The Influence of Plasma Composition on the Properties of Plasma Treated Biomaterials
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The Influence of Plasma Composition on the Properties of Plasma Treated Biomaterials. Nilson C. Cruz, Elidiane C. Rangel, Giovana Z. Gadioli, Rogério P. Mota, Roberto Y. Honda, Mauricio A. Algatti and Wido H. Schreiner*. Laboratório de Plasmas e Aplicações, UNESP, Campus de Guaratinguetá, 12516-410, Guaratinguetá, SP, Brazil *Laboratório de Interfaces e Filmes Finos, Departamento de Física, UFPR, 81531-990, Curitiba , PR, Brazil INTRODUCTION The response of a biological environment when in contact with an artificial material is primarily determined by the material surface properties such as composition, contact angle and free surface energy [1,2]. Owing to that, different treatments have been employed to improve the performance of biocompatible materials. In this sense, plasma-based techniques are very attractive because they enable the surface processing of materials with virtually any geometry preserving bulk properties. Furthermore, other characteristics make plasma treatment of particular interest in biomaterial processing. Those characteristics include, for instance, a) the possibility of using a large number of different chemicals to introduce any desired functional group on the surface, b) the treatment is performed in an intrinsically sterile environment and, c) different kind of materials (such as ceramics, metals and polymers) including those chemically inert can be treated. The selection of the best material to be used as biomaterial may be a hard task. For instance, titanium and its alloys present excellent biocompatibility and high resistance to corrosion. However, their poor wear resistance restricts their usage as prostheses and clinical devices. With the polymers this situation is not different. Polyurethanes, as an illustration, are non-thrombogenic, flexible and mechanically resistant. These properties make them very promising. In fact, they have already been used in some cardiovascular devices [3,4]. Generally the first result of the interaction blood-artificial material is the adsorption of proteins. This adsorption, which can result in serious problems such as the production of thrombosis, is strongly determined by chemical properties of the material surface. However, it has been shown [5] that as the surface becomes more hydrophilic the protein adsorption decreases. Furthermore, it has been observed [6] that in hydrophilic surfaces occur predominantly the adsorption of albumin which causes the surface to become more non-thrombogenic. In this sense, the usual polyurethane hydrophobicity (water contact angles of about 115°) is a great inconvenient. In this work, glow discharge plasmas and Plasma Immersion Ion Implantation (PIII) techniques have been applied in the treatment of some metals (Ti and Ti6Al4V) and polymers (teflon, silicone rubber, nylon, PVC and polyurethane) employed in biomedical devices. EXPERIMENTAL The treatment plasmas were generated in a glass chamber by applying radiofrequency power (13.56MHz, 0-300W) to two external electrodes. During the experiments the chamber is continuou
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