In vivo distribution, pharmacokinetics, and toxicity of aqueous synthesized cadmium-containing quantum dots

Fluorescent Ⅱ-Ⅳ Quantum dots (QDs) have demonstrated to be highly promising biological probes for various biological and biomedical applications due to their many attractive merits, such as robust photostabilty, strong photoluminescence, and size-tunable fluorescence. Along with wide ranging bioapplications, concerns about their biosafety have attracted increasingly intensive attentions. In comparison to full investigation of in vitro toxicity, there has been only scanty information regarding in vivo toxicity of the QDs. Particularly, while in vivo toxicity of organic synthesized QDs (orQDs) have been investigated recently, there exist no comprehensive studies concerning in vivo behavior of aqueous synthesized QDs (aqQDs) up to present. Herein, we investigate short- and long-term in vivo biodistribution, pharmacokinetics, and toxicity of the aqQDs. Particularly, the aqQDs are initially accumulated in liver after short-time (0.5-4 h) post-injection, and then are increasingly absorbed by kidney during long-time (15-80 days) blood circulation. Moreover, obviously size-dependent biodistribution is observed: aqQDs with larger sizes are more quickly accumulated in the spleen. Furthermore, histological and biochemical analysis, and body weight measurement demonstrate that there is no overt toxicity of aqQDs in mice even at long-time exposure time. Our studies provide invaluable information for the design and development of aqQDs for biological and biomedical applications.