Abstract
Quantum dots (QDs) have many remarkable optical properties compared to conventional fluorophores and are ideal candidates for versatile biological applications. It is thus important to understand their toxicity and how they are distributed within a body. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is a powerful analytical tool for investigating the spatial distribution of elements in biological samples. In this study, we explore the feasibility of LA-ICP-MS to study QDs biodistribution in tissue sections from mice and rats. CdSeTe/ZnS core–shell QDs were administered to the animals by intratracheal instillation or intravenous injection. We demonstrated that QDs are accumulated in mouse lungs following intratracheal instillation and rat liver, spleen and adrenal gland following intravenous injection. Cd-114 is the specific marker of biodistribution of QDs because it is the major component of QDs and the most abundant isotope. From the high correspondence between locations of QDs from the fluorescence observation and the distribution image of Cd-114, and the high correlation coefficients between QDs component element, we can confirm that Cd-114 indeed come from QDs. On the other hand, the bad correlations between Cd-114 and Se-82 and their LA-ICP-MS signal ratio can be an indicator of partial dissociation of QDs. These results which cannot be obtained by fluorescence microscopy illustrated the advantages of LA-ICP-MS. Not only LA-ICP-MS can locate QDs but also provide the information on whether QDs dissociation occurred. In this work, for the first time, we showed that LA-ICP-MS can be employed to investigate QDs biodistribution in tissue sections from animals.