Development of Antibacterial Carbon Dots by Using a One-Pot Microwave-Assisted Approach

Abstract

Carbon dots (CDs), as emerging nanomaterials, have garnered significant attention for their exceptional properties including high biocompatibility, environmental friendliness, and versatile functionalization capabilities. These characteristics make CDs and carbon-dot-based nanomaterials promising candidates for various biomedical applications. In this study, we developed a novel microwave-assisted method to produce broad-spectrum antibacterial CDs, offering a cost-effective and green alternative to traditional synthesis. Using citric acid, ascorbic acid, tetraethylenepentamine, spermidine, and urea as carbon sources, N-doped CDs were synthesized at 200°C with 800W power, followed by purification via centrifugation and size exclusion chromatography. The resulting CDs were characterized by UV, FL, FT-IR, TEM, DLS and XRD. The agar well diffusion method and broth dilution method were employed to test and determine their activities of bacterial growth inhibition via MIC and MBC assays against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and methicillin-resistant Staphylococcus aureus (MRSA). The time-kill kinetics assays of CDs against those three strains were conducted to investigate their antibacterial effect upon time. The CDs demonstrated significant inhibition, with MIC values of 0.625mg/mL for S. aureus and MRSA, and 1.250mg/mL for E. coli. Cytotoxicity tests on HaCaT cells showed over 80% viability at concentrations below 200 mg/mL, indicating low toxicity. Our findings highlight the potential of microwave-synthesized CDs in biomedicine and pharmaceutical science, with future research to explore their antibacterial mechanisms and applications in bioimaging and photodynamic therapy.