Enhancing biological properties of porous coatings through the incorporation of manganese

• A porous Mn-Ca-P coating was prepared on bio-inert titanium through MAO process.
• Manganese doesn't alter the coating topography, but changes the chemical property.
• Manganese within MAO coating improves cell differentiation.
• The MAO coating containing optimal manganese can be applied to biomedical materials.

Titanium (Ti) and titanium alloys are bio-inert materials ideally suited to the fabrication of dental and orthopedic implants. A number of surface modifications have been proposed to enhance the bioactivity of the titanium surface. Micro-arc oxidation (MAO) has proven to be a simple, controllable, and cost-effective process for the fabrication of porous oxide coatings. In a previous study, a porous 3D structure comprising calcium and phosphate improved the biocompatibility of titanium. Nonetheless, the biological behavior of coatings, such as differentiation, is important for successful osseointegration. Because manganese has been shown to have advantageous effects on osteoblastic cell differentiation and bone metabolism, this study investigated whether manganese-containing MAO coatings could improve the biological performances of titanium implants. EDX, ICP-OES, and XPS analysis demonstrated that manganese was successfully incorporated within the MAO coatings. TF-XRD results showed that the phases of the coatings were anatase, rutile, and titanium. SEM results demonstrated that the addition of manganese produced coatings with continuous uniformity while preserving the topography. Additionally, manganese-containing coatings induced higher bone-related gene expression than that afforded by standard MAO coatings in a culture of osteoblastic cells. This indicates that manganese could improve cell-mediated mineralization. Our findings suggest that incorporating manganese within MAO coatings leads to the formation of a porous 3D topography which is capable of improving osteoblastic cell differentiation. Thus, the proposed Mn–MAO coating shows considerable promise as a biomaterial for implants with enhanced biological properties.