In vitro degradation and cytocompatibility of a silane/Mg(OH)2 composite coating on AZ31 alloy by spin coating

A new organic-inorganic composite coating was generated on AZ31 alloy surface with sol-gel method to improve the anti-corrosion performance and biocompatibility of AZ31 alloy in the physiological environment. The results of electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, pH variations in modified-simulated body fluid (m-SBF) demonstrated that the silane/Mg(OH)2 composite coating significantly enhanced the anti-corrosion ability and slowed down the degradation of AZ31 alloy under in vitro condition. Fourier-transform infrared spectroscopy (FTIR) showed that the major composition of in-situ formation layer was Mg(OH)2. The surface morphology, chemical and phase constitutions of the composite coating were detected using scanning electron microscopy (SEM). The results demonstrated that the composite coating was uniform and defect-free. X-ray diffraction analysis (XRD) was also employed to characterize the corrosion products of all specimens immersed in m-SBF after 30 days. MTT and ALP tests indicated that the composite coating greatly enhanced the cell proliferation and osteogenic differentiation of osteoblasts on the AZ31 alloy surface.