Fluorescence resonance energy sensors, designs

Takakusa, H., Kikuchi, K., Urano, Y., Sakamoto, S., Yamaguchi, K. and Nagano, T. (2002). Design and synthesis of an enzyme-cleavable sensor molecule for phosphodiesterase activity based on fluorescence resonance energy transfer. J. Am. Chem. Soc. 124, 1653-1657. 

Blagoi, G., Rosenzweig, N. and Rosenzweig, Z. (2005). Design, synthesis, and application of particle-based fluorescence resonance energy transfer sensors for carbohydrates and glycoproteins. Anal. Chem. 77, 393-399. 

Fluorescence resonance energy transfer (FRET) has also been used very often to design optical sensors. In this case, the sensitive layer contains the fluorophore and an analyte-sensitive dye, the absorption band of which overlaps significantly with the emission of the former. Reversible interaction of the absorber with the analyte species (e.g. the sample acidity, chloride, cations, anions,...) leads to a variation of the absorption band so that the efficiency of energy transfer from the fluorophore changes36 In this way, both emission intensity- and lifetime-based sensors may be fabricated. 

Hong SW, Kim KH, Huh J, Ahn C-H, Jo WH (2005) Design and synthesis of a new pH sensitive polymeric sensor using fluorescence resonance energy transfer. Chem Mater 17 6213... 

More sophisticated designs involved semiconductor quantum dots with fluorescent protein receptors immobilized on the surface [146], The binding site of the protein receptor is occupied with an efficient fluorophore. On excitation a series of FRET (Forster resonant energy transfer) processes takes place excitation energy is transferred from the core of the quantum dot to the fluorescent protein and subsequently to the fluorophore. On substrate binding only one FRET step takes place and luminescence of the receptor is observed [146], In the simplest sensor architecture the protein contains bound quencher. Upon interaction with analyte the quencher is liberated and luminescence of the quantum dot is observed (Figure 16.25c). 

---