Use of semiconductor nanocrystals to encode microbeads for multiplexed analysis of biological samples

Microbeads encoded with semiconductor quantum dots (QDs) are suitable tools for multiplexed analyses of various biological markers using flow cytometry. We have prepared a panel of microbeads encoded with QDs of different colors emitting with different luminescence intensities using the layer-by-layer deposition technique, which consists in layering of alternately charged polyelectrolytes and negatively charged QDs onto the surface of microbeads. This method allows QDs to be separated with one or several polymer layers in order to prevent Förster resonance energy transfer (FRET) and the resultant quenching of QD fluorescence in multicolor microbeads.