Carbon dots nanoparticles derived from showy Asian grapes ( <i>Medinilla speciosa</i> ) for free radical scavenger

Carbon dot nanoparticles (CNPs) were synthesized from the peels of showy Asian grapes (Medinilla speciosa) using microwave irradiation for free radical scavenging. The optimal emission and absorption intensities were achieved with a 50-min irradiation duration, at wavelengths of 430 nm and 267 nm, respectively. XRD analysis revealed characteristic peaks at angles of 26.37° and 29.63°. FTIR analysis indicated that antioxidant potential is attributed to hydroxyl and carboxyl groups on the CNPs’ surface. TEM images showed diameters ranging from 2 nm to 8 nm. The CNPs exhibited 73.82% antioxidant activity at 5 mg/mL, with an IC 50 value of 6.89 ppm, indicating strong antioxidant activity. Additionally, the CNPs demonstrated good storage stability, suggesting potential applications in food supplements and biomedical materials.