Selective chemical vaporization of exogenous tellurium for characterizing the time-dependent biodistribution and dissolution of quantum dots in living rats†
Quantum dots (QDs) are generally toxic as a result of their heavy metal content. However, direct characterization of their dissolution behavior in living systems remains complicated because of the lack of differentiation methods suitable for analyzing the released components and residual nanostructures. To investigate the degree of dissolution of QDs in living rats, we used a chemical vapor generation scheme as a novel strategy to selectively vaporize the chalcogen (Te) species released from CdSeTe–ZnS core–shell QDs (QD705) in organ/tissue samples from rats. Under optimized conditions, we established a chemical differentiation method that had a better performance and applicability than the commonly used filtration method. We used Solvable tissue solubilizer to dissolve the tissues harvested from rats that had been administered with QD705 intravenously. Our experimental results showed differences in the Te- and Cd-based biodistribution patterns of QD705. In addition, we found that the ratio of the concentrations of the Te species released from the dissolution of QD705 to the total Te species (Ter/Tetotal) increased in the blood, liver, and spleen of the rats, but decreased in their kidneys from 2 to 16 weeks post-administration. Therefore the QD705 administered in living rats must have dissolved and redistributed progressively during the time course of the experiment, suggesting that the long-term chemical fate of nanosized materials in vivo should be considered in future nanotoxicological research.