Abstract

A comparative evaluation of acute toxicity of synthesized nano-silvers using two different procedures (biological and chemical reduction methods) and effect of silver ions on the bacteria Vibrio fischeri were investigated. The bacterial light inhibition testas a toxicological endpoint was used by applying of a homemade luminometer. To compare the toxicity effects as a quantitative parameter, after 5 min and 30 min exposure times, nominal effective concentration (EC) of chemicals and susceptibility constant (Z-value) were calculated. After 5 and 30 min contact times, the EC₅₀ values of two silver nanoparticles and the EC₂₀ values were about similar. The EC values of nanoparticles were larger than those of the silver ions. The susceptibilities of V.fischeri (L/mg) to the silver ions were greater than those of the nano silvers. According to the EC and Z values, the toxicity of silvers decreased in the following order: silver ions >> silver nanoparticles from chemical reduction method ~ silver nanoparticles from biological method.

Key words: Vibrio fischeri, toxicity, luminometer, bioluminescence, silver nano particles.