A Sustainable Strategy for Preparing Fluorescent and Antibacterial CDs from Traditional Herb Solanum Lyratum

Carbon dots (CDs) have emerged as a promising class of nanomaterials owing to their remarkable fluorescence, excellent water solubility, and low cytotoxicity. In this study, phosphorus doped CDs were synthesized via a simple, green, one-step hydrothermal method using Solanum lyratum, a traditional Chinese medicinal herb, as a carbon source and phosphoric acid as a dopant. The resulting CDs exhibited uniform spherical morphology with an average particle size of 3.46 nm, as revealed by TEM. FTIR and XPS analyses confirmed the presence of multiple surface functional groups including C–N, C=O, N=N, and P–O, indicating successful heteroatom doping. The CDs showed excitation-dependent photoluminescence and good aqueous dispersibility. Antibacterial evaluation demonstrated that the CDs effectively inhibited the growth of Escherichia coli and Staphylococcus aureus, with minimum inhibitory concentrations of 0.0115 mg/mL and 0.010 mg/mL, respectively. These results highlight the potential of Solanum lyratum-derived CDs as a novel, eco-friendly antimicrobial nanomaterial from medicinal plants.