Antibacterial Activity of Nanosilver Ions and Particles

• Published in: Environmental science & technology 2010-07, Vol.44 (14), p.5649-5654
• Main Authors: Sotiriou, Georgios A, Pratsinis, Sotiris E
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacology; E coli; Ecotoxicology and Human Environmental Health; Escherichia coli - drug effects; Gram-negative bacteria; Ions; Metal Nanoparticles - chemistry; Nanoparticles; Particle Size; Silica; Silver; Silver - chemistry; Silver - pharmacology
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es101072s

The antibacterial activity of nanosilver against Gram negative Escherichia coli bacteria is investigated by immobilizing nanosilver on nanostructured silica particles and closely controlling Ag content and size. These Ag/SiO2 nanoparticles were characterized by S/TEM, EDX spectroscopy, X-ray diffraction the exposed Ag surface area was measured qualitatively by O2 chemisorption. Furthermore, the fraction of dissolved nanosilver was determined by measuring the released (leached) Ag+ ion concentration in aqueous suspensions of such Ag/SiO2 particles. The antibacterial effect of Ag+ ions was distinguished from that of nanosilver particles by monitoring the growth of E. coli populations in the presence and absence of Ag/SiO2 particles. The antibacterial activity of nanosilver was dominated by Ag+ ions when fine Ag nanoparticles (less than about 10 nm in average diameter) were employed that release high concentrations of Ag+ ions. In contrast, when relatively larger Ag nanoparticles were used, the concentration of the released Ag+ ions was lower. Then the antibacterial activity of the released Ag+ ions and nanosilver particles was comparable.