Abstract:
Multilayer anti-microbial materials formed to produce an interference colour, and thus an indictor of anti-microbial effect, are provided. The materials include a partly reflective base layer and a partly reflective, partly transmissive top layer balanced to produce an interference colour. The top layer is formed from an anti-microbial metal with atomic disorder. Dissolution or a change in composition of the top layer on contacting an alcohol or electrolyte causes a change in optical path length so as to produce a change in the interference colour of the material. Multilayer, laminated wound dressings are also provided. The dressing includes a first and second layer, and preferably a third layer. The first and third layers are formed of perforated, non-adherent materials and most preferably carry an anti-microbial coating as above. The second layer is sandwiched between the first and third layers and is formed of an absorbent material. At least one of the layers is formed from a plastic material. The layers are laminated together by ultrasonic welds spaced intermittently on the dressing to allow the dressing to be cut to size with delaminating.
Abstract:
Anti-microbial coatings and powders and method of forming same on medical devices are provides. The coatings are preferably formed by depositing an anti-microbial biocompatible metal by vapour deposition techniques to produce atomic disorder in the coating such that a sustained release of metal ions sufficient to produce an anti-microbial effect is achieved. Preferred deposition conditions to achieve atomic disorder include a lower than normal substrate temperature, and one or more of a higher than normal working gas pressure and a lower than normal angle of incidence of coating flux. Anti-microbial powders formed by vapour deposition or altered by mechanical working to produce atomic disorder are also provided. The anti-microbial effect of the coatings or powders may be further activated or enhanced by irradiating with a low linear energy transfer form of radiation such as gamma radiation. Novel anti-microbial silver materials are defined, characterized by having a positive rest potential, a Trec/Tm less than 0.33, and a grain size less than 200 nm. Anti-microbial fine grain or nanocrystalline materials are provided, together with methods of preparation, wherein the anti-microbial metal if deposited in a matrix with atoms or molecules of a different material such as other biocompatible metals (ex. Ta), trapped or absorbed oxygen, or compounds of anti-microbial metals or biocompatible metals (ex. Ag0 or TaO). The invention also extends to a method of producing an anti-microbial effect with silver materials that form complex silver ions other than Ag?+, Ag2+ and Ag3+¿.