Osteogenic activity and angiogenesis of a SrTiO₃ nano-gridding structure on titanium surface

Osteogenesis and angiogenesis have been considered to be the most direct and necessary requirements for Ti-based implants used in bone regeneration. In this study, an alveolate double-layered SrTiO₃ nano-gridding (NG-Sr) was obtained using two steps of anodization followed by a hydrothermal process. Different Sr gradient contents (NG-Sr0.02, NG-Sr0.04, NG-Sr0.08, NG-Sr0.12 and NG-Sr0.16) were generated by altering the precursor solution concentrations. The in vitro studies indicated that NG-Sr samples with nanoscale topography and long-lasting Sr release could enhance the biofunction of both osteoblast-like cells (MC3T3-E1 cells) and human umbilical vein endothelial cells (HUVECs) to varying degrees. The NG-Sr0.08 was the optimal substrate for MC3T3-E1 cell growth, while the NG-Sr0.04 was the best choice for HUVEC growth. In vivo X-ray analysis and histological observations demonstrated that the NG-Sr0.08 samples had notable osteogenesis and angiogenesis, as significant new bone formation and fresh blood vessels were observed. Hence, the nanoscale topography with sufficient Sr supplementation offers a new independent regulator of two types of cell growth, which should be considered in biomaterial design for regenerative medicine.