Agave-Derived Carbon Dots Incorporated into PVA/Chitosan Nanofibers for Prolonged Antibacterial Activity

The rise of antimicrobial-resistant pathogens, including drug-resistant Escherichia coli (E. coli), underscores the urgency of developing alternative antibacterial strategies. In this study, natural carbon dots (CDs) were synthesized from agave using a simple carbonization method and incorporated into poly-(vinyl alcohol)-chitosan (PVA/QS) nanofibrous scaffolds via electrospinning. The CDs exhibited blue fluorescence, a bandgap of 4.14 eV, and nanoscale dimensions, as confirmed by transmission electron microscopy (TEM), Raman spectroscopy, and dynamic light scattering (DLS). Fourier transform infrared (FTIR) analysis revealed surface functional groups (-OH, -NH₂, -COOH, and -CO) derived from the natural precursor. Their incorporation into the polymer matrix enhanced intermolecular interactions, resulting in uniform, porous, and hydrophilic nanofibers (NF) with improved structural stability. Scanning electron microscopy (SEM) confirmed nanofiber morphology, and field-emission transmission electron microscopy (FETEM) imaging revealed that the CDs appeared enriched toward the fiber periphery, suggesting a shell-like distribution likely driven by charge-induced migration during electrospinning. Antibacterial assays against E. coli showed a time-dependent increase in inhibition zones over 4 days, exceeding the single-day inhibition observed with gentamicin, indicating prolonged antibacterial activity. This effect is likely associated with the surface chemistry of the CDs, their interaction with bacterial membranes, and potential reactive oxygen species (ROS)-related mechanisms. Overall, the PVA/QS/CD nanofibers represent a promising biomaterial for topical antimicrobial applications, offering localized and sustained antibacterial activity while reducing reliance on conventional antibiotics.