The effects of the combined use of carbon quantum dots and antibacterial agents on pathogenic bacteria

This study evaluates the challenges associated with overcoming antimicrobial resistance and innovative approaches to combat multidrug-resistant (MDR) bacterial infections.

Novel codoped carbon quantum dots (CCQDs) were synthesized using citric acid as the carbon source and L-cysteine as the nitrogen codoping atom. The formulation in which citric acid was retained was designated as CCQDs-1, whereas the purified version, from which citric acid was removed, was termed CCQDs-2. The antibacterial properties of CCQDs-1 and CCQDs-2 were compared using the agar well diffusion method. This study comprehensively characterizes these nanomaterials and evaluates their antibacterial potential, both alone and in combination with antibiotics, against a spectrum of gram-positive (G+) and gram-negative (G-) bacterial strains.

The study demonstrates the significant antibacterial efficacy of CCQDs, with notable variations observed between citric acid-containing and citric acid-neutralized formulations. The QDs exhibited remarkable characteristics, including a quantum yield of 90.3%-90.6%, intense fluorescence, and distinctive interactions with various antibiotics. In addition to their intrinsic antibacterial activity, the QDs also exhibited synergistic effects when combined with certain antibiotics. A synergistic effect was particularly observed when CCQDs-2 were combined with antibiotics such as gentamicin, levofloxacin, and clindamycin, suggesting potential mechanisms such as membrane permeability disruption and efflux pump saturation.

These findings underscore the promising potential of carbon-based QDs as innovative, biocompatible solutions to address the critical global challenge of antimicrobial resistance.