Green Synthesis of Silver Nanoparticles via the Aqueous Extracts of Prunus africana and their Antimicrobial Activities

The alarming effect of antibiotic resistance prompted the search for alternative medicines to resolve the microbial resistance conflict. Over the last two decades, scientists have become increasingly interested in the new dimensions of metallic nanoparticles. Prunus africana is a traditional medicinal plant rich in phytochemicals. In this study, we expand this knowledge by synthesizing antibacterial silver nanoparticles (AgNPs) using Prunus africana stem bark extract as a reducing, capping, and stabilizing agent. The biosynthesis of AgNPs was carried out with 0.1 M silver nitrate and 2% w/v stem bark extract. The effects of temperature, contact time, and concentration on the synthesis of AgNPs were examined via UV‒Vis spectroscopy. The formation of AgNPs was indicated by the development of a dark-brown color from red‒brown. Using a UV‒Vis spectrophotometer, the surface plasmon resonance observed at 432.5 nm indicated the formation of silver nanoparticles. Probable vibrational stretches that are characteristic of silver nanoparticles, such as OH and C=O vibrations, were identified via an FT-IR spectrophotometer. The characteristic peaks of the XRD pattern confirmed the synthesis of pure AgNPs with an average crystalline size of 17.07 nm. TEM (transmission electron microscopy) analysis confirmed that the synthesized AgNPs were spherical with sizes ranging from 15.95 nm to 43.04 nm. DLS analysis confirmed the stability of the AgNPs in solution at -12.44 mV. The synthesized silver nanoparticles (AgNPs) exhibited antibacterial activity against four bacterial strains ( Pseudomonas aeruginosa , Escherichia coli, Staphylococcus aureus , and Bacillus subtilis ) and one fungus ( Candida albicans ).