Investigating uptake of water-dispersible CdSe/ZnS quantum dot nanoparticles by Arabidopsis thaliana plants

Interest on the environmental impacts of engineered nanomaterials has rapidly increased over the past years because it is expected that these materials will eventually be released into the environment. The present work investigates the potential root uptake of water-dispersible CdSe/ZnS quantum dots (QDs) by the model plant species, Arabidopsis thaliana. Experiments revealed that Arabidopsis exposed to QDs that are dispersed in Hoagland's solution for 1–7 days did not internalize intact QDs. Analysis of Cd and Se concentrations in roots and leaves by inductively-coupled plasma mass spectrometry indicated that Cd and Se from QD-treated plants were not translocated into the leaves, and remained in the root system of Arabidopsis. Furthermore, fluorescence microscopy showed strong evidence that the QDs were generally on the outside surfaces of the roots, where the amount of QDs adsorbed is dependent on the stability of the QDs in suspension. Despite no evidence of nanoparticle internalization, the ratio of reduced glutathione levels (GSH) relative to the oxidized glutathione (GSSG) in plants decreased when plants were exposed to QD dispersions containing humic acids, suggesting that QDs caused oxidative stress on the plant at this condition.

This study highlights the importance of quantum dot (QD) structural stability in preventing phytotoxicity. Overall, there is no evidence that Arabidopsis thaliana plants can internalize intact QDs within 1–7 days of exposure, with or without humic acids.Figure optionsDownload as PowerPoint slideHighlights
► Potential uptake of water-dispersible CdSe/ZnS QDs by Arabidopsis was demonstrated.
► QDs were not internalized by Arabidopsis as intact particles.
► Plants exposed to Cd-, Se-, and QD + HA suspensions experienced oxidative stress.
► An effective LC–MS method proves detection of low levels of glutathione in plants.
► Uptake of Cd and/or Se leached from QDs is of major concern.