Synthesis and characterization of silver nanoparticles using Sphaerophysa kotschyana fruit and the assessment of their antioxidant activity

Nanoparticles have attracted great interest recently due to their application in many fields. In this study, an eco-friendly, scalable, cost-effective method was used for the synthesis of silver nanoparticles (s-AgNPs) using the fruit extract of Sphaerophysa kotschyana as a reducing agent, and their structure was elucidated by extensive spectroscopic techniques. The color change from yellow to dark brown indicated the formation of s-AgNPs. In the UV-Vis spectrum, the maximum absorption was observed at 437 nm. Fourier transform infrared (FTIR) spectroscopy displayed the functional group of the natural compounds in the extract that capped and stabilized the s-AgNPs. The characteristic hydroxyl vibrational signal appeared at 3168 cm–1. The X-ray diffraction (XRD) pattern indicated that the s-AgNPs were face-centered cubic crystalline structures. Scanning electron microscopy (SEM) exhibited the spherical-shaped nanoparticles with an average size of 67.37 nm. The antioxidant activity of the extract and s-AgNPs was established using the DPPH, ABTS, and FRAP assays. In the DPPH test, the effect of s-AgNPs was observed to be significantly higher than that of the extract, and the activity of s-AgNPs in the FRAP test was also reported to be higher than the extract. In the ABTS assay, the s-AgNPs displayed outstanding activity, which was even better than the standards. Consequently, s-AgNPs synthesized from S. kotschyana are promising drug products for diseases caused by oxidative stress.