Fabrication and Characterization of Silk Braided Sutures

Silk sutures are already used in surgery. Silk is a natural protein fiber and easily prone to microbial infection hence we have developed novel antimicrobial silk braided sutures. Braided silk sutures were fabricated using a circular braiding machine with a 16 carrier arrangement normally used to produce braided structures. The same structure was used to manufacture braids with three different take-up speed levels obtained by changing the cogwheel ratio on the braiding machine. The influence of braid angle, test parameters such as gauge length and extension rate on tenacity and knot strength of braided silk sutures were studied. Silk sutures fabricated at higher braid angle, tested at shorter gauge length and greater test speed showed lower values of tenacity and knot strength. Chitosan was applied on braided silk sutures to impart antimicrobial characteristics. The Scanning electron microscopy study reveals the absence and presence of chitosan on the surface of untreated and treated sutures respectively. The antimicrobial properties of chitosan and tetracycline hydrochloride drug were tested using Agar diffusion method SN 195920 both when applied independently and collectively on silk sutures against Escherichia coli and Staphylococcus aureus. The combined antimicrobial effect of chitosan and tetracycline hydrochloride drug is very good and can be used to develop antimicrobial silk sutures for providing protection against microbial infections.