In Situ Growth of Tunable Gold Nanoparticles by Titania Nanotubes Templated Electrodeposition for Improving Osteogenesis through Modulating Macrophages Polarization

Driving macrophages M2 polarization has attracted growing attention for improving osteogenesis. Here, the in situ growth of tunable gold nanoparticles (AuNPs) on titania nanotubes (TiNTs) array was realized by electrodeposition, with the guidance of TiNTs. The fabricated Au layer showed excellent biocompatibility with different osteoimmune effects. Briefly, the Au deposition on 5 and 10 V anodized TiNTs surface could induce RAW264.7 cells to M2 polarization, whereas the Au deposition on 20 V anodized TiNTs surface showed M1 polarization, as indicated by various markers determination through immunofluorescence staining, qPCR, Western blot, and ELISA. Furthermore, the osteogenic differentiation of MC3T3-E1 was significantly enhanced by the macrophages conditioned medium from the Au@10VNTs surface. The in vivo tests also confirmed denser and thicker new trabecula bone formation and more M2 macrophages infiltration both on and adjacent to the Au@10VNTs implant surface. In mechanism, the cytokine array analysis of macrophages conditioned medium from the Au@10VNTs surface revealed the upregulation of pro-healing cytokines such as IL-10 and VEGF and downregulation of pro-inflammatory cytokines such as IL-1β and MCSF. In addition, the NF-κB pathway was significantly inhibited. In conclusion, the electrodeposition of a Au layer guided by TiNTs is a promising strategy for reducing postoperative inflammatory reactions and improving osseointegration through modulating macrophages polarization.