The role of surface chemistry in determining in vivo biodistribution and toxicity of CdSe/ZnS core-shell quantum dots.

To examine the effect of surface chemistry and surface charge on in vivo biodistribution and toxicity of CdSe/ZnS core-shell quantum dots (QDs), QDs with positive, negative, or PEG coating are used in this study for in vivo evaluation in a mouse model. The results suggest that QDs coated with cationic polydiallyldimethylammonium chloride (PDDA) preferentially deposit in the lung other than in the liver, while the negative and PEGylated QDs render abundant accumulation in the liver. At higher doses positive QDs with PDDA coating show severe acute toxicity due to pulmonary embolism. Independent of their surface coatings, all QDs cause injuries in specific tissues like liver, spleen, lung, and kidney, after acute and long-term exposure, and the degree of injuries is dominated by their surface properties. For the positively charged QDs, the acute phase toxicity is primarily contributed by the coating material PDDA, while coating on QDs may amplify both in vitro and in vivo toxicity of PDDA. PEGylated QDs display the slightest chronic injuries in the long-term toxicity examination in comparison to positive or negative ones.