Statistical optimization of eco-friendly synthesized silver nanoparticles using Discopodium penninervium Hochst leaf extract for enhanced antimicrobial efficacy

Infectious diseases caused by pathogenic microorganisms are a significant global threat, affecting millions of people. The aim of this study was optimizing the eco-friendly synthesis of silver nanoparticles (AgNPs) using Discopodium Penninervium Hochst leaf extract via a response surface methodology approach. The ANOVA results revealed that the quadratic model (p < 0.0001) was sufficient to achieve the most precise prediction of particle size (R² = 0.995). A minimum AgNPs size of 21.65 nm, was achieved under optimal conditions. The ultraviolet-visible (UV-vis) UV-vs spectroscopy of the synthesized AgNPs revealed a strong absorption peak at 402 nm. The X-ray diffraction (XRD) analysis confirmed a face-centered cubic crystal structure with average crystallite size of 17.60 nm. Dynamic light scattering (DLS) value (38.62 nm) displays AgNPs was in the nanoscale whereas the zeta potential value (-14.20 mV) indicates its stability. The scanning electron microscopy (SEM) image showed spherical in shape and exhibited an average particle size of 2 μm with some agglomeration. Fourier transform infrared spectroscopy (FTIR) spectra depicted the presence of functional groups from plant extract, which used as a capping agent and bioreduction process. thermogravimetric analysis (TGA) measurement suggested that AgNPs exhibit good thermal stability. The AgNPs exhibited good antimicrobial activities against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria, as well as fungus (Candida albicans) with corresponding inhibition zones of 25 mm (mm), 21 mm, and 20 mm, respectively. The phytochemical screening revealed the presence of bioactive components such as phenols, alkaloids, flavonoids, tannins, steroids, and terpenoids. This study presented rapid, simple, and eco-friendly methods for synthesizing AgNPs with potential antimicrobial applications.