Metal-enhanced fluorescence advantages

NEAR-INFRARED METAL ENHANCED FLUORESCENCE ADVANTAGES... 

If absorptions are limited to the UV range, interferences can become a considerable problem. The lack of selectivity of the Cy was also mentioned before. Future choices for chiral hosts will be based upon different association mechanisms and presumably will emphasize greater potential for selectivity. Virtually any material that has seen use as a stationary phase for chiral chromatography is a candidate, and others will eventually appear. Some of these have in fact been employed already, although not to the same degree that the Cy have, (e.g. cryptands, vesicles, micelles, metal complexes, and proteins). Their immediate most obvious advantage is a substantial increase in the magnitude of the induced ellipticity, which can be enhanced even further by fluorescence detection. 

Some lanthanide ions when complexed with UV-absorbing ligands, can efficiently accept energy from the excited state of the ligand and produce highly enhanced emission characteristics of the metal ion. Rare earth complexes have some advantages over organic fluorescent probes such as fluorescein, rhodamines, umbelliferones such as... 

Since the pioneering work by Cotton et al. on heme proteins (Cotton et al., 1980), surface enhanced resonance Raman spectroscopy (SERRS), Sec. 6.1, has been used to study a large variety of biomolecules, such as retinal proteins (Nabiev et al., 1985), flavoproteins (Coperland et al., 1984 Holt and Cotton, 1987), chlorophylls (Cotton and Van Duyne, 1982 Hildebrandt and Spiro, 1988), and oxyhemoglobins (de Groot and Hesters, 1987). The advantages of this technique include low sample concentration and fluorescence quenching. The main question is whether or not the native structure and function of the molecule is preserved on the metal surface. 

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