Carboxymethyl chitosan functionalization of CPED-treated magnesium alloy via polydopamine as intermediate layer

To improve the corrosion resistance and cytocompatibility of magnesium alloy (Mg alloy), an anticorrosive and bioactive composite coating was triumphantly prepared on Mg alloy surface. First, Mg alloy substrates were treated by cathodic plasma electrolytic deposition (CPED). Then, bioactive carboxymethyl chitosan (CMCS) was covalently immobilized on CPED-treated Mg alloy via polydopamine as intermediate layer. X-ray photoelectron spectroscopy and scanning electronic microscopy were employed to detect the change of chemical composition and surface morphology of Mg alloy substrate at various stages of surface modification. Results of water contact angle measurement showed that the hydrophilicity of the surface has improved significantly after surface modification. Potentiodynamic polarization data and hydrogen evolution test demonstrated that corrosion resistance of modified Mg alloy significantly increased compared with that of pristine sample. Cytotoxicity test and cell morphology analysis confirmed that adhesion and proliferation of osteoblasts on CMCS-modified Mg alloy surface were improved remarkably. The approach presented here would be attractive for surface modification of biomaterials.