POLYMERS FOR MEDICAL USES

An increasing demand for biomaterials corresponds to the deficiency in the knowledge on biocompatibility. To increase this knowledge the mod ification of polymer surfaces, their characterization, and the investi gation of the response of the biosystem is considered to be a suitable approach. Surface modification may be performed in the wet-chemical w ay (heterogeneous reaction) or by means of treatment with a suitable p lasma (glow discharge). Surface sensitive methods such as X-ray photoe lectron spectroscopy, infrared spectroscopy in the attenuated total re flexion mode as well as surface energy measurements are useful for sur face characterization. To determine the bioresponse to the polymer sur face, enzyme-linked immunosorbent assays, cell growth and full blood t ests may be used. In the present paper several systems are described w ith respect to their surface modification, characterization, and biore sponse. It is shown that the protein adsorption is triggered by the su rface, that SO2 plasma treatment enhances cell growth and that there s eems to be a biocompatibility window for a surface characterized by a zeta-potential between -4 and -8 mV and a ratio of dispersive to polar contributions of surface energy around 12. It is stressed, however, t hat the final solution for a biomaterial is a material which, in the c ourse of degradation, constantly presents a new biocompatible surface.