Green synthesis, analysis and characterization of silver nanoparticles loaded on Ginkgo biloba and estimation of their antibacterial activity

Abstract

A scientific study evaluated the effectiveness of green synthetic nanoparticles containing Ginkgo biloba extract and silver nitrate as an antibacterial agent. The scientists created the green nanoparticles by mixing the plant extract with different amounts of silver nitrate (1 mM, 1.5 mM, 1.75 mM, and 2 mM). The combination changed color from yellowish to brown in 10 minutes, and after an hour, it turned into a dark brown shade. This color change indicates the formation of silver nanoparticles. The researchers observed a distinct surface Plasmon resonance (SPR) band at around 433 nm, which suggests the presence of nanoparticles with a green color. The highest peak intensity of this band is observed at a concentration of 1.75 mM AgNO3. Atomic Force Microscopy is used to analyze the form and size of the green nanoparticles. The findings showed that the nanoparticles' size depended on the silver nitrate concentration. The average diameters are 74.86, 42.70, 36.01 and 39.27 nm for AgNO3 concentrations of 1 mM, 1.5 mM, 1.75 mM, and 2 mM, respectively. The height of the nanoparticles varied based on the concentration of silver nitrate. The heights measured are 46.497 nm, 18.360 nm, 19.233 nm, and 24.293 nm for silver nitrate concentrations of 1 mM, 1.5 mM, 1.75 mM, and 2 mM, respectively. The silver nanoparticles synthesized had a mostly spherical shape. The study tested the efficacy of green synthetic silver nanoparticles against two strains of bacteria: Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus. The findings showed that nanoparticles at different doses (1, 1.5, 1.75 and 2 mM) successfully suppressed bacterial growth, resulting in inhibition zones of different sizes. The inhibitory zones for Staphylococcus aureus are measured to be 8 mm, 8 mm, 9 mm, and 7 mm at concentrations of 1 mM, 1.5 mM, 1.75 mM and 2 mM, respectively. The inhibitory zones for Pseudomonas aeruginosa are 9 mm, 10 mm, 11 mm, and 9 mm at concentrations of 1 mM, 1.5 mM, 1.75 mM and 2 mM, respectively.