Catalytic reduction, antibacterial, and antioxidant activities of green synthesized silver nanoparticles using Coccinea grandies (L) Voigt leaf extract

In this study, silver nanoparticles (AgNPs) were synthesized using the aqueous extract of Coccinia grandis (L) Voigt leaf (CGL) extract using microwave irradiation method and the structure was elucidated by various techniques such as UV–Visible spectroscopy, Fourier transformation infrared spectroscopy (FT-IR), x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive x-ray spectroscopy (EDX), and high-resolution transmission electron microscopy (HR-TEM). The UV–visible spectroscopy confirmed the formation of AgNPs and SPR band appear at 420 nm. FT-IR analysis indicated the presence of –OH and –NH functional groups from secondary molecules of CGL capping the AgNPs surface. HR-TEM revealed spherical aggregates with an average size of 29.4 nm. EDX confirmed the presence of elemental silver. XRD analysis showed that the AgNPs had a face-cantered cubic (FCC) crystal structure. The CGL-AgNPs were used as a heterogeneous catalyst to reduce RhB and CR dyes from aqueous solutions in the presence of sodium borohydride (NaBH₄). The results showed that greater than 95 % of catalytic reduction can be accomplished within 9 min. The biosynthesized AgNPs demonstrated notable antioxidant activity (82.89 % in the DPPH assay) and antibacterial activity with a Zone of inhibition ranging from 9 to 11 mm. These findings suggest that CGL can be used to synthesize new, cost-effective AgNPs using an environmentally friendly approach.