Electrochemiluminescence ECL

The model immunoassay is the enzyme-linked immunosorbent assay (ELISA) in which a non-specific capture antibody is bound to a surface, such as a multi-well plate or small tube [13]. In the basic form of ELISA, a second antibody tagged with an enzyme interacts specifically with the analyte. The enzyme assay produces a colored product that is read with a spectrophotometer. There are many variations on the basic immunoassay format that serve to increase sensitivity, specificity, linear range, and speed. Many commercial instruments have been developed to take advantage of various technologies for reporter molecules. The immunoassay may be coupled to an electronic sensor and transducer, such as a surface acoustical wave (SAW) sensor. Electrochemiluminescence (ECL) is a method in which the detector antibody is tagged with a ruthenium-containing chelate [13-15]. When the tag is... 

The most versatile technique for producing emission by the generation of ion radicals followed by their oxidation or reduction in situ is the electrochemical method. The emission produced by this technique has been termed electrochemiluminescence (ECL). Chemical oxidants and reductants have also been widely used, although their employment, especially in quantitative work, is more cumbersome. This review attempts to describe the current knowledge, both experimental and... 

Very recently, the electrochemiluminescent (ECL) response of ALP was studied in aqueous media in wide pH range (pH 2-13) using ignition (FI) analysis. It was revealed that ALP itself had no ECL activity but could greatly enhance the ECL of Ru(bpy)3 in alkaline media giving rise to a sensitive FI-ECL response <2006TAL1544>. 

ILs have been used in the CE-electrochemiluminescence (ECL) method to determine bioactive constituents in Chinese traditional medicine [58]. CE/Tris(2,2-bipyridyl) ruthenium(II) (Ru(bpy)3 +) ECL, CE-ECL, with an IL detection system was established to determine bioactive constituents in Chinese traditional medicine opium poppy, which contains large amounts of coexistent substances. Running buffer containing 25 mM borax-8 mM [C2CiIm][BF4] (pH 9.18) was used, which resulted in significant changes in separation selectivity and obvious enhancement in ECL intensities for those alkaloids with similar structures. Quantitative analysis of four alkaloids was... 

As described above, spectroelectrochemical methods are useful in studying the reactivity of radical anions and cations in non-aqueous solutions. Related to this, electrochemiluminescence (ECL), which is often caused by the reaction between radical... 

Peak Potentials, Estimated Lifetimes of Radical-Ions, and Electrochemiluminescence (ecl) Emission Data for Some Benzo[c]furans (in jV,JV -Dimethylformamide) ... 

Photonic electrochemistry, taken in its most general sense, involves the intimate interaction of light with electrochemical processes. Thus, piocesses in which illumination of the electrode-electrolyte interface produces charge-transfer events as well as electrochemical reactions that produce light as a product (electrochemiluminescence, ECL) fall in this category. A third related area is the elec-troanalytical detection of transient species formed by a photochemical process which takes place in solution. Techniques such as spectroelectrochemistry are excluded from consideration, since they utilize photons as a nonperturbing probe of purely electrochemical processes. 

CL detection can also be achieved using the electrochemical reaction. Therefore, this mode is called electrochemiluminescence (ECL). To date, two systems, which are the Ru(bpy)2+ (TBR) [725,726] and Ru(phen)2+ (TPR) [725], have been achieved on-chip. 

Academic and commercial interest in electrochemiluminescence = ECL gave a great impetus to research in elechtrochemically generated radical ions. The simplified scheme for ECL is shown by Eq. (240) ... 

The chapter has been structured into several sections first, there is a brief introduction, including a description of the concept and general principles of CL and how it is used in the field of explosives. The second section describes CL applications in the field of explosives and focuses in particular on the thermal energy analyser (TEA) because of its important role in the trace detection of explosives. The recent applications of luminol CL and electrochemiluminescence (ECL) to explosive detection are also described. Finally, because much of the research into explosive detectors has been directed towards civilian safety, a third section describes how CL is used as a security measure to detect explosives. 

Fig. 9. Enzyme electrochemiluminescence (ECL) immunoassay protocol, (a) Trinitrotoluene (TNT) and dini-trophenyl of haptenylated dextran compete for antibody-binding sites, (b) Antibodies attached to dextran bound to streptavidin-coated paramagnetic beads, (c) ECL detection of enzyme-labelled antibodies magnetically concentrated on electrode. Reprinted from Wilson et al. [68], Copyright (2003), with permission...

A slightly different application is where species produced electrochem-ically lead to photon emission in the visible spectrum, via the formation of organic radicals by homogeneous reaction from electrochemically generated precursors. The electrode controls the quantity of precursor, enabling quantitative parameters of the homogeneous reaction to be elucidated. This is known as electrogenerated chemiluminescence or electrochemiluminescence (ECL). 

Electrochemiluminescence (ECL) is a homogeneous, bead-based technology using the Origen platform. ECL utilises ruthenium chelates conjugated to an... 

Andrzej Kapturkiewicz gives a thorough account on the theory of electron transfer reactions that lead to electrochemiluminescence (ECL). He discusses in detail the conditions under which the Marcus theory can give a more quantitative description of ECL processes. 

It may be that ultrasonic enhancement of mass transport sweeps the intermediate radicals that have escaped the electrode back to the electrode surface where they are further oxidized, although this would depend upon radical lifetimes. Direct enhancement of the second electron transfer to give the cation while species remain in first contact with the electrode would be complicated by the decarboxylation step after the first electron transfer, and also by an observation of weak electrochemiluminescence (ECL) from the electrolysis cell in phenylacetate electrooxidation (see Section 5.2) [215]. This is enhanced by ultrasound, as are a number of other ECL systems. This suggests that at least a proportion of the reaction pathway involves benzyl radicals which escape the electrode, although the sonoelectrochemilumines-cence reaction conditions of low carboxylate concentration, low current density, and presence of electrolyte salt are different to those for the preparative electrolyses. 

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