Formation fluorescence study techniques

Intercalation of BPDE. Several groups have studied the reversible intercalative binding of BPDE to DNA. The fluorescence quantum yield of BPDE is much lower than that of BP derivatives which do not contain an epoxide group and fluorescence techniques have not been widely used to study BPDE physical binding to DNA (4). Association constants for the DNA intercalation of BPDE have been obtained by measuring red shifts in the UV absorption spectra of BPDE which occur upon the formation of intercalated complexes and from fluorescence studies (8) of the kinetics of DNA catalyzed hydrolysis of BPDE. The hydrolysis reaction is conveniently monitored by following the fluorescence of the hydrolysis product, BPT, which has a quantum yield many times greater than BPDE. 

Zhao, C. L., M. A. Winnik, G. Riess, and M. D. Croucher. 1990. Fluorescence probe techniques used to study micelle formation in water-soluble block copolymekangmuir.6 514-516. 

Solid-surface room-temperature phosphorescence (RTF) is a relatively new technique which has been used for organic trace analysis in several fields. However, the fundamental interactions needed for RTF are only partly understood. To clarify some of the interactions required for strong RTF, organic compounds adsorbed on several surfaces are being studied. Fluorescence quantum yield values, phosphorescence quantum yield values, and phosphorescence lifetime values were obtained for model compounds adsorbed on sodiiun acetate-sodium chloride mixtures and on a-cyclodextrin-sodium chloride mixtures. With the data obtained, the triplet formation efficiency and some of the rate constants related to the luminescence processes were calculated. This information clarified several of the interactions responsible for RTF from organic compounds adsorbed on sodium acetate-sodium chloride and a-cyclodextrin-sodium chloride mixtures. Work with silica gel chromatoplates has involved studying the effects of moisture, gases, and various solvents on the fluorescence and phosphorescence intensities. The net result of the study has been to improve the experimental conditions for enhanced sensitivity and selectivity in solid-surface luminescence analysis. 

The upgrade of a frequency-domain fluorescence lifetime imaging microscope (FLIM) to a prismless objective-based total internal reflection-FLIM (TIR-FLIM) system is described. By off-axis coupling of the intensity-modulated laser from a fiber and using a high numerical aperture oil objective, TIR-FLIM can be readily achieved. The usefulness of the technique is demonstrated by a fluorescence resonance energy transfer study of Annexin A4 relocation and two-dimensional crystal formation near the plasma membrane of cultured mammalian cells. Possible future applications and comparison to other techniques are discussed. 

Fourier transform infrared (FTIR) spectroscopy, 13C nuclear magnetic resonance (NMR) spectroscopy, ultraviolet-visible (UV-VIS) and fluorescence spectroscopy can be integrated with chromatographic techniques especially in the study of ageing and degradation of terpenic materials. They can be used to study the transformation, depletion or formation of specific functional groups in the course of ageing. 

The phenomenon of fluorescence has been synonymous with ultraviolet (UV) and visible spectroscopy rather than near-infrared (near-IR) spectroscopy from the beginning of the subject. This fact is evidenced in definitive texts which also provide useful background information for this volume (see, e.g., Refs. 1-6). Consequently, our understanding of the many molecular phenomena which can be studied with fluorescence techniques, e.g., excimer formation, energy transfer, diffusion, and rotation, is based on measurements made in the UV/visible. Historically, this emphasis was undoubtedly due to the spectral response of the eye and the availability of suitable sources and detectors for the UV/visible in contrast to the lack of equivalent instrumentation for the IR. Nevertheless, there are a few notable exceptions to the prevalence of UV/visible techniques in fluorescence such as the near-IR study of chlorophyll(7) and singlet oxygen,<8) which have been ongoing for some years. 

Even lower temperatures have been used to study possible intermediate stages in the formation of the acyl enzyme. A tetrahedral intermediate (with a covalent bond between the substrate carbonyl carbon atom and the oxygen atom of the active site serine) (Fig. 2) had been suggested by analogy with nonenzymatic reactions. With rapid reaction techniques, spectrophotometric evidence has been obtained for an additional intermediate before the acyl enzyme in the case of chromophoric substrates. By using first the protein fluorescence emission (Fink and Wildi, 1974)... 

The time-resolved spectroscopy is a sensitive tool to study the solute-solvent interactions. The technique has been used to characterize the solvating environment in the solvent. By measuring the time-dependent changes of the fluorescence signals in solvents, the solvation, rotation, photoisomerization, or excimer formation processes of a probe molecule can be examined. In conventional molecular solutions, many solute-solvent complexes. 

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