Recently,developing multiplexed bioassays and molecular imaging have become more and more important in gene profiling,drug discovery and clinical diagnostics.Spectroscopic coding technology based on both color and intensity of the light emitted from more than one coloring materials which are embedded inside or attached on the surface of the microparticles has been developed for multiplexed bioassays.Organic dyes have widely separated absorption and excitation spectra and now QDs have been developed as an alternative way.