FRET-gating

Xu QH, Wang S, Korystov D, Mikhailovsky A, Bazan GC (2005) The fluorescence resonance energy transfer (FRET) gate a time-resolved study. Proc Natl Acad Sci USA 102 530-535... 

Redford, G. and Clegg, R. M. (2005). Real time fluorescence lifetime imaging and FRET using fast-gated image intensifiers. In Methods in... 

Attractive for the use of QDs are their long lifetimes (typically 5 ns to hundreds of nanoseconds), compared to organic dyes, that are typically insensitive to the presence of oxygen. In conjunction with time-gated measurements, this provides the basis for enhanced sensitivity [69]. This property can be also favorable for time-resolved applications of FRET. The complicated size-, surface-, and wavelength-dependent, bi- or multi-exponential QD decay behavior (Fig. 2) can complicate... 

Wang S, Gaylord BS, Bazan GC (2004) Fluorescein provides a resonance gate for FRET from conjugated polymers to DNA intercalated dyes. J Am Chem Soc 126 5446-51... 

TR-FRET measurements present interesting alternatives to the FRET quench format to minimize compound interference. Time-gated measurements allow the exclusion of compound auto-fluorescence from the detection. The technology is very popular due to its sensitivity, ease of use, and simplicity of assay development. The high costs for the reagents are the major disadvantage of... 

Erickson, M.G., Alseikhan, B.A., Peterson, B.Z. and Yue, D.T. (2001) Preassociation of calmodulin with voltage-gated Ca(2+) channels revealed by FRET in single living cells. Neuron. 31, 973-985. 

Fluorescent-labelled oligonucleotides have been applied to the development of photonic logic gates,which may have application in molecular computation. A machine which undergoes extension-contraction motion is described, which is monitored by FRET, between a duplex and a quadruplex structure. The motion is driven by the addition of single-stranded oligonucleotide that causes the quadruplex to collapse and leads to a duplex structure. 

Fig. 2 Time-resolved FRET assay in a protein-protein interaction with europium-chelate and acceptor-labeled proteins as partners. Respective gated emissions are shown before and after the binding reaction showing the emerged sensitized long decay acceptor emission. Typical wavelength windows are shown at 613 nm for europium donor and 665 nm for sensitized emission...

TR-FRET assays are, by definition, assays applying gated detection. Due to their relatively wide use in drug discovery, practically all plate reader vendors have adapted their instmments to read TR-FRET assays too. Both xenon flash lamps and nitrogen lasers are applied in the plate readers to create short-lived and intense excitation pulses at the area of 330-340 nm. 

The most common assays for ion channel HTS are fluorescent dye-based, measuring influx of, for example, calcium into the cell. Fluorescent resonance energy transfer (FRET) may also be used. However, these methods lack control of voltage over the membrane. To investigate state-dependent voltage-gated ion channek methods with much lower throughput need to be applied [136]. 

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