Light-induced osteogenic differentiation of BMSCs with graphene/TiO2 composite coating on Ti implant.

Light-induced surface potential have been demonstrated as an effective bone marrow mesenchymal stem cells (BMSCs) osteogenic differentiation regulator. However, traditional bone repair implants almost were weak or no light-responsive. Fortunately, surface modification was a feasible strategy to realize its light functionalization for bone implants. Herein, a graphene oxide (GO)/titanium dioxide (TiO2) nanodots composite coating on the surface of titanium (Ti) implant was constructed, and GO was reduced to reduced graphene oxide (rGO) with the method of UV-assisted photocatalytic reduction. After rGO deposited on the surface of TiO2, a heterojunction formed at the interface of rGO and TiO2. With visible light illumination, positive charges accumulated on the surface of rGO/TiO2 film, and performed as a positive surface potential change. The light-induced surface potential which was generated under proper light intensity is harmless to the cell adhesion and proliferation behavior, but presented a good BMSCs osteogenic differentiation promoting effect, and the activation of the voltage-gated calcium channels through surface potential and the promotion of the adsorption of osteogenic growth factors could be the reason. This work given a new insight of the modification for Ti implant with a light-induced surface potential, and shows potential application for bone regeneration on the clinical practice through light stimulation.