Quantum dots protected with tiopronin: a new fluorescence system for cell-biology studies.

Nanocrystals of semiconducting materials, otherwise included in the term quantum dots (QDs), have fascinated physicists, chemists and electronic engineers since the 1970s. The most striking feature of these materials is that their chemical and physical properties differ markedly from those of the bulk solid.[1] Since their quantum size effects are understood, fundamental and applied research on these systems has become increasingly popular. One of the most interesting applications is the use of nanocrystals as luminescent labels for biological systems.[2-5] The quantum dots have several advantages over conventional fluorescent dyes: they emit light at a variety of precise wavelengths depending on their size and have long fluorescent lifetimes