U.S. patent application number 14/745592 was filed with the patent office on 2015-12-24 for reduction of infections in healthcare settings using photocatalytic compositions.
The applicant listed for this patent is WELL Shield LLC. Invention is credited to Devron R. Averett, Stewart B. Averett.
Application Number | 20150367007 14/745592 |
Document ID | / |
Family ID | 54868693 |
Filed Date | 2015-12-24 |
United States Patent
Application |
20150367007 |
Kind Code |
A1 |
Averett; Stewart B. ; et
al. |
December 24, 2015 |
REDUCTION OF INFECTIONS IN HEALTHCARE SETTINGS USING PHOTOCATALYTIC
COMPOSITIONS
Abstract
Methods of reducing the incidence of healthcare-associated
infections in various healthcare settings are provided. Methods for
preventing or reducing the number of infections in a human or
animal population are also provided. The methods as provided herein
reduce the presence of various infectious agents that are commonly
acquired or transmitted and are present on both animate and
inanimate surfaces, including those infectious agents commonly
found in healthcare settings. By reducing the presence of such
infectious agents, the incidence of various types of infection or
disease is thereby reduced.
Inventors: |
Averett; Stewart B.; (Boca
Raton, FL) ; Averett; Devron R.; (Berkley,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
WELL Shield LLC |
Boca Raton |
FL |
US |
|
|
Family ID: |
54868693 |
Appl. No.: |
14/745592 |
Filed: |
June 22, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62015596 |
Jun 23, 2014 |
|
|
|
Current U.S.
Class: |
422/28 |
Current CPC
Class: |
B05D 1/04 20130101; A61L
2202/25 20130101; B01J 35/0013 20130101; B01J 35/023 20130101; B01J
35/004 20130101; B01J 23/06 20130101; A61L 2/088 20130101 |
International
Class: |
A61L 2/08 20060101
A61L002/08 |
Claims
1. A method of reducing the incidence of healthcare-associated
infections in a healthcare facility comprising treating at least
one inanimate surface of the healthcare facility structure, or at
least one object therein, or a combination thereof, with a
photocatalytic composition comprising titanium dioxide (TiO.sub.2)
doped with zinc and at least one other doping agent.
2. The method of claim 1, wherein the healthcare-associated
infection is selected from the group consisting of bone infection,
joint infection, bloodstream infection, central nervous system
infection, cardiovascular system infection, pneumonia, reproductive
tract infection, surgical site infection, gastrointestinal
infection, lower respiratory infection, upper respiratory
infection, skin or soft tissue infection, bloodstream infection,
eye infection, ear infection, nose infection, throat infection,
mouth infection, and urinary tract infection.
3. The method of claim 1, wherein the photocatalytic composition is
applied at a rate of from about 500 ft.sup.2 per liter to about
1500 ft.sup.2 per liter.
4. The method of claim 3, wherein the photocatalytic composition is
applied by spraying, atomizing, coating, immersion, or dipping.
5. The method of claim 1, wherein the incidence of
healthcare-associated infections is reduced by at least 20% over a
twelve month period after one treatment of the inanimate surfaces
of the healthcare facility structure, at least one object therein,
or a combination thereof.
6. The method of claim 1, wherein the incidence of
healthcare-associated infections is reduced by at least 30% over a
twelve month period after one treatment of the inanimate surfaces
of the healthcare facility structure, or at least one object
therein, or a combination thereof.
7. The method of claim 1, wherein the step of treating inanimate
surfaces of the healthcare facility structure, or at least one
object therein, or a combination thereof, prevents and reduces the
presence at least one infectious agent selected from the group
consisting of species of Acinetobacter, adenovirus, Bacillus,
Burkholderia, Bordetella, Brucella, caliciviruses, herpes including
zoster (chickenpox), Clostridium, corona viruses including SARS,
MERS, and PEDV, Enterococcus, Escherichia, Hemophilus, hepatitis
viruses A and B, influenza and parainfluenza viruses, Klebsiella,
Listeria, Legionella, measles virus, mumps virus, Mycobacterium,
Neisseria, norovirus, Pseudomonas, parvovirus, poliovirus,
rhinovirus, respiratory syncyticia virus, rotavirus, rubella,
Salmonella, Streptococcus, Staphylococcus, Vibrio, MRSA
(methicillin-resistant Staphylococcus aureus, VISA (vancomycin
intermediate Staphylococcus aureus), MRE (multiply resistant
enterococci), and VRE (vancomycin-resistant enterococci)).
8. The method of claim 1, wherein the at least one inanimate
surface includes walls, fixtures, floors, and ceilings of hallways,
offices, bathrooms, elevators, stairwells, kitchens/cafeterias,
common areas, nurses' stations, and doctors' stations.
9. The method of claim 1, wherein the at least one object is
selected from the group consisting of curtains, call buttons,
computers, monitors, wall computer kiosks, blood pressure cuffs,
wheelchairs, lifts, carts, and beds.
10. The method of claim 1, wherein the at least one other doping
agent increases the absorbance of light across the range of about
200 nm to about 500 nm.
11. The method of claim 1, wherein the absorbance of light of
wavelengths longer than about 450 nm is less than 50% the
absorbance of light of wavelengths shorter than about 350.
12. The method of claim 1, wherein the at least one other doping
agent is selected from the group consisting of Ag, Si, C, S, Fe,
Mo, Ru, Cu, Os, Re, Rh, Sn, Pt, Li, Na, and K.
13. The method of claim 1, wherein the titanium dioxide
nanoparticles have an average particle size of from about 2 nm to
about 20 nm.
14. The method of claim 1, wherein the at least one other doping
agent is silicon.
15. The method of claim 1, wherein the at least one other doping
agent is silicon dioxide.
16. The method of claim 15, the photocatalytic composition having a
ratio of titanium dioxide to silicon dioxide of from about 3 to
about 20.
17. The method of claim 15, the photocatalytic composition having a
ratio of titanium dioxide to zinc from about 5 to about 150 and a
ratio of titanium dioxide to silicon dioxide from about 1 to about
500.
18. The method of claim 1, wherein the photocatalytic composition
consists essentially of: (A) about 5000 to about 10000 ppm of
titanium dioxide, (B) about 50 to about 150 ppm of zinc, and (C)
about 300 to about 1000 ppm of silicon dioxide.
19. A method for preventing or reducing the number of infections in
a human or animal population comprising treating inanimate surfaces
of a structure occupied by the population, or at least one
inanimate object present therein, or a combination thereof, with a
photocatalytic composition comprising titanium dioxide (TiO.sub.2)
doped with zinc and at least one other doping agent.
20. The method of claim 19, wherein the structure occupied by the
population is selected from the group consisting of an agricultural
facility, food-processing facility, catering facility, restaurants,
hotel, motel, and childcare facility.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent
Application No. 62/015,596 filed Jun. 23, 2014, the content of
which is incorporated herein in its entirety.
FIELD
[0002] The present disclosure relates to preventing and reducing
the incidence of infectious agents found on a surface and
particularly on surfaces found in healthcare settings.
BACKGROUND
[0003] Infectious agents found in and on building structures and
surfaces of objects therein can lead to various health problems.
Common offending infectious agents include microorganisms such as
bacteria (e.g., gram negative rods such as Escherichia coli and
gram-positive cocci such as Staphylococcus aureus). These and other
bacteria can cause health problems such as dermal infections,
respiratory infections, intestinal infections, and kidney disease.
Also, pathogenic viruses such as influenza viruses are commonly
found in buildings where they spread among those occupying the
structure. Particularly, infectious agents within healthcare
settings lead to healthcare-associated infections which, in turn,
result in greater than a billion dollars in excess healthcare costs
annually. These infections have created a challenge for healthcare
management teams due to multi-drug resistant bacteria becoming
commonplace in healthcare settings such as hospices, hospitals, and
assisted-living or long-term care facilities.
[0004] Systems and methods designed to encourage, effect, monitor
and enforce hand sanitation and other hygienic practices may aid in
the reduction of the spread of infectious agents in healthcare
settings, however, such measures alone are not sufficient. Thus,
there remains a need for compositions and associated methods that
prevent and reduce the presence of infectious agents in a variety
of settings, including healthcare settings or facilities.
SUMMARY
[0005] According to one aspect, a method of reducing the incidence
of healthcare-associated infections in a healthcare facility is
provided. The method includes the step of treating at least one
inanimate surface of the healthcare facility structure, or at least
one object therein, or a combination thereof, with a photocatalytic
composition. The photocatalytic composition comprises, consists
essentially of, or consists of titanium dioxide (TiO.sub.2) doped
with zinc and at least one other doping agent.
[0006] According to one embodiment, the healthcare-associated
infections susceptible to treatment include bone infection, joint
infection, bloodstream infection, central nervous system infection,
cardiovascular system infection, pneumonia, reproductive tract
infection, and surgical site infection. According to another
embodiment, the healthcare-associated infections susceptible to
treatment include gastrointestinal infection, lower respiratory
infection, upper respiratory infection, skin or soft tissue
infection, bloodstream infection, eye infection, ear infection,
nose infection, throat infection, mouth infection, and urinary
tract infection.
[0007] The method is suitable for reducing the abundance in air and
on surfaces of infectious agents including, but not limited to
species of Acinetobacter, adenovirus, Bacillus, Burkholderia,
Bordetella, Brucella, caliciviruses, herpes including zoster
(chickenpox), Clostridium, corona viruses including SARS, MERS, and
PEDV, Enterococcus, Escherichia, Hemophilus, hepatitis viruses A
and B, influenza and parainfluenza viruses, Klebsiella, Listeria,
Legionella, measles virus, mumps virus, Mycobacterium, Neisseria,
norovirus, Pseudomonas, parvovirus, poliovirus, rhinovirus,
respiratory syncytial virus, rotavirus, rubella, Salmonella,
Streptococcus, Staphylococcus, and Vibrio. The infectious agents
that are reduced include both those susceptible to antibiotics and,
without limitation, those resistant to antibiotics such as MRSA
(methicillin-resistant Staphylococcus aureus, VISA (vancomycin
intermediate Staphylococcus aureus), MRE (multiply resistant
enterococci), and VRE (vancomycin-resistant enterococci).
[0008] According to one embodiment, the photocatalytic composition
is applied at a rate of from about 500 ft.sup.2 per liter to about
1800 ft.sup.2 per liter. According to one embodiment, the
photocatalytic composition is applied by spraying, atomizing,
coating, immersion, or dipping.
[0009] According to one embodiment, the incidence of
healthcare-associated infections is reduced by at least 20% over a
twelve month period after one treatment. According to another
embodiment, the incidence of healthcare-associated infections is
reduced by at least 30% over a twelve month period after one
treatment.
[0010] According to one embodiment, the at least one inanimate
surface of the healthcare facility structure includes any or all
walls, fixtures, floors, and ceilings, including those parts of
hallways, offices, bathrooms, elevators, stairwells, and
kitchens/cafeterias, common areas, nurses' stations, and doctors'
stations. According to one embodiment, the at least one object of
the healthcare facility includes the curtains, call buttons,
computers, monitors, wall computer kiosks, blood pressure cuffs,
wheelchairs, lifts, carts, and beds.
[0011] According to one embodiment, the photocatalytic composition
utilized in the methods provided herein comprises, consists
essentially of, or consists of titanium dioxide that is doped with
zinc and at least one other doping agent. According to one
embodiment, the doping agent(s) increase the absorbance of light
across the range of about 200 nm to about 500 nm. According to one
embodiment, the absorbance of light of wavelengths longer than
about 450 nm is less than 50% the absorbance of light of
wavelengths shorter than about 350. According to one embodiment,
the at least one other doping agent (i.e., in addition to zinc) can
be one or more of Ag, Si, C, S, Fe, Mo, Ru, Cu, Os, Re, Rh, Sn, Pt,
Li, Na, and K. According to one embodiment, the titanium dioxide
nanoparticles have an average particle size of from about 2 nm to
about 20 nm. According to one embodiment, the at least one other
doping agent is silicon. According to one embodiment, the at least
one other doping agent is silicon dioxide. According to one such
embodiment, the photocatalytic composition exhibits a ratio of
titanium dioxide to silicon dioxide of from about 3 to about 20.
According to yet another embodiment, the photocatalytic composition
exhibits a ratio of titanium dioxide to zinc from about 5 to about
150 and a ratio of titanium dioxide to silicon dioxide from about 1
to about 500. According to one embodiment, the photocatalytic
composition comprises, consists essentially of, or consists of (A)
about 5000 to about 10000 ppm of titanium dioxide, (B) about 50 to
about 150 ppm of zinc, and (C) about 300 to about 1000 ppm of
silicon dioxide.
[0012] According to another aspect, a method for preventing or
reducing the number of infections in a human or animal population
is provided. The method includes the step of treating inanimate
surfaces of a structure occupied by the population, or at least one
inanimate object present therein, or a combination thereof, with a
photocatalytic composition. The photocatalytic composition
comprises, consists essentially of, or consists of titanium dioxide
doped with zinc and at least one other doping agent. According to
one embodiment, the structure occupied by the population includes
an agricultural facility, food-processing facility, catering
facility, restaurants, hotel, motel, office, or childcare
facility.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a graphic representation of solar energy capture
of various TiO.sub.2 compositions.
[0014] FIG. 2 is a graphic representation of the photocatalytic
activity of various TiO.sub.2 compositions when irradiated at 354
nm.
DETAILED DESCRIPTION
[0015] Methods of reducing the incidence of healthcare-associated
infections in various healthcare settings are provided. Methods for
preventing or reducing the number of infections in a human or
animal population are also provided. The methods as provided herein
reduce the abundance of various infectious agents that are commonly
acquired or transmitted and are present on both animate and
inanimate surfaces, including those infectious agents commonly
found in healthcare settings. Further, airborne infectious agents
also are reduced because such agents make contact with treated
surfaces and are inactivated. By preventing and reducing the
presence of such infectious agents, the incidence of various types
of infection or disease is thereby reduced.
[0016] As used herein, the phrase, "at least one" means one or more
and thus includes individual components as well as
mixtures/combinations.
[0017] The term "comprising" (and its grammatical variations) as
used herein is used in the inclusive sense of "having" or
"including" and not in the exclusive sense of "consisting only
of."
[0018] The terms "a" and "the" as used herein are understood to
encompass the plural as well as the singular. The terms "doped" or
"doping" as used herein are understood to encompass the
introduction of one or more impurities (e.g., dopant, doping agent)
into a material for the purpose of modifying the properties of the
material.
[0019] The terms "treatment" and "treating" include mitigation of a
pre-existing microbial disease or infestation by application or
introduction of a photocatalytic composition as provided herein to
an inanimate structure or object or an animate surface.
[0020] The terms "prevention" and "prophylaxis" include reduction
of the incidence or severity of disease or infestation in either
individuals or populations.
[0021] The term "healthcare-associated infection" as used herein
refers to any localized or systemic condition resulting from an
adverse reaction to the presence of an infectious agent (or its
toxin) that was not present and without evidence of incubation at
the time of admission to a healthcare setting.
[0022] The term "infectious agent" includes, but is not limited to,
viruses, mold, and bacteria that cause or contribute to infection
or disease in the human population Such organisms include but are
not limited to species of Acinetobacter, adenovirus, Bacillus,
Burkholderia, Bordetella, Brucella, caliciviruses, herpes including
zoster (chickenpox), Clostridium, corona viruses including SARS,
MERS, and PEDV, Enterococcus, Escherichia, Hemophilus, hepatitis
viruses A and B, influenza and parainfluenza viruses, Klebsiella,
Listeria, Legionella, measles virus, mumps virus, Mycobacterium,
Neisseria, norovirus, Pseudomonas, parvovirus, poliovirus,
rhinovirus, respiratory syncytial virus, rotavirus, rubella,
Salmonella, Streptococcus, Staphylococcus, and Vibrio. The
infectious agents that are reduced include both those susceptible
to antibiotics and, without limitation, those resistant to
antibiotics such as MRSA (methicillin-resistant Staphylococcus
aureus, VISA (vancomycin intermediate Staphylococcus aureus), MRE
(multiply resistant enterococci), and VRE (vancomycin-resistant
enterococci).
[0023] Methods of reducing the incidence of healthcare-associated
infections in various healthcare settings as described herein are
provided. According to one embodiment, the method includes the step
of treating at least one inanimate surface of the healthcare
facility structure, the objects (e.g., medical equipment) therein,
or a combination thereof with a photocatalytic composition as
provided herein. Exemplary healthcare settings that include such
structures and objects include, but are not limited to, hospitals,
doctors' offices, elder or specialty care homes (e.g., assisted
living, long-term care) and hospices. Exemplary structures of the
facility subject to treatment include, but are not limited to, the
walls, fixtures, floors, and ceilings, including those parts of
hallways, offices, bathrooms, elevators, stairwells, and
kitchens/cafeterias, common areas, nurses' stations, and doctors'
stations. Exemplary inanimate objects in such a setting include the
various equipment or medical devices that may be present including,
but not limited to, curtains, call buttons, computers, monitors,
wall computer kiosks, blood pressure cuffs, wheelchairs, lifts,
carts, beds, and other similar objects.
[0024] According to one embodiment, healthcare-associated
infections that can be acquired or transmitted in a healthcare
setting and susceptible to treatment with the photocatalytic
compositions provided herein include, but are not limited to, bone
and joint infection (e.g., osteomyelitis, disc space infection,
joint or bursa infection, prosthetic joint infection), bloodstream
infection, central nervous system infection (e.g., intracranial
infection, meningitis, or ventriculitis), cardiovascular system
infection (e.g., myocarditis, pericarditis, endocarditis,
mediastinitis, arterial or venous infection),
Eye/ear/nose/throat/mouth infection (e.g., conjunctivitis, ear
infection, oral infection, sinusitis, upper respiratory infection,
pharyngitis, laryngitis, epiglottitis), gastrointestinal system
infection (e.g., gastroenteritis, gastrointestinal tract infection,
hepatitis, intraabdominal infection, necrotizing enterocolitis),
lower respiratory infection (e.g., bronchitis, tracheobronchitis,
tracheitis), pneumonia, reproductive tract infection (e.g.,
endometritis, episiotomy infection, vaginal cuff infection),
surgical site infection, skin/soft tissue infection (e.g., breast
abscess, mastitis, burn infection, circumcision infection,
decubitus ulcer infection, infant pustulosis, skin infection,
omphalitis), systemic infection, or urinary tract infection.
According to a preferred embodiment, healthcare-associated
infections that can be acquired or transmitted in a healthcare
setting and are usceptible to treatment include gastrointestinal
infection, lower respiratory infection, upper respiratory
infection, skin or soft tissue infection, bloodstream infection,
eye infection, ear infection, nose infection, throat infection,
mouth infection, and urinary tract infection.
[0025] According to one embodiment, the incidence of
healthcare-associated infections is reduced by at least 20% over a
twelve month period after one treatment as provided herein.
According to a preferred embodiment, the incidence of
healthcare-associated infections is reduced by at least 30% over a
twelve month period after one treatment as provided herein.
[0026] The compositions as provided herein may be applied in any
known or suitable manner, including using application techniques
such as spraying (e.g., electrostatic), atomizing, coating,
immersion, or dipping. The best method of application may vary
according to the nature of the surface to be coated. For many
settings a preferred method is to use electrostatic spray, wherein
droplets of the aqueous composition ranging in size from 5
micrometers to 100 micrometers are afforded a small electrical
charge so that the droplets are attracted to the surface to be
coated. In a further preferred technique, the coating is applied as
a series of two to five spraying steps with drying allowed between
each step. The photocatalytic coating can be applied at a rate of
from about 500 ft.sup.2 per liter to about 1500 ft.sup.2 per
liter.
[0027] According to yet another embodiment, a method for preventing
or reducing the number of infections in a human or animal
population is provided. The method includes treating inanimate
structures used by the human or animal population, the inanimate
objects that may be found within such structures, or a combination
thereof, with a photocatalytic composition as provided herein. The
step of treating the inanimate structures may include treating
either a finished structure or a structure under construction.
Exemplary settings that include such structures and objects
include, but are not limited to, agricultural facilities,
food-processing facilities, catering facilities, restaurants,
hotels, motels, and childcare facilities. Exemplary parts of the
structures that can be treated include, but are not limited to,
walls, fixtures, floors, and ceilings, including those parts of
hallways, offices, bathrooms, elevators, stairwells, and
kitchens.
[0028] The methods as provided herein utilize photocatalytic
compositions that include titanium dioxide (TiO.sub.2)
nanoparticles, which are useful in the prevention and reduction of
infectious agents found on a surface and particularly useful in the
reduction of healthcare-associated infections. The photocatalytic
compositions as provided herein, including any nanoparticles
therein, are free of any polymer or polymer composition (e.g.,
polymer-stabilized inorganic composition). The photocatalytic
compositions as provided herein can be used to treat both animate
and inanimate surfaces in a variety of environments where an
infectious agent is located. The photocatalytic compositions
provided herein contain only well characterized and safe materials,
can be easily applied to surfaces using ordinary spray equipment,
exhibit photocatalytic activity, and are effective in settings of
low UV irradiance, including interior artificial lighting.
[0029] According to one embodiment, the methods as provided herein
utilize photocatalytic compositions that comprise, consist
essentially of, or consist of titanium dioxide (TiO.sub.2) doped
with zinc and at least one other doping agent. Doping agents
suitable in the photocatalytic compositions provided herein, in
addition to zinc, include Ag, Si, C, S, Fe, Mo, Ru, Cu, Os, Re, Rh,
Sn, Pt, Li, Na, and K, and combinations thereof. Particularly
preferred doping agents include zinc and silicon.
[0030] According to one embodiment, the composition comprises,
consists essentially of, or consists of titanium dioxide doped with
zinc and the ratio of titanium dioxide to zinc is from about 5 to
about 150. According to a preferred embodiment, the ratio of
titanium dioxide to zinc is from about 40 to about 100. The
photocatalytic composition can further comprise, consist
essentially of, or consist of silicon dioxide (SiO.sub.2).
According to such an embodiment, the ratio of titanium dioxide to
silicon dioxide can range from about 1 to about 500. According to a
preferred embodiment, the ratio of titanium dioxide to silicon
dioxide is from about 3 to about 20. According to one embodiment,
the titanium dioxide nanoparticles as provided herein have an
average particle size of from about 2 nm to about 20 nm.
[0031] According to a preferred embodiment, the photocatalytic
composition as provided herein comprises, consists essentially of,
or consists of from about 5000 to about 10000 ppm of titanium
dioxide, from about 50 to about 150 ppm of zinc, and from about 300
to about 1000 ppm of silicon dioxide. According to one embodiment,
the photocatalytic composition as provided herein absorbs
electromagnetic radiation in a wavelength range of from about 200
nm to about 500 nm. According to one embodiment, the absorbance of
light of wavelengths longer than about 450 nm is less than 50% the
absorbance of light of wavelengths shorter than about 350 nm.
[0032] The invention will be further understood by the following
examples, which are intended to be illustrative of the invention,
but not limiting thereof.
Example 1
[0033] Absorption characteristics of nanoscale TiO.sub.2 were
compared to nanoscale TiO.sub.2 doped with two differing zinc
levels and SiO.sub.2, over the wavelength range of 350 nm to 500
nm. The nanoparticle compositions were manufactured by a modified
sol-gel process, to produce formulations containing nanoparticles
of anatase TiO.sub.2 whose average size was 6 to 7 nm. Zinc was
incorporated as a doping agent to provide either low zinc content
(0.125% relative to TiO.sub.2) or high zinc content (1.25% relative
to TiO.sub.2). When SiO.sub.2 was an additional dopant, it was
present at 10% relative to TiO.sub.2. The preparations were dried
and absorbance was measured using standard methods for obtaining
diffuse reflectance spectra (DRS) of powders. The solar irradiance
(hemispherical, 37 degree tilt) from ASTM G173-03 across this
spectral range is shown for reference, (See FIG. 1).
[0034] It is evident upon inspection that the TiO.sub.2
preparations doped with hetero-atoms absorb more strongly than
otherwise similar undoped TiO.sub.2 in the near-UV and violet
region of the spectrum. The doped preparations absorb 25 to 35
percent more of the energy available from 400 to 450 nm, a region
of the spectrum that is present in typical interior light as well
as sunlight.
Example 2
Photocatalytic Activity of Various Formulations of TiO.sub.2 Doped
with Zn and SiO.sub.2 Under UV Illumination
[0035] The four formulations described in Example 1 were tested for
their photocatalytic activity in a standardized system. Each
preparation was suspended in water at approximately 8000 ppm and
applied to a glass panel using a robotic high volume low pressure
sprayer, and allowed to dry for 24 hours. These panels were each
attached to a glass tube to form a container, into which was placed
30 ml of an aqueous solution of methylene blue at a concentration
providing an optical density of 2.3 at 664 nm. The tubes were
covered with a glass panel and subjected to illumination at an
energy density of approximately 0.5 mW/cm.sup.2 from a lamp (GE
item F18T8/BLB) affording ultraviolet illumination at 354 nm. This
lamp provides no light at wavelengths below 300 nm or above 400 nm.
The optical density of the methylene blue solution in each sample
was monitored over a period of 48 hours and is shown in FIG. 2.
[0036] FIG. 2 shows that the nanocoatings caused a decline in
optical density, which results from photocatalytic degradation of
the organic dye methylene blue. The coatings that had the higher
amounts of dopants afforded the most rapid declines, consistent
with greater absorbance of light from the lamp in the UV range (354
nm).
Example 3
Photocatalytic Activity of Various Formulations of TiO.sub.2 Doped
with Zn and SiO.sub.2 Under Visible Light Illumination
[0037] The four formulations described in Example 1 were tested for
their photocatalytic activity in a second system, in which the
experimental illumination was changed to more closely mimic
relevant illumination such as daylight or interior light, which are
deficient in the ultraviolet energy used in Example 2. Also, for
this example the nanoparticle formulations were evaluated as
colloidal suspensions in 20 mM phosphate buffer, pH 7.2, rather
than on a static surface. The experiment was performed in a 96-well
plate format, in which each well contained methylene blue (observed
OD.sub.655 ranging from 0.05 to 0.5) and a nanoparticle formulation
or appropriate controls in a final volume of 200 microliters. The
plate was illuminated from a distance of 20 cm with light from two
Sylvania Gro-Lux lamps (F20 T12 GRO/AQ). These lamps emit only 2%
of their total emitted energy below 400 nm, whereas approximately
36% of their total energy is emitted between 380 and 500 nm, with a
peak at 436 nm (reference: Technical Information Bulletin "Spectral
Power Distributions of Sylvania Fluorescent Lamps", Osram Sylvania,
www.sylvania.com).
[0038] The compositions of the four preparations tested in this
experiment were independently verified by the analytical technique
known as ICP-AES (inductively coupled plasma atomic emission
spectrometry), which demonstrated their equivalent TiO.sub.2
content and variations in Si and Zn composition as described in
Example 1. The nanoparticle preparations were diluted in buffer to
provide final concentrations of 75 ppm of titanium dioxide of each
formulation, with twenty replicate wells of each formulation. After
a short period of equilibration in the dark, each plate was exposed
to illumination with shaking, and optical density at 655 nm was
measured at multiple times over using a Molecular Devices
SpectraMax Plus spectrophotometer. The observed linear declines in
optical density due to each formulation were measured to give the
rates summarized in Table 1.
TABLE-US-00001 TABLE 1 Trial 1 Trial 2 TiO.sub.2, low Zn 0.0017*
0.0016 TiO.sub.2, low Zn, high Si 0.0020 Not tested TiO.sub.2, high
Zn, high Si 0.0019 Not tested TiO.sub.2 only Not tested 0.0013 *All
values reported are the decline in optical density at 655 nm, per
minute
[0039] It is evident that all the doped TiO.sub.2 formulations show
significantly increased rates (25% to 50%) compared to the undoped
TiO.sub.2 formulation. The magnitude of the increase in the rate of
photocatalytic activity is highly consistent with the increased
absorption of light energy in the range of 400 nm to 450 nm that is
evident in the spectra described in Example 1.
Example 4
[0040] Infections in a long term acute care healthcare facility
were evaluated upon treatment with a photocatalytic composition as
provided herein. The results show that the typical infections
arising in a healthcare facility may be significantly reduced as a
result of such treatment.
[0041] A photocatalytic composition including titanium dioxide
nanoparticles doped with zinc and silicon dioxide was prepared. The
individual nanoparticles were approximately six to ten nanometers
in dimension, and were dispersed in water to provide about 8000 ppm
TiO.sub.2, about 100 ppm Zn, and about 500 ppm SiO.sub.2. This
dispersed colloidal suspension of doped nanoparticles was used to
coat essentially all accessible surfaces in a 42 bed health care
facility that provides long term acute care services to patients
after surgery and other medical procedures.
[0042] The coating was applied using the following procedure.
Vacant rooms and bathrooms were thoroughly cleaned by housekeeping
staff, including removal of all linens and surface disinfection
according to institutional procedures. The photocatalytic coating
was then applied using electrostatic spray at a rate of about 1200
ft.sup.2 per liter. All objects in the room were coated, including
both hard and soft surface furniture and nearby walls, window and
privacy curtains, and equipment such as call buttons and remote
controls. Bathroom walls, fixtures, and floors were specifically
coated. A minimum of 15 minutes was allowed for drying of coated
surfaces, after which the room was ready for occupancy. In addition
to patient rooms, all common areas, including hallways, offices,
visitor restrooms, elevators, stairwells, kitchen, and nurse's
stations (including computers) were coated. Equipment was also
coated, including wall computer kiosks, blood pressure cuffs,
wheelchairs, lifts, carts, and other similar surfaces.
[0043] The healthcare facility made no changes to institutional
infection control processes or procedures. The number of infections
were recorded in compliance with existing institutional protocols.
Table 2 reports the number of infections occurring in each quarter
of the year following treatment, compared with the number of
infections at the same institution during the same quarter of the
year prior to treatment. Infections were fewer in every quarter
after treatment than in any quarter prior to treatment. When summed
over the entire assessment period, infections declined 40% in the
year following surface coating with the photocatalytic
composition.
TABLE-US-00002 TABLE 2 Infections per three month period Year
Before Year After Coating Coating Q1 17 8 Q2 15 7 Q3 16 11 Q4 12
6
Example 5
[0044] The composition described in Example 4 was applied using the
procedure described in Example 4 to a 250 bed health care facility
that provides sub-acute long term residential care. Similar to
Example 4, no change was made to institutional processes or
procedures, and infections occurring in the facility were
enumerated in accord with standard protocols. Table 3 reports the
number of infections occurring in each quarter of the year
following treatment, compared with the number of infections at the
same institution during the same quarter of the year prior to
treatment. Infections were fewer in every quarter after treatment
compared to any quarter prior to treatment. When summed over the
entire assessment period, infections declined 32% in the year
following surface coating with the photocatalytic composition.
TABLE-US-00003 TABLE 3 Infections per three month period Year
Before Year After Coating Coating Q1 78 50 Q2 73 52 Q3 58 42 Q4 66
41
[0045] The larger size of this facility allowed an examination of
selected categories of infections, as defined by the USA Centers
for Disease Control (CDC), because of the larger total number of
events. For this evaluation, the absolute numbers of infections and
the actual patient population were used to calculate the rate of
each infection for each month of the evaluation interval. The rates
were reported in the unit of events per 1000 patient days. These
monthly rates were averaged for the year before application of the
coating and the year after application, and compared.
[0046] The results are shown in Table 4, below, along with the
results of a two-tailed homoscedastic t-test. The decline in total
of all infection rates was statistically significant. Six of the
seven infection categories that were monitored showed a decline in
their average rates. However, not all infection categories were
equally affected. Also, because the statistical test did not
presume the direction of change that might occur, the p-values were
suggestive but not conclusive that the observed results did not
occur by chance.
TABLE-US-00004 TABLE 4 12 months 12 months p Type of Infection
before after value Gastrointestinal 0.358 0.333 0.858 Skin and Soft
Tissue 1.017 0.767 0.192 Bloodstream 0.033 0.017 0.557 Eye, Ear,
Nose, 0.708 0.367 0.108 Throat, or Mouth Urinary Tract 1.683 1.025
0.079 Upper Respiratory 0.217 0.050 0.219 Lower Respiratory 0.533
0.648 0.536 TOTAL 4.567 3.225 0.016
[0047] To strengthen the statistical analysis, additional data was
included in a subsequent analysis, and is shown in Table 5 below,
along with the results of a two-tailed homoscedastic t-test. As
before, results for the grouped infections of all types were
statistically significantly different. Six of the seven individual
infection categories that were monitored showed a decline in the
average rate of occurance. However, the one infection category that
showed an increase changed from lower respiratory to blood stream.
It is likely that such shifts are a result of the relatively low
number of events overall, and that larger studies are needed to
define the full range of benefit. Nevertheless, five of the seven
categories showed a decline in both analyses. This analysis also
strengthened the statistical evidence for a non-chance reduction in
eye, ear, nose throat or mouth infection (EENT), urinary tract
infections (UTI), and upper respiratory infections (URI), with both
EENT and UTI achieving formal statistical significance
(p<0.05).
TABLE-US-00005 TABLE 5 12 months 17 months p Type of Infection
before after value Gastrointestinal 0.358 0.300 0.626 Skin and Soft
Tissue 1.017 0.911 0.538 Bloodstream 0.033 0.044 0.764 Eye, Ear,
Nose, 0.708 0.350 0.043 Throat, or Mouth Urinary Tract 1.683 0.978
0.027 Upper Respiratory 0.217 0.058 0.158 Lower Respiratory 0.533
0.499 0.836 TOTAL 4.567 3.172 0.004
[0048] It is important to note that the construction and
arrangement of the methods and steps shown in the exemplary
embodiments is illustrative only. Although only a few embodiments
of the present disclosure have been described in detail, those
skilled in the art will readily appreciate that many modifications
are possible without materially departing from the novel teachings
and advantages of the subject matter recited in the claims.
Accordingly, all such modifications are intended to be included
within the scope of the present disclosure as defined in the
appended claims. The order or sequence of any process or method
steps may be varied or re-sequenced according to alternative
embodiments. Other substitution, modification, changes and
omissions may be made in the design, operating conditions and
arrangement of the embodiments without departing from the spirit of
the present disclosure as expressed in the appended claims.
[0049] All publications, patents and patent applications cited in
this specification are herein incorporated by reference, and for
any and all purposes, as if each individual publication, patent or
patent application were specifically and individually indicated to
be incorporated by reference. In this case of inconsistencies, the
present disclosure will prevail.
* * * * *
References