Green synthesis of silver nanoparticles from Catunaregam tomentosa extract

Silver nanoparticles (AgNPs) have been widely used in many fields (e.g., sensors, medical supplies, food, cosmetics, medicines, etc.) due to their unique properties such as optical property, antibacterial property, and high conductivity. AgNPs are normally synthesized by chemical, physical, or biological methods. Among these methods, biological synthesis or green synthesis of AgNPs has drawn much attention since it is an easy and environmental-friendly method. Herein, AgNPs synthesized using Catunaregam tomentosa extracts were studied. The extracts obtained from different C. tomentosa fruit were found to be blue, green, and brown. It was found from the foam test and IR spectra that all extracts (blue, green, and brown extracts) contained saponins. According to the DPPH assay, the blue and the green extracts had the antioxidant activities of 84.47 +/- 12.13 and 47.66 +/- 2.86 mg ascorbic acid equivalent/g of C. tomentosa powder, respectively. This showed that the blue and the green extracts could act as reducing agents in AgNPs synthesis. The successfully synthesized AgNPs using C. tomentosa extracts showed the surface plasmon resonance peak at 400 nm corresponding to literatures. The particle sizes and zeta potential values measured by dynamic light scattering also indicated the size stability of the synthesized AgNPs during seven-day period with no significant difference (P > 0.05).