Biosynthesis of silver nanoparticles in green way using aqueous extract of henna leaves and investigate its antibacterial activity

As much as human beings become aware of the side effects of chemical pesticides, the demand for natural alternatives increases. In this study, antibacterial effects of different concentrations of methanolic extract of henna leaves (0.50, 0.25, 0.12, 0.06, 0.03 and 0.01 mg/mL DMSO) on three gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus, and Rathayibacter toxicus), and five gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Pseudomonas syringae subsp. syringae, Pseudomonas viridiflava, and Xanthomonas campestris pv. Campestris) was measured with disk diffusion method. Also, silver nanoparticles were synthesized at different amounts of silver nitrate, extract, temperature, time, and pH. The size and shape of the synthesized particles were determined by DLS and SEM techniques. The results showed that the methanolic extract of henna leaves has an excellent antibacterial effect on all tested bacteria except Pseudomonas aeruginosa and Pseudomonas viridiflava. In addition, the antibacterial activity of the synthesized nanoparticles at a concentration of 0.01 M was measured on the tested bacteria and the results showed that the optimized nanoparticles were effective in terms of antibacterial properties. Also, the nanoparticle size in the presence of aqueous extract of henna leaves was 8.5 nm. The results of this study show that nanoparticles can be considered in the field of organic agriculture.