Aqueous Cymbopogon citratus Extract Mediated Silver Nanoparticles: Part I. Influence of Synthesis Parameters, Characterization, and Biomedical Studies

This study explores the green synthesis of silver nanoparticles (AgNPs) using <i>Cymbopogon citratus</i> (lemongrass) extract as a reducing agent. Synthesis was confirmed by a color change (light yellow to dark brown) under optimal conditions: 1.50 mM silver nitrate, 3.5% <i>v</i>/<i>v</i> extract, at 100 °C, with a pH of 9, and for 60 min. The AgNPs exhibited spherical morphology, a hydrodynamic diameter of 135.41 ± 49.30 nm, a zeta potential of -29.9 ± 1.4 mV, crystalline structure, and minimal aggregation. AgNPs showed significant antibacterial activity, particularly at >20 µg/well, with the zones of inhibition varying by bacterial strain. In vitro studies demonstrated anti-inflammatory, antidiabetic (α-glucosidase and α-amylase inhibition), and antioxidant activities, with AgNPs outperforming plant extract and nearing standard efficacy at higher concentrations. Cyto-toxicity studies indicated that AgNPs and plant extract were less toxic than doxorubicin but exhibited concentration-dependent effects on cancerous and non-cancerous cells. Eco-toxicity assays revealed that AgNPs were less acutely toxic than controls but posed risks with prolonged exposure. This work highlights the eco-friendly synthesis of AgNPs and their potential in biomedical applications, demonstrating efficacy in antibacterial and antioxidant activities.