Biogenic synthesis and antibacterial activity of controlled silver nanoparticles using an extract of Gongronema Latifolium

Abstract

Biogenic synthesis of silver nanoparticles (AgNPs) was conducted via an aqueous extract of fresh leaf of Gongronema Latifolium (FLGL) an herbaceous flowering plant as a fuel agent. The effects of different AgNO3 concentration with the fixed volume of FLGL on the properties of the formulated AgNPs were investigated. Also, the antibacterial activity AgNPs formed was observed through the solid agar plates supplemented with different concentrations of nano-sized AgNPs on Gram-negative (Coliform, Escherichia coli), and Gram-positive (Staphylococcus Aurea) bacterial strain. We observed from the various characterizations of AgNPs that the variation in the concentration of AgNO3 coupled with the incubation period played a major role in controlling the particle sizes and dispersions. The UV–visible confirmed the formation of AgNPs with the surface Plasmon resonance (SPR) peak value at 430 nm in the visible region showing the type as well as the nature of the particles in the colloidal solution. The Fourier transform infrared spectroscopy revealed the functional groups liable for the biogenic process of AgNPs. The X-ray diffraction pattern shows a single-phase crystalline structures in size range of 9–31 nm for the three concentrations. The Scanning and transmission electron microscopies results indicate the spherical shape of the formed AgNPs with proper coating from the bioactive compounds and a diameter of 19 nm for the highest concentration. The energy-dispersive X-ray spectroscopy analysis shows a strong signal for silver. It is noteworthy that the colloidal solutions obtained show effective therapeutic ability of the AgNPs against the bacterial strains using FLGL as a reducing agent for the first time. A bactericidal was observed through the inhibitory zone, against the bacterial strains, with a higher activity above Ciprofloxacin (the positive control). Hence, the biocompatible, nontoxicity and eco-friendly formulated AgNPs is auspicious and efficient as a therapeutic tool for antibacterial activities against human pathogens.