Wet spun chitosan–collagen fibers, their chemical N-modifications, and blood compatibility

Based on an in vitro test for an improvement of the blood compatibility of chitin by blending with tropocollagen, we prepared a novel biocompatible blended fiber and its chemically N-modified fibers. Each (1 g/30 ml) of a clear mixed solution of chitosan with tropocollagen or collagen and a clear solution of chitosan itself in aqueous 2% acetic acid–methanol (2 : 1 , v/v) was spun through a viscose-type spinneret into an aqueous 5% ammonia solution containing 40–43% ammonium sulfate at room temperature to afford a white fiber of chitosan–tropocollagen blends (1.08–1.65 g/denier for the tenacity and 10.9–43.2% for the elongation). The tropocollagen content up to 50% by weight) in the blended fiber affected little their tenacity and elongation values. The blended fiber was chemically N-modified at the fiber state by treatment with a series of carboxylic anhydrides and aldehydes to afford the corresponding N-modified fiber (0.86–1.31 g/denier for the tenacity and 8.0–12.1% for the elongation). A transparent blended hydrogel of N-acetylchitosan (chitin) with tropocollagen was produced from the above mixed solution by treatment with acetic anhydride, and its membrane and sponge sheet were also prepared from the hydrogel.