Probing Structural Perturbations of Proteins with QDs

In another example, QDs were applied to probe the structural perturbation of an enzyme during the substrate-binding process, with the fluorescence changes being 

The FRET process that occurs between QDs and a dye-labeled substrate bound to the recognition pocket of a protein, may provide a general means for following the recognition events that occur between the proteins and their native substrates, by a displacement mechanism or a competitive assay. For example, when CdSe/ZnS QDs 

Fluorescence changes of the MBP-functionalized QDs with increasing concentrations of maltose. (Reprinted by permission from Macmillan Publishers Ltd. Nature Materials Ref [73]). 

Interactions between the HIV-1 regulatory protein. Rev, and the Rev responsive element (RRE) RNA, as well as the effect of inhibitors on these interactions, were monitored using a single-particle fluorescence-based method [203]. This biosensing method combined FRET and the colocalization of fluorophores as the means of detection. In the presence of an analyte, the dye-labeled recognition complex was assembled on the fluorescent QDs, and these were tunneled, under flow, into two detector channels that simultaneously analyzed the fluorescence of the QDs and the FRET emission of the dye. The two emissions were observed simultaneously only if 

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