Functional Titanium Substrates Synergetic Photothermal Therapy for Enhanced Antibacterial and Osteogenic Performance via Immunity Regulation.

Implant-associated infections (IAIs) significantly impair the integration between titanium (Ti) implant and bone tissues. Moreover, bacteria colonized on the surface of the implant can induce innate immune suppression of the host to resist clearance. Herein, an interfacial functionalization strategy was employed to immobilize Fe III TA nanoparticles (NPs) and acetyl bletilla striata polysaccharide (acBSP) on the Ti substrate to obtain Ti-TF-acBSP system. Under near-infrared (NIR) irradiation, Fe III TA NPs generated hyperthermal effect to directly kill bacteria. Meanwhile, the acBSP could make macrophages polarize into pro-inflammatory M1 phenotype, which enhanced the phagocytosis ability of macrophages and produced a long-term antibacterial effect. More importantly, the asBSP instructed macrophages to secrete pro-osteogenic cytokine (OSM), which promoted osteogenic differentiation of MSCs. The results of animal experiment in vivo confirmed that the Ti-TF-acBSP implant could effectively eliminate bacterial infection under NIR irradiation, enhance the expression of M1 marker (CD86), and promote the production of bone-forming related factors at the implant/bone tissue interface in a rat model. In a word, the functionalized Ti implant not only had direct bactericidal effect, but also regulate macrophage polarization as well as macrophage-mediated bactericidal and osteogenic effect. The strategy of combining photothermal therapy with immunoregulation will present a potential candidate for the development of novel antibacterial orthopedic devices. This article is protected by copyright. All rights reserved.