CdTe quantum dots: Synthesis, photostability, toxicity and biological applications

Quantum dots (QDs) are semiconductor nanocrystals with a diameter less than 100 nm. They have gained tremendous attention during the last decade in the chemical, physical and biological sciences due to their unique electro-optical properties. CdTe is one of the most important semiconductors in the II-VI group. CdTe QDs can be directly synthesized in the aqueous phase with a quantum yield reaching 80%, which makes them one of the most attractive nanomaterials for biological applications. In this chapter, we provide an overview of synthesis approaches in aqueous and organic phases, optical properties, toxicity and biological applications of CdTe QDs. In the introduction section, we introduce the development of QDs, address some fundamental physical principles needed to understand the properties of QDs, and emphasize the advantages of CdTe QDs in biological applications. In the section on synthesis, we review organometallic methods and aqueous methods for the preparation of CdTe QDs. In the section on photostability, we discuss the effect of pH, capping ligands and so forth, on the optical properties of CdTe, including the photostability of CdTe QDs in cells and tissues. In the toxicity section, the toxicity of CdTe QDs both in vitro and in vivo is discussed and the effect of surface modification on the toxicity is highlighted. The biological application section covers biosensing and cell imaging. The advantages and disadvantages of CdTe QDs will be presented.