Preparation of silver nanoparticles as antibacterial agents through DNA damage

AgNPs were prepared through electrochemical method in this study. Scanning electron microscope images showed that particles size of prepared AgNPs with concentration of 10 ppm was in the range of 8-27 nm while its ranged from 8 nm to 40 nm for sample prepared with concentration of 50 ppm. The antibacterial activity of AgNPs against the clinical isolates of Pseudomonas aeruginosa and Staphylococcus aureus was detected by disc diffusion and colony count methods. Colony count assay for P. aeruginosa that treated by 50 ppm of AgNPs confirmed a killing percentage of 81% and 95% at direct or 2h post-exposure, respectively while the growth of S. aureus isblocked with a percentage of 58% and 99%. Bacterial DNA replication was evaluated in AgNPs-treated or untreated P. aeruginosa cultures, and exoA gene expression was detected by real-time polymerase chain reaction assay. Results showed lower amplification efficiency in AgNPs treated samples.