Corrosion resistance of Ca-P coating induced by layer-by-layer assembled polyvinylpyrrolidone/DNA multilayer on magnesium AZ31 alloy

A hydrothermal deposition method was utilized to fabricate Ca-P composite coating induced by the layer-by-layer (LbL) assembled polyvinylpyrrolidone/deoxyribonucleic acid (PVP/DNA)20 multilayer on AZ31 alloy. The surface morphology and compositions were characterized by SEM, EDS, FTIR and XRD. Besides, the corrosion resistance and degradation behavior of the coating were tested via electrochemical polarization, impedance spectroscopy and immersion measurements. Results show that the main components of Ca-P coatings are hydroxyapatite, Ca3(PO4)2 and Mg3(PO4)2·nH2O. The LbL-assembled DNA and PVP promote the adsorption of Ca-P deposits on the sample surface, and structures and functional groups of the polyelectrolyte in the outermost layer are the primary influencing factor for the induction of the Ca-P coating. Carboxyl groups have the best biomineralization effect among all related functional groups. The enhanced corrosion resistance and adhesion highlight a promising use of (PVP/DNA)20-induced Ca-P coatings in the field of biomedical magnesium alloys.