Fabrication and biological assessment of halloysite-doped micro/nano structures on titanium surface

Titanium (Ti) is widely used as a biomaterial for dental implants, but its insufficient angiogenic and osteogenic properties prolong the restoration period. In this study, halloysite nanotubes (HNTs) were embedded on the surface of Ti via micro arc oxidation (MAO) treatment to enhance its early osseointegration. The surface phys-iochemical properties were examined, and the results confirmed that HNTs were successfully incorporated into the MAO coating. It was also discovered that the surface wettability and negative charge of the corresponding samples increased. In cytocompatibility tests involving human umbilical vein endothelial cells (HUVECs) and MC3T3-E1 cells, the HNT group exhibited no cytotoxicity compared with the MAO group and the best perfor-mance for cell adhesion and spreading among the three groups (Ti, MAO and HNT). Regarding angiogenesis, the HNT group outperformed the Ti and MAO groups in cell migration, tube formation, and angiogenic gene expression of HUVECs. Furthermore, with regard to osteogenesis, the HNT group exhibited the highest levels of alkaline phosphatase activity, collagen secretion, mineralized calcium nodules, and osteogenic gene expression of MC3T3-E1 cells among the three groups with significant differences. These findings indicated that the HNT specimens could significantly promote angiogenesis as well as osteogenesis at both the cellular and molecular levels.