ABSTRACT
The physiological milieu is a hostile and highly corrosive environment that causes the degradation of materials with consequent changes in their bulk and surface properties, mechanical performance, and biocompatibility. Blood compatibility poses the severest requirement on materials. Many materials can adversely affect the plasma proteins, enzymes, clotting factors, and the formed blood elements as the result of their interactions with materials. Prolonged periods of implantations may even lead to carcinogenesis by various mechanisms. In contrast to most synthetic materials, there is no evidence that the living endothelium adsorbs proteins under physiological conditions. Acute toxicity testings are limited by the fact that polymers degrade by a time-dependent mechanism in the physiological environment. If polymeric materials have been subjected to ethylene oxide sterilization, care must be exercised to assure that all residual ethylene oxide, ethylene chlorohydrin, and ethylene glycol are removed before testing.
