Using laser ablation inductively coupled plasma mass spectrometry to characterize the biointeractions of inhaled CdSe quantum dots in the mouse lungs

Abstract

Quantum dots (QDs) show great promise for use as drug delivery carriers and fluorescent markers, with potential applications in, for example, pulmonary drug delivery and lung imaging, respectively. Nevertheless, few adequate analytical techniques are available for mapping or determining QDs in tissue samples. In this study, we employed laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to map the spatial distribution of inhaled CdSe QDs in mouse lung slices. Mapping of control and QD-inhaled samples revealed a distribution of Cd atoms in the lungs arising from QDs accumulated in the bronchiolar area, as confirmed through fluorescence spectroscopy imaging. We also simultaneously monitored other selected elements, namely ¹³C, ³¹P, ³⁴S, ⁵⁶Fe, ⁵⁷Fe, ⁶³Cu, ⁶⁶Zn, ⁸²Se, ¹²⁵Te, ¹¹¹Cd, ¹¹²Cd, and ¹¹⁴Cd. The high correlation between the spatial distributions of ¹¹⁴Cd and ⁸²Se suggested that the QDs underwent no obvious degradation during a span of 17 days, providing insight into the potential cytotoxicity of the QDs. The LA-ICP-MS data coupled with hematoxylin and eosin (H&E)-stained images revealed that the inhaled QDs appeared in the same locations as the lymphocytes accumulated in the lungs. These results, in conjunction with the observed distribution of Cu atoms, suggest that the lymphocytic system was involved in inflammation triggered by the inhaled QDs. The observed enrichment of Cu atoms in the sample was probably due to certain immune responses induced by the inhaled QDs. Finally, spiking with standard solutions allowed us to quantify the QDs in the tissue slices.