Toxicity of citrate stabilized silver nanoparticles with different size and shape on Pseudokirchneriella subcapitata (Chlorophyta)
Jessika Teuber, Andrea Knauer and J Michael Köhler
University of Technology Ilmenau, German
: Forensic Toxicol Pharmacol 2015, 4:3
Abstract
T he growing numbers of applications of silver nanoparticles (AgNP) in industrial and consumer products cause an increasing liberation of these particles in the ecosystems. The toxic effects and the environmental impacts are widely unknown. The use of droplet based microfluidic techniques can help to reveal the environmental risk of such effectors by the high resolved dose/response curves in two standarized media. To generate segments of about 500 nL volume, the aqueous phase consisting of the cultivation medium, the green algae, and the AgNP was injected into a flow of an immiscible carrier fluid by the help of a computer controlled syringe pump system. The accurate flow control of the fluids allows the generation of droplet sequences with gradually different and well defined droplet composition. The well established model organism for environmental pollution monitoring, Pseudokirchneriella subcapitata is used for the analysis of the growth inhibition effect of citrate stabilized AgNP with different sizes (d = 2.9 23.4 nm) and shapes. Since sodium citrate is non toxic for the investigated algae, we avoid toxic by effects of the stabilizer. The investigated AgNP show narrow size distributions and high stability, measured by zeta potential analyses, scanning electron microscope recordings, and ultraviolet visible spectrophotometry. Interestingly, the culture medium influences the toxicity on P. subcapitata of AgNP dramatically, compared to silver ions. Above this, we detected a strong dependence of the sizes of the particles and their toxicity. In contrast to results reported in the literature, this work demonstrate that the shape has no influence on the toxicity of AgNP.
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