Biodegradability of conducting chitosan-g-polycaprolactone/polypyrrole conduits

Conducting chitosan-g-polycaprolactone(CPC)/polypyrrole(PPy) conduits were fabricated for potential applications in nerve repair. Their mechanical and conducting properties as well as in vitro and in vivo degradation behaviors were mainly examined. It was found that some CPC/PPy conduits showed significantly stronger tensile and lateral compressive strength in the wet state, and notably higher conductivity in the overall tested PPy-load range, in comparison with chitosan/PPy conduits. After being consecutively exposed to PBS systems for various periods up to 10 weeks, the CPC/PPy conduits exhibited relatively slow degradation compared to chitosan/PPy conduits, and their degradation behaviors were measurably mediated by the composition of CPCs. The pH values of media corresponding to some selected CPC/PPy conduits did not significantly deviate from the initial pH value due to the buffering effect of chitosan component. After being implanted into rabbits for various periods, it was observed that the explanted chitosan/PPy conduits could only sustain a very low compressive load after 6-week degradation, and most of them were partially or fully collapsed after 8-week or longer degradation and showed very low conductivity. In contrast to these observations, some explanted CPC/PPy conduits were able to maintain enough strong mechanical strength in the wet state for the required period, and still showed acceptable conducting properties after 10-week in vivo degradation. Results suggested that some CPC/PPy conduits having proper compositional proportions could serve as desirable candidates to bridge nerve gaps in vivo. (C) 2010 Elsevier Ltd. All rights reserved.