Fluorophore properties enhancement

The tunability on emission wavelength of cyanine derivatives is based on the understanding of structure-photophysical property relationships, which allows the development of near-IR fluorophores [80, 84—87]. Enhancement of the rigidity in... 

A fluorophore in the proximity of the NP senses the altered EM-field and its fluorescence properties are consequently modified. There are (at least) two enhancement effects an increase in the excitation of the fluorophore and an increase in its quantum efficiency (QE). The increased excitation of the fluorophore is directly proportional to the to the square of the strength of the E-field and is a function of the wavelength and relative position of the NP. The maximum enhancement of this type is achieved if /.res equals the peak absorption wavelength of the dye. 

Among several fluorescence properties, fluorescence quantum yield and lifetime are the two most important characteristics of a fluorophore. Studies of the effects of the silica nanomatrixes on these two characteristics reveal the mechanism of enhanced fluorescence intensity of DDSNs. 

A high degree of sensitivity and selectivity can be obtained with certain biomolecules by the chemical attachment of fluorophores. The most common fluorescent derivatization reagents include fluorescamine, dansyl chloride, pyridoxal, pyridoxal 5-phosphate, dansyl hydrazine, and pyr-idoxamine. Such derivatization procedures can be used to enhance the fluorescence of compounds with low quantum yields as well as impart fluorescent properties to compounds that do not fluoresce naturally. 

We are now looking at extending the simple model for free-space fluorescence to the case of Metal Enhanced Fluorescence (MEF). We therefore consider a fluorophore with known free-space properties in the presence of optically-active objects (in particular metallic objects). 

When a fluorophore is located in close proximity to a metal surface, both its absorption and emission properties may be affected dramatically. This in turn affects its fluorescence properties and may result in either a quenching or an enhancement of the fluorescence signal. This latter situation is obviously of interest for many applications using fluorophores. Let us discuss these steps in more detail. 

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