Synthesis and Exploitation of InP/ZnS Quantum Dots for Bioimaging

Nano- and cytotoxicity becomes increasingly more important with an increasing number of potenital bio-medical applications for semiconductor Quantum Dots (QDs). Therefore, the frequently used CdSe-based QDs are unsuitable per-se, since cadmium is highly toxic heavy metal and may leach out of QDs. Cadmium-free QDs have not been available for a long time, because the synthesis of e.g. monodisperes and highly crystalline InP QDs caused many problems. We report on the synthesis of InP/ZnS QDs with optical properties similar to those displayed by typical CdSe/ZnS QDs. A major break-through has been reached by addition of zinc ions into the reaction mixture. Furthermore, the transfer of InP/ZnS QDs to water and their exploitation for bioanalytical applications are reported. It is shown that InP/ZnS QDs can be used to replace CdSe-based ones for almost any bio-medical application.