Fluorescence dansyl

Addition of lanthanide ions to dendrimer solutions showed that (a) the absorption spectrum of the dendrimer is almost unaffected, (b) the fluorescence of the dansyl units is quenched (c) the quenching effect is very large for Nd3+ (Fig. 7) and Eu3+, moderate for Er3+ and Yb3+, small for Tb3+, and very small for Gd3+ (d) in the case of Nd3+ (Fig. 7), Er3+, and Yb3+ quenching of the dansyl fluorescence is accompanied by the sensitized near-infrared emission of the lanthanide ion [42]. 

A reversible, direct fluoroimmunosensor for human serum albumin (HS A) measurement has been described by Bright et al.(m> Antibody Fab fragments are first immobilized on small quartz plates by hinge-region thiols, and then dansylated. The immunosensor is formed by attaching the quartz plates with bound Fab to the distal end of a bifurcated fiber-optic probe, which transmits both the excitation and emission. Binding of ffSA to the immunosensor results in a three- to five-fold enhancement of dansyl fluorescence. The sensor can be reused up to 50 times, with a detection limit of about 1.8 x 10-8 M, and a somewhat limited dynamic range. 

Fig. 6.19 a Interaction of metal ions with the dimethylamino groups of the peripheral dansyl units (shown as red ellipses) of a POPAM dendrimer The original dansyl fluorescence of the dendrimer is quenched - partially in this case (light grey ellipses)... 

The percentage of receptors that bind the substrate is concentration-dependent - at high concentrations nearly all of the library members bind the substrate, which shows that the observed binding specificity is not a result of selective quenching of the dansyl fluorescence rather than selective binding. 

Ghiggino, K. P., Lee, A G., Meech, S. R., O Cbnnor, D. V., Phillips, D. Time-Resolved Emission Spectroscopy of the Dansyl Fluorescence Probe. BIOOHEM (in press)... 

The oscilloscope tracing in Figure 7 demonstrates the rapid enhancement of dansyl fluorescence following mixing of 1 X 10" M Dns-(Gly)3-L-OPhe and 2.5 X 10" M carboxypeptidase A and reflects the extremely rapid equilibration of enzyme and substrate to form the ES complex. The decrease in the signal is a considerably slower process and, as... 

Figure 31 Redox switching of the dansyl fluorescence of the two-component system illustrated in Figure 30. The Ni" derivative, in aqueous ethanol, displays the dansyl emission (solid line) on addition of S20g , quick one-electron oxidation to the Ni" derivative takes place and fluorescence is quenched (dashed line) on subsequent addition of N02, Ni " is reduced to Ni" and fluorescence is revived (dotted line).

Sensors for Detecting Organic Compounds by Dansyl Fluorescence... 

In the indication reaction, binding of Cn + down to micromolar concentrations in a 9 1 DMSO-water solution induced a strong quenching of the dansyl fluorescence, mediated by the close proximity of bound Cu " "... 

Dansyl-labeled lipids (Figure 30.2(D)) are useful probes for investigating the assembly of proteins on and within membranes, either by monitoring the spectral shift of dansyl fluorescence or via fluorescence resonance energy transfer measurements using protein-inherent tryptophan as donor [9]. Rhodamine DHPE (Figure 2(E)) does not easily transfer between separated lipid bilayers. Therefore this label is extensively used for membrane fusion assays [8]. 

Horie, K. Yamada, S. Machida, S. Takahashi, S. Isono, Y. Kawaguchi,H.(2003).Dansyl fluorescence and local structure of dansyl-labeled coreshell and core-hair type microspheres in solution, Macromol. Chem. Phys.,2QA, 3> -138. 

The use of 1-dimethylamino-5-naphthyl sulphonate ("dansyl") as a label was first introduced in 1952 for the determination of the rotational diffusion of protein molecules from the anisotropy of the dansyl fluorescence (1). Somewhat later, (2) it was found that the emission intensity of fluorophores of this type is strongly increased when they are adsorbed from water solution on proteins This increase in quantum yield of emission (accompanied by a blue-shift of the emission spectrum) could be correlated with a decreasing polarity of the medium (3). The effect can be explained as follows If the dipolar interaction of the excited chromophore with the solvent is smaller than this interaction in the ground state, the emitted quantum will be increased at the same time, the probability of nonradiative deactivation will be reduced, increasing the quantum yield of fluorescence (4). If the fluorescent label can be attached to a well-defined site on a protein, its emission characteristics will "report" about the polarity of this site (5) and the use of... 

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