Development of a novel biomimetic micro/nano-hierarchical interface for enhancement of osseointegration

Surface modification of biomedical materials plays a significant role in enhancing in vivo osseointegration. In the present study, a biomimetic hierarchical titanium implant with micro-and nano-pores (Micro/Nano-Ti) was developed utilizing spark plasma sintering combined with electrochemical anodization. The surface morphology, phase composition, and wettability were characterized through scanning electron microscopy (SEM) and atomic force microscopy (AFM), X-ray diffraction (XRD), and contact angle (CA) measurement, respectively. Bone marrow cells were cultured, and the in vitro cell-material interactions were evaluated according to cell adhesion (SEM), cell viability (MTT), cell differentiation (ALP activity), mineralization (calcium deposition), focal protein adhesion (CLSM), and osteogenic factor expression (qRT-PCR). Additionally, the in vivo osseointegration properties were assessed by employing a tibia implantation rat model with subsequent histological analysis, micro-computed tomography, and biomechanical tests. The results showed that, in comparison with the untreated, Micro-Ti, and Nano-Ti implants, the Micro/Nano-Ti implant featured a hydrophilic surface (CA = 21 +/- 2.1 degrees) due to the presence of micro-pores (diameter: 30-100 mm) and nano-pores (diameter: 50-120 nm). Furthermore, the Micro/Nano-Ti implant greatly enhanced the in vitro cell-material interactions in terms of cell adhesion, viability, differentiation, mineralization, focal protein adhesion, and osteogenic factor expression, and accelerated osseointegration in vivo. The biomimetic hierarchical micro/nano-structure may represent an effective surface modification for potential application in the field of endosseous implants.