Types of fluorophores

Fluorophnes can be part of a molecule and m this case we call them intrinsic fluorophores. or they can be added to a molecule and th will be Icnown as extrinsic fluorophores. We are going here to describe the properties of ibe most known fluorophores. 

In proteins, three amino acids are responsible of the absoiption and fluorescence of the pt eins in the U.V., tryptophan, tyrosine and phenylalanine (figures 1.7 and 3.1). 

F ure 3.1. Fluorescence emission spectra of aromatic amino acids. 

F ure 3.2. Fluorescence emission spectra flavodetiydn enase extracted from the yeast Hansemdaammtia in phosphate buffer ( 443 nm) (a) and in 6 M guanidine pli 7 (  

upon binding of a ligand to a protdn. Tip observables (intensity, polarization and lifetime) can be altered and one can follow this InniEiig with Tip fluorescence. 

---

BODIPY is a short for 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene, the basic structure of this type of fluorophore (see Fig. 6.5). Derivatives of this dye have been created by modification of positions 1, 3, 5, 7, and 8, generating an array of fluorophores with very distinct excitation and emission properties [38]. Molecular Probes has synthesized a wide number of BODIPY dyes whose excitation... 

The dendrimer of mixed POPAM/Frechet type shown in Fig. 5.5 formally bears several types of fluorophores in three shells naphthyl units on the periphery two layers with dimethoxybenzene character further inside and finally the strongly fluorescing dansyl groups - adding up to a total of 64 luminophoric moieties. Incident UV radiation interacts first with the naphthyl groups, which... 

Although on-column fluorescence detection can provide excellent detection limits, the technique is less versatile than UV detection because many solutes of interest do not exhibit native fluorescence and must be derivatized with some type of fluorophore. Consequently, the literature contains many examples of capillary electrophoresis separations of fluorescence-labeled solutes such as dansylated amino acids.50,51... 

Characteristics of proposed CL reaction. In the preliminary study, CL intensities of several types of fluorophores were measured after mixing with only aryloxalate and without addition of hydrogen peroxide. DBP derivatives and pyrimidopyrimidine derivatives showed CL, but the CL was not observed with typical fluorophores that are frequently used in conventional PO-CL reactions such as dansyl, benzoxazole, lophine and fluorescein derivatives. Therefore, it is proposed that this CL reaction can detect DBP derivatives selectively in the presence of other fluorophores. 

In steady-state fluorescence measurements on a specimen containing multiple types of fluorophores, the expected intensity is given by... 

In spite of these investigations, there is still considerable ambiguity regarding the mechanisms involved. Such studies are hampered by the very nature of the reaction subtle changes in the oxalate structure, chemical environment, and type of fluorophore can result in large variations in overall quantum yield and emission intensity versus time profiles. 

---