The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Chemical Technology for public examination and debate in Auditorium Ke 2 at Helsinki University of Technology (Espoo, Finland) on the 21st of April, 2006, at 12 noon.
Overview in PDF format (ISBN 951-22-8107-4) [1316 KB]
Dissertation is also available in print (ISBN 951-22-8106-6)
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.
This thesis consists of an overview and of the following 10 publications:
Keywords: electrochemiluminescence, chemiluminescence, label, bioaffinity, hot electron
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© 2006 Helsinki University of Technology