Characterization and evaluation of a femtosecond laser-induced osseointegration and an anti-inflammatory structure generated on a titanium alloy.

Cell-material interactions during early osseointegration of the bone-implant interface are critical and involve crosstalk between osteoblasts and osteoclasts. The surface properties of titanium implants also play a critical role in cell-material interactions. In this study, femtosecond laser treatment and sandblasting were used to alter the surface morphology, roughness and wettability of a titanium alloy. Osteoblasts and osteoclasts were then cultured on the resulting titanium alloy disks. Four disk groups were tested: a polished titanium alloy (pTi) control; a hydrophilic micro-dislocation titanium alloy (sandblasted Ti (STi)); a hydrophobic nano-mastoid Ti alloy (femtosecond laser-treated Ti (FTi)); and a hydrophilic hierarchical hybrid micro-/nanostructured Ti alloy [femtosecond laser-treated and sandblasted Ti (FSTi)]. The titanium surface treated by the femtosecond laser and sandblasting showed higher biomineralization activity and lower cytotoxicity in simulated body fluid and lactate dehydrogenase assays. Compared to the control surface, the multifunctional titanium surface induced a better cellular response in terms of proliferation, differentiation, mineralization and collagen secretion. Further investigation of macrophage polarization revealed that increased anti-inflammatory factor secretion and decreased proinflammatory factor secretion occurred in the early response of macrophages. Based on the above results, the synergistic effect of the surface properties produced an excellent cellular response at the bone-implant interface, which was mainly reflected by the promotion of early ossteointegration and macrophage polarization.