Fluorescent quantum dots: Synthesis, modification, and application in immunoassays

Abstract

Fluorescent semiconductor nanocrystals (called quantum dots (QDs)) possess unique optic properties which make them promising material in various applications. In particular, QDs demonstrate narrow florescence peaks with a location depending on the size of the nanocrystal, a wide absorption spectra, and high photostability. The current review is devoted to the synthesis and modification of semiconductor QDs used as fluorescent probes in bioanalysis. Such QDs should exhibit bright fluorescence, form stable aqueous colloid solutions at various pH, and have functional groups available for covalent binding with biomolecules. Major steps of QD preparation that meet these requirements are presented: synthesis of cores in organic solvent, methods of coating cores with shells of higher band-gap semiconductors, and ways of QD hydrophilization. Particular attention has been given to the preparation and modification of QDs using stable and available reagents. Advantages of QDs over organic dyes and recent advances in the application of QDs as fluorescent probes in immunochemical assays have been also considered.