[Chemotaxis as a method for testing of the biological effects of silver nanoparticles]

A method for assessing the abiotic efficiency of water-dispersed nano-sized silver particles is suggested. Nanoparticles were obtained by the method of biochemical synthesis in reversed micelles made from anionic surfactant bis-(2-ethylhexyl) sodium sulfosuccinate (AOT). A water dispersion of nanoparticles was prepared from the micellar solution in organic solvent by means of a special procedure. The abiotic efficiency assay is based on the capacity of cells to respond by the negative chemotaxis to chemical agents with harmful metabolic action. In plasmodium of myxomicete Physarum polycephalum, the biocide and repellent effects of silver nanoparticles, Ag+ ions, and AOT were tested in order to compare the abiotic efficiency of these substances in water solution and after introduction into agar substrate. The increase in the oscillation period, the reduction in the area of spreading, and the avoidance reaction in the spatial test, taken together, revealed a much higher repellent efficiency of silver nanoparticles as compared with that of Ag+ ions and AOT. The NSP concentrations lethal for Physarum were similar to those found earlier for bacteria and viruses. The chemotaxis-based tests applied in this study allow one to quantitatively assess cell reactions and monitor their time course. Besides, they have a much higher resolving capacity than the tests based on lethal effects of abiotic substances.