Near-infrared light control of bone regeneration with biodegradable photothermal osteoimplant

Mild heat stimulation can promote the restoration of bone defects but unfortunately, the delivery of exo-hyperthermy into human body is not efficient enough. In this study, mild heat-induced osteogenesis with high efficacy is demonstrated on an osteoimplant composed of black phosphorus nanosheets and poly(lactic-co-glycolic acid) (BPs@PLGA) with the participation of near-infrared (NIR) light irradiation. BPs@PLGA with only 0.2 wt% BPs show the highly-efficient NIR photothermal response even when being covered by a biological tissue as thick as 7 mm. In addition, this composite is completely biodegradable and the final degradation products are harmless H2O, CO2 and PO43- which can serve as necessary bone ingredient. The BPs@PLGA specimen mediated by low intensity and periodic NIR irradiation can effectively up-regulate the expressions of heat shock proteins and finally promote osteogenesis in vitro and in vivo. Boasting good biodegradability and NIR-mediated osteogenetic performances, the BPs@PLGA implant has great potential in orthopedic applications and this study provides new insights into the design and fabrication of new-style osteoimplants which can be remotely controlled.