Novel biostable and biocompatible amphiphilic membranes.

Abstract

We determined the biostability and biocompatibility of two types of amphiphilic conetworks (APCNs): (1) hydrophilic poly(N,N-dimethyl acrylamide) (PDMAAm) and hydrophobic polydimethylsiloxane (PDMS) microdomains co-crosslinked with polymethylhydrosiloxane (PMHS) clusters (PDMAAm/PMHS/PDMS), and (2) poly(ethylene glycol) (PEG) and PDMS microdomains co-crosslinked with two specially designed small-molecule crosslinking agents SiC(6)H(5)(SiH)(2)OEt (Y) and polypentamethylhydrocyclosiloxane (PD(5)) (PEG/Y or PD(5)/PDMS). Negative standards for comparing biocompatibility and biostability were crosslinked PDMS. Biostability was assessed by quantitatively determining extractables, equilibrium water swelling, mechanical properties (stress-strain response) of polymer samples before and after implantation in rats for up to 8 weeks, and oxidative accelerated degradation test. Biocompatibility was assessed by determining body weight, fibrous tissue encapsulation, fluid accumulation, and by histological evaluation of lymphocyte infiltration, fibrous tissue accumulation and collagen deposition. According to these stringent metrics PDMAAm/PMHS/PDMS is both biostable and biocompatible, whereas PEG/Y or PD(5)/PDMS degrades in living tissue but is biocompatible. Surprisingly, the overall biocompatibility scores of these APCNs were superior to those of the PDMS negative standard.