Carbon dots derived from dopamine for potent photodynamic bactericidal and antibiofilm application with biocompatibility and low bacterial resistance

Given the ongoing proliferation of bacterial resistance, particularly the rise of “superbugs”, it is imperative to create novel, effective, non-toxic, and non-resistant antibacterial materials and technologies for use in medical settings. Carbon dots derived from dopamine hydrochloride and citric acid (DA-CDs) were effectively produced through a two-step method, displaying photodynamic therapy (PDT) characteristics with low-drug resistance. Only a concentration of 0.125 μg mL⁻¹ of DA-CDs can effectively break down established S. aureus biofilms when exposed to blue light (450–500 nm), resulting in a biofilm destruction rate of 96.2 %. And after 28 passages, the sensitivity of S. aureus and E. coli to DA-CDs when irradiated with blue light stays the same. The ultra-high negative zeta potential of DA-CDs (-35 mV) and excess intracellular reactive oxygen species (ROS) induced by DA-CDs accounted for their antibacterial and antibiofilm effects. Furthermore, DA-CDs exhibit outstanding biocompatibility without causing harm to red blood cells (RBCs), 3T3 Cells, bone marrow mesenchymal stem cells (BMSCs) and human umbilical vein endothelial cells (HUVECs). The DA-CDs from this study can effectively kill harmful bacteria and destroy established biofilms using PDT, providing a new alternative to antibiotics and a valuable tool for exploring new treatments for biofilm-related infections.