In vitro study of nanostructured diopside coating on Mg alloy orthopedic implants

•The diopside coating was applied on Mg alloy using the combined MAO and EPD methods.•The corrosion resistance of the diopside coated Mg alloy was noticeably improved.•The in vitro bioactivity of the diopside coated Mg alloy was considerably increased.•The mechanical stability of biodegradable Mg alloy was enhanced by diopside coating.•The cytocompatibility of the Mg alloy was improved employing diopside coating.

The high corrosion rate of Mg alloys has hindered their application in various areas, particularly for orthopedic applications. In order to decrease the corrosion rate and to improve the bioactivity, mechanical stability and cytocompatibility of the Mg alloy, nanostructured diopside (CaMgSi2O6) has been coated on AZ91 Mg alloy using a combined micro arc oxidation (MAO) and electrophoretic deposition (EPD) method. The crystalline structure, the morphology and the composition of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical corrosion test, immersion test, and compression test were used to evaluate the corrosion resistance, the in vitro bioactivity and the mechanical stability of the samples, respectively. The cytocompatibility of the samples was tested by the cell viability and the cell attachment of L-929 cells. The results confirmed that the diopside coating not only slows down the corrosion rate, but also enhances the in vitro bioactivity, mechanical stability and cytocompatibility of AZ91 Mg alloy. Therefore, Mg alloy coated with nanostructured diopside offers a promising approach for biodegradable bone implants.