Probes luminescence quenching

The Use of Extramlcellar Probe Luminescence Quenching to Monitor Binding of Charged Substrates to Micelles... 

Time-resolved luminescence quenching measurements using the probe Tb(pyridine-2,6-dicarboxylic acid)i and the quencher bromophenol blue show the existence of micellar clusters in AOT-based w/o microemulsions. The fast exchange appearing over several microseconds was attributed to intracluster quenching, whereas the slow exchange on the millisecond time scale was attributed to intercluster exchange [243]. 

Abstract Pressure-sensitive paint (PSP) is applied to the areodynamics measurement. PSP is optical sensor based on the luminescence of dye probe molecules quenching by oxygen gas. Many PSPs are composed of probe dye molecules, such as polycyclic aromatic hydrocarbons (pyrene, pyrene derivative etc.), transition metal complexes (ruthenium(II), osumium(II), iridium(III) etc.), and metalloporphyrins (platinum (II), palladium(II), etc.) immobilized in oxygen permeable polymer (silicone, polystyrene, fluorinated polymer, cellulose derivative, etc.) film. Dye probe molecules adsorbed layer based PSPs such as pyrene derivative and porphyrins directly adsorbed onto anodic oxidised aluminium plat substrate also developed. In this section the properties of various oxygen permeable polymer for matrix and various dye probes for PSP are described. 

Several papers reported on the spatial determination of photoactive molecule in organized assemblies (76-79), and Pallavicini and coworkers reviewed on the use of luminescence as probe in self-assembly of multicomponent fluorescent sensors (80). Also, luminescence quenching studies on [Rufbpyls] in sodiiun dodecyl sulfate (SDS) micelles and hemimicelles by using a variety of quenchers were reported by Tiuro and coworkers (81) and then reviewed by De Schryver and coworkers (82). 

Depending on the timescales involved and the nature of the chemical reaction, the kinetic information can be obtained from product distribution, luminescence quenching, or kinetic measurements in the presence of a kinetic probe or a radical precursor. Inevitably, however, the result is obtained as a relative rate constant. The conversion to the absolute value requires that the rate constant for the competing process(es) be known. 

CdS nanoparticle synthesis Buffering pFI up to 7 Nucleophilic substitution reactions Interfacial tension studies Phase behavior, conductivity (percolation) Luminescence quenching to probe microenvironment... 

Xu W, Schmidt R, Whaley M, Demas J N, DeGraff B A, Karikari E K and Farmer B L 1995 Oxygen sensors based on luminescence quenching interactions of pyrene with the polymer supports Anal. Chem. 67 3172-80 Peterson J I, Goldstein S R, Fitzgerald R V and Buckhold D K 1980 Fiber optic pH probe for physiological use Anal. Chem. 52 864-9 Peterson J 1 and Vurek G 1984 Fiber-optic sensors for biomedical applications Science 123 123-7... 

Long-decay luminescent dyes and probes that are effectively quenched by molecular oxygen can be used for its quantitation. Examples of such probes include ruthe-nium(II)-rm(diphenyl phenanthroline) and phosphorescent platinum(II) porphyrins. Their long emission lifetimes facilitate quantitation by lifetime or intensity measurements. Other chemical specie, such as heavy-metal ions and heterocyclic compounds, can be quantified by luminescence quenching, according to Eq. 3. 

The most important applications of luminescence probing in microemulsions involve the deactivation dynamics or excitation energy transfer properties of the excited states. With a brief flash of light a population of excited species is created in the sample, and the subsequent deactivation is observed over time. The decay of the excited probe, and the fluorescence spectrum, may depend on the interactions with the environment, which reveal useful information. In time-resolved luminescence quenching (TRLQ), however, it is the interaction of the probe with another added component, a quencher, that is studied. This method is dealt with here. For micellar systems, several publications have already discussed it in both experimental and theoretical detail [1-6]. 

Figure 1 Simplified reaction scheme for dynamic and static luminescence quenching. L denotes the probe molecule in the electronically ground state, L is the excited luminescer, and Q is a quencher molecule.

A MLC probe which intercalates Into double-helicsl DNA, [Ru(bpy)2(dppz)], where dppz is dipyrido-(3,2a 2, 3 -c]phenaziDB shown in Figure 20.14. This probe is quenched in water and is highly luminescent when bound to DNA. The emission spectrum of (Ru(bpy)2(dppz)] bound to calf thymus DNA is shown... 

There is a substantial literature indicating that fluorescence and phosphorescence behavior of many dyes are sensitive to various relaxation processes of the polymer matrices in which they are dissolved (17,18). Large scale motions of a probe couple to chain motions responsible for the glass transition and provide a measure of Tg. Smaller scale rotations can sense matrix chain motions responsible for more localized (3 or y) relaxation processes. It is also well known that diffusion of gasses in glassy polymers is also very sensitive to these relaxations. If this diffusion leads to luminescence quenching, one expects the emission intensity or decay time of a luminescent sensor to be sensitive to these relaxation processes. 

Some molecules or ions can function as quenchers and inhibit luminescence. Quenching, caused by interactions between the luminescent probe and a quencher, may be reversible or irreversible. Excimer formation is a case of reversible quenching. Some luminescent probes react, in the excited state, with an identical molecule in the ground state and form an excimer ... 

The first experiments characterizing DNA-mediated CT over a precisely defined distance between covalently appended redox probes were reported in 1993 [95]. Remarkably, the luminescence of a photoexcited Ru(II) intercala-tor was quenched by a Rh(III) intercalator fixed to the other end of a 15-mer DNA duplex over 40 A away (Fig. 4). Furthermore, non-intercalating, tethered Ru(II) and Rh(III) complexes did not undergo this quenching reaction. In this way the importance of intercalative stacking for efficient CT was demonstrated. 

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