Effect of Silver Nanoparticle Size on Antibacterial Activity

The ubiquitous use of products containing AgNPs results in the entry of nanoparticles into the environment. Both nanoparticles and Ag⁺ released upon their oxidative dissolution have a toxic effect on living microorganisms. The antibacterial activity of spherical silver nanoparticles of 10.8 ± 0.8 nm and 22.7 ± 2.2 nm in size stabilized by carbonate ions was studied against <i>Escherichia coli</i> and other bacteria. The biocidal action of silver increases as the particle size decreases. Analysis of these results and other known data made it possible to substantiate a linear proportional relationship between the minimum inhibitory concentration (MIC) or the half-maximal inhibitory concentration (IC50) and silver nanoparticle size and determine empirical parameters for this relationship. The antibacterial activity (toxicity) is directly proportional to the specific surface area of nanosized silver.