Self-Healable and Injectable Nanocomposite Hydrogel Loading Iron-Doped Carbon Dots for Synergistic Antibacterial Peptide-Photothermal-Photodynamic Antibacterial Therapy

The abuse of antibiotics greatly increases the risk of bacterial resistance. Therefore, it is crucial to develop an efficient nonantibiotic antibacterial treatment strategy. As a result, a self-healable and injectable nanocomposite hydrogel with synergistic antibacterial peptide-photothermal (PTT)-photodynamic (PDT) antibacterial activities was designed and fabricated. The nanocomposite hydrogel was prepared through the facile mixing of hydroxypropyl chitosan-graft-ε-poly­(l-lysine) (HPCS-g-EPL), oxidized dextran (OD), and iron-doped carbon dots (Fe-CDs) with the formation of Schiff base bond between HPCS-g-EPL and OD. With the hydrolysis of an amide bond in the hydrogel, EPL grafted onto HPCS will be released continuously. Under near-infrared irradiation for 10 min, Fe-CDs can act as photothermal therapeutic agents to generate heat (approximately 50 °C) and photodynamic therapeutic agents to rapidly catalyze the decomposition of hydrogen peroxide to produce hydroxyl radicals. After the treatment of synergistic antibacterial treatment, the antibacterial rate against Escherichia coli and Staphylococcus aureus can reach more than 99%. Therefore, the antibacterial peptide (EPL)-PTT-PDT synergistic antibacterial therapy strategy without antibiotics has broad prospects in the field of bacterial infection treatment.