Corrosion resistance of bioinspired DNA-induced Ca–P coating on biodegradable magnesium alloy

Bioinspired coatings with decreased corrosion rate and enhanced bond strength are at the core of future clinic applications on degradable magnesium (Mg)-based implants. The hybrid of organic and inorganic compounds offers a strategy to fabricate biodegradable, biocompatible and compact coatings on biomedical Mg alloys. Hereby, a comparison with and without DNA addition was made on the corrosion resistance and adhesion strength of CaP coatings fabricated on AZ31 alloy via hydrothermal deposition. The morphology, chemical composition, and crystallographic structure of the coatings were investigated by means of SEM, EDS and FTIR as well as XRD before and after corrosion tests. Corrosion resistance was evaluated via potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and hydrogen evolution tests in Hank's solution. Results show that the coatings are mainly characterized by tricalcium phosphate (TCP), dicalcium phosphate anhydrous (DCPA) and calcium-deficient hydroxyapatite (CDHA). The presence of DNA leads to the formation of CaP coating with improved corrosion resistance and adhesion strength. Additionally, the formation mechanism for DNA-induced CaP coating is proposed. The DNA-induced CaP coating exhibits a promising future for controlling the corrosion rate of biodegradable Mg alloys.