Strengthened corrosion control of biodegradable poly(trimethylene carbonate) coating on bioabsorbable Mg alloy by introducing graphene oxide

Abstract

Corrosion control of bioabsorbable Mg alloy stents is an attractive topic in recent years. Biodegradable polymer modification is a potential anti-corrosion method, but cannot achieve the desired corrosion protection due to the high water permeability of biodegradable polymers. In this study, a strengthened corrosion control strategy is proposed: Graphene oxide (GO) was introduced into a poly(trimethylene carbonate) (PTMC) coating to improve its anti-corrosion performance. GO/PTMC composite coatings with different GO contents were applied to AZ31b Mg alloy surfaces, and the effect of GO content (0, 0.2, 1, 3, 6, and 10 wt%) on surface characteristics, corrosion resistance, and in vitro biosafety was investigated. The results showed that the increase of GO content in the PTMC coating (<6 wt%) could improve its corrosion resistance by prolonging the permeation path of solution. Meanwhile, the addition of GO (<6 wt%) had little negative effects on cytocompatibility and hemocompatibility. However, when the addition of GO exceeded 6 wt%, GO aggregated on the coating surface, resulting in the formation of new defects and a rapid decrease in corrosion resistance. The optimized sample (GO content: 6 wt%) had the highest impedance modulus of 8.9 × 107 Ω·cm2 at 0.1 Hz and good in vitro biocompatibility, which shows great potential for application in vascular stents.