Fig. 1: The molecular design of OsteoSAVE-BGD nanoparticles for selective and targeted therapeutic systems.

a By intravenous injection, the bone-targeted OsteoSAVE-BGD nanoparticles are recruited to the bone surface and passively target OCs. When the nanoparticles are phagocytosed by OCs, CTSK in lysosomes triggers their conversion into nanofibers, inducing OCs apoptosis and producing ABs rich in PDGF-BB. These ABs can activate the PI3K/AKT signaling pathway in BMSCs to promote their osteogenic differentiation, ultimately achieving the goal of restoring bone homeostasis in vivo. b The structure of the nanoparticle with bone targeting and CTSK responsiveness.