Toxicity assessment of phospholipid micelle-encapsulated cadmium-based quantum dots using Kunming mice

Cadmium-based quantum dots (QDs) have been extensively used for biomedical applications for the last decade. They have also been researched for drug and gene delivery. For this reason, efforts have been placed on evaluating their toxicity at in vivo level. The most widely used quantum dots are CdSe QDs and thus it is important for one to investigate the potential toxicity in vivo. In this contribution, we systematically study the effect of phospholipid micelle-encapsulated CdSe/CdS/ZnS QDs on the long term in vivo toxicity in Kunming mice. The biodistribution, animal survival, animal weight, hematology, blood biochemistry, and organ histology and their respective fluorescent images were determined at an overdose (50 mg kg(-1)) of phospholipid micelle-encapsulated QDs over 112 days (16 weeks) period. The results show that the phospholipid micelle-encapsulated QDs formulation did not result in noticeable toxicity. Serum analysis has shown no changes in the treated mice when compared to mice treated with PBS buffer solution. Histological analysis of tissues from major organs indicated that there are no acute toxic effects of the QDs in vivo. Fluorescent images indicated that the majority of the QDs accumulated in the liver and spleen. Due to the widespread use of Cd-based QDs and the potential for clinical use, these results are necessary and confirm the minimal health risk to use QDs as optical contrast agents and therapeutic carriers.