Hexafluoroisopropanol based silk fibroin coatings on AZ31 biometals with enhanced adhesion, corrosion resistance and biocompatibility

Biomacromolecule coating on biomedical magnesium alloys have generated considerable interest for the improved corrosion resistance and biocompatibility. Silk fibroin (SF) based on aqueous solvent has been demonstrated to be a promising coating for magnesium alloy, but pretreatment process is necessary due to the corrosion susceptibility to water. Herein, the SF coating with hexafluoroisopropanol(HFIP) solvent was prepared without preteatment for simplified processing and enhanced adhesion. Ethylene glycol diglycidyl ether(EGDE) was applied to stabilize the coating with more chemical crosslinking. The morphologies and nano-scratch test verify that the compactness and adhesion strength of HFIP based SF are better than that of aqueous based SF. The electrochemical evaluation and in vitro degradation in simulated body fluid indicated that the HFIP based SF coating exhibited significantly enhanced corrosion resistance. Moreover, the application of EGDE post-treatment significantly improved corrosion resistance (the corrosion current density Icoor of the SF-HFIP-EGDE samples stands at 9.93*10-10A cm-2, representing a reduction by two orders of magnitude in comparison to pure SF samples). Cytoskeleton, cell adhesion and cytotoxicity tests with MC3T3-E1 cells verifies the improved cell adhesion and biological activity of silk coating. This study provides a simple method for physical deposition of biomacromolecule coatings on magnesium alloys, while improving adhesion and corrosion resistance.