Immunomodulation and osteointegration of infected implants by ion-riched and hierarchical porous TiO2 matrix

Infection is a main cause of implant failure. The microenvironment cell experiencing after antimicrobial therapy of infected implants is very crucial for immunomodulation and subsequent osteointegration. Based on the superiority of photothermal therapy in anti-infection, a matrix of nanograined TiO2 with (Si/P)-dual ions and hierarchical nano/microporous topography is developed on Ti implant by micro-arc oxidation. It shows good photothermal properties due to the lattice distortion induced by ion doping and can kill bacteria with near-infrared (NIR) light irradiation efficiently. Due to the combined action of porous topography and release of Si/P ions, the TiO2 matrix achieves M1 -to -M2 phenotype switch of macrophages timely at different simulating infection stage and accelerates recruitment, proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in vitro. In vivo, the TiO2 matrix also shows desired antibacterial performance after photothermal therapy and exhibits outstanding immunomodulatory ability and new bone formation efficiency. This study provides a promising TiO2 matrix applied in clinic for settling implant infection by NIR light irradiation and promoting bone regeneration through osteoimmunomodulation.

Automated summary

This study developed a TiO2 matrix with excellent photothermal properties and antibacterial performance, which can promote the phenotype switch of macrophages and the proliferation and differentiation of bone marrow mesenchymal stem cells. In vitro and in vivo experiments demonstrated the outstanding immunomodulatory and bone regeneration ability of this TiO2 matrix.