Double-layer calcium phosphate sandwiched siloxane composite coating to enhance corrosion resistance and biocompatibility of magnesium alloys for bone tissue engineering

Abstract

As a potential new metal biomaterial implant, the problem of fast degradation of magnesium (Mg) alloy and the resulting hydrogen release and local alkalinization need to be solved urgently. To this end, a double-layer dicalcium phosphate dihydrate (DCPD) sandwiched siloxane composite coating was prepared on Mg alloy via chemical conversion, immersion treatment and biomimetic deposition methods. The morphologies and compositions of the samples were systematically analyzed, and the corrosion resistance, as well as the biocompatibility, was specifically explored. The electrochemical test result evidenced that the corrosion current density of the composite coated sample was 3.0 × 10−8 A/cm2, which was much smaller than that of Mg alloy (1.4 × 10−5 A/cm2). The immersion experiment showed that the coating provided continuous protection to the sample. The hydrogen evolution of the optimal coating was only 1/9 of that of Mg alloy, and the coated sample had good biomineralization ability. The coated samples also showed good biocompatibility in cell experiments (cell viability ≥116.5 %). This study proposes a novel idea for the construction of surface coatings of biomedical Mg alloys for bone tissue engineering.