(CdSe)ZnS QDs emitting at peak wavelengths of 500, 550, 600, and 650 nm and dispersed in chloroform were prepared using a well-established organometallic procedure.11 Qdot 705, AlexaFluor488, AlexaFluor532, AlexaFluor568, AlexaFluor633 and AlexaFluor680 were used as purchased (Q21361MP A-20000 A-20001 A-20003 A-20005 A-20008, Invitrogen, Carlsbad, California). QD excitation and emission fluorescence spectra (Fig. 1), and absorption spectra were acquired using a scanning spectrofluorometer (Fluorolog 3, Horiba Jobin-Yvon, Edison, New Jersey, USA) and a UV-Vis spectrometer (Cary 300, Varian, Inc. Palo Alto, California, USA), respectively. The quantum yield of each was calculated as the total emitted fluorescence divided by the absorption coefficient at 385 nm for the QDs and at 488, 532, 568, 633, and 680 for the organic dyes. The values were then normalized to the known (0.92) quantum yield of AlexaFluor488.