WO2004073763A1

WO2004073763A1 - Antimicrobial and electrically conducting materials

Info

Publication number: WO2004073763A1
Application number: PCT/CA2004/000246
Authority: WO
Inventors: Dominic Tessier; Martin Filteau
Original assignee: Drm International
Priority date: 2003-02-20
Filing date: 2004-02-20
Publication date: 2004-09-02

Abstract

The present invention relates to a process for the preparation of an antimicrobial and electrically conductive materials comprising the steps of coating at least one surface of a support with an effective amount of a suitable metallic compound and treating at least one coated surface with a salt forming solution in an effective concentration for formation of metallic salts on the substrate surface.

Description

ANTIMICROBIAL AND ELECTRICALLY CONDUCTING MATERIALS

BACKGROUND OF THE INVENTION

(a) Field of the Invention

[0001] This invention relates to antimicrobial and electrically conducting materials comprising a mixture of metallic compound and metallic salt thereof.

(b) Description of Prior Art

[0002] It is well known in the art that silver and silver salts are having antimicrobial properties justifying there use in wound dressing, but also in solutions, to help healing and cicatrisation of wounds.

[0003] It was developed methods were silver is projected on a substrate by plasma together with an organic compound or is evaporated on the substrate together with the polymerization by plasma or an organic compound. These methods are enhancing the encapsulation of silver particles in a three-dimensional organic matrix at the surface of the substrate. However, the material obtained by these methods present discontinuities in its surface, which render the material improper for medical or high tech applications. As for example, Westaim technologies Inc has developed a product described in U.S. Patents Nos. 5,985,308, 6 017,553, 6,080,490, 6,238,686 and 6,333,093. This product is a silver coated dressing made of three plies, the center one being made of absorbent rayon and the two external plies being covered with silver. Westaim has also developed a silver foam dressing wherein silver is incorporated in a gel made of a collagen's derivative.

[0004] Silver wound dressings were also prepared in the past by introducing silver fibers in the preparation of the dressing itself, or by introducing doping particles.

[0005] Matson (U.S. Patent No. 4,728,323) coats a substrate with a film of silver salt deposited by vapor or sputter coating techniques. However, this dressing is having a limited antimicrobial activity. [0006] Other dressings have been developed, all of them having not a quality and uniformity acceptable for the medical and high tech industry.

[0007] Despite the availability of numerous techniques for the delivery of silver and silver compounds in vitro and in vivo, it would be highly desirable to be provided with a delivery system of a quality and uniformity acceptable for the medical and high tech industry and providing an improved microbial inhibition at the application site and antimicrobial effect duration.

SUMMARY OF THE INVENTION

[0008] One aim of the present invention is to provide an antimicrobial material comprising a suitable metallic compound and a suitable metallic salt for inhibiting the activity of bacteria upon contact with the material and creating an inhibition zone in periphery of the material.

[0009] Another aim of the present invention is to provide an electrically conductive material suitable for use in fields such as, but not limited to, aerospace.

[0010] In accordance with the present invention, there is provided a process for the preparation of an antimicrobial material comprising the steps of:

(a) coating at least one surface of a support with an effective amount of a suitable metallic compound; and

(b) treating said at least one coated surface with a salt forming compound in an effective concentration for formation of metallic salts on said substrate surface.

[0011] In accordance with the present invention, there is provided a process for the preparation of an electrically conductive material comprising the steps of:

(b) treating said at least one coated surface with a salt forming compound in an effective concentration for formation of metallic salts on said substrate surface. [0012] In accordance with a preferred embodiment of the present invention, the process further comprises a step (i) prior to step (a), the step (i) being:

(i) cleaning said surface to facilitate its eventual coating.

[0013] In accordance with a preferred embodiment of the present invention, the, compound is selected from the group consisting of an acid and an oxidant.

[0014] In accordance with a preferred embodiment of the present invention, the compound is in a form selected from the group consisting of a solution and a vapor.

In accordance with a preferred embodiment of the present invention, the coating is provided by plasma sputter coating.

[0015] The plasma sputter coating is performed by using a plasma selected from the group consisting of argon argon/nitrogen, argon/nitrogen/hydrogen, krypton, krypton/nitrogen, krypton/nitrogen/hydrogen, xenon, xenon/nitrogen, xenon/nitrogen/hydrogen, helium, helium/nitrogen, helium/nitrogen/hydrogen, neon, neon/nitrogen and neon/nitrogen/hydrogen plasma, preferably using argon plasma.

[0016] In accordance with a preferred embodiment to the present invention, the metallic compound is selected from the group consisting of silver, platinum, gold, copper, zinc, tin, antimony, bismuth and mixtures thereof, preferably silver.

[0017] In accordance with a preferred embodiment of the present invention, the metallic salt is selected from the group consisting of silver bromide, silver perchlorate, silver fluoride, silver chloride, silver nitrate, silver sulfate, silver iodate, silver alkylcarboxylate, silver sulphadiazine and silver arylsulfonate, preferably silver nitrate.

[0018] The salt forming compound is selected from the group consisting of nitric acid, perchloric acid, fluoridric acid, hydrochloric acid, bromic acid, iodic acid, sulfuric acid and arylsulfonic acid, preferably nitric acid and is present in a concentration of at least 0.05M, preferably at least 0.4M and more preferably 1M.40. Use of a material prepared in accordance with a process of one of claims 21-39 for the preparation of static electricity dissipating material.

[0019] In accordance with the present invention, there is provided the use of the material prepared in accordance with the present invention for the preparation of an antimicrobial wound dressing.

[0020] In accordance with the present invention, there is provided the use of a material prepared in accordance with the present invention for the preparation of a microwave absorptive material.

[0021] In accordance with the present invention, there is provided the use of a material prepared in accordance with the present invention for the preparation of composite material.

In accordance with a preferred embodiment of the present invention, the composite material is laminated with elastomeric resin, the elastomeric resin being selected from the group consisting of epoxy, polyimide and polyester.

[0022] In accordance with the present invention, there is provided the use of a material prepared in accordance with the present invention for the preparation of a material detecting, and reacting to, a environmental stimuli. This material react by at least one selected from the group consisting of changing color, oscillating, swelling and static electricity dissipation and the environmental stimuli is selected from the group consisting of temperature, luminosity, humidity and electronic signal.

[0023] In accordance with the present invention, there is provided an antimicrobial material comprising a support having at least one surface coated with a metallic compound suitable for topical use or made of the metallic compound and having at least one metallic salt adsorbed on the surface.

[0024] In accordance with the present invention, there is provided an electrically conductive material comprising a support having at least one surface coated with a metallic compound or made of the metallic compound and having at least one metallic salt adsorbed on the surface.

[0025] For the purpose of the present invention the following terms are defined below. [0026] The term "zone of inhibition" is intended to mean a clear area of disappearing or destruction of a microorganism in proximity of the borders of a specimen placed in direct contact with the surface of interest.

[0027] The term "material" is intended to mean any material which is suitable for plasma sputtering deposition of silver followed by a chemical treatment producing silver ions at the surface of the material. The material can be selected from, but not limited to, acetate, flax, gloss, modacrylic, olefin polyester, polyethylene, rubber, saran, spandex, lycra, vinyl, vinyon, cotton, wool, silk, rayon, nylon, glasswool, acrylic, paper, Kevlar, polyolefin polymers, such as propylene, aramid polytetra fluoroethylene and related polymers, synthetic polymers and mixtures thereof.

[0028] The term "antimicrobial" refers to a product having the capacity to destroy or inhibit the growth of microorganisms, which are including, without limitation, gram+ and gram- bacteria, fungi and viruses.

[0029] The term "wound" refer to a tissue damage or loss of any king, including but not limited to cuts, incisions, abrasions, lacerations, fractures, contusions, burns, amputations and the like.

[0030] The term "salt forming compound" is intended to mean a compound having a dissociation capacity, when in solution or in a vapor form, suitable for forming a salt in presence of metallic ions. Salt forming compound can be selected from, but not limited to, nitric acid, perchloric acid, fluoridric acid, hydrochloric acid, bromic acid, iodic acid, sulfuric acid and arylsulfonic acid. A metallic salt can also be comprised in the salt forming compound, when in a solution, such as, but not limited to, metallic nitrate, perchlorate, fluoride and thiosulfate.

[0031] It is intended that the antimicrobial material as described in the present application is particularly useful in applications in the medical field.

[0032] It is also intended that the electrically conductive material as described in the present application can be used in a variety of applications, including the fields of aerospace, industrial and commercial products.

[0033] All references herein are hereby incorporated by reference. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Fig. 1 illustrates the plasmionique's magnetron sputtering system used in one preferred embodiment of the present invention;

[0035] Figs. 2A-D are photographs of scanning electron microscopy of samples of non silver-coated and silver-coated material with a 100X resolution;

[0036] Figs. 3A-D are photographs of scanning electron microscopy of samples of non silver-coated and silver-coated material with a 1000X resolution;

[0037] Figs. 4A-D are photographs of scanning electron microscopy of samples of non silver-coated and silver-coated material, with a 8000X resolution;

[0038] Fig. 5 is a schematic representation of the coating composition before and after post-treatment;

[0039] Fig. 6 represents the inhibition zone on K. Pneumoniae in function of post-treatment HNO3 concentration;

[0040] Fig. 7 represents the inhibition zone on S. aureus in function of post-treatment HNO₃ concentration;

[0041] Figs. 8A-D are photographs of inhibition zone on S. aureus with post-treatment with HNO₃ at concentrations of 0.3M, 0.4M, 0.5M and 0.6M;

[0042] Figs. 9A-D are photographs of inhibition zone on S. aureus with post-treatment with HNO₃ at concentrations of 0.6M during 60 seconds and during 120 seconds; and

[0043] Fig. 10 is a photograph of the recto of a material in accordance with a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0044] In accordance with the present invention, there is provided a process for producing antimicrobial and electrically conducting materials.

Deposition by cold plasma technique

[0045] In this process, the material is displaced on a support in a low- pressure environment. Fig. 1 illustrates the apparatus used for performing the coating step of one preferred embodiment of the process of the present invention. The material is placed in a sample holder 10 while a • silver cathode is pulverized under Argon plasma resulting in the deposition of metallic silver at the surface of the material.

Material

[0046] The material used was a Nylon / Lycra woven material. The

Nylon used is Nylon 6 (standard 40 deniers, BASF) in proportion of 74% and the Lycra was used in a proportion of 26%. The material was woven using a polymer-based lubricant.

Method

[0047] The deposition was performed in three steps using different parameters as described below:

^B Cleaning of the silver cathode: time 5 mins, 10 watts, Azote flowrate 2.5 seem at a pressure of 10 Pa, with shutter; ^a Surface activation treatment: time 1 min, 10 watts, Azote flowrate 2.5 seem at a pressure of 10 Pa, without shutter;

^■ Silver deposition: time variable, 10 watts, Azote flowrate 4.2 seem at a pressure of 10 Pa, without shutter.

Chemical treatment of the silver-coated material

[0048] The silver-coated material was then treated with a solution of nitric acid 1 M for different incubation times as shown n Table 7. After the incubation, the material is shaken for removing the s Iver deposit or other residual particles from the incubation step and it is dri ed at 50°C for about

30 minutes. This chemical treatment is allowing the transformation of a part of the metallic silver from the material into a silver salt which is having an improved mobility around the material when adhered to patient's skin and therefore allowing an increased inhibition zone.

[0049] It is also possible to use ultrasounds during the incubation of the material in the acid solution. The acid solution containing the fabric is introduced in a ultrasounds bath of 2.81 L (model 2510R-MTH, Branson Ultrasonics, CT, USA) having a mechanical timer and a heater. The operating frequency of the ultrasound bath is of 40 kHz. Scanning electron microscopy

[0050] Analysis of the material obtained was performed by scanning electron microscopy at a voltage of 5 kV. Photographs have been taken at 1000, 3000 and 5000X for the material prepared with the process of the present invention and at 100, 1000, 3000 and 8000X for the material prepared with other processes.

Silver deposition to obtain conductivity and electrostatic dissipation properties for a surface

[0051] Some materials are conductive by specific treatment performed at their surface. These material are characterized by their surface resistivity ps which is expressed in ohm or square ohm:

_Ps = 2,73R / log (r1/r2) (1) where R is the resistivity and r1 and r2 are the radius of the external and internal circular electrodes respectively.

Evaluation of ps performed using the normalized test:

[0052] Electrical Resistivity of Fabrics AATCC 76-1995 which is enclosed by reference. A potential difference (DC) of 100 volts is applied between the electrodes and the measure of the resulting current is providing R. Before making the measurements, the samples must be conditioned for at least 24 hours at 22+1 °C and 20+2% of relative humidity since the conductivity is affected by the water content of the sample and by its temperature.

[0053] The electrostatic dissipation capacity of the textile was evaluated by the Electrostatic decay of fabrics FT S 191A 5931-1990 assay. This assay determines the time required for reducing electric charge on a fabric to reach a safe level. A potential difference 5 KV and of -5KV are applied on one surface of the fabric having a conductive polymer coating in both weft and chain directions. The fabric is accepted only if the dissipation average time is under or equal to 0,5 second in both directions.

[0054] These electrical properties have to be conserved after several washings as per the ISO 6330-1984 norm which is enclosed herewith by reference. The fabric must also be resistant to chemical products. Evaluation of the surface composition of the material

[0055] The evaluation of the surface composition of the material was performed by X-Rays photoelectron spectroscopy using a system Escalab MKII™ from VG having a double anode of Mg and Al. Only Mg radiation at an energy of 1253,6 ev was used. The source was set at 240 watts and an inside pressure of 1x10^"9 Torr was maintained in the chamber. The exit angle of the photoelectrons was of 0°.

Antimicrobial activity assessment of the fabric

[0056] The antimicrobial activity was assessed according to the AATCC

Test Method 147-1998 which is described here and which is a qualitative procedure that demonstrates the bacteriostatie activity by the diffusion of the antibacterial agent through agar. AATCC Test Method 147-1998 is included herein by reference.

Test bacteria

[0057] Staphylococcus aureus, American Type Culture Collection No.

6538, Gram positive organism and Klebsiella pneumoniae, American Type Culture Collection No. 4352

Culture Medium

[0058] Suitable broth/agar media are Nutrient, Trypticase Soy and

Brain-Heart Infusion.

Nutrient Broth:

Peptone (Bacto-peptone) 5g Beef extract 3g

Distilled water to 1000 ml

[0059] Heat to a boil to disperse ingredients. Adjust to pH 6,8 + 0,1 with 1N NaOH solution (This is not necessary if prepared, dehydrated medium is used).

[0060] Dispense in 10,0 ± 0,5 ml amounts in conventional bacteriological culture tubes (i.e., 125 x 17 mm). Plug and sterilize at 103 kPa (15 psi) for 15 min. (May be sterilized in 1 000 ml borosilicate glass flasks and Petri dishes poured from this). Maintenance of Culture of Test Organisms

[0061] Using a 4 mm inoculating loop, transfer the culture daily in nutrient (or appropriate medium) broth for not more than two weeks. At the conclusion of two weeks, make a fresh transplant from stock culture. Incubate cultures at 37 ± 2°C.

[0062] Maintain stock cultures on nutrient or appropriate agar slants.

Store at 5 ± 1 °C and transfer once a month to fresh agar.

Test specimens

[0063] Test specimens (non-sterile) are cut by hand or with a die. They may be any convenient size. Rectangular specimens cut 25x50 mm are recommended. A 50 nm length permits the specimens to lie across 5 parallel inoculum's streaks each of diminishing width from about 8 mm to 4 mm wide.

Procedure

[0064] Dispense sterilized nutrient (or appropriate medium) agar

[cooled to 47 ± 2°C] by pouring 15 ± 2 ml into each standard (15 x 100 mm) flat bottomed Petri dish. Allow agar to gel firmly before inoculating.

[0065] Prepare inoculums by transferring 1 ,0 ± 0,1 ml of a 24 h broth culture into 9,0 ± 0,1 ml of sterile distilled water contained in a test tube or small flask. Mix well using appropriate agitation.

[0066] Using a 4 mm inoculating loop, load one loopful of the diluted inoculums and transfer to the surface of the sterile agar plate by making five streaks approximately 60 mm in length, spaced 10 mm apart covering the central area of a standard Petri dish without refilling the loop. Take care not to break the surface of the agar while making the streaks.

[0067] Gently press the test specimen transversely across the five inoculums streaks to ensure intimate contact with the agar surface. This may be accomplished more easily by pressing the specimen to the agar surface with a biological section lifter or with a spatula which has been sterilized by flaming and then air cooled immediately before use. [0068] If the specimen curls, preventing intimate contact with the inoculated surface, place sterile glass slides on the ends of the specimen to hold it in place.

[0069] Incubate at 37 ± 2°C for 18-24 h.

Evaluation

[0070] Examine the incubated plates for interruption of growth along the streaks of inoculums beneath the specimen and for a clear zone of inhibition beyond its edge. The average width of a zone of inhibition along a streak on either side of the test specimen may be calculated using the following equation:

W = (T-D)/2 where:

W = width of clear zone of inhibition in mm

T = total diameter of test specimen and clear zone in mm

D = diameter of the test specimen in mm

[0071] An alternative method for the evaluation of the inhibition zone consists in incubating the sample as previously described, the recto side (as illustrated in Fig. 10) against the culture, at a temperature of 37°C during 24 hours on Mueller-Hinton agar plates. The length of the inhibition zone is determined by measuring the length of the inhibition zone at the periphery of the 2 longer sides and calculating the mean value.

Results

Scanning electron microscopy

[0072] The samples described in Table 1 were observed by scanning electron microscopy. Table 1 scanning electron microscopy samples

[0073] Figs. 2A-D show 100X micrographic images of the samples 1 , 9,

9A and 4 respectively. Figs. 3A-D show 1000X micrographic images of the samples 1 , 9, 9A and 4 respectively. Figs. 4A-D show 8000X micrographic images of the samples 1 , 9, 9A and 4 respectively.

Surface resistivity

[0074] Table 2 is showing surface resistivity results obtained from the testing of different samples.

Table 2 Resistivity values for silver-coated material

Surface chemical composition A tricot non silver-coated and a tricot of the same material but silver-coated were analyzed by spectroscopy at a depth of 5 nanometers. Table 3 shows the surface composition of the non silver-coated material and Table 4 shows the chemical link of carbon and oxygen of the non silver-coated material.

Table 3 surface composition of non silver-coated material

Table 4 carbon and oxygen chemical links for non silver-coated material

[0076] It appears from the following that the material is slightly contaminated with silica, and therefore a step of cleaning the material prior to silver deposition is preferable.

[0077] Table 5 shows the surface composition of the silver-coated material.

Table 5 Surface composition of silver-coated material

[0078] Further analysis was performed with silver-coated material having been treated with HNO₃ 1M as previously described in the description of the sample 9A. The HNO₃ post-treatment provides the formation of silver nitrate salt at the surface of the material following the reaction:

Ions Ag⁺ and NO₃ ^" and therefore presents at the surface of the material.

[0079] Table 6 shows the surface composition of the silver-coated material with post-treatment. Table 6

Surface composition of silver-coated material with post-treatment

[0080] Fig. 5 illustrates the composition of the silver-coated material at different stages.

Bacterial activity

[0081] Table 7 is providing results for bacterial activity of fabric samples having different deposition parameters and chemical treatment time. These results show that the silver-coated fabric obtained by the combination of silver-coating and chemical treatment is providing an inhibition zone against both gram positive and gram negative bacteria.

Table 7 Bacterial activity for several silver-coated samples

[0082] Figs. 6 and 7 are illustrating the effect of the concentration of the

HNO3 used for the post-treatment on the inhibition zone for both K. Pneumoniae and S. Aureus. It appears that an increase of incubation time from 60 seconds to 120 seconds is having a significant effect on the inhibition zone size. Figs. 8A-D are photographs of the inhibition zone against S. aureus after post-treatment with HNO₃ 0.3 M, 0.4 M, 0.5 M and 0.6 M respectively. Figs. 9A-B are photographs of the inhibition zone against S. aureus after post-treatment with HNO2 0.6M during 60 seconds and 120 seconds.

[0083] Several gases and combinations thereof can be used for the silver deposition. These gases can be selected from, but not limited to argon, argon/nitrogen, argon/nitrogen/hydrogen, krypton, krypton/nitrogen, krypton/nitrogen/hydrogen, xenon, xenon/nitrogen, xenon/nitrogen/hydrogen, helium, helium/nitrogen, helium/nitrogen/hydrogen, neon, neon/nitrogen, neon/nitrogen/hydrogen.

[0084] Soluble salts are having better antimicrobial activity. However, it is possible turn insoluble silver salts into soluble salts by reacting then with sodium thiosulfate as shown in the following equation:

[0085] AgX(s) + 2 Na₂S₂O₃ → Na₃[Ag(S₂O₃)₂] + NaX

[0086] wherein X is Cl, Br or I and the reaction products are soluble in water.

[0087] While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as follows in the scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A process for the preparation of an antimicrobial material comprising the steps of:

2. The process of claim 1 , further comprising a step (i) prior to step (a),

(i) cleaning said surface to facilitate its eventual coating.

3. The process of claim 1 , wherein said compound is selected from the group consisting of an acid and an oxidant.

4. The process of claim 3, wherein said compound is in a form selected from the group consisting of a solution and a vapor.

5. The process of claim 1 , wherein said coating is provided by plasma sputter coating.

6. The process of claim 5, wherein said plasma sputter coating is performed by using a plasma selected from the group consisting of argon argon/nitrogen, argon/nitrogen/hydrogen, krypton, krypton/nitrogen, krypton/nitrogen/hydrogen, xenon, xenon/nitrogen, xenon/nitrogen/hydrogen, helium, helium/nitrogen, helium/nitrogen/hydrogen, neon, neon/nitrogen and neon/nitrogen/hydrogen plasma.

7. The process of claim 5, wherein said plasma sputter coating is performed by using argon plasma.

8. The process of claim 1 , wherein said material is selected from the group consisting of acetate, flax, gloss, modacrylic, olefin polyester, polyethylene, rubber, saran, spandex, vinyl, vinyon, cotton, wool, silk, rayon, nylon, glasswool, acrylic, paper, polyolefin, aramid, polytetrafluoroethylene, synthetic polymers and mixtures thereof.

9. The process of claim 1 , wherein said metallic compound is selected from the group consisting of silver, platinum, gold, copper, zinc, tin, antimony, bismuth and mixtures thereof.

10. The process of claim 1 , wherein said metallic compound is silver.

11. The process of claim 1 , wherein said metallic salt is selected from the group consisting of silver bromide, silver perchlorate, silver fluoride, silver chloride, silver nitrate, silver sulfate, silver iodate, silver alkylcarboxylate, silver sulphadiazine and silver arylsulfonate.

12. The process of claim 1 , wherein said metallic salt is silver nitrate.

13. The process of claim 1 , wherein said salt forming compound is selected from the group consisting of nitric acid, perchloric acid, fluoridric acid, hydrochloric acid, bromic acid, iodic acid, sulfuric acid and arylsulfonic acid.

14. The process of claim 1 , wherein said salt forming compound is nitric acid.

15. The process of claim 1 , wherein said salt forming compound is in a concentration of at least 0.05M.

16. The process of claim 1 , wherein said salt forming compound is in a concentration of at least 0.4M.

17. The process of claim 1 , wherein said salt forming compound is in a concentration of at least 1M.

18. The process of claim 1 , wherein a metallic salt is comprised in the salt forming solution.

19. The process of claim 18, wherein said metallic salt is selected from the group consisting of metallic nitrate, iodate, perchlorate, fluoride and thiosulfate.

20. Use of a material prepared in accordance with a process of one of claims 1-19 for the preparation of an antimicrobial wound dressing.

21. A process for the preparation of an electrically conductive material comprising the steps of: (a) coating at least one surface of a support with an effective amount of a suitable metallic compound; and

22. The process of claim 21 , further comprising a step (i) prior to step (a),

(i) cleaning said surface to facilitate its eventual coating.

23. The process of claim 21 , wherein said compound is selected from the group consisting of an acid and an oxidant.

24. The process of claim 23, wherein said compound is in a form selected from the group consisting of a solution and a vapor.

25. The process of claim 21 , wherein said coating is provided by plasma sputter coating.

26. The process of claim 25, wherein said plasma sputter coating is performed by using a plasma selected from the group consisting of argon argon/nitrogen, argon/nitrogen/hydrogen, krypton, krypton/nitrogen, krypton/nitrogen/hydrogen, xenon, xenon/nitrogen, xenon/nitrogen/hydrogen, helium, helium/nitrogen, helium/nitrogen/hydrogen, neon, neon/nitrogen and neon/nitrogen/hydrogen plasma.

27. The process of claim 25, wherein said plasma sputter coating is performed by using argon plasma.

28. The process of claim 21 , wherein said material is selected from the group consisting of acetate, flax, gloss, modacrylic, olefin polyester, polyethylene, rubber, saran, spandex, vinyl, vinyon, cotton, wool, silk, rayon, nylon, glasswool, acrylic, paper, polyolefin, aramid, polytetrafluoroethylene, synthetic polymers and mixtures thereof.

29. The process of claim 1 , wherein said metallic compound is selected from the group consisting of silver, platinum, gold, copper, zinc, tin, antimony, bismuth and mixtures thereof.

30. The process of claim 21 , wherein said metallic compound is silver.

31. The process of claim 21 , wherein said metallic salt is selected from the group consisting of silver bromide, silver perchlorate, silver fluoride, silver chloride, silver nitrate, silver sulfate, silver iodate, silver alkylcarboxylate, silver sulphadiazine and silver arylsulfonate.

32. The process of claim 21 , wherein said metallic salt is silver nitrate.

33. The process of claim 21 , wherein said salt forming compound is selected from the group consisting of nitric acid, perchloric acid, fluoridric acid, hydrochloric acid, bromic acid, iodic acid, sulfuric acid and arylsulfonic acid.

34. The process of claim 21 , wherein said salt forming compound is nitric acid.

35. The process of claim 21 , wherein said salt forming compound is in a concentration of at least 0.05M.

36. The process of claim 21 , wherein said salt forming compound is in a concentration of at least 0.4M.

37. The process of claim 21 , wherein said salt forming compound is in a concentration of at least 1 M.

38. The process of claim 21 , wherein a metallic salt is comprised in the salt forming solution.

39. The process of claim 38, wherein said metallic salt is selected from the group consisting of metallic nitrate, iodate, perchlorate, fluoride and thiosulfate.

40. Use of a material prepared in accordance with a process of one of claims 21-39 for the preparation of static electricity dissipating material.

41. Use of a material prepared in accordance with a process of one of claims 21-39 for the preparation of a microwave absorptive material.

42. Use of a material prepared in accordance with a process of one of claims 21-39 for the preparation of composite material.

43. The use as claimed in claim 42, wherein said composite material is laminated with elastomeric resin.

44. The use as claimed in claim 43, wherein said elastomeric resin is selected from the group consisting of epoxy, polyimide and polyester.

45. Use of a material prepared in accordance with a process of one of claims 21-39 for the preparation of a material detecting, and reacting to, a environmental stimuli.

46. The use as claimed in claim 45, wherein said material react by at least one selected from the group consisting of changing color, oscillating, swelling and static electricity dissipation.

47. The use as claimed in claim 45, wherein said environmental stimuli is selected from the group consisting of temperature, luminosity, humidity and electronic signal.

48. An antimicrobial material comprising a support having at least one surface coated with a metallic compound suitable for topical use or made of said metallic compound and having at least one metallic salt adsorbed on said surface.

49. The material of claim 48, wherein said metallic compound is selected from the group consisting of silver, platinum, gold, copper, zinc, tin, antimony, bismuth and mixtures thereof.

50. The material of claim 48, wherein said metallic compound is silver.

51. The material of claim 48, wherein said metallic salt is selected from the group consisting of silver nitrate, silver bromide, silver fluoride, silver chloride, silver sulfate, silver alkylcarbonate, silver iodate, silver sulphadiazine and silver arylsulfonate.

52. The material of claim 48, wherein said metallic salt is silver nitrate.

53. The material of claim 48, wherein said metallic salt is a product from the reaction between a non-soluble metallic salt and sodium thiosulfate.

54. The material of claim 53, wherein said non-soluble metallic salt is a halogenated silver compound.

55. An electrically conductive material comprising a support having at least one surface coated with a metallic compound or made of said metallic compound and having at least one metallic salt adsorbed on said surface.

56. The material of claim 55, wherein said metallic salt is selected from the group consisting of silver bromide, silver fluoride, silver chloride, silver nitrate, silver sulfate, silver alkylcarboxylate, silver iodate, silver sulphadiazine and silver arylsulfonate.

57. The material of claim 55, wherein said metallic salt is silver nitrate.

58. The material of claim 55, wherein said metallic compound is selected from the group consisting of silver, platinum, gold, copper, zinc, tin, antimony, bismuth and mixtures thereof.

59. The material of claim 55, wherein said metallic compound is silver.

60. The material of claim 55, wherein said support consists in fibers made of said metallic compound.