Surface fluorescence

Sawicki (13) used solid-surface fluorescence techniques extensively in the 1960 s for air pollution research. In 1967, Roth (14) reported the RTF of several pharmaceuticals adsorbed on filter paper. Schulman and Walling (15) showed that several organic compounds gave RTF when adsorbed on filter paper. Faynter et al. (16) reported the first detailed analytical data for RTF and gave limits of detection, linear dynamic ranges, and reproducibilities for the compounds. 

Solid-surface fluorescence and phosphorescence quantum yield values were obtained from +23° to -180°C for the anion of p-aminobenzoic acid adsorbed on sodium acetate (11). Fhosphorescence lifetime values were also obtained for the adsorbed anion from +23° to -196°C. Table 1 gives the fluorescence and phosphorescence quantum yield values acquired. The fluorescence quantum yield values remained practically constant as a function of temperature. However, the phosphorescence quantum yield values changed substantially with temperature. The phosphorescence lifetime experiments indicated two decaying components. Each component showed a gradual increase in phosphorescence lifetime with cooler temperatures, but then the increase appeared to level off at the coldest temperatures. 

In recent studies on perfused rats hearts (Veitch et al., 1992), it was found that differences in the sensitivity of complexes 1-lV to ischaemic damage were dependent upon the duration of ischaemia and the presence of oxygen. The demonstration that complex 1 is a major defective site dependent upon isolation of mitochondria from homogenates of the tissue by in vitro methods seemed important to us. We therefore decided to attempt to make noninvasive measurements of mitochondrial function soon after reperfusion in transplanted rabbit kidneys by surface fluorescence (for mitochondrial NADH levels) and near infra-red spectroscopy (NIRS) for the redox state of cytaas. 

Micelles (CTAB, SDS, Triton-XlOO) Aqueous surface Fluorescence (HC, AC) 32 448... 

Micelles (various types) Aqueous surface Fluorescence (p-CHO) 35 15 449... 

Aluminum coating (for surface fluorescence quenching see Section 13.5.5) can be accomplished in a standard vacuum evaporator the amount of deposition can be made reproducible by completely evaporating a premeasured constant amount of aluminum. After deposition, the upper surface of the aluminum film spontaneously oxidizes in air very rapidly. This aluminum oxide layer appears to have some similar chemical properties to the silicon dioxide of a glass surface it can be derivatized by organosilanes in much the same manner. 

Fig. 2. Fluorescence image of surface localization in cultured cells. OVCAR-3 human ovarian cancer cells were incubated with monoclonal antibody Kl, followed by antimouse IgG conjugated to rhodamine as described in the protocol (3). The intense diffuse speckled surface fluorescence image is shown on multiple cells in this area of the culture, with reinforced bright images at the vertical cell margins generating a cobblestone appearance (bar = 4 jm).

NADH/NADPH SURFACE FLUORESCENCE IN LIVING TISSUES... 

Surface fluorescence of NADH/NADPH can be recorded continuously with a DC fluorimeter and correlated with changes in experimental conditions. A mercury arc lamp (with a 340-375 nm filter in front) is used as a hght source for fluorescence excitation. The fluorescence response of reduced NADH/NADPH was measured at 450-510 nm. The DC fluorimeter and the Hg arc lamp are connected to the kidney by a trifurcated fiber optics light guide. NADH/NADPH fluorescence emission can be corrected for changes in tissue opacity by a 1 1 subtraction of reflectance changes at 340-375 nm from the fluorescence. To determine NADH/NADPH redox state of the total surface area of kidney cortex and to evaluate whether certain areas were insufficiently perfused, fluorescence photographs of the total surface area were taken. The study demonstrated that the surface fluorescence method is simple and provides specific information about the mitochondrial oxidation-reduction state. 

Mitochondrial oxidation-reduction state, NADH/NADPH SURFACE FLUORESCENCE IN LIVING TISSUES MITOGEN-ACTIVATED PROTEIN KINASE... 

Transient bleaching and recovery rates of CdS excitonic absorption, determined by picosecond pump-probe spectroscopy, depended on [H20]/[A0T] ratio and micellar surface. Fluorescence spectra and lifetimes depended on [Cd2+]/[S2 ] ratios... 

These data can be compared with those for a/w films shown in Figure 15. Such comparison suggests that there is substantially less protein at the interface in o/w thin films, indeed almost five times less. However, care needs to be exercised when equating surface concentration to fluorescence intensity. It is possible that the fluorophore is located in different environments in the two types of thin film and that the difference in fluorescence intensity is a fluorescence quantum yield effect. However, this is unlikely since the surface concentration, as judged by the surface fluorescence signal at which surface diffusion is first observed, in both a/w and o/w films is very similar at approximately 600 counts per channel. It is reasonable to assume that the structure of the adsorbed layer is similar at the point where surface diffusion is first observed. The presence of similar surface counts indicates that the quantum yield of fluorescence is similar at both o/w and a/w interfaces. Thus, this strongly supports the... 

Further, it has difficult to distinguish between covalent bonding and strong adsorption in most cases via XPS. Off-surface fluorescence measurements have provided data to determine the relative amounts of the two modes of immibilization in one case (60). Wider usage of fluorescence methods is predicted. 

Using the solution-based procedure, we obtain fully covered substrates, while by the //CP-based procedure, discrete areas of coverage are patterned on the substrate, which is convenient in terms of microarray fabrication because different fluorophore probes can be placed on specific, discrete regions of the same glass substrate. Such an array could then be exposed to a guest solution and subsequently the surface fluorescence emission scanned by a confocal microscope for the simultaneous acquisition of the optical data from the individually addressable areas [60-63]. 

Imre, D.G., Kinsey, J.L., Field, R.W., and Katayama, D.H. (1982). Spectroscopic characterization of repulsive potential energy surfaces Fluorescence spectrum of ozone, J. Phys. Chem. 86, 2564-2566. 

Leon MB, Lu DY, Prevosti LG, et al. Human arterial surface fluorescence atherosclerotic plaque identification and effects of laser atheroma ablation. J Am Coll Cardiol 1988 12(I ) 94-102. 

E.K. Krasnowska, E. Gratton, T. Parasassi, Prodan as a membrane surface fluorescence probe Partitioning between water and phospholipid phases. Biophys. J. 74, 1984 (1998)... 

Figure 3.4. Comparison of the reflectivity and the excited fluorescence of one crystal, under the same conditions, at 1.7 K. (The bulk fluorescence is shown to scale out the weakness of the surface fluorescence.) The exact coincidence of the surface fluorescence structures with the reflectivity counterparts reveals the coherent (ultrafast) emission of the surface molecules, subsequent to the intramolecular relaxation of the excited state (cf. Section 1V.A).

This section has been devoted to the study of the surface excitons of the (001) face of the anthracene crystal, which behave as 2D perturbed excitons. They have been analyzed in reflectivity and transmission spectra, as well as in excitation spectra bf the first surface fluorescence. The theoretical study in Section III.A of a perfect isolated layer of dipoles explains one of the most important characteristics of the 2D surface excitons their abnormally strong radiative width of about 15 cm -1, corresponding to an emission power 10s to 106 times stronger than that of the isolated molecule. Also, the dominant excitonic coherence means that the intrinsic properties of the crystal can be used readily in the analysis of the spectroscopy of high-quality crystals any nonradiative phenomena of the crystal imperfections are residual or can be treated validly as perturbations. The main phenomena are accounted for by the excitons and phonons of the perfect crystal, their mutual interactions, and their coupling to the internal and external radiation induced by the crystal symmetry. No ad hoc parameters are necessary to account for the observed structures. 

These direct data confirm our previous analysis (Section III) of the surface reflectivity and of the zero-phonon surface fluorescence, which predicts a lifetime1,61,79,148 of the surface exciton of about 0.3 ps, corresponding to a... 

Figure 12.29. Fluorescence Recovery After Photobleaching (FRAP) Technique. (A) The cell-surface fluoresces because of a labeled surface component. (B) The fluorescent molecules of a small part of the surface are bleached by an intense light pulse. (C) The fluorescence intensity recovers as bleached molecules diffuse out of the region and unbleached molecules diffuse into it. (D) The rate of recovery depends on the diffusion coefficient.

---