Synthesis and antibacterial activities of silver nanoparticles

Abstract

Silver nanoparticles (AgNPs) were synthesized from silver nitrate and sodium borohydride and the structures were characterized using ultraviolet-visible, fourier transforms infrared and energy-dispersive X-ray (EDS) spectroscopy. Zeta potential measurements and scanning electron microscopy were also used to measure the dimensions of silver nanoparticles. The particle radii were in the range of 50 to 80 nm with typical surface plasmon absorption maxima at 428 nm. The synthesized AgNPs showed antibacterial activity against Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration (MIC) of AgNPs was achieved at 5 µg/mL for Staphylococcus aureus and Yersinia spp. and at 1 µg/mL for Acinetobacter spp., Streptococcus pyogenes, Salmonella typhi and Vibrio cholera. Escherichia coli isolate showed a visible inhibitory effect compared to the positive control, but the highest studied concentration of AgNPs (5 µg/mL) did not inhibit the bacterial growth completely. These results suggested that silver nanoparticles can be used as an effective antibacterial agent.