Fluorescence resonance energy transfer FRET principles

Figure 4.16 Schematic to show the principles of fluorescence resonance energy transfer (FRET). Top...

Figure 16.25 Semiconductor nanoparticle-based fluorescent sensors (a) Forster resonant energy transfer (FRET) between two nanoparticles induced by analyte, (b) crown ether receptor for potassium ions, and (c) operation principle of maltose fluorescent sensor. (Adapted from Chen et at. [144] and Medintz et at. [146])...

More recently double stranded DNA-binding dyes, (e.g., SYBR Green), have been introduced (Giulietti et al. 2001) which removed the need for an expensive, specific probe to be designed. Other sophisticated tools have been developed to work in conjunction with the Taqman method, for example molecular beacons, scorpions and hybridisation probes. These techniques rely on the FRET (Fluorescence Resonance Energy Transfer) principle but do not require the nuclease activity of the Taq polymerase. The different real-time... 

Details on the mechanisms and theories of excitation energy transfer via dipole-dipole interaction (FRET Forster resonance energy transfer) and via exchange interaction (Dexter s mechanism) can be found in B. Valeur, Molecular Fluorescence. Principles and Applications, Wiley-VCH, Weinheim, 2002, chap. 4 and 9. 

In previous chapters it was shown that FRET can be reliably detected by donor fluorescence lifetime imaging. Here, we will focus on what is perhaps the most intuitive and straightforward way to record FRET imaging of sensitized emission (s.e., that is, the amount of acceptor emission that results from energy transferred by the donor through resonance) by filterFRET. While simple in principle, determinations of s.e. are complicated by overlap of excitation and emission spectra of the donors and acceptors, and by several imperfections of the recording optics, light sources and detectors. 

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