Almost all sutures in current usage only play one role, i.e. to mechanically tie wound tissues together. Drug-loaded composite nanofibers obtained through coaxial electrospinning can initiate the development of a new type of biodegradable sutures with drug release. In this work, electrospun poly(L-lactic acid) (PLLA) nanofibers with uniaxial alignment were made into braided wires and were coated with chitosan and applied as tissue sutures. Toxicity evaluation on cells for the chitosan-coated PLLA braided wires was carried out using the MTT (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) test, and an in vivo study was conducted by implanting the braided wires into muscle tissues of rats. The inflammation responses were examined at 3, 7, 14, 21 and 28 days after implanting. Experimental results indicated that the braided PLLA nanofiber wires coated with chitosan exhibited comparable tensile and knot strengths to those of a commercial suture, could tie wounded tissues for a complete healing without any breakage, had no cellular toxicity and could promote cell growth well. The chitosan-coated PLLA sutures showed better histological compatibility than a silk suture in the in vivo study. Braided PLLA nanofiber wires fabricated using an electrospinning process followed by a braiding technique and coated with chitosan are applicable for uses within the body. (C) 2009 Society of Chemical Industry