FRET-based sensing

Fig. 37 (a) QD-based sensing of cocaine by the formation of a cocaine-aptamer supramolecular structure that triggers FRET and (b) time-dependent luminescence spectra of the system in the presence of cocaine. The inset shows a calibration curve for variable concentrations of cocaine and a fixed so observation time of 15 min. (c) Schematic of the FRET-based TNT sensor and (d) increase of the QD luminescence upon addition of TNT in the competitive assay format. (Reprinted with permission from [220, 221], Copyright 2009 Royal Society of Chemistry and 2005 American Chemical Society)... 

A potential limitation of using QD donors for FRET-based optical sensors involves the bigger physical dimensions of semiconductor nanocrystals compared to organic dyes. To overcome this problem, a two-step FRET QD-MBP sugar-sensing assembly containing a fluorescent dye acting as a relay station was also successfully evaluated.85... 

A fluorescein boronic acid derivative was prepared to function as the fluorescent partner and a series of methyl-red-inspired diols were synthesized as qnencher partners to probe the FOrster resonance energy transfer (FRET) quenching sensing regime based on boronate ester formation (Fignre 11). ... 

FRET sensing based on protic equilibrium in the acceptor that changes its absorption spectrum and thus modulates the overlap integral [35]. There are many fluorescent pH indicators that display pH-dependent absorption spectra in the visible with their different positions depending on ionization state. Thus, the change in pH can be translated into the change of FRET efficiency. 

Sensing Based on Fluorescence Resonance Energy Transfer (FRET)... 

Figure 12.5 Sugar-sensing nanoassembly based on a FRET process. (Adapted from Reference 85.)...

These sensing architectures have in common that the FRET contrast is based on (reversibly or irreversibly) displacing the acceptor from the NC donor. 

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