Green Synthesis of Gold Nanoparticles, Silver Nanoparticles and Gold-Silver Alloy Nanoparticles Using Ziziphus spina-christi Leaf Extracts and Antibacterial Activity against Multidrug-Resistant Bacteria

Abstract

Multidrug-resistant bacteria continue to pose the greatest threat to public health. Metallic nanoparticles are one of the more promising strategies for combating antibiotic resistance. This research aims to determine the effect of gold and silver nanoparticles and gold-silver alloy nanoparticles as antibacterial agents. On the other hand, biogenic synthesized gold and silver nanoparticles using Ziziphus spina-christi leaf extract and preparation of gold-silver alloy nanoparticles for treatment of multidrug-resistant bacteria were studied. The formation of nanoparticles was characterized using ultraviolet-visible spectrophotometer, fourier transforms infrared spectroscopy, X-ray diffraction and transmission electron microscopy. Antibacterial activity of the biosynthesized gold nanoparticles, silver nanoparticles and gold-silver alloy nanoparticles was studied against Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Acinetobacter baumannii and Enterococcus faecalis. In the present study, the minimum inhibitory concentration ranged from 61.33 to 64 μg/ml and the minimum bactericidal concentration of the silver nanoparticles ranged from 85.33 to 93.33 μg/ml against multidrug-resistant strains. Synthesized gold nanoparticles had no inhibition zone, indicating that silver nanoparticles have no negative effect on multidrug-resistant bacteria. Minimum inhibitory concentration of gold nanoparticles was in high concentration against multidrug-resistant strain was not bactericidal. The highest minimum inhibitory concentration of gold nanoparticles was 114 μg/ml. Finally, the minimum inhibitory concentration ranged from 53.33 to 62 μg/ml and the minimum bactericidal concentration of the gold-silver alloy nanoparticles ranged from 77.33 to 93.33 μg/ml against multidrug-resistant strains. These results indicate that gold-silver alloy nanoparticles showed higher antimicrobial ability when compared to silver nanoparticles and gold nanoparticles alone. Finally, the synthesized nanoparticles could be used as an alternative antimicrobial agent against multidrug-resistant bacteria, according to our findings.