Time-resolved luminescence

A large body of very fine work is being performed by flie group of D. Parker at Durham University on luminescent cyclen derivatives with two major aims. One is the design of responsive ratiometric probes for the determination of several analytes, including pH, O2 and various anions within the frame of luminescent time-resolved immunoassays [134]. In this context, a rapid and reliable analytical method enabling the measurement of citrate in seminal fluids has been vahdated citrate is a key metabohte the concentration of which falls by up to a factor of ten in individuals having prostate cancer [135]. 

U. Lemmer. R. F. Malm, Y. Wada, A. Greiner, H. Basslcv. E.O. Gobel, Time resolved luminescence study of recombination processes in electroluminescent polymers, Appl. Phys. Lett. 1993, 62, 2827. 

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]. 

In the mechanism of an interfacial catalysis, the structure and reactivity of the interfacial complex is very important, as well as those of the ligand itself. Recently, a powerful technique to measure the dynamic property of the interfacial complex was developed time resolved total reflection fluorometry. This technique was applied for the detection of the interfacial complex of Eu(lII), which was formed at the evanescent region of the interface when bathophenanthroline sulfate (bps) was added to the Eu(lII) with 2-thenoyl-trifuluoroacetone (Htta) extraction system [11]. The experimental observation of the double component luminescence decay profile showed the presence of dinuclear complex at the interface as illustrated in Scheme 5. The lifetime (31 /as) of the dinuclear complex was much shorter than the lifetime (98 /as) for an aqua-Eu(III) ion which has nine co-ordinating water molecules, because of a charge transfer deactivation. 

Parameters Radiometric proximity assays (SPA, Flashplate) Fluorescence polarization (FP) Time- resolved fluorescence (HTRF) Amplified luminescence (ALPHAScreen) Enzyme (p-galactosidase) complementation Electrochemilumines cence... 

Charbonniere LJ, Hildebrandt N, Ziessel RF, Lohmannsroben HG (2006) Lanthanides to quantum dots resonance energy transfer in time-resolved fluoro-immunoassays and luminescence microscopy. J Am Chem Soc 128 12800-12809... 

Figure 17 Experimental setup for time-resolved luminescence microscopy with lanthanide ions.

Marriott, G., Heidecker, M., Diamandis, E. P. and Yan-Marriott, Y. (1994). Time-resolved delayed luminescence image microscopy using an europium ion chelate complex. Biophys. J. 67, 957-65. 

Different lanthanide metals also produce different emission spectrums and different intensities of luminescence at their emission maximums. Therefore, the relative sensitivity of time-resolved fluorescence also is dependent on the particular lanthanide element complexed in the chelate. The most popular metals along with the order of brightness for lanthanide chelate fluorescence are europium(III) > terbium(III) > samarium(III) > dysprosium(III). For instance, Huhtinen et al. (2005) found that lanthanide chelate nanoparticles used in the detection of human prostate antigen produced relative signals for detection using europium, terbium, samarium, and dysprosium of approximately 1.0 0.67 0.16 0.01, respectively. The emission... 

Lanthanide chelates also can be used in FRET applications with other fluorescent probes and labels (Figure 9.51). In this application, the time-resolved (TR) nature of lanthanide luminescent measurements can be combined with the ability to tune the emission characteristics through energy transfer to an organic fluor (Comley, 2006). TR-FRET, as it is called, is a powerful method to develop rapid assays with low background fluorescence and high sensitivity, which can equal the detection capability of enzyme assays (Selvin, 2000). 

H. Harma, T. Soukka, S.Lonnberg, J. Paukkunen, P. Tarkkinen, and T. Lovgren, Zeptomole detection sensitivity of prostate-specific antigen in a rapid microtitre plate assay using time-resolved fluorescence. Luminescence 15, 351-355 (2000). 

A similarly wide choice of lumophores can be found within photophysics and photochemistry.191 The excitation (or absorption) and emission bands of luminescence come in a variety of wavelength positions, intensities and shapes. Another parameter, which is gaining in popularity among designers, is the luminescence lifetime. Time-resolved observation is a neat way of dissecting out the response of the luminescent device from the emissive noise of real-life matrices. Photostability of lumophores is a parameter which perhaps deserves more attention as more and more demanding applications are being tackled. 

R. Hidayat, S. Tatsuhara, D.W. Kim, M. Ozaki, K. Yoshino, M. Teraguchi, and T. Masuda, Time-resolved study of luminescence in highly luminescent disubstituted polyacetylene and its blend with poorly luminescent monosubstituted polyacetylene, Phys. Rev. B, 61 10167-10173, 2000 and references therein. 

Molecular Studies on Laser Ablation Processes of Polymeric Materials by Time-Resolved Luminescence Spectroscopy... 

Pulse radiolysis, using as time-resolved detection methods optical absorption, luminescence, electrical conductivity or electron spin resonance can be expected to give information on the formation of transient or permanent radiation products and on their movement. 

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