Tannic acid-assisted deposition of silk sericin on the titanium surfaces for antifouling application

Silk sericin (SS), a by-product in the field of sericulture, is degummed from raw silk and mostly discarded in silk processing wastewater, causing water pollution. However, it could be interesting to explore the possible utilization of hydrophilic SS as a value-added product in the antifouling application. In this work, natural tannic acid (TA) and SS were conjugated via hydrogen bonding interactions, and the resulting TA/SS conjugates were deposited on the titanium (Ti) surfaces through surface adhesive trihydroxyphenyl groups in TA. The current coating strategy avoids the usage of toxic reagents and reactants and represents an eco-friendly way to fabricate antifouling coatings. The successful co-deposition of TA and SS on the Ti surfaces were confirmed by the static contact angle, X-ray photoelectron spectroscopy (XPS), and surface zeta potential measurements. The TA/SS codeposited Ti (Ti-TA/SS) surfaces show good protein repellent as well as platelet and bacterial anti-adhesive properties. In addition, the Ti-TA/SS surfaces exhibit low cytotoxicity towards L929 mouse fibroblast cells.