A near-infrared light-triggered platform for on-demand drug release in bone repair

Three-dimensional (3D) of multifunctional bone scaffolds is currently a major research hotspot in the field of bone repair. Nevertheless, achieving on-demand modulation of scaffold performance remains a significant and unresolved challenge. In this study, the photothermal agent indocyanine green (ICG) was loaded into ZIF-8 and co-encapsulated with the osteogenic drug total flavonoids of Drynaria (TF) in thermosensitive PLGA microspheres to construct a NIR-triggered on-demand release module TF/ICG/ZIF-8@PLGA (TZP). This module was further integrated into a PLGA/β-TCP scaffold to develop a multifunctional biomimetic scaffold (TZP/PT).The system exhibited a dual-mode release behavior, showing sustained release over 28 days under non-NIR conditions and significantly accelerated release upon NIR irradiation, demonstrating an "on-off" switchable drug delivery profile. Biological evaluation demonstrated good biocompatibility, high antibacterial activity with a bacterial inhibition rate of 99%, and the formation of mineralized hydroxyapatite layers within 7 days, which can be attributed to combined osteogenic drug delivery and NIR-triggered photothermal (PTT) and photodynamic (PDT)-related effects.