Mg-incorporated micro/nano-topographical calcium silicate coatings with enhanced osteogenic properties and reduced inflammatory reactions

Abstract

Orthopedic implant coatings with optimized surface topography and chemistry can achieve favorable osteogenesis and inflammatory responses. In this work, to take advantage of micro/nano-topography and nutrient element Mg, atmosphere plasma spray and hydrothermal treatment were employed to fabricate two kinds of Mg-incorporated micro/nano-topographical calcium silicate coatings with 0.9 and 15.7 wt% Mg content (Mg1-CS and Mg2-CS). MgSiO3 microspheres composed of nano-flakes were formed on the CS coating surface. We investigated the effects of surface topography and released Mg ion on the protein adsorption and the behaviors of bone mesenchymal stem cells (BMSCs) and RAW264.7 macrophages. Compared with the CS coating, the Mg2-CS coating had 1.8-fold increase in specific surface area, which favored serum protein adsorption and BMSC adhesion. With higher Mg2+ release, the Mg1-CS coating exerted greater effect on enhancing fibronectin adsorption, integrin activation, and osteogenic behaviors of BMSCs. The gene expression profiles showed that the Mg-incorporated CS coatings could modulate macrophage polarization towards M2 phenotype with Mg2-CS showing greater effect. These results showed that the nanostructured Mg-containing surface can promote osteogenic responses and mitigate inflammatory reactions.