It is instructive to consider the different fluorescence properties of the probes. With a 75-fold enhancement of fluorescence intensity upon hybridization, C7-QB-OMe provided a markedly higher responsiveness than C7-2AF568-QB-OMe (18-fold, Table ). However, light-harvesting rendered C7-2AF568-QB-OMe much brighter than C7-QB-OMe (Br = 229,000 M -1 •cm -1 vs. Br = 72,000 M -1 •cm -1 , Tables and) pointing to the importance of brightness when measurements are affected by noise and/or autofluorescence.