Moringa Gum-derived Polymeric Carbon Dots for Antimicrobial Activity

Abstract

The scientific community is actively developing innovative nanomaterials with broad-spectrum antimicrobial properties. In this study, moringa gum-derived polymeric carbon dots (MGCDs) were synthesized via a rapid and eco-friendly microwave irradiation technique using aqueous moringa gum as the precursor. The resulting MGCDs exhibited strong green fluorescence under UV light, with a UV-Vis absorption peak at ~290 nm and excitation-dependent fluorescence at 360 nm. They demonstrated significant antioxidant activity, achieving 87% DPPH scavenging efficiency at 0.9 mg/mL, comparable to ascorbic acid. Zeta potential analysis confirmed high colloidal stability, with values of 29 ± 0.9 mV (DI water), 30 ± 0.8 mV (SBB), 28 ± 9 mV (PBS), and 23 ± 0.8 mV (DMEM). Hydrodynamic sizes ranged from 86 ± 3 nm to 135 ± 4 nm, indicating solvent-dependent dispersion. TGA showed high thermal stability, while XRD confirmed an amorphous carbon structure with a broad peak at 22°. MGCDs demonstrated the antibacterial activity against Staphylococcus aureus and Bacillus subtilis, resulting in inhibition zones of 17.4 ± 0.8 mm and 15.2 ± 0.6 mm, respectively, at 40 mg/mL. Their multifunctionality, simple synthesis, and cost-effectiveness highlight their potential in bioimaging, antimicrobial applications, and fluorescent materials.