Development of Flexible Osteoconductive and Antibacterial Fabric Using Raw Silk Derived from Bombyx Mori.

概要

Purpose of this study is to develop flexible osteoconductive materials with antibacterial activity. “Raw silk fabric” was chosen as a base material so that not only the early treatment of bone defects and prevention of surgical site infections but also easy handling will be realized. Since raw silk fabric contains abundant hydrophilic amino acids, it is expected to be useful as osteoconductive materials. Hence, raw silk fabric was heated in argon gas at under 500℃ to induce antibacterial property. However, it was suggested that osteoconductivity of raw silk fabric declined by heat treatment and antibacterial activity was not sufficient for the clinical application. Thus, instead of heat treatment, I attempted to realise the goal by incorporating metallic elements into raw silk fabric because raw silk fabric has a great affinity to metallic elements. Calcium-doping can improve the osteoconductive property, and copper or zinc-doping can give antibacterial activity to raw silk fabric. From the results of the simulated body fluid soaking test, calcium-doped raw silk fabric (R-Ca) showed a possibility of osteoconduction. Besides, from the results of the antibacterial test, R-Ca, copper-doped, and zinc-doped raw silk fabric (R-Cu and R-Zn) showed strong antibacterial activity against Escherichia coli. The antibacterial mechanism of R-Ca was proposed to be due to a decrease in water activity of the culture medium. Further, the extracts of R-Ca did not show strong cytotoxicity to fibroblasts and osteoblasts, whereas R-Cu and R-Zn showed fatal cytotoxicity to fibroblasts. In conclusion, R-Ca can be a promising candidate for flexible osteoconductive materials with antibacterial activity and safety.