Accumulation, translocation, and transformation of two CdSe/ZnS quantum dots in rice and pumpkin plants

As a widely applied semiconductor nanomaterial, quantum dots (QDs) have drawn considerable interest. In this study, pumpkin and rice seedlings were hydroponically exposed to two core/shell CdSe/ZnS QDs coated with cysteamine (CdSe/ZnS-CA) and polyethylene glycol-carboxy (CdSe/ZnS-PEG-COOH) for 10 days to analyze their time-varying up -take, translocation, and transformation behaviors in plants. Both QDs were mainly adsorbed/absorbed by the roots in the particulate state, and more CdSe/ZnS-CA accumulated than CdSe/ZnS-PEG-COOH. For CdSe/ZnS-CA-treated plants, the Se and Cd concentrations (CSe and CCd) associated with the roots were 561 +/- 75 and 580 +/- 73 mu g/g (dw) for rice and 474 +/- 49 and 546 +/- 53 mu g/g (dw) for pumpkin, respectively, on day 10. For CdSe/ZnS-PEG-COOH-treated plants, the concentrations of Se and Cd associated with roots were 392 +/- 56 and 453 +/- 56 mu g/g (dw) for rice and 363 +/- 52 and 417 +/- 52 mu g/g (dw) for pumpkin, respectively. The surface charges and coatings sig-nificantly affected the accumulation of QDs at the beginning of exposure; however, the impaction decreased with time. The ratios between the Cd and Se concentrations (CCd/CSe) in the stems and leaves varied from those of the QD stan-dards, indicating the transformation of the QDs in the exposure system. Se and Cd were more likely to translocate in CdSe/ZnS-PEG-COOH-treated plants than in CdSe/ZnS-CA-treated plants. The vertical translocation of Se was greater

Automated summary

In this study, pumpkin and rice seedlings were exposed to two different types of CdSe/ZnS quantum dots (QDs) to analyze their uptake, translocation, and transformation behaviors in plants. The results showed that both QDs were mainly absorbed by the roots in particulate state, with CdSe/ZnS-CA accumulating more than CdSe/ZnS-PEG-COOH. Surface charges and coatings significantly affected the initial accumulation of QDs, but the impact decreased over time. The ratios of Cd and Se concentrations in stems and leaves differed from QD standards, indicating QD transformation in the exposure system. Se and Cd were more likely to translocate in CdSe/ZnS-PEG-COOH-treated plants.