New silicone rubbers, 2. Biocompatible silicone rubbers

Biokompatible silicone rubbers have been prepared using fillers based on two types of modified amorphous silica: (i) silica containing covalently bonded reactive H-Si-groups ( 1 ) obtained by reaction of silica with methyldichlorosilane, and (ii) silica with covalently immobilized antithrombogenic agent ( 5 ), prepared by reaction of 1 with divinylbenzene, graft copolymerization with acrylic acid and subsequent esterification with amylose sulfuric acid esters ( 2 ) as a heparinoid. Silicone rubbers (SR's) were obtained by hydrosilation curing of commercially available silicone components using 1 or 5 as fillers. In contrast to 5, 1 is incorporated covalently into the silicone network. Both SR types exhibited good mechanical properties as well as excellent tissue compatibility: contrary to SR's filled with nonmodified silica the cell growth of endothelian cells on the SR's with modified fillers was found to be almost identical to that on cell culture plates.