Multifunctional carbon dots from Polygonatum kingianum and Gastrodia elata: synthesis, characterization, and biomedical applications

Carbon dots (CDs) derived from Polygonatum kingianum (Pk-CDs) and Gastrodia elata (Ge-CDs) were synthesized via a one-step hydrothermal method and characterized using TEM, XPS, and FTIR. Pk-CDs and Ge-CDs exhibited uniform spherical morphologies (6.2 ± 0.3 nm and 6.8 ± 0.4 nm, respectively) and excitation-dependent fluorescence. Antibacterial assays demonstrated potent inhibition against Gram-positive (S. aureus, B. cereus) and Gram-negative bacteria (E. coli, P. aeruginosa). In vitro antioxidant assays demonstrated that Pk-CDs outperformed Ge-CDs in DPPH radical and superoxide anion scavenging, with IC50 values of 2.994 mg mL−1 and 0.30 mg mL−1, respectively. In vivo studies in a D-galactose-induced oxidative stress model confirmed significant improvements in SOD, GSH-Px, and MDA levels. These findings highlight the multifunctional properties of Pk-CDs and Ge-CDs, and underscore their potential as natural product-derived nanomaterials for biomedical applications, particularly as antibacterial and antioxidant agents.