Siqi Wang, Colin P. McCoy, Gavin P. Andrews, Matthew Wylie, Yi Ge
Carbon dots (CDs) are emerging nanomaterials, attracting increasing attention due to their exceptional properties, such as good biocompatibility, environmental friendliness, versatile functionalization capabilities, and cost-effectiveness. These attributes position CDs and CD-based nanomaterials as promising candidates for various biomedical applications. This study focuses on the development of functional CD-based nanomaterials conjugated with a photosensitizer Chlorin E6 to enhance bacterial inhibition. By employing a novel microwave-assisted approach, we successfully fabricated N-doped CDs from diverse carbon sources various carbon sources (e.g. citric acid, ascorbic acid, tetraethylenepentamine (TEPA), spermidine and urea). Characterized through various analytical techniques including UV, fluorescence, FT-IR, TEM, DLS, and XRD, the resulting CDs demonstrated broad-spectrum antibacterial activities against E. coli, S. aureus, and MRSA. Remarkably, upon conjugation with Chlorin E6, these functional nanomaterials exhibited significantly enhanced antimicrobial efficacy under light exposure. At a concentration of merely 10 μg/mL, the conjugated CDs completely eradicated S. aureus and showed a substantial increase in inhibitory action against E. coli. Cytotoxicity assays on HaCaT cells indicated low toxicity, with cell viability above 80% for concentrations below 200 mg/mL. Our findings have revealed the great potential of these microwave-synthesized and photosensitizer-conjugated CDs in biomedicine, highlighting their applicability in photodynamic therapy and bioimaging. The profound antibacterial activity under light exposure opens new avenues for developing more efficient and cost-effective antimicrobial nanomaterials.
