Study On The Effect Of NanoMaterials On Environmental Safety Using A Tetrahymena Thermophila System

Recently, Nanotechnology was rapid evolving fields leading to nanomaterials and their possible applications continue to grow exponentially. The biological effect and environment security of nanomaterials have brought great concern to scientific circles. Nanosilver is the most common used metal nanomaterial among all commercial nanomaterial products due to its favorable photoelectricity, catalysis, superconductivity and antimicrobial properties. The chance of silver nanopaticle released to the environment has increased because its widely applied and abundantly produced, it is possible that silver nanopaticle could pose a threat to human health. Fe₃O₄ nanopaticle has properties of stability, target, high drugs containing and controlled release and so on, so it has been widely applied to target drugs carrier, immunoassay and X ray agent that in target drugs treatment. The chance of exposing to nanomaterials is increased, so the security of nanomaterials is received more attention from all people gradually.Four kinds of size-dependent silver nanopaticles (AgNPs) (3-20nm) were synthesized using liquid phase method and one kind of Fe₃O₄ nanopaticle (Fe₃O₄NPs) was synthesized by hydrothermal method. The toxicity effect of synthetic nanomaterials to Tetrahymena thermophila have been studied in this paper. The degree of inhibition on Tetrahymena thermophila growth by silver nanopaticles and Fe₃O₄NPs in different concentration were determined and the assay that the size-dependent AgNPs toxicity and interaction of the AgNPs toxicity with light was also discussed. The cell number of Tetrahymena thermophila was studied by hemocytometer measurement. Results show that: the degree of inhibition on Tetrahymena thermophila growth by AgNPs is very obviously. It indicated that the nanosilver toxicity is related by size and light. The silver nanoparticle with small size has higher toxicity that is because proton and Ag0 have a series of reactions when there has been dissolved oxygen in silver nanopaticle colloid. Furthermore, toxicity of size-dependent AgNPs could be weakened by light but this trend was decreased with increasing particle size. The inhibition ratio of Fe₃O₄NPs in different concentrations to Tetrahymena thermophila were all higher than control at different exposure time but there were not obviously difference between different doses.