3).sub.2 solutions of
different concentrations (0.1 mM-6.0 mM) yielding 10 mL of
Cd.sup.2+/PAA solutions with different [Cd.sup.2+] between 0.1 mM
and 3.0 mM and a final PAA concentration of 1 mg/ml. The relative
viscosity of each solution was measured with an Ostwald viscometer.
The viscosity as a function of Cd(NO.sub.3).sub.2 concentration
changed suddenly at between 1-2 mM; this was taken as the PAA
collapse point with Cd.sup.2+, such that at lower concentrations,
the PAA is primarily in an extended configuration. Addition of more
Cd(NO.sub.3).sub.2 such that the final concentration >2 mM
caused a white precipitate to form. Solutions with a final
concentration of 1.2 mM Cd(NO.sub.3).sub.2 and approx 0.7 mg/ml PAA
were then prepared for use in subsequent examples below; this
solution is referred to as Cd.sup.2+/PAA in this work.
Example 6
Polyanion Collapse with (+3) Cation
In a 400 ml plastic beaker, 400.0 mg of poly(styrene sulfonic acid)
(PSS) (Alfa Aesar, Average M.sub.W 1 million) was dissolved in 200
ml deionized water. 5 ml aliquots of the PSS solution were
obtained, and placed in 20 ml scintillation vials. To each was
added dropwise with vigorous stirring 5.0 ml of aqueous solutions
containing FeCl.sub.3 of different concentrations (0.2 mM-20.0 mM)
yielding 10 mL of Fe.sup.3+/PDDA solutions with different
[Fe.sup.3+] between 0.1 mM and 10.0 mM and a final PSS
concentration of 1 mg/ml. The relative viscosity of each solution
was measured with an Ostwald viscometer. The viscosity as a
function of FeCl.sub.3 concentration changed suddenly at
approximately 2 mM; this was taken as the PSS collapse point with
Fe.sup.3+ such that at lower concentrations, the PSS is primarily
in an extended configuration.
Example 7
Polyanion Collapse with 2 Cations
In a 400 ml plastic beaker, 400.0 mg of PAA (Sigma, Average M.sub.V
1.2 million) was dissolved in 200 ml deionized water. The plastic
beaker was immersed in a hot water bath (approximately
80-90.degree. C.) and was stirred vigorously for at least 30
minutes or until all of the solid PAA has dissolved. Once the
solution had cooled to room temperature, the pH was adjusted to 6.8
using 0.1 M NaOH. pH measurements were done using narrow range pH
paper. 5.0 ml aliquots were obtained, and placed in 20 ml
scintillation vials. To each was added dropwise with vigorous
stirring 5.0 ml of aqueous solutions containing FeCl.sub.2 and LiCl
at a mole ratio of (2:1) of different concentrations* (0.2 mM-8.0
mM) yielding 10 mL of (2Fe.sup.2+, Li.sup.+)/PAA solutions with
different [2Fe.sup.2+, Li.sup.2+] between 0.1 mM and 4.0 mM and a
final PAA concentration of 1 mg/ml. The relative viscosity of each
solution was measured with an Ostwald viscometer. The viscosity as
a function of FeCl.sub.2 and LiCl concentration changed suddenly at
approximately 0.3 mM; this was taken as the PAA collapse point with
2Fe.sup.2+, Li.sup.+ such that at lower concentrations, the PAA is
primarily in an extended configuration. *concentrations refer to
the total concentration of both metal ions combined
Example 8
Preparation of Cd.sup.2+/PAA Crosslinked Composite Nanoparticles
According to the Invention Using Mercury Arc Lamp
A solution of Cd.sup.2+/PAA was prepared by dropwise addition of 10
ml of 0.005M Cd(NO.sub.3).sub.2 solution to 10 ml of 2 mg/ml
aqueous solution of PAA (Sigma, Ave M.sub.w 1.2 million PAA, pH
adjusted to 6.8 with 0.1 M NaOH). The solution was exposed to light
from a 200 W mercury arc lamp for approximately 1 hour to effect
collapse, while undergoing vigorous stirring. The irradiated
solution was then dialyzed against deionized water for 3 hours. The
dialysis is expected to substantially reduce the concentration of
ions in solution, thus reversing the polymer collapse. However, it
was found that the solution viscosity remains unchanged (still
low), indicating that the collapsed configuration is retained, and
that the collapsed polymer has been crosslinked to remain in the
collapsed configuration. An aliquot of the solution was cast onto
mica and allowed to air dry. Atomic force microscopy imaging
indicated the presence of particles 10-25 nm in size.
Example 9
Preparation of Zn.sup.2+/PAA and Cd.sup.2+/PAA Crosslinked
Composite Nanoparticles According to the Invention Using Laser
Irradiation
A solution of Zn.sup.2+/PAA was prepared by dropwise addition of 10
ml of 0.005M Zn(NO.sub.3).sub.2 solution to 10 ml of 2 mg/ml
aqueous solution of PAA (Sigma, Ave M.sub.w 1.2 million PAA, pH
adjusted to 6.8 with 0.1 M NaOH) with vigorous stirring. The
solution was exposed to 5000 pulses from an excimer laser source
(10 mJ/cm.sup.3) while undergoing vigorous stirring. The laser
irradiated solution was then dialyzed against deionized water for 3
hours, changing the deionized water reservoir every hour. The
solution viscosity remained unchanged by dialysis, indicating that
the collapsed configuration is retained.
A solution of Cd.sup.2+/PAA was prepared by dropwise addition of 10
ml of 0.005M Cd(NO.sub.3).sub.2 solution to 10 ml of 2 mg/ml
aqueous solution of PAA (Sigma, Ave M.sub.w 1.2 million PAA, pH
adjusted to 6.8 with 0.1 M NaOH) with vigorous stirring. The
solution was exposed to 5000 pulses from an excimer laser source
(10 mJ/cm.sup.3) while undergoing vigorous stirring. The laser
irradiated solution was then dialyzed against deionized water for 3
hours, changing the deionized water reservoir every hour. The
solution viscosity remained unchanged by dialysis, indicating that
the collapsed configuration is retained.
Example 10
Preparation of Zn.sup.2+/PAA Crosslinked Composite Nanoparticles
According to the Invention Using Chemical Crosslinking Agent
Zn.sup.2+/PAA solution was prepared according to example 9. 2.0 ml
of Zn.sup.2+/PAA was placed in a 5 ml glass vial and 160 .mu.l of a
solution that was 26.4 mg/mL in
1-Ethyl-N'(3-dimethylaminopropyl)carbodiimide (EDC) and 33.45 mM in
2,2'-(Ethylenedioxy)bis-(ethylamine) (EDE) was added under constant
stirring. The resulting solution was stirred for 12 hours and was
then dialyzed against deionized water for 3 hours, changing the
deionized water reservoir every hour. Zn.sup.2+/PAA that was not
treated with the EDC/EDE solution was also dialyzed against
deionized water for 3 hours, changing the deionized water reservoir
every hour. After dialysis, the viscosity of the EDC/EDE treated Zn
2+/PAA solution was much lower than that of an untreated
Zn.sup.2+/PAA solution. This indicates that the collapsed
configuration is retained after Zn.sup.2+/PAA was treated with the
EDC/EDE solution.
Example 11
Polyacrylic Acid Crosslinking with Gamma Radiation to Produce
Cd.sup.2+/PAA Composite Nanoparticles According to the
Invention
20 ml of Cd.sup.2+/PAA, prepared as described in Example 5, was
placed in a 20 ml scintillation vial. To this, 200 .mu.l of
isopropanol (ACS grade) was added. The vial was sealed with a
rubber septum and was vortexed for 10 seconds. The solution was
exposed to a total dose of .about.15 kGy of gamma radiation at a
dose rate of 3.3 kGy/hr. The irradiated solution was then dialyzed
against deionized water for 3 hours, changing the deionized water
reservoir every hour. Similarly, Cd.sup.2+/PAA that was not exposed
to gamma radiation was also dialyzed in a similar manner. After
dialysis, the viscosity of the collapsed irradiated, dialyzed
solution was much lower than that of a collapsed, un-irradiated
solution. Na.sup.+/PAA prepared according to example 4,
[Na.sup.+]=2 mM, was also exposed to the same gamma radiation dose,
and similarly the viscosity of the collapsed irradiated, dialyzed
Na.sup.+/PAA solution was much lower than that of a collapsed,
un-irradiated solution.
Example 12
Polyacrylic Acid Crosslinking with 4 G25T8 Germicidal Lamps to
Produce Cd.sup.2+/PAA Composite Nanoparticles According to the
Invention
20 ml of Cd.sup.2+/PAA was prepared according to Example 5 was
placed in a 50.0 ml glass beaker. The solution was exposed to 4
G25T8 germicidal UV lamps (approximate power is 12 .mu.W/mm.sup.2)
for approximately 1.5-2 hours under vigorous stirring. The
irradiated solution was then dialyzed against deionized water for 3
hours, changing the deionized water reservoir every hour.
Cd.sup.2+/PAA that was not exposed to the UV lamp was also dialyzed
in a similar manner. The viscosity of the irradiated, dialyzed
Cd.sup.2+/PAA solution was much lower than that of a Cd.sup.2+/PAA
solution that was not exposed to the UV lamp. Collapsed PAA with
Zn(NO.sub.3).sub.2, Pb(NO.sub.3).sub.2, Cd/Pb(NO.sub.3).sub.2,
Zn/Cd(NO.sub.3).sub.2, FeCl.sub.2, LiCl, FeCl.sub.3, Co(SO.sub.4),
Cu(SO.sub.4), Mn(SO.sub.4), Ni(CH.sub.3COOH),
Zn(NO.sub.3).sub.2/MgCl.sub.2 was also UV irradiated in a similar
manner and the viscosity of the collapsed irradiated, dialyzed
solutions were much lower than that of a collapsed, un-irradiated
solutions. These solutions were filterable using a 0.2 .mu.m nylon
syringe filter.
Example 13
CdS/PAA Composite Nanoparticles According to the Invention
20 ml of crosslinked Cd.sup.2+/PAA composite nanoparticles was
prepared according to example 12 and was placed in a 50 ml glass
beaker. Under vigorous stirring, 20.0 ml of 0.60 mM Na.sub.2S
solution was added dropwise at a rate of 2 ml/min using a syringe
pump. The resulting solution was yellow in color. Absorbance and
emission spectra of the resulting solution are shown in FIG. 1. The
maximum emission wavelength can be tuned to different frequencies
by varying the ratio of Na.sub.2S to the amount to Cd.sup.2+ ions
present in the Cd.sup.2+/PAA solution. This is shown in FIG. 2. A
red shift in the Emission.sub.max is observed as more Na.sub.2S is
added. Scanning Transmission Electron microscopy images of the
CdS/PAA prepared are shown in FIG. 3.
Example 14
CdSe/PAA Composite Nanoparticles According to the Invention
300 mL of Cd.sup.2+/PAA was prepared according to Example 12. The
pH of the solution adjusted to .about.8.5-9.0 with 0.1 M NaOH and
was bubbled with N.sub.2(g) for 30 minutes in a 500 ml round bottom
flask. 18.2 mg of 1,1'-dimethylselenourea was dissolved in 5 ml of
degassed, deionized water and was sealed with a septa in a 5 ml
glass vial. Using a 5 ml syringe, 4.1 ml of this dimethlyselenourea
solution was added to the Cd.sup.2+/PAA under N.sub.2 atmosphere.
The resulting solution was stirred for 10 minutes and then heated
on a heating mantle to a temperature of approximately 80.degree. C.
for 1 hour. After one hour, the solution was allowed to cool. The
resulting solution has an absorption and emission spectra shown in
FIG. 4.
Example 15
(CdSe--CdS)/PAA Composite Nanoparticles According to the
Invention
150 ml of CdSe/PAA nanoparticles produced according to Example 14
was placed in a 250 ml round bottom flask. 125.0 ml of 0.30 M
thioacetamide in water was added to the flask containing the
CdSe/PAA nanoparticles. The resulting mixture was stirred
vigorously for 5 minutes, and was then heated to 80.degree. C. on a
heating mantle with very light stirring for 24 hours. The
absorption and emission spectra of the resulting (CdSe--CdS)/PAA
composite nanoparticles are shown in FIG. 5.
Example 16
CdTe/PAA Composite Nanoparticles According to the Invention
Under ambient conditions, 300 ml of Cd.sup.2+/PAA produced
according to Example 12 was placed in a 500 ml round bottom flask.
To this solution, 0.156 g of NaBH.sub.4 and 0.312 g of trisodium
citrate was added while the solution was being stirred. Immediately
after the addition of the borohydride and the citrate, 12.5 ml of
0.01M NaTeO.sub.3 was added. Upon addition of the NaTeO.sub.3
solution, the solution develops a yellow color. The solution was
then refluxed for approximately 20 hours to allow CdTe/PAA
nanoparticles to form. The absorption and emission spectra of the
resulting solution after 20 hours of reflux is shown in FIG. 6.
Example 17
(CdTe--ZnS)/PAA Composite Nanoparticles According to the
Invention
In 50 a ml falcon tube, 1.7 ml of 3M NaCl was added to 15 ml
CdTe/PAA nanoparticles particles formed according to Example 16.
The resulting mixture was vortexed for 10 seconds after which 30 ml
of absolute ethanol was added and was centrifuged at 8500 rpm for
15 minutes. After centrifugation, the brown pellet formed at the
bottom of the falcon tube was rinsed with 20 ml 70% ethanol. The
resulting solution was centrifuged at 8500 rpm for 10 mins. The
brown pellet was isolated and resuspended in 15 ml deionized water.
To 10 ml of the resuspended CdTe/PAA nanoparticles, 278 .mu.L of 24
mM Zn(NO.sub.3).sub.2 was added. The solution was stirred for 10
minutes after which 167 .mu.L 39.5 mM Na.sub.2S was added. After 10
minutes of stirring, a second 278 .mu.L of 24 mM Zn(NO.sub.3).sub.2
was added. The solution was stirred for 10 minutes after which 167
.mu.L 39.5 mM Na.sub.2S was added. After 10 more minutes of
stirring, a third 278 .mu.L of 24 mM Zn(NO.sub.3).sub.2 was added.
The solution was stirred for 10 minutes after which 167 .mu.L 39.5
mM Na.sub.2S was added. The solution was left in a 50 ml falcon
tube for at least 3 days before taking the emission spectra. The
resulting solution's absorption and emission spectra after 3 days
is shown in FIG. 7.
Example 18
Formation of LiFePO.sub.4/PAA Composite Nanoparticles According to
the Invention
A 20 ml solution of (Fe.sup.2+, Li.sup.+)/PAA was prepared
according to Example 7 with some modifications. Briefly, in a 400
ml plastic beaker, 400.0 mg of PAA (Sigma, Average M.sub.V 1.2
million) was dissolved in 200 ml deionized water. The plastic
beaker was immersed in a hot water bath (approximately
80-90.degree. C.) and was stirred vigorously for at least 30
minutes or until all of the solid PAA has dissolved. Once the
solution has cooled to room temperature, the pH was adjusted to 3.0
using 0.1 M HNO.sub.3. pH measurements were done using narrow range
pH paper. 10.0 ml of this PAA solution was taken and placed in a 50
ml glass beaker to which 10.0 ml of a solution that was 6.7 mM in
both FeCl.sub.2 and LiCl was added dropwise with vigorous stirring.
The solution was crosslinked for 1.5 hours under 4 G25T8 Germicidal
lamps. 5.0 ml of a 13 mM NH.sub.4H.sub.2PO.sub.4 was then added to
the UV exposed (Fe.sup.2+, Li.sup.+)/PAA. The solvent (water) of
the resulting solution was removed using a rotary evaporator. When
all of the solvent was removed, a light green colored residue
remained and was then dried under vacuum for 12 hours. This light
green residue was placed in tube furnace and was heated under
N.sub.2 atmosphere for 12 hours at 600.degree. C. After 12 hours of
heating in the furnace, the light green residue tuned black. The
STEM images with EDX analysis of the LiFePO.sub.4/PAA composite
nanoparticle are shown in FIG. 8. FIG. 8a is a STEM image of
LiFePO.sub.4/PAA prepared according to the present invention, and
wherein FIG. 8b shows the cross-sectional abundance of phosphorous
along the scanned line in FIG. 8a acquired using electron
dispersive x-rays; and FIG. 8c shows the cross-sectional abundance
of iron along the scanned line in FIG. 8a acquired using electron
dispersive x-rays. The XRD pattern for the LiFePO.sub.4/PAA
composite nanoparticle is shown in FIG. 9.
Example 19
Formation of Fe.sub.2O.sub.3/PAA Composite Nanoparticles According
to the Invention
Fe.sub.2O.sub.3/PAA is formed by following exactly Example 18 with
only one modification. The pH of the PAA should be adjusted to pH
6.8 instead of pH 3.0 using 0.1M NaOH before adding the FeCl.sub.2
and LiCl solution. The rest of the procedure remains the same.
Surprisingly, this single modification leads to the formation of
Fe.sub.2O.sub.3/PAA instead of LiFePO.sub.4/PAA. The STEM images
with EDX analysis of the LiFePO.sub.4/PAA nanocomposite particles
are shown in FIG. 10. FIG. 10a is a STEM image Fe.sub.2O.sub.3/PAA
nanocomposite prepared according to the present invention, and
wherein FIG. 10b shows the cross-sectional abundance of iron along
the scanned line in FIG. 10a acquired using electron dispersive
x-rays; and FIG. 10c shows the cross-sectional abundance of
phosphorous along the scanned line in FIG. 10a acquired using
electron dispersive x-rays. The XRD pattern is shown in FIG. 11,
wherein H is hematite, alpha-Fe203 and M is defect spinal structure
of magnetite, gamma-Fe203, maghemite. Note that although the EDX
images show the presence of phosphate, the XRD pattern suggests
that Fe.sub.2O.sub.3 is present and not LiFePO.sub.4.
Example 20
Formation of ZnO/PAA Composites Nanoparticles According to the
Invention
A 20 ml solution of Zn.sup.2+/PAA was prepared by dropwise addition
of 10 ml of 0.005M Zn(NO.sub.3).sub.2 solution to 10 ml of 2 mg/ml
aqueous solution of PAA (Sigma, Ave M.sub.w 1.2 million PAA, pH
adjusted to 6.8 with 0.1 M NaOH) with vigorous stirring. The
solution was exposed to UV radiation for 1.5 hours under 4 G25T8
Germicidal lamps as in Example 12. The pH UV exposed Zn.sup.2+/PAA
was adjusted to pH 11.0 with 0.1 M NaOH, and then refluxed for 1
hour. After reflux, the solution turns slightly cloudy. The
absorbance, emission spectra and STEM image are shown in FIG. 12
and the absorbance and emission spectra are shown in FIG. 13.
Example 21
Incorporation of CdS/PAA Composite Nanoparticles According to the
Invention into Layer-by-Layer Thin Films
Polystyrene substrates were sonicated in 0.01M sodium dodecyl
sulfate +0.1M HCl solution for 3 minutes, rinsed with distilled
water, and dried with nitrogen. Layer by Layer (LbL) thin films
were formed by immersing the substrate in 1 mg/ml PAH
(poly(allylamine) hydrochloride) in 0.1M NaCl for 5 minutes,
followed by a 5 minute rinse in 0.1M NaCl, then immersed in a
solution of CdS/PAA nanoparticle solution (prepared according
Example 13) for 5 minutes, then rinsed in 0.1M NaCl solution for 5
minutes. This process was repeated 100 times. Emission spectra of
the polystyrene substrate coated with the LbL thin films of
PAH:CdS/PAA composite nanoparticles is shown in FIG. 14.
Example 22
Ag/PAA Composite Nanoparticles According to the Invention
20 ml of Ag.sup.+/PAA was made according to Example 4. Briefly, in
a 400 ml plastic beaker, 400.0 mg of PAA (Sigma, Average M.sub.V
1.2 million) was dissolved in 200 ml deionized water. The plastic
beaker was immersed in a hot water bath (approximately
80-90.degree. C.) and was stirred vigorously for at least 30
minutes or until all of the solid PAA has dissolved. Once the
solution has cooled to room temperature, the pH was adjusted to 6.8
using 0.1 M NaOH. pH measurements were done using narrow range pH
paper. 10.0 ml of this PAA solution was placed in a 20 ml
scintillation vial and to this, 10 ml of 4.0 mM AgNO.sub.3 solution
was added drop wise under constant stirring. 0.5 mL of 2-propanol
was added to the mixture. The final solution volume was 20 mL. The
vials were sealed with rubber septa and subjected to .sup.60Co
irradiation using a gamma cell type G.C. 220 with a dose rate of
3.3 kGy/hr, at a total dose of 15 kGy. The UV-vis spectra and STEM
images of the resulting Ag/PAA composite nanoparticles are shown in
FIGS. 15 and 16, respectively.
Example 23
Au/PAA Composite Nanoparticles According to the Invention
20 ml of Au.sup.3+/PAA was made according to Example 4. Briefly, in
a 400 ml plastic beaker, 400.0 mg of PAA (Sigma, Average M.sub.V
1.2 million) was dissolved in 200 ml deionized water. The plastic
beaker was immersed in a hot water bath (approximately
80-90.degree. C.) and was stirred vigorously for at least 30
minutes or until all of the solid PAA has dissolved. Once the
solution has cooled to room temperature, the pH was adjusted to 6.8
using 0.1 M NaOH. pH measurements were done using narrow range pH
paper. 10.0 ml of this PAA solution was placed in a 20 ml
scintillation vial, and to this 10 ml of 4.0 mM HAuCl.sub.3
solution was added drop wise under constant stirring. 0.5 mL of
2-propanol was added to the mixture. The final solution volume was
20 mL. The vials were sealed with rubber septa and subjected to
.sup.60Co irradiation using a gamma cell type G.C. 220 with a dose
rate of 3.3 kGy/hr, at a total dose of 15 kGy. The UV-vis spectra
and STEM images of the resulting Au/PAA composite nanoparticles are
shown in FIGS. 17 and 18, respectively.
Example 24
(Au, Ag)/PAA Composite Nanoparticles According to the Invention
20 ml of (Ag.sup.+, Au.sup.3+)/PAA was made according to Example 4.
Briefly, in a 400 ml plastic beaker, 400.0 mg of PAA (Sigma,
Average M.sub.V 1.2 million) was dissolved in 200 ml deionized
water. The plastic beaker was immersed in a hot water bath
(approximately 80-90.degree. C.) and was stirred vigorously for at
least 30 minutes or until all of the solid PAA has dissolved. Once
the solution has cooled to room temperature, the pH was adjusted to
6.8 using 0.1 M NaOH. pH measurements were done using narrow range
pH paper. 10.0 ml of this PAA solution was placed in a 20 ml
scintillation vial, and to this 5 ml of 4.0 mM HAuCl.sub.3 solution
was added drop wise under constant stirring. This was then followed
by the drop wise addition of 5.0 ml 4 mM Ag(NO.sub.3), and finally
the addition of 0.5 ml of 2-propanol. The final solution volume was
20 mL. The solution was exposed to 4 G25T8 germicidal UV lamps
(approximate power is 12 .mu.W/mm.sup.2) for approximately 1.5-2
hours under vigorous stirring. After irradiation, the solution
changed from colorless to light purple. The UV-vis spectra and STEM
images of the resulting (Au.Ag)/PAA composite nanoparticles are
shown in FIGS. 19 and 20, respectively. FIG. 20a is a STEM image
(Au, Ag)/PAA nanocomposite prepared according to the present
invention; and wherein FIG. 20b shows the cross-sectional abundance
of silver along the scanned line in FIG. 20a acquired using
electron dispersive x-rays; and FIG. 20c shows the cross-sectional
abundance of gold along the scanned line in FIG. 20a acquired using
electron dispersive x-rays.
Example 25
Formation of CdSePAA-Fluorescein Conjugate According to the
Invention
In a 1.5 mL microfuge tube, 400 .mu.L of CdSePAA (.about.0.2 mg/mL
in ddH.sub.2O) was combined with 4.9 mg
1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and 6 mg
N-hydroxysuccinimide (NHS) in 500 .mu.L of ddH.sub.2O. 100 .mu.L of
250 mM 2-morpholinoethanesulfonic acid (MES) (pH .about.6.5) was
added. And finally, 20 .mu.L of 5 mg/mL fluorescein in
N,N-dimethylformamide (DMF) was also added. The tube containing
this mixture was wrapped in aluminum foil and placed on a rotating
table for .about.20 h at room temperature. The resulting mix was
placed in a 10 kDa MWCO dialysis bag and dialyzed against
ddH.sub.2O. The dialysis solution (.about.200 fold dilution each
time) was changed five times over a period of .about.24 h. The
solution remaining in the dialysis bag was recovered and
centrifuged for 10 min at 15,000 RCF. A brown pellet is found after
the centrifugation. The fluorescent supernatant was transferred to
a new microfuge tube and further purified by precipitation with the
addition of .about.1/10 volume of 3M sodium acetate (pH .about.5.5)
and 2.times. volume of absolute ethanol. The resulting fluorescent
precipitate was then isolated by centrifugation for 10 min at
15,000 RCF and resuspended in 200 .mu.L ddH.sub.2O.
The presence of fluorescein conjugated to CdSePAA was confirmed by
gel permeation chromatography using a fluorescence detector
(excitation at 480 nm and emission at 515 nm).
Example 26
Formation of CdSePAA-BSA Conjugate According to the Invention
In a 1.5 mL microfuge tube, 900 .mu.L of CdSe/PAA (.about.0.2 mg/mL
in ddH.sub.2O) was combined with 5.3 mg EDC and 10.8 mg NHS in 100
.mu.L of 250 mM MES (pH .about.6.5). And finally, 5.1 mg bovine
serum albumin (BSA) was also added. The tube containing this
mixture was placed on a rotating table for .about.19 h at room
temperature. The resulting mix was centrifuged for 10 min at 15,000
RCF. .about.500 .mu.L of the supernatant was transferred to a 100
kDa MWCO centrifugal filter and centrifuged for 12 min at 14,000
RCF. The resulting filtrate was discarded, and the retenate was
resuspended in 500 .mu.L of ddH.sub.2O in the same filter and
centrifuged again. This was repeated three more times. The final
retenate was recovered for characterization.
Removal of unconjugated BSA using the 100 kDa MWCO filter was
confirmed by gel permeation chromatography. And the presence of BSA
conjugated to CdSe/PAA remaining in the retenate was confirmed by
assay with BioRad protein reagent.
Example 27
CdS/PSS Composite Nanoparticles According to the Invention
400 mg of Poly(styrene sulfonic acid) sodium salt (Alfa Aesar, Ave
M.sub.w 1 million) was dissolved in 200.0 ml deionized water. 20.0
ml of this solution was placed in an 80 ml vial and to this, 20.0
ml 4.8 mM Cd(NO.sub.3).sub.2 solution was added dropwise with
vigorous stirring. The solution was exposed to 4 G25T8 germicidal
UV lamps (approximate UV power is 12 .mu.W/mm.sup.2) for 1 hour
under vigorous stirring. CdS was formed by adding 0.5 ml 1.4 mM
Na.sub.2S to 0.5 ml of the irradiated Cd.sup.2+/PSS solution.
UV-visible absorbance and emission spectra are shown in FIG.
21.
Example 28
CdS/PDDA Nanoparticles
15.0 ml of poly(diallyldimethylammonium chloride) (PDDA) [Sigma,
Average M.sub.w 400-500K, 20 wt % in water] was diluted to 300 ml
with deionized water. The solution was stirred for 10 minutes. 5.0
ml of this solution was diluted to 25.0 ml with deionized water in
a 80 ml glass beaker. To this solution, 25.0 ml of 4 mM Na.sub.2S
was added dropwise with vigorous stirring. The solution was exposed
to 4 G25T8 germicidal UV lamps (approximate UV power is 12
.mu.W/mm.sup.2) for 1 hour under vigorous stirring. CdS/PDDA was
formed by adding 0.50 ml of 2.68 mM Cd(NO.sub.3).sub.2 to 0.50 ml
of irradiated S.sup.2-/PDDA. UV-visible absorbance and emission
spectra are shown in FIG. 22.
Example 29
Polyanion Collapse with Cd.sup.2+/Pb.sup.2+ Cations
In a 400 mL plastic beaker, 400.0 mg of PAA (Sigma, Average M.sub.V
1.2 million) was dissolved in 200 mL deionized water. The plastic
beaker was immersed in a hot water bath (approximately
80-90.degree. C.) and was stirred vigorously for at least 30
minutes or until all of the solid PAA had dissolved. Once the
solution had cooled to room temperature, the pH was adjusted to 6.8
using 0.1 M NaOH. pH measurements were done using narrow-range pH
paper. 25 mL of a Cd.sub.xPb.sub.1-x(NO.sub.3).sub.2 solution was
prepared by the addition of 5 mM Cd(NO.sub.3).sub.2 and 5 mM
Pb(NO.sub.3).sub.2 salt solutions in various proportions, where
x=0.1, 0.2, 0.3, 0.4, 0.5, 0.6, . . . , 1. The total concentration
of metal ions in the final solution was 5 mM. 20 mL of the
pH-adjusted PAA and 25 mL of deionized water were obtained and
placed in a 100 mL beaker. 15 mL of the metal solution was then
added dropwise under vigorous stirring to yield 60 mL of a
Cd.sub.x.sup.2+Pb.sub.1-x.sup.2+/PAA solution with a final
[Cd.sub.x.sup.2+Pb.sub.1-x.sup.2+] of 1.25 mM and final PAA
concentration of 0.67 mg/mL.
Example 30
Polyanion Collapse with Cd.sup.2+--Mg.sup.2+ (10%) Cations
In a 400 mL plastic beaker, 400.0 mg of PAA (Sigma, Average M.sub.V
1.2 million) was dissolved in 200 mL deionized water. The plastic
beaker was immersed in a hot water bath (approximately
80-90.degree. C.) and was stirred vigorously for at least 30
minutes or until all of the solid PAA had dissolved. Once the
solution had cooled to room temperature, the pH was adjusted to 6.8
using 0.1 M NaOH. pH measurements were done using narrow-range pH
paper. 25 mL of a Cd.sub.0.9Mg.sub.0.1(NO.sub.3).sub.2 solution was
prepared by mixing together of 22.5 mL and 2.5 mL of 5 mM
Cd(NO.sub.3).sub.2 and 5 mM Mg(NO.sub.3).sub.2 solutions,
respectively. The total concentration of metal ions in solution was
5 mM. 20 mL of the pH-adjusted PAA and 25 mL of deionized water
were obtained and placed in a 100 mL beaker. 15 mL of the metal
solution was then added dropwise under vigorous stirring to yield
60 mL of a Cd.sub.0.9.sup.2+Mg.sup.2+/PAA solution with a final
[Cd.sub.0.9.sup.2+Mg.sub.0.1.sup.2+] of 1.25 mM and final PAA
concentration of 0.67 mg/mL.
Example 31
Polyanion Collapse with Cd.sup.2+--Zn.sup.2+ (90%) cations
In a 400 mL plastic beaker, 400.0 mg of PAA (Sigma, Average M.sub.V
1.2 million) was dissolved in 200 mL deionized water. The plastic
beaker was immersed in a hot water bath (approximately
80-90.degree. C.) and was stirred vigorously for at least 30
minutes or until all of the solid PAA had dissolved. Once the
solution had cooled to room temperature, the pH was adjusted to 6.8
using 0.1 M NaOH. pH measurements were done using narrow-range pH
paper. 10 mL of a Cd.sub.0.1Zn.sub.0.9(NO.sub.3).sub.2 solution was
prepared by mixing together of 1 mL and 9 mL of 5 mM
Cd(NO.sub.3).sub.2 and 5 mM Zn(NO.sub.3).sub.2 solutions,
respectively. The total concentration of metal ions in solution was
5 mM. 10 mL of pH-adjusted PAA was obtained and placed in a 50 mL
beaker followed by the dropwise addition of 10 mL of the metal salt
solution under vigorous stirring to yield 20 mL of a
Cd.sub.0.1.sup.2+Zn.sub.0.9.sup.2+/PAA solution with a final
[Cd.sub.0.1.sup.2+Zn.sub.0.9.sup.2+] of 2.5 mM and final PAA
concentration of 1 mg/mL.
Example 32
Polyanion Collapse with Cd.sup.2+--Zn.sup.2+ (10%) Cations
In a 400 mL plastic beaker, 400.0 mg of PAA (Sigma, Average M.sub.V
1.2 million) was dissolved in 200 mL deionized water. The plastic
beaker was immersed in a hot water bath (approximately
80-90.degree. C.) and was stirred vigorously for at least 30
minutes or until all of the solid PAA had dissolved. Once the
solution had cooled to room temperature, the pH was adjusted to 6.8
using 0.1 M NaOH. pH measurements were done using narrow-range pH
paper. 6 mL of a Cd.sub.0.9Zn.sub.0.1(NO.sub.3).sub.2 solution was
prepared by mixing together of 5.4 mL and 0.6 mL of 5 mM
Cd(NO.sub.3).sub.2 and 5 mM Zn(NO.sub.3).sub.2 solutions,
respectively. The total concentration of metal ions in solution was
5 mM. 10 mL of pH-adjusted PAA and 4 mL of deionized water were
obtained and placed in a 50 mL beaker. 6 mL of the metal salt
solution was then added dropwise under vigorous stirring to yield
20 mL of a Cd.sub.0.9.sup.2+Zn.sub.0.1.sup.2+/PAA solution with a
final [Cd.sub.0.9.sup.2+Zn.sub.0.3.sup.2+] of 1.5 mM and final PAA
concentration of 1 mg/mL.
Example 33
Polyanion Collapse with Cd.sup.2/Mn.sup.2+ (1%) Cations
In a 400 mL plastic beaker, 400.0 mg of PAA (Sigma, Average M.sub.V
1.2 million) was dissolved in 200 mL deionized water. The plastic
beaker was immersed in a hot water bath (approximately
80-90.degree. C.) and was stirred vigorously for at least 30
minutes or until all of the solid PAA had dissolved. Once the
solution had cooled to room temperature, the pH was adjusted to 6.8
using 0.1 M NaOH. pH measurements were done using narrow-range pH
paper. 25 mL of a Cd.sub.0.99Mn.sub.0.01(NO.sub.3).sub.2 solution
was prepared by mixing together of 24.75 mL and 0.25 mL of 5 mM
Cd(NO.sub.3).sub.2 and 5 mM Mn(NO.sub.3).sub.2 solutions,
respectively. The total concentration of metal ions in solution was
5 mM. 20 mL of the pH-adjusted PAA and 25 mL of deionized water
were obtained and placed in a 100 mL beaker. 15 mL of the metal
solution was then added dropwise under vigorous stirring to yield
60 mL of a Cd.sub.0.99.sup.2+Mn.sub.0.01.sup.2+/PAA solution with a
final [Cd.sub.0.99.sup.2+Mn.sub.0.01.sup.2+] of 1.25 mM and final
PAA concentration of 0.67 mg/mL.
Example 34
Polyanion Collapse with Cd.sup.2+/Hg.sup.2+(50%) Cations
In a 400 mL plastic beaker, 400.0 mg of PAA (Sigma, Average M.sub.V
41.2 million) was dissolved in 200 mL deionized water. The plastic
beaker was immersed in a hot water bath (approximately
80-90.degree. C.) and was stirred vigorously for at least 30
minutes or until all of the solid PAA had dissolved. Once the
solution had cooled to room temperature, the pH was adjusted to 6.8
using 0.1 M NaOH. pH measurements were done using narrow-range pH
paper. 25 mL of a Cd.sub.0.5Hg.sub.0.5(NO.sub.3).sub.2 solution was
prepared by mixing together of 12.5 mL and 12.5 mL of 5 mM
Cd(NO.sub.3).sub.2 and 5 mM Hg(NO.sub.3).sub.2 solutions,
respectively. The total concentration of metal ions in solution was
5 mM. 20 mL of the pH-adjusted PAA and 25 mL of deionized water
were obtained and placed in a 100 mL beaker. 15 mL of the metal
solution was then added dropwise under vigorous stirring to yield
60 mL of a Cd.sub.0.5.sup.2+Hg.sub.0.5.sup.2+/PAA solution with a
final [Cd.sub.0.5.sup.2+Hg.sub.0.5.sup.2+] of 1.25 mM and final PAA
concentration of 0.67 mg/mL.
Example 35
Polyacrylic Acid Crosslinking with 4 G25T8 Germicidal Lamps
60 mL of Cd.sub.x.sup.2+Pb.sub.1-x.sup.2+/PAA was prepared
according to Example 29 and was placed in a 150.0 mL glass beaker.
The solution was exposed to 4 G25T8 germicidal UV lamps
(approximate power is 12 .mu.W/mm.sup.2) for approximately 30
minutes under vigorous stirring. The irradiated solution was then
dialyzed against deionized water for 3 hours, changing the
deionized water reservoir every hour. Collapsed PAA with
Cd.sub.xZn.sub.1-x(NO.sub.3).sub.2,
Cd.sub.xMn.sub.1-x(NO.sub.3).sub.2,
Cd.sub.xMg.sub.1-x(NO.sub.3).sub.2 . . . was UV-irradiated in a
similar manner for approximately 1 hour. The viscosity of the
collapsed irradiated, dialyzed solutions was much lower than that
of collapsed, un-irradiated solutions. These solutions were
filterable using a 0.2 .mu.m nylon syringe filter.
Example 36
Cd.sub.0.5Pb.sub.0.5Te/PAA Nanoparticles
Under ambient conditions, 20 ml of
Cd.sub.x.sup.2+Pb.sub.1-x.sup.2+/PAA produced according to Example
35 was placed in a 100 mL round bottom flask. The pH was adjusted
to 11 using 1.1 M NaOH. pH measurements were done using
narrow-range pH paper. To this solution, 20.4 mg of NaBH.sub.4 and
28.3 mg of trisodium citrate were added while the solution was
being stirred. Immediately after the addition of the borohydride
and the citrate, 0.625 mL of 0.01 Na.sub.2TeO.sub.3 was added. The
solution develops a yellow colour upon addition of the
tellurium-containing salt. The solution was then refluxed for
approximately one hour under N.sub.2 atmosphere to allow CdPbTe/PAA
nanoparticles to form. The absorbance and emission spectra of the
resulting solution after one hour of reflux is shown in FIG. 23.
Unfortunately, the colloidal solutions were extremely unstable upon
exposure to air and this was marked by a quick disappearance of the
characteristic absorbance and emission spectra shown in FIG.
23.
Example 37
Cd.sub.0.9Zn.sub.0.1Te/PAA Nanoparticles
Under ambient conditions, 8 mL of
Cd.sub.0.9.sup.2+Zn.sub.0.1.sup.2+/PAA produced according to
Example 32 was placed in a 25 mL round bottom flask, and
cross-linked using the permitted lamp as hereinabove described. To
this solution, 15 mg of NaBH.sub.4 and 30 mg of trisodium citrate
were added while the solution was being stirred. Immediately after
the addition of the borohydride and the citrate, 0.3 mL of 0.01
Na.sub.2TeO.sub.3 was added. The solution develops a peach colour
upon addition of the tellurium-containing salt. The solution was
then refluxed for approximately two hours to allow CdZnTe/PAA
nanoparticles to form. The absorbance and emission spectra of the
resulting solution after two hours of reflux are shown in FIG.
24.
Example 38
Cd.sub.0.99Mn.sub.0.01Te/PAA Nanoparticles
Under ambient conditions, 10 mL of
Cd.sub.0.99.sup.2+Mn.sub.0.01.sup.2+/PAA produced according to
Example 33 was placed in a 25 mL round bottom flask, and
cross-linked using the permitted lamp as hereinabove described. To
this solution, 20 mg of NaBH.sub.4 and 37 mg of trisodium citrate
were added while the solution was being stirred. Immediately after
the addition of the borohydride and the citrate, 0.313 mL of 0.01
Na.sub.2TeO.sub.3 was added. The solution develops a peach colour
upon addition of the tellurium-containing salt. The solution was
then refluxed for approximately one hour to allow CdMnTe/PAA
nanoparticles to form. The absorbance and emission spectra of the
resulting solution after one hour of reflux are shown in FIG.
25.
Example 39
Cd.sub.0.5Hg.sub.0.5Te/PAA Nanoparticles
Under ambient conditions, 10 mL of
Cd.sub.0.5.sup.2+Hg.sub.0.5.sup.2+/PAA produced according to
Example 34 was placed in a 25 mL round bottom flask, and
cross-linked using the permitted lamp as hereinabove described. To
this solution, 16 mg of NaBH.sub.4 and 29 mg of trisodium citrate
were added while the solution was being stirred. Immediately after
the addition of the borohydride and the citrate, 0.313 mL of 0.01
Na.sub.2TeO.sub.3 was added. The solution remained colourless upon
addition of the tellurium-containing salt. The solution was then
refluxed for approximately one hour to allow CdHgTe/PAA
nanoparticles to form. However, the refluxed solution was not
fluorescent.
Example 40
Formation of Methylene Blue/PAA Nanoparticles
In a 400 ml plastic beaker, 400.0 mg of PAA (Sigma, Average M.sub.V
1.2 million) was dissolved in 200 ml deionized water. The plastic
beaker was immersed in a hot water bath (approximately
80-90.degree. C.) and was stirred vigorously for at least 30
minutes or until all of the solid PAA has dissolved. Once the
solution has cooled to room temperature, the pH was adjusted to 6.8
using 0.1 M NaOH. pH measurements were done using narrow range pH
paper. 20.0 ml of this PAA solution was placed in a glass beaker
and to this, 20.0 ml of aqueous 5.0 mM Methylene Blue solution was
added dropwise under vigorous stirring. After all of the Methylene
Blue solution was added, the viscosity of the mixture was observed
to be much less than the original PAA solution. The resulting
solution was exposed to UV radiation using 4 G25T8 germicidal UV
lamps for 1.5 hours. The viscosity of the UV-irradiated Methylene
Blue/PAA solution was less than the viscosity of the solution not
exposed to UV radiation.
All literature and similar material cited in this application,
including, patents, patent applications, articles, books,
treatises, dissertations and web pages, regardless of the format of
such literature and similar materials, are expressly incorporated
by reference in their entirety. In the event that one or more of
the incorporated literature and similar materials differs from or
contradicts this application, including defined terms, term usage,
described techniques, or the like, this application controls.
The section headings used herein are for organizational purposes
only and are not to be construed as limiting the subject matter
described in any way.
While the present inventions have been described in conjunction
with various embodiments and examples, it is not intended that the
present inventions be limited to such embodiments or examples. On
the contrary, the present inventions encompass various
alternatives, modifications, and equivalents, as will be
appreciated by those of skill in the art. Accordingly, the
descriptions, methods and diagrams of should not be read as limited
to the described order of elements unless stated to that
effect.
Although this disclosure has described and illustrated certain
preferred embodiments of the invention, it is to be understood that
the invention is not restricted to those particular embodiments.
Rather, the invention includes all embodiments which are functional
or mechanical equivalence of the specific embodiments and features
that have been described and illustrated.
The claims should not be read as limited to the described order or
elements unless stated to that effect. It should be understood that
various changes in form and detail may be made without departing
from the scope of the appended claims. Therefore, all embodiments
that come within the scope and spirit of the following claims and
equivalents thereto are claimed.
* * * * *