Nanoparticles have diverse applications in electronics, medical devices and cosmetics. The increasing production and use of nanoparticles results in their higher concentrations in the environment. This may lead to undesirable environmental effects. Therefore, investigating the potential aquatic toxicity of nanomaterials has become an important issue.
The aim of this study was to examine the acute toxicities of of three platinum nanoparticles (PtNPs, 3.1–24.4 nm) and two silver nanoparticles (AgNPs 0.7–18.2 nm) to aquatic organisms and find out the biological effect of small and large sized nanoparticles. Concentrations for each organism were chosen on the basis of the range finding test. Nanoparticles were characterized by transmission electron microscopy (TEM) and by dynamic light scattering (DLS). Tests were conducted with representatives of freshwater ecosystem (water fleas Daphnia magna) and marine ecosystem (bacteria Vibrio fischeri). Experiments were carried out methodologically in accordance with the following standards: OECD 202 guideline and ISO 11348–2.
The ecotoxicity of platinum and silver nanoparticles varies considerably according to the test organisms and particle size. Daphnia magna showed the highest sensitivity to the tested AgNPs. Vibrio fischeri was the least sensitive to the silver nanoparticles. The 30´EC50 value for AgNPs was 1255–9090 µg.Ll-1. Such a low toxicity of AgNPs to marine bacteria results probably from changes in toxic effect of silver due to chloride complexation. While the marine bacteria responded most sensitively to the presence of platinum nanoparticles. The effective concentration of Pt1 (3.1–10 nm) and Pt3 (8.7-24.4 nm) that caused 50% inhibition in bioluminescence of Vibrio fischeri was 135.47 µg.L-1 and 254.64 µg.L- 1, respectively.
The low EC50 values show high toxicity to Daphnids and confirm the strong bactericidal effects of NPs. The smaller sized platinum nanoparticles showed higher toxicity to Daphnia magna and Vibrio fischeri. These organisms are good bioindicators for assessing the acute toxicity of environmental contaminants.