Enhanced corrosion resistance and biocompatibility of an elastic poly (butyleneadipate-co-terephthalate) composite coating for AZ31 magnesium alloy vascular stents

Surface modification has been considered to provide an effective solution to the poor corrosion resistance of magnesium alloys. A large number of relevant studies have demonstrated that various protective coatings can reduce the degradation rate of magnesium alloys, but most of them are for magnesium alloy materials and devices without deformation. For biodegradable magnesium alloy stents, the selection of protective coating is vitally important due to the residual stress during implantation and cyclic loading after implantation. Therefore, compared with commonly used poly-D,(L)-lactide (PDLLA), a reliable protection was proposed on HF-treated Mg alloy via application of poly(butyleneadipate-co-terephthalate) (PBAT) with high elongation at break in this paper. In the long term, the corrosion resistance of PBAT-F coating of both flake samples and stents was decisively superior to PDLLA, which could be attributed to its outstanding barrier performance and mechanical properties. Simultaneously, PBAT composite coating exhibited better hemocompatibility and higher cell proliferation rates. The above results show that PBAT is an excellent coating material for vascular stents whereas PBAT composite coating could be a promising candidate as a protective coating for Mg stents.