Antibacterial effect of different concentrations of silver nanoparticles

Abstract

Silver has been in use since time immemorial in the form of metallic silver, silver nitrate, silver sulfadiazine for the treatment of burns, wounds and several bacterial infections. Silver has long been known to show a strong antimicrobial effect to microorganisms. The antimicrobial effect of 30 and 100 ppm silver nanoparticles were investigated against Escherichia coli, Staphylococcus aureus, Salmonella typhimurium, Enterococcus faecalis, Bacillus cereus, Bacillus subtilis, Paenibacillus larvae, Candida albicans and Aspergillus niger. The microorganisms were diluted with sterile distilled water and prepared dilutions of 10(6) of test microorganisms. Dilutions of microorganisms cultured to blood agar base and incubated at 37 degrees C for 24 hours. One mL dilution of 10(6) of all of microorganisms was centrifuged at 3500 rpm for 20 minutes then 30 and 100 ppm of silver nanoparticle solutions were added. Samples were inoculated in blood agar for different time intervals i.e., 0, 2, 5, 10, 30, 60 minutes and 24 hour. Antibacterial activity of silver nanoparticles against various microorganisms was detected at 0, 2, 5, 10, 30, 60 minutes and 24 hours. As results, yeast, fungi and bacteria were inhibited at 30 and 100 ppm. But, P. larvae were not inhibited, while B. subtilis also could not be inhibited at 30 ppm. The antibacterial activity of 100 ppm was stronger than the antibacterial activity of 30 ppm of nanoparticles. Nanosilver is very effective to important pathogens.