Electrochemiluminescent and chemiluminescent labels for bioaffinity assays

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Doctoral thesis (article-based)
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100, [87]
TKK dissertations, 29
This thesis describes the electrochemiluminecence (ECL) of luminophores generated by cathodic pulse polarization of oxide film-coated electrodes in aqueous medium, and the chemiluminecence (CL) of luminophores induced by the dissolution of oxide film-covered aluminum or magnesium in appropriate aqueous medium. Their extremely sensitive ECL and CL signals allow these luminophores to be used as labels in bioaffinity assays, such as immunoassays and DNA probe assays in place of radioactive and enzymatic labels. In this work, the weight is on the exploration of usable electrochemiluminescent labels and electrochemiluminescence in general. Three types of luminophores were studied: organic luminophores, transition metal chelates, and lanthanide chelates. The ECL mechanisms of the luminophores were of interest. In principle, the tunnel emission of hot electrons into the aqueous electrolyte, which successively generate hydrated electrons, is the common initial step for ECL of all the studied luminophores. All of the present label molecules (except luminol) seem most efficiently to be excited by a route in which the label is first one-electron oxidized (or reduced) and the resulting radical is immediately reduced (or oxidized) by the primary or secondary radicals of the system. The ECL systems are characterized by the coreactant involved, the thickness of oxide film, and pH of the buffer solution. The hot electron-induced ECL excitation method provides a basis for time-resolved measurements. Thus, novel immunoassays and DNA-probe assays can be developed in which a combination of time-resolution and wavelength discrimination is applied in the simultaneous detection of several different labels. Some applications of immunoassays based on Tb(III) chelate labels and hot electron-excited ECL at insulating film-coated electrodes were demonstrated. The assays were reasonably sensitive and it was shown that it is possible to develop both non-competitive and competitive immunoassays based on the detection of hot electron-induced ECL of labels. ECL of organic luminophores and metal chelates with different characteristic emission properties can be induced by hot electron excitation method in aqueous medium. Present studies widen the choices for electrochemiluminescent and chemiluminescent labels in immunoassays.
electrochemiluminescence, chemiluminescence, label, bioaffinity, hot electron
Other note
  • J. Suomi, M. Håkansson, Q. Jiang, M. Kotiranta, M. Helin, A. J. Niskanen, S. Kulmala, Time-Resolved Detection of Electrochemiluminescence of Luminol, Analytica Chimica Acta, 541 (2005) 167-169. [article1.pdf] © 2005 Elsevier Science. By permission.
  • M. Helin, Q. Jiang, H. Ketamo, M. Håkansson, A.-M. Spehar, S. Kulmala, T. Ala-Kleme, Electrochemiluminescence of Coumarin Derivatives Induced by Injection of Hot Electrons into Aqueous Electrolyte Solution, Electrochimica Acta, 51 (2005) 725-730. [article2.pdf] © 2005 Elsevier Science. By permission.
  • Q. Jiang, A.-M. Spehar, M. Håkansson, J. Suomi, T. Ala-Kleme, S. Kulmala, Hot Electron-Induced Cathodic Electrochemiluminescence of Rhodamine B at Disposable Oxide-Coated Aluminum Electrodes, Electrochimica Acta, 51 (2006) 2706-2714. [article3.pdf] © 2006 Elsevier Science. By permission.
  • Q. Jiang, M. Håkansson, J. Suomi, T. Ala-Kleme, S. Kulmala, Cathodic Electrochemiluminescence of Lucigenin at Disposable Oxide-Coated Aluminum Electrodes, Journal of Electroanalytical Chemistry, accepted for publication. [article4.pdf] © 2006 by authors and © 2006 Elsevier Science. By permission.
  • Q. Jiang, J. Suomi, M. Håkansson, A. J. Niskanen, M. Kotiranta, S. Kulmala, Cathodic Electrogenerated Chemiluminescence of Ru(bpy)<sub>3</sub>2+ Chelate at Oxide-Coated Heavily Doped Silicon Electrodes, Analytica Chimica Acta, 541 (2005) 159-165. [article5.pdf] © 2005 Elsevier Science. By permission.
  • Q. Jiang, M. Kotiranta, K. Langel, J. Suomi, M. Håkansson, A.-M. Spehar, T. Ala-Kleme, J. Eskola, S. Kulmala, Ruthenium(II) Tris(2,2'-Bipyridine) Chelate as a Chemiluminophore in Extrinsic Lyoluminescences of Aluminium and Magnesium in Aqueous Solution, Analytica Chimica Acta, 541 (2005) 179-186. [article6.pdf] © 2005 Elsevier Science. By permission.
  • Q. Jiang, S. Sun, M. Håkansson, K. Langel, T. Ylinen, J. Suomi, S. Kulmala, Electrochemiluminescence and Chemiluminescence of a Carboxylic Acid Derivative of Ruthenium(II) Tris-(2,2'-Bipyridine) Chelate Synthesized for Labeling Purposes, Journal of Luminescence, 118 (2006) 265-271. [article7.pdf] © 2006 Elsevier Science. By permission.
  • Q. Jiang, M. Håkansson, A.-M. Spehar, J. Ahonen, T. Ala-Kleme, S. Kulmala, Hot Electron-Induced Time-Resolved Electrogenerated Chemiluminescence of a Europium(III) Label in Fully Aqueous Solutions, Analytica Chimica Acta, 558 (2006) 302-309. [article8.pdf] © 2006 Elsevier Science. By permission.
  • T. Ala-Kleme, S. Kulmala, Q. Jiang, Generation of Free Radicals and Electrochemiluminescence from Simple Aromatic Molecules in Aqueous Solutions, Luminescence, in press.
  • J. Eskola, P. Mäkinen, L. Oksa, K. Loikas, M. Nauma, Q. Jiang, M. Håkansson, J. Suomi, S. Kulmala, Competitive Immunoassay by Hot Electron-Induced Electrochemiluminescence Detection and Using a Semiautomatic Electrochemiluminometer, Journal of Luminescence, 118 (2006) 238-244. [article10.pdf] © 2006 Elsevier Science. By permission.
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