Cu-doping site regulation in carbon dots for concurrent cuproptosis-like death anti-bacteria and osteogenesis of infected bone defects

Infected bone defect repair suffers frequently from the insufficient bone differentiation activity and the stubborn biofilm formation resulting from bacterial infections. In addition, the incorporation of non-biocompatible antibiotics into scaffolds may not only induce the proliferation of multidrug-resistant bacteria but also hinders the repair of the bone defects. Herein, we present, for the first time, a Cu-doping site regulation strategy in carbon dots (CDs) to boost both antibacterial and osteogenic activities for the repair of infected bone defects. The balanced osteogenic and antibacterial activity enhancements have been achieved by regulating the Cu doping sites: those in the plane rather than at the edge of CDs have endowed the doped CDs with excellent antibacterial activity through a ROS production-mediated cuproptosis-like death mechanism. In contrast, the edge-doped Cu species was found to present a Cu-crosslinked CD assembly (Cu⁺@CD), resulting in only antibacterial activity without osteogenic activity. Significantly, transcriptome sequencing analysis reveals Cu-CD-mediated cuproptosis-like death of bacteria by impairing tricarboxylic acid cycle and damaging cell membranes, leading to the further enhancement of antibacterial and antibiofilm activities. Finally, the injectable Cu-CD-incorporated GelMA hydrogels achieve complete healing of infected bone defects after implanting for two months through the negative-charge-facilitated osteogenic differentiation and cuproptosis-like antibacterial effect by ROS production. Overall, this work presents a novel perspective on the Cu doping site regulation in CDs for concurrent antibacterial and osteogenic activities in the repair of infected bone defects.