Note: Descriptions are shown in the official language in which they were submitted.
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ANTIMICROBIAL COATING METHODS
[0001] This application claims benefit of U.S. Publication No. 2005-0003019
filed
Dec. 18, 2003.
[0002] FIELD OF THE INVENTION
[0003] The invention relates to cathodic arc ion plasma deposition methods for
preparing modified metal coatings useful for forming an anti-microbial surface
on devices
and materials used in medical applications. In particular, the invention
relates to a process
for depositing silver (Ag), and other anti-microbial metals, or combinations
thereof under
highly controlled conditions to form antimicrobial coatings that have improved
adhesion and
maintain activity over extended periods of time.
[0004] BACKGROUND
[0005] The germicidal properties of metals such as silver, zinc, niobium,
tantalum,
hafnium, zirconium, titanium, chromium, nickel, copper, platinum and gold are
well
documented. Of these metals, silver, in the form of ions or compounds, is
probably the best
known and most widely used anti-microbial metal. Elemental silver has some
anti-microbial
benefit, but is generally too unreactive for most anti-microbial applications.
An oxidized
form of silver is considered to be more active as an anti-microbial as
indicated by the
observation that painting and inking of silver oxides leads to a decrease in
their reactivity and
solubility.
[0006] Attempts have been made to improve the reactivity of silver through the
use of
silver oxides and combinations of silver with other materials using accepted
methods of
solution-based chemistry. U.S. Pat. No. 4,828,832 describes the use of
metallic silver salt
solutions such as aqueous silver nitrate in combination with an oxidizing
agent, such as
benzoyl peroxide, to treat skin infections.
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[0007] U.S. Pat. No. 5,824,267 discloses imbedding the surface of a plastic
article
with silver metal particles and ceramic or base metal particles to impart
antibacterial
properties to the plastic article. The extremely fine silver metal particles
are obtained by
chemical deposition from an aqueous silver salt solution.
[0008] Although solution methods of generating silver particles are able to
provide
anti-microbially active silver, there is little control over the structure of
the resulting silver
particles, so that these methods are limited in their applications. Moreover,
some ionic
species, such as aqueous silver nitrate, are too reactive for most
applications because of the
potential for skin irritation and must therefore be carefully monitored and
controlled.
Another problem with solution-based chemistry is the development of stable
combinations
without generating harmful byproducts. Silver ions bound in solutions of
pastes, paints,
polymers or gels tend to have a short shelf life, in part because of the side
reactions with
various constituents that can occur in water-based solutions.
[0009] There is a distinct need for anti-microbial surfaces that are capable
of
generating a sustained release of anti-microbial metal ions. The ability of a
surface to
generate a sustained release of anti-microbial ions would be particularly
useful in surgical
and wound dressings and bandages, surgical sutures, catheters and other
medical devices,
implants, prosthetics, dental applications and tissue regeneration. Other
devices that would
also benefit from a sustained release of anti-microbial materials include
medical tools and
surfaces, restaurant surfaces, face masks, clothing, door knobs and other
fixtures, swimming
pools, hot tubs, drinking water filters, cooling systems, porous hydrophilic
materials,
humidifiers and air handling systems.
[00010] A method for generating a sustained release of metallic ions is
described in
U.S. Pat. No. 4,886,505. According to the method, a device is coated with a
first metal, such
as silver, and a second metal, such as platinum, which is connected to the
first metal through
a switch. The presence of the silver and platinum metals in the presence of
body fluids
results in a galvanic action which is intended to release or liberate silver
ions. The release of
ions is controlled by the switch, which is operated external to the device.
[00011] The technique of applying a current to a silver-coated wound dressing
or
medical device is also the subject matter of U.S. Pat. Nos. 4,219,125 and
4,411,648.
Although the use of external switch controls or an external electric current
can enhance the
rate of metal ion release, such external controls or currents-may not be
practical for a variety
J:\1FC\10IXC]TPC7\Ann\FFr_tnty,,i,ro~T_-- . ===
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of applications.
[00012] U.S. Pat. No. 6,365,220 describes a process for producing an anti-
microbial
surface that provides a sustained release of anti-microbial ions without the
need for an
external electric current to maintain the release. According to the
disclosure, multiple layers
of metallic thin films are deposited on a substrate using a sputtering or
evaporation process.
By using different metal combinations for the different layers, and employing
etching
techniques to roughen or texture the surface of the layers, multiple
microlayer interfaces can
be generated. The multiple interfaces, when exposed to body fluids, provide
for release of
ions by galvanic and non-galvanic action.
[00013] U.S. Pat. No. 5,837,275 also discloses anti-microbial coatings that
provide a
sustained release of anti-microbial ions. Coatings are prepared by a sputter
technique using
specific deposition parameters. The coatings are described as metal films
exhibiting "atomic
disorder" which is claimed to be required for sustained release of metallic
ions.
[00014] Single ordered crystals of tetrasilver tetroxide (Ag404) are claimed
to be
useful as an anti-microbial in treating skin diseases (U.S. Pat. No.
6,258,385.) Such a
composition, however, is not practical for other than topical use, and its
ability to provide a
sustained release of anti-microbial materials over a long period of time
(i.e., several days)
without reapplication, has not been demonstrated.
[00015] Deposition of anti-microbial materials is commonly limited to one of
three
distinct methods for producing silver and silver oxide coatings. Each of these
methods has
serious disadvantages and none have been developed to efficiently produce
highly adherent,
evenly distributed anti-microbial films on surfaces of medical devices and
instruments.
Commonly used state of the art processes, such as sputtering, dip and Ion Beam
Assisted
Deposition, produce coatings with limited adhesion to flexible substrates or
elastic devices.
Additional layers to increase adhesion are sometimes necessary at a
significant cost in
processing time.
[00016] Deposition of metal materials on a substrate by cathodic are in a
vacuum is
known in the art. In contrast to other plasma vapor deposition methods, ion
plasma deposition
(IPD) can produce dense multi-component coatings of high purity as described
in U.S. Patent
Application Pub. No. 2004/0185182. However, conventional cathodic are
deposition methods
suffer from certain disadvantages. A waste of expensive material can occur due
to inefficient
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use of the target material and the lack of particle control. The lack of
control over the material
being deposited can result in the formation of particles of varying sizes,
which leads to the
deposition of non-uniform coatings. Typically, the cathodic arc processes also
require the
substrate surface to be heated to very high temperatures, which can damage the
substrate
material and severely restrict the choice of substrates.
[00017] BRIEF SUMMARY OF THE INVENTION
[00018] The present invention addresses the continuing need for anti-microbial
materials that will adhere to any surface, have controlled release rates and
longevity, and are
nontoxic in a desired application. Anti-microbial coatings with these
characteristics can be
deposited on a wide range of substrate surfaces using the novel cathodic arc
IPD deposition
process, herein described.
[00019] It is an object of the present invention to provide a method of
depositing anti-
microbial materials onto a substrate by using an ionic plasma deposition
process to form
discrete layers of anti-microbial particles.
[00020] A further object of the invention is to provide a method for producing
anti-
microbial surfaces on any finished product, thus eliminating the need to
employ complex
chemistry, pasting, printing and bonding technologies.
[00021] Another object of the invention is to provide an anti-microbial
surface that
provides a sustained release of an anti-microbial agent in vivo at
therapeutically effective
levels for extended periods of time.
[00022] Another object of the invention is to provide an anti-microbial
surface by
impregnating or depositing dispersed metals and/or metal/metal oxides of one
or more
elements into a substrate for the sustained release of metal ions.
[00023] Accordingly, in particularly preferred embodiments, the present
invention
provides the deposition, impregnation or layering of silver or other metal
ions bound into
solid state structures of nano-, pico-, and micro-sized crystalline metal and
metal oxide
compounds which can be designed as combinations of mono-, di-, and polyvalent
oxides
dispersed into or onto a surface. The silver ions will then be released by
contact with
pathogens due to enzyme activity or released by the addition of water or
contact with body
fluids.
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[00024] The disclosed process is useful for the manufacture of a wide variety
of
devices which require a controlled composition, but is particularly useful in
the manufacture
of small to very large area rolls, such as bandages, or individual parts, such
as catheters,
stems or implants, that require a germicidal, bactericidal, biocidal or
antimicrobial surface.
The process results in the control of the amount, particle size and energy of
ionized material
to be combined with ionized oxygen or other gases, and is applicable to a wide
range of
monovalent, divalent, and polyvalent oxides and nitrides and combinations of
layers.
[00025] The process can be used to make anti-microbial products or to surface
treat
existing products and raw materials. The process can be used concurrently to
create small
scale energy devices to enhance anti-microbial activity or to power other nano-
technology
devices; for example, silver oxide batteries to power micropumps, implants,
galvanic surfaces
and other devices needing power.
[00026] Accordingly, one aspect of the invention is to provide a process for
depositing
an anti-microbial surface on a substrate which comprises the steps of placing
a cathode target
comprising a potential anti-microbial metal into an evacuated chamber and
powering the
cathode to generate an are at the cathode which ionizes the cathode metal into
a plasma of
ionized particles; introducing a reactive gas, such as oxygen, into the vacuum
chamber such
that the gas reacts with the ionized plasma particles, and controlling
deposition of the plasma
particles on the substrate by moving the substrate closer or further from the
target in a
controlled manner during the deposition process.
[00027] Further control of the deposition process may be achieved by an arc
control
means whereby the power supply to the cathode is adjusted to alter the speed
of arc
production.
[00028] An additional aspect of the invention is to provide on a substrate, an
anti-
microbial surface comprising a dispersion of metal oxide particles, wherein
the metal is
selected from the group consisting of silver, nickel, zinc, copper, gold,
platinum, niobium,
tantalum, hafnium, zirconium, titanium, chromium, and combinations thereof.
[00029] The present invention relates to a process of depositing anti-
microbial
materials onto a selected substrate material. The substrate can be of any
material, such as
metal, ceramic, plastic, glass, flexible sheets, porous papers, ceramics or
combinations
thereof. Although the substrate can comprise any of a number of devices,
medical devices are
particularly preferred. Such medical devices include catheters, implants,
stents, tracheal
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tubes, orthopedic pins, shunts, drains, prosthetic devices, dental implants,
dressings and
wound closures. However, it should be understood that the invention is not
limited to such
devices and may extend to other devices useful in the medical field, such as
face masks,
clothing, surgical tools and surfaces.
[00030] There are two important factors regarding implant infection: the
introduction
of bacteria during implant surgery; and, transdermal openings following
surgery.
Transdermal devices are a prime location for infections. As the device
separates from the
skin, a fissure forms between the skin and device, allowing bacterial
contamination.
[00031] This invention, in further aspects, is related to improved and more
economical
methods for providing tuned anti-microbial surfaces or other components on
medical devices
for use in the human body as well as in veterinary and other applications.
[00032] Anti-microbial material can be any solid material or combination of
materials
having anti-microbial properties. Preferred materials are metals having
potential anti-
microbial properties and which are biocompatible (i. e., not damaging in the
intended
environment). Such metals include silver, zinc, niobium, tantalum, hafnium,
zirconium,
titanium, chromium, nickel, copper, platinum and gold (also referred to herein
as "anti-
microbial metals"). The term "potential anti-microbial properties" is meant to
recognize the
fact that these metals, in their elemental state, are typically too unreactive
to act as effective
anti-microbials. However, there is a much stronger anti-microbial effect when
the metals are
ionized. Thus, the anti-microbial metals have potential anti-microbial
properties, which are
realized upon ionization of the metals. When ionized, the anti-microbial
metals can also be
combined with various reactive gases, for example, nitrogen or oxygen to form
compounds of
nitrides, oxides, and/or combinations thereof.
[00033] DEFINITIONS
[00034] Ionic Plasma Deposition (IPD) is a method of creating highly energized
plasma by using a cathodic are discharge on a target material.
[00035] Cathodic are, also known as a vacuum arc, is a device for creating a
plasma
from solid metal. An arc is struck on the metal, and the arc's high power
density vaporizes
and ionizes the metal, creating a plasma which sustains the arc. A vacuum are
is different
from a high-pressure arc because the metal vapor itself is ionized, rather
than an ambient gas.
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[000361 Macros or macroparticles are particles larger than a single ion; nano
(or small)
particles are particles about 100 nanometers in size; medium macro particles
are 100
nanometers to about 1 micron; large macro particles are particles larger than
1 micron.
[000371 Coulomb explosion occurs when a sufficiently intense power source
disrupts a
group of atoms such as a gas cluster, object, or target so that the electric
field of the power
source drives some or all of the electrons off the atoms. Without electrons,
the group of ions
explodes due to the Coulombic repulsion of the positive charges.
[00038] Plasma vapor deposition (PVD) is a thin film deposition process in the
gas
phase in which source material is physically transferred in the vacuum to the
substrate
without any chemical reaction involved. This type of deposition includes
thermal evaporation
electron-beam deposition and sputtering deposition. The IPD process is a
subtype of physical
vapor deposition.
[00039] The term "medical device" as used herein is intended to extend broadly
to all
devices used in the medical field, including stents, catheters, various
implants and the like
regardless of the material from which it is fabricated. References herein to
medical devices
and other medical references are understood to also include veterinary devices
and
applications.
[000401 The term "potential anti-microbial properties" is meant to recognize
the fact
that some metals, in their elemental state, are typically too unreactive to
act as effective anti-
microbials, but may, however, exhibit a much stronger anti-microbial effect
when ionized.
Thus, the anti-microbial metals have potential anti-microbial properties,
which in many cases
are realized upon ionization of the metals. When ionized, the anti-microbial
metals can also
be combined with various reactive gases, for example, nitrogen, or oxygen to
form
compounds of nitrides or oxides, and combinations thereof.
[00041] "Multivalent" as used herein refers to one or more valence states and
should be
understood to refer to the charge on an ion or the charge that may be assigned
to a particular
ion based on its electronic state.
[00042] Silver oxide, unless otherwise indicated, is defined as the singlet
form of silver
oxide (Ago).
[00043] The term "about" as used herein is intended to indicate that a
particular
number is not necessarily exact but may be higher or lower as determined by
the particular
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procedure or method used.
[00044] PEEK - poly ether ether ketone
[00045] PTFE - poly tetra fluoro ethylene
[00046] EPTFE - expanded poly tetra fluoro ethylene
[00047] UHMWPE is ultra high - molecular weight polyethylene
[00048] It is understood that "a" as used to define the claims is not
necessarily limited
to a single species.
[00049] BRIEF DESCRIPTION OF THE DRAWINGS
[00050] FIG. 1 is a sketch of an IPD apparatus. I. Target material, 2.
Substrate being
coated, 3. Mechanism for moving the substrate closer or further away from the
target, 4.
Vacuum chamber, and 5. Power supply for the target.
[00051] FIG. 2 is another embodiment of the IPD apparatus. 1. Target material,
2.
Substrate being coated, 3. Mechanism that has the ability to move the
substrate closer or
further away from the target, 4. Vacuum chamber, 5. Power supply for the
target, and 6. Arc
control that determines the speed of the are.
[00052] DETAILED DESCRIPTION OF THE INVENTION
[00053] The present invention provides a number of advantages over other state
of the
art anti-microbial coatings and processes for depositing anti-microbial
coatings, including
controllable release, embedding the coating into the substrate, lower run
temperatures for
certain materials, significantly improved throughput in processing efficiency
compared with
conventional cathodic arc processes, scalability, and application to a wide
range of substrate
materials.
[00054] Additionally, superior coatings unavailable using conventional IPD
methods
have been obtained, including silver oxide, copper oxide and hafnium nitride
coatings. These
materials have a higher anti-microbial activity at comparable thicknesses
compared to more
expensive processes, such as those outlined in U.S. Pat No. 5,454,886.
Thus, thinner coatings and shorter processing time can be achieved with the
same
anti-microbial results by employing the new IPD-based methods. Higher
throughput is
possible, which can result in production cost savings and is a very
significant advantage,
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especially for the medical industry.
[00055] A factor contributing to the superiority of films obtained using the
disclosed
process is the discovery that the new IPD process produces an increase, rather
than a
decrease, in macro particle deposition, which in fact improves film quality.
The predominant
trend for one skilled in the use of traditional cathodic are deposition
processes has for years
been to reduce macro particles deposited in order to produce cleaner and more
uniform films.
Conventional wisdom in the industry has been that macro-particles in general
are deleterious
to the quality of deposited films.
[00056] The present invention relates to a process of depositing anti-
microbial
materials onto a selected substrate material. The substrate can be of any
material, such as
metal, ceramic, plastic, glass, flexible sheets, porous papers, ceramics or
combinations
thereof. Although the substrate can be any of a number of devices, medical
devices are
particularly preferred, including catheters, implants, stents, tracheal tubes,
orthopedic pins,
shunts, drains, prosthetic devices, dental implants, dressings and wound
closures. However, it
should be understood that the invention is not limited to such devices and may
extend to other
devices useful in the medical field, such as face masks, clothing, surgical
tools and surfaces.
[00057] There are two important factors regarding implant infection: the
introduction
of bacteria during implant surgery; and, transdermal openings following
surgery.
Transdermal devices are a prime location for infections. As the device
separates from the
skin, a fissure forms between the skin and device, allowing bacterial
contamination.
[00058] The present invention, therefore, is related to improved and more
economical
methods for providing anti-microbial surfaces or other components on medical
devices for
use in the human body as well as in veterinary and other applications The anti-
microbial
material can be any solid material or combination of materials having anti-
microbial
properties. Preferred materials are metals having potential anti-microbial
properties and
which are biocompatible (i.e., not damaging in the intended environment). Such
metals
include silver, zinc, niobium, tantalum,
hafnium, zirconium, titanium, chromium, nickel, copper, platinum and gold
(also referred to
herein as "anti-microbial metals"). In accordance with the present invention,
anti-microbial
metals are deposited onto or into the surface of a substrate by ionizing, in a
vacuum, a
cathode of a target metal into a plasma of particulate constituents. Ionic
plasma deposition
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devices, such as those described in International Patent Application
publication WO 03-
044240, can be modified in
accordance with the invention and used to carry out the controlled deposition
of the anti-
microbial materials in accordance with the described methods.
[00059] A factor contributing to the superiority of films obtained using the
new IPD
process is the discovery that an increase, rather than a decrease, in macro
particle deposition
in fact improves film quality. The predominant trend for one skilled in the
use of cathodic are
deposition processes has for years been to reduce the number of macro
particles in order to
produce cleaner and more uniform films. Conventional wisdom in the industry is
that macro-'
particles in general are deleterious to the quality of deposited films.
[000601 In contrast, an increased amount of macro particles has been found to
result in
an effective way to control the anti-bacterial activity of silver oxide films.
For a quick release
of silver into the surrounding tissue, a thick, fairly macro-particle free
coating of pure AgO
can be applied. For a more tuned release, a time-release scheme is used.
[00061] When depositing a coating on a substrate using cathodic are, the
relative
amount of macro-particles ejected from the target can be controlled. Macro-
particles are
molten blobs of metal that are ejected from the target without being fully
vaporized. These
blobs are dense and comprised of pure target material. The surfaces of these
blobs usually are
charged, while the bulk of the material is neutral.
1000621 When the macro particles pass through the plasma, the outside surface
is
oxidized, forming an "coated candy" like structure with a coating of AgO on
the outside of
the particle and pure silver on the inside. This acts like a time-release
capsule.
[00063] Time-release effects occur due to the inherent instability of the
outer "shell" of
AgO and a more stable inner "shell" of pure silver. The silver oxide outer
coating releases its
anti-microbial activity relatively quickly, killing any bacteria in the
surrounding area. During
the release process, the inner pure silver is oxidized and slowly released to
maintain anti-
microbial activity over time. The time period is determined by the size of the
macro-particle.
Thus, specific coatings of specific sizes of macro-particles can be designed
to maintain anti-
microbial activity for a selected time period. Typical size ranges for macro-
particles are 10
nm to 10 microns, depending on the length of time desired to maintain
activity.
[000641 Elution is an important factor in anti-microbial activity; however the
amount
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of silver eluted is related to the anti-microbial activity of a Ag/AgO coated
device. The
elution rate must occur at a certain level in order to be effective against
infection and biofilm
formation. The minimum rate is approximately 0.005 mg Ag per square inch
(0.0048 mg/sq
inch). The anti-microbial activity of a silver oxide coating prepared by the
method disclosed
herein will elute at this rate for at least 60 days. Silver/silver oxide
coatings prepared by other
methods do not elute at a constant rate for longer than a 7 day period.
[00065] Another important feature of the present invention is the ability to
imbed a
silver oxide coating into the surface of the device, thus obtaining superior
adhesion compared
to coatings deposited by other deposition methods. The imbedding process can
be controlled
by using the arc control method at a specific distance from the target, so
that coatings
embedded up to 100 nm and more for plastics and up to 10 nm and more for
metals and
ceramics can be obtained.
[00066] A suitable device for carrying out the ionic plasma deposition process
is
illustrated in FIG. 1. As shown in FIG. 1, a cathode 1 of the target material
is disposed within
a vacuum chamber 4. The cathode 1 is ionized by generating an arc at the
cathode from a
power supplied by a power source 5 to the cathode. The plasma constituents are
selected,
controlled or directed toward the substrate by a controlling mechanism 3 that
moves the
substrate 2 toward or away from the target 1.
[00067] Additional control of the power supply 6 as shown in FIG. 1 can also
be used
to provide further control of the plasma constituents by controlling arc
speed.
[00068] In the case where the desired anti-microbial metal is silver, for
example, a
silver cathode is placed in the vacuum chamber of the ionic plasma deposition
device, along
with a selected substrate. The silver used as the cathode is preferably
medical grade (i. e.
99.99% pure) silver to avoid any potentially toxic materials, although silver
metal of lower
purity can also be used.
[00069] The vacuum chamber is pumped to a suitable working pressure typically
in the
range of 0.1 mT to 30 mT; however, the ability of the IPD process to produce
effective anti-
microbial surfaces having sustained release rates is not dependent on any
specific working
pressure within the typical range of 0.1 mT to 30 mT. Similarly, the ionic
plasma deposition
process is not dependent upon operating temperature. Typical operating
temperatures are in
the range of 25 to 75 C and any temperature within this range is suitable for
producing anti-
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microbial surfaces.
[000701 The substrate can be rotated, such as on turntables, or rolled past
the
deposition area in any orientation relative to the trajectory of the incoming
deposition
material. Power is supplied to the cathode to generate an electric are at the
cathode. This
power can range from a few amps of current to several hundred amps, at a
voltage
appropriate for the source material. Voltage is typically in the range of 12
volts to 60 volts,
and is appropriately scaled to the size of the source material, which can be a
few inches to
several feet in length. The electric arc ionizes the silver metal cathode into
a plasma of silver
ions, neutrally charged particles and electrons. Oxygen is introduced into the
plasma at a
typical rate of 10 to 1000 sccm and combines with the silver ions to form
silver oxide
particles. The silver oxide particles can have a particle size ranging from
less than I
nanometer to about 50 microns, depending upon the desired ion release rate and
ultimate use
of the substrate.
[000711 It is also possible to control the metal ion release rate of the anti-
microbial
surfaces in order to obtain an effective release rate over a sustained period
of time. Such
controlled metal release is obtained by depositing a combination of oxides of
various
structures, including monovalent, divalent and multivalent oxides, onto the
substrate.
Combinations of oxides exhibit different ion release rates which contribute to
the control of
ion concentrations and the sustained release of the metal ions for enhanced
anti-microbial
activity. Multivalent oxides can also be created on neutral metal particles as
they are oxidized
in the plasma. This further enhances the sustained release of the deposited
materials by
creating combinations of oxides of various sizes and valence states. The
benefit of such
combinations is an increase in ion release over a longer period of time. The
silver oxide
particles are then deposited onto the substrate surface in the form of a
dispersion of silver
oxide particles.
[000721 The effectiveness of the anti-microbial surface in delivering an anti-
microbial
response is also dependent upon the processing time for forming the anti-
microbial surface.
Longer processing times from 5 seconds to multiple minutes result in anti-
microbial surfaces
having different anti-microbial responses.
[00073] Controlled metal release is also obtained by depositing a combination
of different
metal oxides onto the substrate. These combinations include silver and
titanium, silver and
gold, silver and copper, silver copper and gold. Other materials can be
combined as co-
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deposited metals, alloys or as alternating layers in various combinations.
Control and
flexibility of the plasma environment allows a much larger range of
combinations and,
accordingly, a wide range of customized coatings.
[00074] The invention is further illustrated by the following non-limiting
examples.
[00075] EXAMPLES
[00076] Materials and Methods
[00077] Sample Elution Testing - Elution testing was performed to determine
the
silver elution profile of coated Polypropylene samples. Silver elution testing
provides a
quantitative method for determining the amount of silver released from the
test article over a
specified period of time. The testing was conducted according to the current
FDA Good
Laboratory Practice, GLP, Standards, 21 CFR, Part 58. Each test article was
extracted in USP
0.9% NaCl for injection at a temperature of 37 1 C for silver elution
analysis by
Inductively Coupled Plasma (ICP) Spectroscopy. Each sample is separately
placed in 10 mL
of USP 0.9% NaCl for a specified period of time. The time periods used during
this study
were 15 min., 30 min., 1 hr, 2 hr, 4 hr, 8 hr, 24 hr, days 2-7, day 10, day
15, day 20, day 25,
and day 30. At each time point, the fluid surrounding the sample was decanted
into a clean
glass container and fresh NaCl was added to the sample container. The decanted
liquid was
brought to a total volume of 50 mL with deionized water, then acid digested
and examined by
ICP for silver content.
[00078] Sample Zone of Inhibition (ZOI) Testing - ZOI testing is an easy, 24
hour
test anti-microbial activity. The test is not quantitative, and only provides
enough information
to indicate if a serial dilution test is warranted. This test provides no
information regarding
tissue re-growth or necrosis.
[00079] Sample Serial Dilution Testing - Serial dilution testing provides an
accurate
measure of the amount of bacteria per given volume. When compared to a control
sample, it
can provide a quantitative measure of anti-microbial coating activity.
[00080] A standard bacterial solution is prepared from a 0.5 McFarland
standard. The
standard is calibrated to read between 0.08 and 0.1 OD at 625 nun, which gives
a standardized
bacterial count of 1.5 X 108 cfu/mL.
[00081] While the following embodiments of the present invention have been
described in
detail, it is apparent that modifications and adaptations of those embodiments
will occur to
CA 02635062 2009-03-30
14
those of skill in the art. It is to be understood that such modifications are
within the scope of
the invention.
[00082] EXAMPLE 1. Silver Coated Catheter (published method)
[000831 A solver-coated catheter was prepared using the same procedure
described in
Example 6 of U.S. Patent No. 5,454,886. Silver metal was deposited on 2.5 cm
sections of a
latex Foley catheter using magnetron sputtering. Operating conditions were
performed as
closely as possible based on the published example; i.e., the deposition rate
was 200 A per
minute; the argon working gas pressure was 30 in Torr; and the ratio of
temperature of
substrate to melting point of the coating metal silver, T/Tm was 0.30. In this
example, the
angles of incidence were variable since the substrate was round and rough;
that is, the angles
of incidence varied around the circumference and, on a finer scale, across the
sides and tops
of the numerous surface features. The anti-microbial effect on S aureus was
tested by a zone
of inhibition, (Table 1).
TABLE 1
Reported Results Experimental Results
5,454,886 patent
Zone of inhibition 0.5 mm
T/Tm 0.38
Zone of inhibition 16 mm <1 mm
T/Tm 0.30 0.30
[000841 Under the same T/Tm conditions, previously published, and repeating
the same
conditions as set forth in Example 6 of the 5,454,889 patent, the observed
zone of inhibition
(ZOI) around the tubing was significantly less than the reported ZOI. The ZOI
test was
performed using S. aureus as reported in example 1 of the 5,454,886 patent.
[000851 EXAMPLE 2. DC magnetron sputtered antimicrobial coating (published
method).
[00086] The procedure of Example 7 in the 5,454,886 patent was followed. A
Teflon
coated latex Foley catheter was coated by DC magnetron sputtering 99.99% pure
silver on
the surface using the conditions used were: 0.5 kW power, 40 mTorr Ag/02, 20
degrees C
initial substrate temperature, a cathode/anode distance of 100 mm, and a final
film thickness
of 300 mu. The working gases used were commercial Ar and 99/1 wt % Ar /02.
CA 02635062 2009-03-30
[00087] The anti-microbial effect of the coating was tested by a zone of
inhibition test.
Mueller Hinton agar was dispensed into Petri dishes. The agar plates were
allowed to surface
dry prior to being inoculated with a lawn of Staphylococcus aureus ATCC425923.
The
TM
inoculant was prepared from Bactrol Discs (Difco, M.) which were reconstituted
per the
manufacturer's directions. Immediately after inoculation, the coated materials
to be tested
were placed on the surface of the agar. The dishes were incubated for 24 hr.
at 37 C. After
the incubation period, the ZOI was measured and a corrected zone of inhibition
was
calculated as follows: corrected zone of inhibition=zone of inhibition-
diameter of the test
material in contact with the agar. The published results showed no zone of
inhibition for the
uncoated samples. A corrected zone of inhibition of 11 mm was reported for
catheters
sputtered in the 99/1 wt % Ar/02 using a working gas pressure of 40 mTorr.
[00088) The experiment was repeated under the published conditions listed in
Table 2.
A small ZOI of less than one mm was observed.
TABLE 2
Conditions of DC Magnetron Sputtering Used for
Anti-Microbial Coatings
Samples Sputtered in Samples Sputtered in
Commercial Argon 99/1 wt % Ar/02
Power 0.1 kW Power 0.5 kW
Argon Pressure: 5 m Torr Ar /02 Pressure: 40 m Torr
Initial Substrate 20 C. Initial Substrate 20 C.
Temperature: Temperature:
Cathode/Anode 40 mm Cathode/Anode 100 mm
Distance: Distance:
Film Thickness: 2500 A Film Thickness: 3000 A
ZOI (reported) 0 11 mm
Experimental (repeat under published conditions above) Results
ZOI 0 <1 mm
[00089] In repeating the above published conditions, the experimental results
showed a
small ZOI of less then one mm.
CA 02635062 2009-03-30
16
[00090] EXAMPLE 3. Composite Silver Anti-microbial Films (published method)
[00091] This example demonstrates a state of the art procedure for preparing a
composite anti-microbial coating formed by reactive sputtering as found in
Example 11 of the
5,454,886 patent. Table 3 lists the published sputtering conditions and the
conditions used for
the comparison study compared with Experimental results obtained by following
the steps in
the published procedure.
TABLE 3
Sputtering Conditions
Published Experimental
Target 99.99% Ag 99.99%
Working gas 80/20% Ar/02 80/20% Ar02
Working gas P 2.5-50 mTorr 40 mTorr
Power 0.1-2.5 kW 0.5 kW
Substrate T -5 to 2011 C 20 C
Anode/Cathode 40 to 100 mm 100 mm
Distance
Base P <4x 104 Torr
ZOI 6-12 mm 0 to 2 mm
[00092] EXAMPLE 4 in vitro testing of silver oxide coated catheters
[00093] This example demonstrates the effectiveness of the antimicrobial
coating over
a range of gram positive and gram negative organisms. The organisms tested for
general zone
of inhibition were: Gram positive bacteria E. faecalls, S. aureus MR, and S.
epidermis. Gram
negative bacteria were E. coli, Kpneumoniae, and P. aerugosia.
[00094] The method used to test for a ZOI was plate-to-plate transfer maximum
for 4
days. Each of the above listed bacteria was plated out on tryptic soy agar.
The pre-made plate
was inoculated with the bacterium, divided into three equal sections, and a
one inch long
Foley catheter sample coated with 200 nm of silver oxide was placed in the
center of each
part after inoculation. The samples were placed in an incubator at 37 C and
the ZOI was
measured at 24, 48, 72 and 96 hours.
[00095] Total ZOI is defined as the ZOI minus the width of the sample. For
this
experiment, measurements were made of the total ZOI and divided in half. If
there was no
CA 02635062 2008-07-28
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17
measurable ZOI and no biof lm, and organism did not grow over or attach to the
sample, the
measurement was noted as 0.0mm. When a biofilm was observed, it was recorded
as -
1.0mm. Plate to plate transfer was repeated until a biofilm was noted or a
measurement of
0.0mm was recorded for 2 transfers. Each organism had three plates and each
plate had three
data points for the side-by-side sample and control catheter. Measurements
were taken daily.
The three measurements per plate were averaged to get a daily plate ZOI. This
was done to
compensate for swipes being too heavy or light in concentration. All
measurements taken
were recorded in mm. A measurement of 0.0 indicated that the organism grew to
the silver
sample but did not adhere or create a biofilm on the silver sample catheter.
All control
samples had biofilms from Day 1 without exceptions. Results are shown in Table
4.
TABLE 4
Dayl
Plate Plate Control Plate Plate Control Plate Plate Control
1 1 Plate 1 2 2 Plate 2 3 3 Plate 3
Zone Zone Zone
E. faecalis Width Width Width
(+) (Mm) ZOI (mm ZOI (mm) ZOl
Dayl 2.0 1.0 0.0 3.0 1.5 0.0 1.0 0.5 0.0
3.0 1.5 0.0 4.0 2.0 0.0 4.0 2.0 0.0
3.0 1.5 0.0 3.0 1.5 0.0 3.0 1.5 0.0
Da y2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Da y3 0.0 0.0 0.0 0.0 0.0 0.0 2.0 1.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 3.0 1.5 0.0
0.0 0.0 0.0 0.0 0.0 0.0 4.0 2.0 0.0
S.
epidermis
Dayl 3.0 1.5 0.0 9.0 4.5 0.0 2.0 1.0 0.0
3.0 1.5 0.0 12.0 6.0 0.0 9.0 4.5 0.0
8.0 4.0 0.0 10.0 5.0 0.0 8.0 4.0 0.0
Day2 1.0 0.5 0.0 0.0 0.0 0.0 2.0 1.0 0.0
0.0 0.0 0.0 1.0 0.5 0.0 4.0 2.0 0.0
2.0 1.0 0.0 0.0 0.0 0.0 2.0 1.0 0.0
Day3 3.0 1.5 0.0 6.0 3.0 0.0 5.0 2.5 0.0
0.0 0.0 0.0 4.0 2.0 0.0 6.0 3.0 0.0
2.0 1.0 0.0 3.0 1.5 0.0 6.0 3.0 0.0
Day4 1.0 0.5 0.0 2.0 1.0 0.0 0.0 0.0 0.0
4.0 2.0 0.0 2.0 1.0 0.0 2.0 1.0 0.0
2.0 1.0 0.0 2.0 1.0 0.0 2.0 1.0 0.0
E. Coli -
Dayl 2.0 1.0 0.0 5.0 2.5 0.0 0.0 0.0 0.0
7.0 3.5 0.0 2.0 1.0 0.0 0.0 0.0 0.0
1.0 0.5 0.0 10.0 5.0 0.0 6.0 3.0 0.0
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18
Day2 0.0 0.0 0.0 4.0 2.0 0.0 0.0 0.0 0.0
4.0 2.0 0.0 5.0 2.5 0.0 0.0 0.0 0.0
2.0 1.0 0.0 2.0 1.0 0.0 0.0 0.0 0.0
Day3 2.0 1.0 0.0 4.0 2.0 0.0 0.0 0.0 0.0
1.0 0.5 0.0 4.0 2.0 0.0 0.0 0.0 0.0
1.0 0.5 0.0 3.0 1.5 0.0 0.0 0.0 0.0
Day4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 2.0 1.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 2.0 1.0 0.0 0.0 0.0 0.0
K.
pneumoniae
Dayl 1.0 0.5 0.0 1.0 0.5 0.0 1.0 0.5 0.0
3.0 1.5 0.0 4.0 2.0 0.0 4.0 2.0 0.0
2.0 1.0 0.0 1.0 0.5 0.0 2.0 1.0 0.0
Day2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
1.0 0.5 0.0 4.0 2.0 0.0 3.0 1.5 0.0
0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Day3 0.0 0.0 0.0 0.0 0.0 0.0 2.0 1.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 3.0 1.5 0.0
0.0 0.0 0.0 0.0 0.0 0.0 4.0 2.0 0.0
P. aerugosia
Dayl 1.0 0.5 0.0 6.0 3.0 0.0 2.0 1.0 0.0
2.0 1.0 0Ø 7.0 3.5 0.0 4.0 2.0 0.0
1.0 0.5 0.0 5.0 2.5 0.0 2.0 1.0 0.0
Day2 0.0 0.0 0.0 4.0 2.0 0.0 1.0 0.5 0.0
1.0 0.5 0.0 5.0 2.5 0.0 0.0 0.0 0.0
1.0 0.5 0.0 4.0 2.0 0.0 1.0 0.5 0.0
Day3 0.0 0.0 0.0 3.0 1.5 0.0 2.0 1.0 0.0
0.0 0.0 0.0 3.0 1.5 0.0 3.0 1.5 0.0
0.0 0.0 0.0 3.0 1.5 0.0 4.0 2.0 0.0
S. aureus
MR +
Dayl 2.0 1.0 0.0 5.0 2.5 0.0 1.0 0.5 0.0
3.0 1.5 0.0 2.0 1.0 0.0 2.0 1.0 0.0
2.0 1.0 0.0 10.0 5.0 0.0 0.0 0.0 0.0
Day2 3.0 1.5 0.0 4.0 2.0 0.0 0.0 0.0 0.0
2.0 1.0 0.0 5.0 2.5 0.0 0.0 0.0 0.0
5.0 2.5 0.0 2.0 1.0 0.0 0.0 0.0 0.0
Day3 0.0 0.0 0.0 4.0 2.0 0.0 3.0 1.5 0.0
0.0 0.0 0.0 4.0 2.0 0.0 4.0 2.0 0.0
0.0 0.0 0.0 3.0 1.5 0.0 3.0 1.5 0.0
Day4 0.0 0.0 0.0 0.0 0.0 0.0 2.0 1.0 0.0
0.0 0.0 0.0 2.0 1.0 0.0 3.0 1.5 0.01
0.0 0.0 0.0 2.0 1.0 0.0 3.0 1.5 0.0
[000961 EXAMPLE 5 in vivo testing of a silver oxide coated catheter
[00097] This example demonstrates in vivo testing of two identical pieces of
catheter
material with a 200 nm silver oxide coating in a rabbit. The test devices were
ETO-sterilized.
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For each of the two catheter pieces, four segments of the antimicrobial
portion of the catheter
(approximately 4 inches in length) were prepared. The test devices were used
as provided and
maintained at room temperature.
[00098] . A total of eight catheter segments (four segments of each catheter
material)
were implanted into a female New Zealand White rabbit. Prior to implantation
on Day 1, the
animal was weighed and anesthetized with an intravenous injection of a
ketamine/xylazine
cocktail (87 mg/mL ketamine, 13 mg/mL xylazine) at 0.1 mL/kg. The animal was
23-25
weeks old and weighed 2.63 kg on Day 1.
[000991 One week following catheter implantation, a challenge organism (S.
aureus or
E. coli) was placed on the skin around each catheter entry site (two segments
of each catheter
material challenged with S. aureus and the remaining two segments of each
catheter material
challenged with E. coli). The animal was sacrificed 48 hours following
bacterial challenge.
[0001001 The treatment parameters are described below in Table 5. The
bacterial
challenge took place on Day 8, in accordance with the protocol used.
TABLE 5
Implantation Implant Bacterial Necropsy
Group No. (8 implant sites) Route Site Challenge (Day)
1 catheter
A 1 segment/site Percutaneous Perispinal Day 8 Day 10
[000101] The paravertebral area was clipped with electric clippers and
prepared with
povidone iodine and 70% alcohol. The animal had eight implantation sites along
the back.
Each site was 2.5-5.0 cm from the midline and sites were approximately 2.5 cm
apart.
Implant sites were identified by permanent marker.
[000102] At each implant site, the skin was punctured into the muscle with a
16-gauge
needle. The catheter segment was fed down the ID of the needle into the muscle
and the
needle removed, leaving half of the catheter segment implanted through the
skin into the
muscle. One section of catheter material was implanted at each site. The
rabbit was implanted
with four segments of each of the two identical pieces, for a total of eight
implants. The
exposed catheter segment was covered with a sterile dressing. Locations of the
implant sites
on the animal's back are identified in Table 6.
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TABLE 6
Implanted
Site No. Side Region Material
I Left Cranial 3659-16
2 Left Cranial - Middle 3659-16
3 Left Caudal - Middle 3659-17
4 Left Caudal 3659-17
5 Right Cranial 3659-16
6 Right Cranial - Middle 3659-16
7 Right Caudal - Middle 3659-17
8 Right Caudal 3659-17
[000103] On Day 8, the sterile dressing was removed from each exposed catheter
segment. The skin around each catheter entry site received a surface
instillation of a 1 mL
suspension containing 2.2 x 105 CFU/mL of S. aureus or 5.10 x 102 CFU/mL of E.
coll. One
segment of each catheter material was challenged with S. aureus and one
segment of each
catheter material was challenged with E. coll. Following inoculation, the
catheter segments
were re-covered with a sterile dressing. The inoculating organism used at each
site is listed in
Table 7.
TABLE 7
Implanted Inoculating
Site No. Side Region Material Organism Comments
Administered I mL bacteria suspension
1 Left Cranial 3659-16 S. aureus topically
Cranial -
2 Left Middle 3659-16 N/A' N/A
Caudal -
3 Left Middle 3659-17 N/A' N/A
4 Left Caudal 3659-17 N/A' N/A
5 Right Cranial 3659-16 N/A' N/A
Cranial - Administered I mL bacteria suspension
6 Right Middle 3659-16 E. coli topically
Caudal - Administered 1 mL bacteria suspension
7 Right Middle 3659-17 E. coli topically
Administered I mL bacteria suspension
8 Right Caudal 3659-17 S. aureus topically
N/A = Not applicable
[000104] On Day 10, the animal was euthanized with an intravenous injection of
a
commercial euthanasia solution according to Brain Chemistry Optimization
Program protocol
01-11-21-22-02-026. The entire implant was collected aseptically and submitted
for
quantitative bacterial determination. A superficial swab of the tract area of
muscle and skin
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21
was taken. Swabs were not collected in this study because several catheters
had backed out
and the implant tract was not visible. A portion of the muscle around the
implant tract was
placed in 10% neutral buffered formalin and submitted to Colorado Histo-Prep
(Fort Collins,
CO) for evaluation by a board-certified veterinary pathologist. For four of
the eight implant
sites (Site Nos. 1, 6, 7, and 8), the internal and external portions of the
implant were collected
separately into Tryptic Soy Broth. These were the sites that still had a
portion of the catheter
exiting the skin.
[000105] Clinical observations showed the rabbit remained healthy and showed
no signs
of infection, as seen in Table 8.
TABLE 8 Clinical observations of rabbit health
Clinical Observations
Group Animal No. Day General Stool Appetite
A 17 2-3 GO So AO
4-5 GO S1 AO
6-8 GO SO AO
9-10 GO S1 AO
Key:
GO = Appeared normal; bright, alert and responsive
SO = Stool normal
S1 = Stool soft
AO = Normal amount of food consumed
[000106] For each test material, one implant site was inoculated with S.
aureus and one
implant site was inoculated with E. coli (Site Nos. 1, 6, 7, and 8). For the
inoculated sites,
two implant locations, identified as internal and external, were evaluated for
microbial
growth and identification. The catheter sections above the skin were
identified as the external
implant sites and the catheter sections below the skin were identified as the
internal implant
sites.
[000107] For the remaining four implant sites (Site Nos. 2-5), no inoculation
was
performed, as there was no visible implant external to the skin on the day of
inoculation (Day
8). For these sites, subcutaneous portions of the catheter were evaluated for
microbial growth
and identification.
[000108] For the site implanted with the 3659-16 catheter material and
challenged with
S. aureus (Site No. 1), positive growth of the challenge organism was
identified at both the
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22
internal and external implant sites. For the site implanted with the 3659-16
catheter material
and challenged with E. coli (Site No. 6), bacterial growth identified as
Staphylococcus
hominis was present at the internal implant site; this growth was due to
environmental
contamination. At this site, no growth of the challenge organism (E. coli) was
identified at the
internal or external implant site.
[000109] For the site implanted with the 3659-17 catheter material anti
challenged with
S, aureus (Site No. 8), positive growth of the challenge organism was
identified at the
external implant site only. For the site implanted with the 3659-17 catheter
material and
challenged with E. coil (Site No. 7), no growth was present at the internal or
external implant
site.
[000110] For the remaining four implant sites, which were not inoculated (Site
Nos. 2-
5), no bacterial growth was present. See Table 9.
TABLE 9
Microbiological Growth Results From Implant sites
Microbiological Growth Identification
Animal Implanted Challenge Bacterial
Group No. Implant Site Material Organism Culture results ID
A 17 1 - Internal 3659-16 S. aureus Positive Growth S. aureus
I - External 3659-16 S. aureus Positive Growth S. aureus
2 3659-16 No bacteria No Growth N/A
applied
3 3659-17 No bacteria No Growth N/A
applied
4 3659-17 No bacteria No Growth N/A
applied
3659-16 No bacteria No Growth N/A
applied
S.
6 - Internal 3659-16 E. coil Positive Growth hominis
6 - External 3659-16 E. coil No Growth N/A
7 - Internal 3659-17 E. coil No Growth N/A
7 - External 3659-17 E. toll No Growth N/A
8 - Internal 3659-17 S. aureus No Growth N/A
8 - External 3659-17 S. aureus Positive Growth S. aureus
N/A = Not applicable
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23
[000111] There was no grossly visible evidence of tissue reaction or infection
at any of
the implant sites. For all implant sites, there was black to gray
discoloration of the
subcutaneous fascia and muscle at location of the implant. Results are
summarized in Table
10.
TABLE 10
Necropsy observations
Necropsy Observations
Animal Implant Implanted General
Group No. Site Material Location Condition Observations2
A 17 1 3659-16 Catheter pulled out of No grossly visible
muscle evidence of tissue
reaction or infection
2 3659-16 Portion of catheter in No grossly visible
muscle, Did back out evidence of tissue
half way reaction or infection
3 3659-17 Portion of catheter in No grossly visible
muscle evidence of tissue
reaction or infection
4 3659-17 Portion of catheter No grossly visible
still in muscle evidence of tissue
reaction or infection
3659-16 Portion of catheter No grossly visible
still in muscle evidence of tissue
reaction or infection
6 3659-16 Catheter pulled out of No grossly visible
muscle evidence of tissue
reaction or infection
7 3659-17 Catheter pulled out of No grossly visible
muscle evidence of tissue
reaction or infection
8 3659-17 Catheter pulled out of No grossly visible
muscle evidence of tissue
reaction or infection
N/A = Not applicable
[000112] The results showed that the silver/silver oxide impregnated
antimicrobial
catheters prevented the formation of bacteria, bacterial colonies, and
biofilms. The
antimicrobial results were consistent across all implant sites, and the
antimicrobial coating
remained effective even following a microbial challenge at Day 8 with E. coli
or S. aureus.
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24
There was no necrosis observed. The lesions were consistent with a foreign
body reaction in
the muscle, with a more acute inflammatory reaction in the subcutaneous
tissue.
[000113] EXAMPLE 6 Elution of silver oxide coating
[000114) A total of twenty test samples, one cm2 polypropylene coated with the
typical
silver oxide coating were evaluated. Two samples were taken from a total of
ten different
samples for both the test groups. The testing was performed in duplicate using
inductively
coupled plasma analysis to determine the amount of silver present at each time
point. The
values were then averaged for a total of ten reported values for each test
group. The elution
values are given as mg/sample, which in this case is mg/square inch.
[000115] The samples all exhibited a consistent behavior over the first 24
hours in the
NaCl solution. There was a slight peak around the four hour time point, before
the values
leveled off around the 24 hour time point.
[000116] All of the samples were very consistent in their behavior. The values
were
fairly stable from day 1 through day 5; the values then peaked around the 6
day time point
and then leveled off from day 7 through day 30-
[0001171 The average elution for the coated Polypropylene samples over all
time points
is approximately 0.005 mg per square inch (0.0048 mg/sq inch). The samples
show a fairly
consistent silver elution over the entire length the study with slight peaks
noted at the 4 hour
time point and after 6 days in saline solution Using the elution values and an
approximate
total silver value of 1.05 mg per sq inch (obtained from outside testing) for
the
Polypropylene.
[000118] EXAMPLE 7 in vivo healing test of ePTFE coated substrate
[000119] This example demonstrates through in vivo testing the ability of the
200 nm
silver oxide coating to not cause necrosis. 1 cm2 ePTFE samples were coated
with the
standard 200 nm silver oxide coating and implanted in a rabbit subcutaneously
as outlined in
example 6 above. The substrates were explanted at 9 and 22 days to study the
healing of the
tissue surrounding the implanted silver oxide coated part. The results are
outlined in Table
11.
CA 02635062 2008-07-28
WO 2007/087269 PCT/US2007/001695
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~.. ~~4=fl aa~E E+Lo aioo) ~0 irSm f
Q. fn
c N v
a) u) o2S co o .c p o m LL N C N c tS a E
,u
"=C .O N O C ..c E U) 'C O c a) .'n N O 2 O C N
o c g c v i o a) C) a c CL c >, 3 N 0
U
a)
N 3 0 3 c cci >.~a `d C V E o ~~ ID
ai0
¾W O U U O N ~ C a o =
F- O U C C Q) U aj
N ?.+ O p n p 4) O O O O N .`_. N Q) U O
i. = ,..a):=. LL co
t- `C U
0 3 N LL Cl) N O C2 O U) Q U) O (a O O
0 f3~ U U L N
O) C LA. N N N F- C i L N U CL a C) > L. N L
+ a) c a
bA
o N N 0 N
YIS; u:N = Ci O C 0 Q) a) N ~
,~ v V C Q L3) U p O U) 't 0 (o CL
O N O U fi3 C co N a) C C
aka a) cn 0- E
O O .. of a) 4) O
C .n
1-'-1 N O in, C N O U)
(d O N N O O (D C U C a
N U V C (D N N a .a CO) N 12 0. (a f6 C 0 :a
m 2 R: 0
~iN~~ L -p .Q L aj > Z - U o2S
.` U N
(D3 0N `C '-0
0 4m)0 U = Ca ~aNiQ omm~.`C
N 0 _~>. aa) O~ C U v N ~ N C .fl -O N N
cl) U) -0 C (D U) T
Ey CL Ga O
N y a o U- v- CL CL >i ++ 2 ;C, W c: LL CL CL >< (0 r O
a) U O o E F- O
E U
a)
C O E .C W C CL in 2 70., ca O to C O V N c. O
O o N E U O E on. 1-ma EaO O:~i I-cn~n CL
0)
N N N
N N
a)
C r t'D t r _
N
Q Q)' O r tN Et
LU-, E
*aa L O fU CE =
. O C 7 O ,a)a ~pr3pY > NO tU) "C3
..Nk. 1. 1=-= (! }U ~~ ~~,. .a, 7.2%`712,'' N'J) C) C Cl)~:N +, s ``(/) O E
f/)
CA 02635062 2008-07-28
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26
The abbreviations used in Table I I are as follows:
Occ occasional
PMSs polymorphonuclear cells
Mps mucopolysaccharides
SSCs spindle-shaped cells
MF microfiber
Base basophils
W with
Ncf neutrophil chemotactic factor
[000120] EXAMPLE 8 - Cathodic Are Deposition with Moveable Substrate
[000121] This example demonstrates how a moveable substrate affects the macro-
particle size, thus controlling the release of the silver oxide.
[000122] The substrate, substrate one, was placed in a moveable holder at a
distance of
30 inches from the target. The chamber was pumped to a level of 5E-4 Torr. The
arc was
initiated with a current of 100 amps and 16 volts. Oxygen was introduced into
the chamber at
a rate of 200 SCCM. The substrate was translated closer to the target at a
speed of one inch
every 15 seconds. This was continued until the substrate was 8 inches away
from the target.
[000123] In a complementary experiment, a substrate, substrate two, was placed
at a
distance of 30 inches from the target with the same current, voltage, total
time and rate of
oxygen flow. This time, the substrate was left stationary.
[000124] Initial ZOI testing showed the same size zone in a 24 hour period.
Plate
transfer was performed for several bacteria and the results are shown in Table
12. It is seen
that the substrate that was moved toward the target during the deposition
process showed
anti-microbial activity for a longer period of time than did the substrate
that was left
stationary.
[000125] In addition to the ZOI testing, cross sections of the two substrates
were
examined using SEM analysis. In sample one, the amount and size of macro-
particles
increased with the thickness of the film; i.e., there were fewer and smaller
macro-particles
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27
close to the substrate, and the number and size increased as the thickness of
the film grew.
Conversely, the cross section in sample two was uniform with very few macro-
particles.
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TABLE 12
Dayl
Substrate 1 Substrate 2
Plate I Plate 2 Control Plate 1 Plate 2 Control
ZOf (mm) ZOI (mm) Plate ZOI (mm) ZOI (mm) Plate
E. faecalis +
Day1 4.0 4.0 0.0 3.0 3.0 0.0
4.0 4.5 0.0 4.0 2.0 0.0
3.0 4.5 0.0 3.0 2.0 0.0
Day2 2.0 3.0 0.0 0.0 0.0 0.0
3.0 1.5 0.0 0.0 0.0 0.0
2.0 3.0 0.0 0.0 0.0 0.0
Day3 1.0 0.5 0.0 0.0 0.0 0.0
1.0 0.5 0.0 0.0 0.0 0.0
0.5 1.0 0.0 0.0 0.0 0.0
S. epidermis
Dayl 10.0 10.0 0.0 9.0 8.0 0.0
11.0 10.0 0.0 12.0 6.0 0.0
9.0 10.0 0.0 10.0 12.0 0.0
Day2 7.0 3.5 0.0 0.0 0.5 0.0
7.0 3.5 0.0 1.0 0.0 0.0
5.0 2.5 0.0 0.0 0.0 0.0
Day3 6.0 6.0 0.0 0.0 0.5 0.0
4.5 5.0 0.0 0.0 0.0 0.0
5.0 5.0 0.0 1.0 0.0 0.0
Day4 1.0 2.0 0.0 0.0 0.0 0.0
4.0 2.0 0.0 0.0 0.0 0.0
2.0 1.0 0.0 0.0 0.0 0.0
E. Coll -
Dayl 5.0 6.0 0.0 5.0 6.0 0.0
7.0 6.0 0.0 8.0 4.0 0.0
1.0 5.0 0.0 10.0 9.0 0.0
Day2 3.0 2.5 0.0 0.0 1.0 0.0
4.0 2.5 0.0 1.0 0.0 0.0
2.0 1.0 0.0 3.0 2.5 0.0
Day3 2.0 2.0 0.0 0.0 0.0 0.0
3.0 2.5 0.0 0.0 0.0 0.0
2.0 2.0 0.0 1.0 0.5 0.0
Day4 1.0 0.0 0.0 0.0 0.0 0.0
1.0 0.5 0.0 0.0 0.0 0.0
0.0 1.0 0.0 0.0 0.0 0.0
K. neumoniae -
Dayl 3.0 4.0 0.0 2.0 2.0 0.0
3.0 2.5 0.0 4.0 3.0 0.0
2.0 3.0 0.0 2.0 3.0 0.0
Day2 2.0 3.0 0.0 0.0 0.0 0.0
1.0 1.5 0.0 1.0 0.0 0.0
1.0 0.5 0.0 0.0 0.0 0.0
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Day3 0.0 0.0 0.0 0.0 0.0 0.0
1.0 0.5 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0
-
P. aerugosia
Dayl 10.0 12.0 0.0 6.0 6.0 0.0
12.0 12.0 0.0 7.0 6.5 0.0
10.0 10.0 0.0 5.0 6.5 0.0
Day2 4.0 3.0 0.0 1.0 0.5 0.0
4.0 2.5 0.0 3.0 2.5 0.0
4.0 1.0 0.0 3.0 0.5 0.0
Day3 2.0 3.0 0.0 = 0.0 0.0 0.0
1.5 1.0 0.0 0.0 0.0 0.0
3.0 1.5 0.0 0.0 0.0 0.0
S. aureus MR +
Dayl 12.0 14.0 0.0 6.0 7.0 0.0
13.0 12.5 0.0 4.0 7.0 0.0
12.0 10.0 0.0 12.0 10.0 0.0
Day2 9.0 8.0 0.0 2.0 2.0 0.0
7.0 7.5 0.0 4.0 2.0 0.0
10.0 7.0 0.0 2.0 4.0 0.0
Day3 4.0 5.0 0.0 1.0 0.0 0.0
5.0 4.5 0.0 4.0 1.0 0.0
6.0 8.0 0.0 0.0 0.0 0.0
Day4 1.0 2.5 0.0 0.0 0.0 0.0
2.0 3.0 0.0 0.0 0.0 0.0
1.0 0.5 0.0 0.0 0.0 0.0
[000126] EXAMPLE 9 - Are Control
[000127] This example demonstrates how arc control is directly related to the
size and
frequency of macro-particles produced. In this example, two sample runs were
preformed.
The first, sample three, had no arc control and the substrate was placed at a
distance of 12
inches from the target. The second, sample four, had arc control and the
substrate was also
placed at a distance of 12 inches from the target. Both samples were placed in
the chamber, at
separate times for separate runs, and pumped to 5E-4 Torr. The arc was set at
100 Amps for
all power supplies to begin with. Each target had two supplies for a starting
total of 200
amps. Sample three was run for five minutes with no arc control. Sample four
was run with
an optimized switching of current at a rate of 300 hertz.
[0001281 The switching always kept 200 amps on the target, but each power
supply was
ramped up and down so at any time, the current was not equal on the supplies.
This forced the
arc to travel a specific distance in a specific time, thereby controlling the
macro-particle
density and size.
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[000129] SEM cross sectional analysis was performed on samples three and four.
It was
observed that, while the films were consistent throughout the entire
thickness, sample four
had a much larger average of macro-particle size and density then did sample
three. The
average size of the macro-particles in sample three was approximately one
micron with a
density of 103 / cm2. The average size of macro-particles in sample four was
approximately
three microns with a density of 104 / cm2.
[000130] EXAMPLE 10 - in vitro Testing of AgO on Metals
[000131] This example demonstrates the effectiveness of the AgO coating on Ti-
6-4 and
CoCrMo. Samples five and six were cleaned using usual procedures and placed in
the
vacuum chamber at a distance of 12 inches from the target. The typical silver
oxide coating
was deposited on the pieces and ZOI testing was done for three days. Sample
five was Ti-6-4
and sample six was CoCrMo. Results are summarized in Table 13.
TABLE 13
Dayl
Substrate 5 Substrate 6
Plate I ZOI Plate 2 ZOI Control Plate I ZOI Plate 2 ZOI Control
mm mm Plate mm mm Plate
S. epidermis
Dayl 12.0 10.0 0.0 10.0 11.0 0.0
12.0 9.5 0.0 11.0 12.0 0.0
10.0 14.5 0.0 11.0 9.0 0.0
Day2 8.0 8.5 0.0 8.0 8.0 0.0
8.0 8.5 0.0 8.0 8.5 0.0
6.0 2.5 0.0 8.0 8.0 0.0
Day3 5.0 6.0 0.0 5.0 4.0 0.0
4.5 3.5 0.0 6.0 7.0 0.0
4.0 3.0 0.0 6.0 4.5 0.0
E. Coll -
Dayl 5.0 2.5 0.0 5.0 2.5 0.0
7.0 3.5 0.0 8.0 4.0 0.0
1.0 0.5 0.0 10.0 5.0 0.0
Day2 3.0 1.5 0.0 0.0 0.0 0.0
4.0 2.0 0.0 1.0 0.5 0.0
2.0 1.0 0.0 3.0 1.5 0.0
Day3 2.0 1.0 0.0 0.0 0.0 0.0
3.0 1.5 0.0 0.0 0.0 0.0
2.0 1.0 0.0 1.0 0.5 0.0
S. aureus MR +
Dayl 12.0 16.0 0.0 16.0 12.0 0.0
13.0 12.5 0.0 14.0 12.0 0.0
12.0 11.0 0.0 12.0 9.0 0.0
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WO 2007/087269 PCT/US2007/001695
31
Day2 10.0 14.0 0.0 10.0 9.0 0.0
9.0 10.0 0.0 9.0 10.0 0.0
11.0 10.0 0.0 9.0 5.0 0.0
Day3 3.0 6.0 0.0 5.0 7.5 0.0
6.0 6.5 0.0 4.0 8.0 0.0
5.0 5.0 0.0 3.0 0.0 0.0
[000132] While the present invention has been described with references to
specific
embodiments thereof, it should be understood by those skilled in the art that
various changes
and modifications may be made and equivalents may be substituted without
departing from
the true spirit and scope of the invention, in particular, it will be
understood that the chemical
and pharmaceutical details of every design may be slightly different or
modified by one of
ordinary skill in the art without departing from the scope of the invention.
All such
modifications are intended to be within the scope of the appended claims.
