Ultraviolet activated antimicrobial surfaces

Abstract

The invention is directed to an ion plasma deposition (IPD) method adapted to coat polymer surfaces with highly adherent antimicrobial films. A controlled ion plasma deposition (IPD) process is used to coat a metal or polymer with a selected metal/metal oxide. Exposing the coated surface to ultraviolet light significantly improves the antimicrobial properties of the deposited coatings.

Claims

1. An antibacterial coated medical implant device, comprising: a metal and metal oxide ion plasma deposited nanoparticulate first layer from a target onto a medical device surface, said first layer consisting of metal and metal oxide nanoparticulates substantially free of macroparticulates formed by the process of: (a) using ion plasma to deposit the first layer onto the substrate; and (b) exposing the metal and metal oxide nanoparticulates to ultraviolet (UV) light irradiation during step (a), thereby activating ground state oxygen in the metal oxide to form a reactive oxygen species to provide an antimicrobially active coating on the medical device.

2. The coated medical implant device of claim 1 wherein step (b) is performed in the presence of a gas selected from the group consisting of Ar/O; O.sub.2; N.sub.2; and Ar.

3. The coated medical implant device of claim 2 wherein the gas is at about 40 mTorr pressure.

4. The coated medical implant device of claim 1 wherein step (b) is performed at about 20 degrees Celsius.

5. The coated medical implant device of claim 1, further comprising the step of: (c) using ion plasma to deposit a second layer onto the substrate, the second layer being formed of macroparticulates; and (d) exposing the macroparticulates to ultraviolet (UV) light irradiation during step (c), thereby activating ground state oxygen in the second layer to a reactive oxygen species to provide an antimicrobially active coating on the medical device.

6. The coated medical implant device of claim 5, wherein the second layer consists of mixed sizes of metal and metal oxide macroparticulates ranging from 100 nm up to about 1 micron.

7. An antibacterial bilayer coated medical implant device, comprising: a metal and metal oxide ion plasma deposited nanoparticulate first layer from a target onto a medical device surface, said first layer consisting of metal and metal oxide nanoparticulates substantially free of macroparticulates; a metal and metal oxide deposited second layer over the first layer, said second layer consisting of mixed sizes of metal and metal oxide macroparticulates ranging from 100 nm up to about 1 micron; formed by the process of: (a) using ion plasma to deposit the first layer and the second layer onto the substrate; and (b) exposing the metal and metal oxide nanoparticulates and the macroparticulates to ultraviolet (UV) light irradiation during step (a), thereby activating ground state oxygen in the metal oxide to a reactive oxygen species to provide an enhanced antimicrobially active coating on the medical device.

8. The coated medical implant device of claim 7 wherein step (b) is performed in the presence of a gas selected from the group consisting of Ar/O; O.sub.2; N.sub.2; and Ar.

9. The coated medical implant device of claim 8 wherein the gas is at about 40 mTorr pressure.

10. The coated medical implant device of claim 7 wherein step (b) is performed at about 20 degrees Celsius.

11. The coated medical implant device of claim 7 wherein the bilayer thickness is about 100 nm.

12. The coated medical implant device of claim 7 wherein the first, second, or first and second layers consist of mixed metal and metal oxide macroparticles selected from groups consisting of: (i) silver (Ag) and silver oxides (AgO and Ag.sub.2O); (ii) copper (Cu) and copper oxides (CuO and Cu.sub.2O); and (iii) titanium (Ti) and titanium oxides (TiO and TiO.sub.2).

13. The coated medical implant device of claim 12 wherein the first and second layers consist of mixed silver metal and silver metal oxides AgO and Ag.sub.2O.

14. The coated medical implant device of claim 13 wherein said layers consist of the silver metal oxides AgO and Ag.sub.2O.

15. An antibacterial bilayer coated medical implant device, comprising: a metal and metal oxide ion plasma deposited nanoparticulate first layer from a target onto a medical device surface, said first layer consisting of metal and metal oxide nanoparticulates substantially free of macroparticulates; a metal and metal oxide deposited second layer over the first layer, said second layer consisting of mixed sizes of metal and metal oxide macroparticulates ranging from 100 nm up to about 1 micron; formed by the process of: (a) placing the substrate in a vacuum chamber at about 20 degrees Celsius; (b) using ion plasma to deposit the first layer and the second layer onto the substrate; and (c) exposing the metal and metal oxide nanoparticulates and the macroparticulates to ultraviolet (UV) light irradiation in the vacuum chamber during step (b), thereby activating ground state oxygen in the metal oxide to a reactive oxygen species to provide an enhanced antimicrobially active coating on the medical device.

16. The antibacterial bilayer coated medical implant device of claim 15 wherein the vacuum chamber is at about 40 mTorr pressure.

17. The antibacterial coated medical implant device according to claim 16, wherein step (a) further comprises including diatomic oxygen in the chamber.

18. The antibacterial coated medical implant device according to claim 16, wherein step (a) further comprises including ozone in the chamber.

19. The antibacterial bilayer coated medical implant device of claim 15 wherein step (a) comprises varying a distance between the target and the substrate.

20. The antibacterial bilayer coated medical implant device of claim 15, wherein step (a) comprises varying a relative speed of movement between the target and the substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a sketch of the IPD apparatus. Target material (1), substrate being coated (2), mechanism for moving the substrate closer and further away from the target (3), vacuum chamber (4), power supply for the target (5).

(2) FIG. 2 is another embodiment of the IPD apparatus. Target material (1), substrate being coated (2), mechanism for moving the substrate closer and further away from the target (3), vacuum chamber (4), power supply for the target (5), device to control arc speed (6).

(3) FIG. 3 is an example of the setup for a modified IPD/UV apparatus for depositing an adherent highly antimicrobial coating on a substrate. The apparatus incorporates the features of FIG. 1 and/or FIG. 2 with a source (7) to input ultraviolet light at selected wavelengths.

DETAILED DESCRIPTION

(4) The invention is directed to the use of ultraviolet radiation in combination with highly controlled IPD conditions to achieve stable highly antibacterial coated substrates. It is the combination of an IPD method for microparticle deposition and the discovery of the use of specific wavelengths of ultraviolet (UV) light that provides the unique aspects of the present invention. The significant improvement in antimicrobial activity of surface coatings is based on the structural features of the deposited materials, the method with which the IPD is controlled, and ultraviolet light activation of the coating surface.

(5) The antimicrobial coatings prepared by the new method may be deposited from any of a number of metals, or combinations of metals that are suitable for ion deposition. Elements include those having an atomic number greater then 21, and a density greater than 4.5 g/cm.sup.2, e.g., Ti, Zr, Cr, Co, Ni, Mo, Pd, Ag, Hf, Ta, W, Ir, Pt, Sn, Bi, Zn, Au, and alloys and compounds of these metals. For commercial biological applications, use of silver, copper, gold, titanium and hafnium are preferred metals. Target materials may also include AgO, TiO, TiO.sub.2, CuO, HfN and higher oxidation forms of silver, copper, and titanium, which may in some cases be more highly antimicrobial compared to lower oxides of these metals. The disclosed IPD-UV process provides highly conformed, adherent, thin, highly antimicrobial coatings, using tunable controls that provide antimicrobial activities within ranges that are typically necessary in medical applications.

(6) Some deposited metals, such as surface film deposited titanium dioxide (TiO.sub.2) do not exhibit antimicrobial activity when deposited by conventional deposition or standard plasma arc deposition. The deposition/surface activation method described herein provides an antimicrobially active surface, as demonstrated in the Examples using the IPD/UV process. An initially inactive deposited TiO.sub.2 surface can be activated to an antimicrobially active surface by the UV process.

(7) Highly adherent antimicrobial coatings have been produced using a modified ion deposition method. The process utilizes a controlled deposition system in combination with substrate exposure to ultraviolet (UV) light.

(8) The disclosed modified IPD process itself generates a significant level of UV photons and high-energy ions when oxygen is present in the system. The spectral profile of the UV energy emitted from the source (target) is determined by the specific metal(s) or alloy(s) used. A high-energy coulomb explosion excites diatomic oxygen (O.sub.2) gas injected into the chamber with a broad range of UV energy, causing the two oxygen atoms of ground state oxygen to dissociate, yielding singlet oxygen. Ground state oxygen is a triplet where at least two electron orbits are unpaired and parallel (Foote, 1995). Singlet oxygen is a singlet molecule (O*) that has undergone an electron spin inversion to pair all the electrons in the oxygen atom. Some of the differences in bonding properties arise because triplet oxygen is paramagnetic while singlet oxygen is slightly magnetic.

(9) Molecules whose outermost pair of electrons have parallel spins, symbolized by ↑↑, are in the “triplet” state; molecules whose outermost pair of electrons have anti-parallel spins, symbolized by ↑↓, are in the “singlet” state. Ground-state oxygen is in the triplet state, indicated by the superscripted “3” in .sup.3O.sub.2; its two unpaired electrons have parallel spins, a characteristic that, according to rules of physical chemistry, does not allow them to react with most molecules. Thus, ground-state or triplet oxygen is not very reactive. However, triplet oxygen can be activated by the addition of energy, and transformed into reactive oxygen species.

(10) Relative intensities of the spectral lines observed for any element depend upon the light source and excitation conditions. Thus, even if the relative intensities observed in a particular experiment are adjusted to correct for the wavelength dependence of the sensitivity of the spectrometer and detector, the intensities will in general be different from relative intensities from previous observation or tabulated in a compilation such as illustrated in Tables 1-3.

(11) Ultraviolet radiation at wavelengths shorter than 242 nm splits molecular oxygen into atomic oxygen. When the energetically excited individual oxygen atoms encounter molecular oxygen, ozone (O.sub.3) can form from the bonding of three-oxygen molecules. Shorter wavelengths in the UV region match several levels of singlet oxygen excitation, resulting in unique modifications to the electron orbit structure. At higher energy levels it is also possible to excite electrons from the oxygen orbital into higher levels, giving rise to efficient absorption in the range of 180-200 nm, the “Schumann-Runge bands.” (http://earthobservatory.nasa.gov/Library/ChemistrySunlight/).

(12) Each target used in the IPD process has its own spectral absorption and emission profile and is capable of generating energy within the UV range to provide the required energy for singlet oxygen formation. Listed below are representative vacuum emission spectral lines associated with a representative group of refractory metals. As shown, silver, and copper arcs yield UV in the Schumann-Runge bands, while titanium has a higher UV range which is still sufficient to yield singlet oxygen. The frequencies shown have been selected from the first excitation level of the atom and are shown as relative intensities. Less prominent wavelengths are not listed and relative intensities are shown only to indicate the stronger emissions in the near UV range of 160 nm to 140 nm (http://physics.nist.gov/cgi-bin/AtData/main_asd).

(13) TABLE-US-00001 TABLE 1 Emission spectra from a silver arc in vacuum. SILVER 1 Wavelength Relative Vac. (nm) Intensity 165.152 60 165.210 50 170.927 50 184.771 20 206.183 200 207.051 100 231.027 30 237.574 50

(14) TABLE-US-00002 TABLE 2 Emission spectra from a copper arc in vacuum COPPER 1 Wavelength Relative Vac. (nm) Intensity 165.532 30 168.809 30 169.108 30 170.384 30 171.336 50 172.566 50 174.157 50 177.482 200 182.535 100 216.577 1300 217.962 1600 218.240 1700 220.027 1700 220.044 1300 222.639 2100 229.455 2500 230.383 1000 239.336 2500

(15) TABLE-US-00003 TABLE 3 Emission spectra from a titanium arc in vacuum. TITANIUM 1 Wavelength Relative Vac. (nm) Intensity 227.7401 130 228.0669 190 230.0567 150 230.3457 140 230.6397 190 238.5246 35

(16) Activation of singlet oxygen is inherent in the IPD process due to the high energies involved. For some materials such as silver oxide, this is sufficient to impart limited antimicrobial activity by increasing the amount of antimicrobially active oxide (AgO). For other deposited surfaces, such as CuO, TiO, or TiO.sub.2, another mode of activating the singlet form can be used to obtain antimicrobial activity. It has been discovered that using selected wavelengths of UV light will excite these metals and metal oxides, which elevates oxygen to the singlet state, thereby creating a coated surface with new or enhanced antimicrobial properties.

(17) The IPD/UV process can include up to at least 20% more diatomic oxygen or nitrogen into the coating surface compared to traditional IPD deposition. Oxygen or nitrogen inclusion is enhanced by first creating an oxygen or nitrogen rich plasma before introducing ultraviolet light into the plasma. This causes diatomic oxygen or nitrogen to incorporate into the substrate surface in a stable form. This results in enhanced antimicrobial activity due to the presence of singlet oxygen or nitrogen which is produced by the dissociation of diatomic oxygen or nitrogen.

(18) It was recognized that an IPD process could be modified to provide a number of advantages over other methods commonly used for coating processes. Several basic features of a plasma arc process have been modified and exploited in developing the IPD/UV process. Unique coatings can now be prepared which have increased surface area due to controlled particle size and significantly increased antimicrobial activity. Several metal/metal oxide coated substrates in addition to silver/silver oxide have been prepared and demonstrated to have new or enhanced antimicrobial properties.

(19) Plasma deposition processes release molecules from the target which deposit on a target surface as various sized clusters and individual atoms. The predominant trend in coating processing has been to adjust conditions to reduce the density and number of macro particle deposition 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. In contrast, the present invention clearly illustrates the advantages of increasing macro particle deposition, not only on metals but also on plastic substrates, in order to obtain adherent films that can be surface irradiated to enhance antimicrobial activity. It has also been found that, in general, higher macro particle deposition rates result in lower temperature depositions, while lower deposition rates result in higher temperature depositions. Higher deposition rates are thus advantageous in coating thermo sensitive materials such as certain plastics.

(20) Arc control in the IPD process can be used for faster movement, which will create fewer and less dense arrays macro particles without the use of sensors or filters, or slower movement, which creates a greater number of more densely packed macro particles. This type of control also provides the option of mixing the two modes to create moderate amounts of macro particles, or creating a near macro-free coating followed by a macro-dense coating. The amount of macro-particles can be directly related to the amount of available silver that combines to form AgO, and therefore aids in the ability to tune the duration of the efficacy of the coating.

(21) Adhesion of metals onto plastics using vapor deposition processes other than IPD, electroplating, or electro-less plating often results in loss of some physical properties of the original substrate. For most metals deposited by these processes, adhesion is dependent on a strike layer of titanium or chromium and even then, tends to delaminate if the substrate is bent, twisted or stretched. The IPD coating process, under the conditions described, imbeds into the substrate so adhesion is not affected by subsequent mechanical stress on the substrate.

(22) Using controlled deposition rates, IPD can be performed at lower temperatures than most vapor deposition processes, which require a pre-heat cycle and glow discharge, the pair usually resulting in temperatures exceeding 200° C. Most plastics melt well below this temperature. The IPD process can be performed at a much lower temperature, allowing for low melting point plastics to be effectively coated without adversely affecting the original substrate specifications. Such low temperature deposition is achieved by controlling the rate at which the metal reacts with oxygen. Making more oxygen available for reaction in the system by inputting molecular oxygen or ozone allows the devices to stay cooler due to conductive cooling and slowing of the ions due to collisions.

(23) IPD increases throughput up to 30 times compared to other plasma vapor deposition processes and dip processes, while at the same time achieving high densities and favorable antimicrobial activity. The disclosed modified IPD process for depositing an antimicrobial coating has a throughput up to ten times greater than traditional cathodic arc.

(24) Unlike traditional PVD and dip processes, the IPD antimicrobial coatings can be scaled as large as necessary and still achieve high throughput while maintaining quality and economy of coating necessary for commercial operations.

(25) The IPD process provides antimicrobial coatings that otherwise are not easily produced, or even possible in some cases, by traditional PVD. Some examples, not intended to be limiting, include silver oxide, copper oxide and hafnium nitride. Silver/silver oxide coatings have a higher antimicrobial activity when produced by the IPD method than the comparably active but thicker coatings obtained from more expensive processes; for example the magnetron sputtered antimicrobial coatings described by Burrell, et al. (1995). Thinner coatings, and therefore shorter processing times, can be applied using the presently disclosed IPD method to achieve at least the same antimicrobial activity as in the thicker films.

(26) Typical PVD and electroplating are line of sight deposition methods. Because of this, it is difficult to coat complex and oddly-shaped devices without complicated fixtures, and even with the correct fixture, it may not be possible to evenly coat the devices. The modified IPD process provides non-line of sight coating but still maintains the antimicrobial qualities of the coating without the use of complicated fixtures because the coatings are readily conformed to the part.

(27) IPD coating rates are extremely fast. With the relatively short time in the plasma to achieve a desirable antimicrobial coating, the temperature of the substrate does not rise very fast or very high. This gives an advantage over other coating methods that require cooling steps or long deposition cycles to achieve the same antimicrobial properties. The fast coating rates are also commercially attractive because higher product throughput, up to 10-fold, than with sputtering, electroplating, or MAD processing is possible.

(28) The new IPD/UV methods and coatings introduce several improvements to existing technology, including use of more/less macro particles to control the duration of antimicrobial coating activity, use of more reactive oxygen to increase the ratio of active to inactive silver oxide (AgO/Ag.sub.2O), use of selected wavelengths of UV light during deposition to activate singlet oxygen, and the ability to lay down a thinner coating than current art allows while maintaining equivalent antimicrobial properties.

Examples

(29) The following examples are intended to illustrate the invention and/or to provide background and are not intended to be limiting.

(30) Methods

(31) Antibacterial activity of the deposited coatings was tested using a zone of inhibition test (ZOI). 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 ATCC #25923. The 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 ZOI was calculated as follows: corrected ZOI=ZOI minus the diameter of the test material in contact with the agar.

(32) Examples 1-3 are provided as background comparisons for the antimicrobial coatings prepared as previously reported by others. The deposition methods of the present invention (see Examples 4, et seq.) are based on a modified IPD process while the previously published comparison procedures in examples 1-3 utilize sputtering deposition.

Example 1. Antibacterial Activity of Sputtered Silver Coating on Latex

(33) This example was performed in accordance with the coating and testing procedures described in U.S. Pat. No. 5,454,886 (the '886 patent). The method and testing were performed in accordance with the procedure detailed in Example 6 of the '886 patent.

(34) Silver metal was deposited on 2.5 cm sections of a latex Foley catheter using a magnetron sputtering facility. Operating conditions were as follows; the deposition rate was 200A° per minute; the argon working gas pressure was 30 m 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 was tested by a zone of inhibition test, identical to the test described in Example 1 of the '866 patent with S. aureus ATCC accession number 25923 as the test organism.

(35) The zone of inhibition (ZOI) was less than 1 mm around the catheter tubing in contrast to the 16 mm ZOI reported in the '886 patent.

Example 2. Antibacterial Activity Of Sputtered Silver Coating Over Teflon™ On Latex

(36) This example follows the procedures reported for preparing a Teflon-coated latex catheter coated by DC magnetron sputtering in accordance with Example 7 in U.S. Pat. No. 5,454,886. Antimicrobial testing was performed with S. Aureus as described.

(37) A Teflon coated latex Foley catheter was coated by DC magnetron sputtering 99.99% pure silver on the surface under the following conditions: 0.5 kW power, 40 mTorr Ar/O.sub.2, 20° C. initial substrate temperature, a cathode/anode distance of 100 mm, and a final film thickness of 300 nm. The working gases were commercial Ar and 99/1 wt % Ar/O.sub.2.

(38) The anti-microbial effect of the coating was tested by a ZOI as described in Example 7 of the '886 patent. 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 ATCC #25923. The inoculant was prepared from Bactrol Discs (Difco, M.) which were reconstituted as 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 zone of inhibition was measured and a corrected zone of inhibition was calculated (corrected zone of inhibition=zone of inhibition-diameter of the test material in contact with the agar).

(39) Uncoated samples showed no zone of inhibition. The coated sample showed a ZOI of less than 1 mm in contrast to the corrected ZOI of 11 mm reported in Example 7 of the '866 patent for the catheters sputtered in the 99/1 wt % Ar/O.sub.2 using a working gas pressure of 40 mTorr.

Example 3. Sputtered Antibacterial Silver Coating

(40) This example was performed in accordance with the procedure described in Example 11 in the '866 patent. Conditions used for this example included: RF magnetron power of 0.5 kW, 40 mTorr pressure, 100 mm anode/cathode distance, and 20° C.

(41) When a working gas of argon and 20 wt % oxygen was used to sputter anti-microbial coatings under the conditions listed above, the zones of inhibition ranged from 0 to 2 mm, in contrast to the ZOI of 6 to 12 mm reported in the '866 patent Example 11.

Example 4. Control of Macro Particle Density in IPD Coatings

(42) Control of the distance/current relationship in IPD procedures determines amount and size of the deposited macro particles. The closer the substrate is to a source (target), the more macro-particles will be present on the substrate. Macro particles evaporate as they are ejected from the target. Therefore, the longer the time of flight, the more material is evaporated from the particle. Macro particle density can also be controlled by the current because either a higher current or limiting the current to a level that occurs just before an arc split tends to cause more and larger macro particles.

(43) A motorized unit capable of moving a substrate closer to and farther away from the target (cathode) was used to initially deposit a substantially macro-free film. This provides a base coat with excellent adhesion properties. A more macro particle dense film is then deposited by positioning the substrate closer to the target. The macro dense surface has enhanced antimicrobial activity by comparison to films having a relatively macro particle free surface. FIG. 1 illustrates an IPD apparatus indicating how the position of the substrate with respect to the target can be moved. The IPD is conducted in an oxygen atmosphere.

(44) Microparticle size can also be controlled by use of a variable IPD power source, which can be configured to sufficiently slow (or accelerate) the speed of the arc. The traveling speed of the arc is directly related to the amount of macro particles produced. Essentially, slowing the speed of the arc on the surface of the target (cathode) will cause it to produce more macro particles, which can be used to increase the macro particle density. Conversely, increasing the speed of the arc on the cathode will decrease production of macro particles, thereby providing more high energy ions that can be embedded into the surface of the substrate to produce better adhesion. FIG. 2 shows an IPD apparatus setup with control of arc speed and substrate position with respect to the target.

(45) Increase and decrease travel speed of the arc can be controlled by an appropriate device such as the mechanical switch described in U.S. Pat. No. 6,936,145. The switch toggles current to two or more points on the target and is an example of one method of speed control, although other methods of control can be used. The increase and decrease of arc speed allows the deposition (without internal movement) of a substantially macro-free film for adhesion followed directly by a macro dense film by manipulation of the arc speed.

Example 5. Increasing AgO in Antimicrobial Films

(46) An advantage of the combined IPD/UV method is that the IPD process itself can be adjusted so that more oxygen and metallic ions can be made available for combination in forming an antimicrobial film. When activated by ultraviolet light, the IPD films have significantly enhanced antimicrobial activity. The control of the plasma arc speed (see FIG. 2) can provide substantially 100% ionized oxygen plasma when the IPD is conducted in an oxygen atmosphere. The percent of singlet oxygen in the plasma can be further enhanced by injecting ozone instead of diatomic oxygen into the system. The presence of oxygen, in addition to the ability of IPD to create a highly ionized metal stream from the target means that more AgO is created films than by other methods and, in combination with exposing the deposited surface to UV light, results in significant enhancement of antimicrobial properties of metal/metal oxide coated surfaces.

Example 6. Ultraviolet Activation of IPD Deposited Ag, Ti and Cu Coatings

(47) The additional use of UV light during or after the deposition activates singlet oxygen in silver/silver oxide deposited coatings. Silver oxide tends to relax to Ag.sub.2O, the more stable form of silver oxide. UV light can also be used to activate Ti/TiO.sub.2 and Cu/CuO coatings. For silver-based surfaces, UV light directed into the system converts deposited Ag.sub.2O to AgO. UV light can be supplied from a source within the vacuum chamber (FIG. 3) or from an outside source after the coated substrate is removed from the chamber.

(48) Glass substrates were coated with 100 nm of a combination of Ag, AgO, and Ag.sub.2O using the IPD process as described in Example 4. Samples were tested by a zone of inhibition (ZOI) test on tryptic soy agar with S. aureus. Half the coated samples were incubated at 37° C. with no light exposure; the other half were incubated at 37° C. after exposure to UV light in the range of 200 to 400 nm. After a 24 hr incubation, the samples not exposed to UV showed a ZOI of up to 6 mm. The samples exposed to UV light showed a zone of inhibition of up to 12 mm, see Table 4.

(49) Glass substrates were coated with 100 nm of a combination of Ti, TiO and TiO.sub.2 using the IPD process described in Example 4. Antibacterial properties of the coated samples were tested using zone of inhibition testing on tryptic soy agar with S. aureus. Half the samples were incubated at 37° C. with no light exposure, the other half were incubated at 37° C. after exposure to Black Light Blue (BLB) in the wavelength range of 300-400 nm. After a 24 hr incubation, the samples not exposed to BLB showed no zone of inhibition. The samples exposed to BLB showed a zone of inhibition of up to 12 mm, see Table 4.

(50) Glass substrates were coated with 100 nm of a combination of Cu, CuO, and Cu.sub.2O using the IPD process. The samples were tested by ZOI on tryptic soy agar with S. aureus. Half the samples were incubated at 37° C. with no light exposure, the other half were incubated at 37° C. after exposure to UV light in the range of 200 to 400 nm. After a 24 hr incubation, the samples not exposed to UV showed no ZOI. The samples exposed to UV all showed a ZOI. The ZOI was enhanced two-fold for the Ag-based coatings. The UV treatment on the Ti and Cu-based coatings produced antibacterial activity comparable to the Ag-based coatings where, unlike the silver coatings, no activity was observed before UV treatment. See Table 4.

(51) TABLE-US-00004 TABLE 4 Metal Coating Light Combination Thickness Wavelength Microbe ZOI (24 hr) Ti, TiO, TiO2 100 nm None S. aureus None 100 nm None C. albicans None 100 nm 300-400 nm S. aureus 12 mm 100 nm 300-400 nm C. albicans 12 mm Cu, CuO, Cu.sub.2O 100 nm None S. aureus None 100 nm None C. albicans None 100 nm 200-400 nm S. aureus 12 mm 100 nm 200-400 nm C. albicans 12 mm Ag, AgO, Ag.sub.2O 100 nm None S. aureus  6 mm 100 nm None C. albicans  6 mm 100 nm 200-400 nm S. aureus 12 mm 100 nm 200-400 nm C. albicans 12 mm

(52) The ZOI was calculated as indicated above. This corrected ZOI is not comparable to the calculated ZOI data reported in Burrell, et al. (1995) which were measured by subtracting the dimensions of the substrate from the dimensions of the observed zone of inhibition.

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