Synthesis and in-vitro performance of nanostructured monticellite coating on magnesium alloy for biomedical applications

Biodegradable magnesium alloy was coated by nanostructured monticellite (Mon; CaMgSiO₄) through electrophoretic deposition (EPD) coupled with plasma electrolytic oxidation (PEO) with the purpose of enhancing the corrosion properties, bioactivity, and cytocompatibility. The monticellite layer with a thickness of 15 μm and strong adhesion with the PEO coated Mg alloy is able to provide the corrosion protection for the Mg substrate. Microstructural analysis depicted that the monticellite coatings were homogeneous with no obvious cracks or pinholes on the surface of PEO coated Mg alloy. The electrochemical tests in SBF exhibited that the corrosion rate of the Mg alloy was considerably reduced after preparation of monticellite layer on its surface. Furthermore, high impedance of the monticellite coated Mg alloy was observed even after 96 h of incubation in SBF. The apatite layer with spherical morphology was formed on the monticellite surface via interaction of OH⁻ ions from SBF which could accelerate the healing process. The biocompatibility was evaluated via examination of the osteoblastic MG-63 cells response in-vitro. Deposition of nanostructured monticellite induces high osteoblastic proliferation and supplies suitable sites for cell attachment and growth. The cell adhesion and viability are also determined to evaluate the biological response. Moreover, biphasic drug release graphs of the monticellite coating containing tetracycline show an initial immediate release which is followed by more stable release patterns. Overall, it is anticipated that the novel proposed nanostructured coatings of monticellite can improve the corrosion resistance and cytocompatability of the Mg alloys, which make it useful for orthopedic implants.