Characterization and in vitro antibacterial activity of silver nanoparticles biosynthesized using phytophthora infestans biomass

Abstract This study investigated the synthesis and characterization of biogenic silver nanoparticles (AgNPs) using biomass from Phytophthora infestans as a reducing and stabilizing agent. Fungal isolates from tomato, eggplant, pepper, and tobacco plants were purified and maintained on potato dextrose agar (PDA). Biomass was filtered and washed with Milli-Q deionized water, followed by the combination of 50 mL of 10 mM AgNO 3 solution with 50 mL of cell filtrate in a 250 mL Erlenmeyer flask. Characterization techniques, including UV‒Vis, PL, FTIR, BET, SEM, and XRD, were employed. UV‒Vis spectroscopy revealed a peak at a wavelength of 441.883 nm with an absorbance of 0.823 a.u. The Tauc plot indicated a direct bandgap of 2.038 eV, reflecting enhanced optical properties. SEM analysis revealed a heterogeneous distribution of spherical and sheet-like AgNPs with an average diameter of 42.05± $$\:0.05$$ nm. XRD confirmed a face-centered cubic structure, with the crystalline size decreasing from 12.03 nm (nonagitation) to 10.71 nm (agitation). Antibiotic assays demonstrated a dose-dependent response, with significant efficacy at 40 and 60 $$\:\mu\:g/ml$$ , while minimal activity was observed at 10 $$\:\mu\:g/ml$$ . These results highlight the potential of Phytophthora infestans biomass for biosynthesizing AgNPs with notable antibacterial properties.