Si–C covalent bonding-mediated interfacial charge transfer enhances photodynamic antitumor effects of selective laser sintered bone scaffolds

Nitrogen-doped carbon dots (NCDs) show promising potential in photodynamic antitumor applications due to their appropriate band gap and photo-responsiveness. Nevertheless, their therapeutic efficacy is limited by both a low reactive oxygen species (ROS) quantum yield and their propensity for aggregation. Herein, NCDs were encapsulated within mesoporous silica nanoparticles (MSNs) to fabricate an effective photosensitizer (NCDs@MSN) via a one-pot hydrothermal method. The covalent Si–C bonds formed between NCDs and MSNs enhanced interfacial charge transfer, thereby substantially amplifying the generation of ROS under hypoxic conditions. Meanwhile, the mesoporous structure of MSNs prevented NCD aggregation and provided a larger accessible surface area with more exposed active sites. Electron spin resonance spectroscopy confirmed the light-triggered generation of ROS, validating its potent ROS generation capacity under hypoxia. Subsequently, NCDs@ MSN were incorporated into poly-L-lactic acid to fabricate a composite scaffold via selective laser sintering, which was designed for postoperative photodynamic management of tumorous bone defects. The resulting scaffold exhibited potent photodynamic cytotoxicity against tumor cells alongside excellent biocompatibility. This work presents a potential strategy for engineering intelligent implants to prevent postoperative tumor recurrence.