Preparation of Cd-free Quantum Dots
Cadmium is known to be a highly toxic element. Recent studies indicate that CdSe-core nanocrystals were cytotoxic if they were not protected in a biological environment. Specifically, oxidation through a variety of pathways leads to the formation of reduced Cd on the nanocrystal surface and releases free cadmium ions that could lead to cell death. Although surface coatings such as ZnS can significantly reduce cytotoxicity, it may not completely eliminate it. The inherent toxicity of cadmium-containing quantum dots prevents their in vivo applications involving animals or humans. Thus, Cd-free quantum dots for life sciences aplications is needed.
Ocean NanoTech is currenlty developing techniques for the synthesis of cadmium-free quantum dots with support from NSF. In the absence of Cd ions, Cd-free QDs are inherently nontoxic and environmentally benign, offering a potential substitute to the widely used cadmium-based nanocrystals. It is anticipated that Cd-free QDs that are animal, human, and environmentally friendly can be used for biomedical applications.