CdSe quantum dots (QDs) with a high fluorescence quantum yield of 25% and a narrow size distribution were synthesized in a single step in H2O using glutathione as a stabilizing mol. The exceptional optical properties enabled for the 1st time the detection of in-H2O-prepd. single quantum dots at room temp. For application as fluorescent bioanal. probes, the QDs were coated with streptavidin. These QDs self-assemble with high contrast on micropatterned biotin while preserving their optical properties and their capability to bind in addn. biotinylated mols., a prerequisite for the development of novel supramol. structures and bioassays. [on SciFinder (R)]