Cathodic Electrogenerated Chemiluminescence of Luminol at Disposable Oxide-Covered Aluminum Electrodes

Abstract

Luminol exhibits strong electrogenerated chemiluminescence during cathodic pulse polarization of oxide-covered aluminum electrodes in aqueous solution. This electrogenerated chemiluminescence can be enhanced by the presence of dissolved oxygen or by the addition of other coreactants such as hydrogen peroxide, peroxydisulfate, or peroxydiphosphate ions. However, luminol detection is most sensitive in the presence of azide ions, which not only enhance the electrogenerated chemiluminescence intensity but also decrease the intrinsic electroluminescence of the thin aluminum oxide film on the electrodes mainly producing the blank emission. The present method is based on tunnel emission of hot electrons into an aqueous electrolyte solution and allows the detection of luminol, isoluminol, and its derivatives below nanomolar concentration levels. The linear logarithmic calibration range covers several orders of magnitude of concentration of luminol or N-(6-aminohexyl)-N-ethylisoluminol. Therefore, the above-mentioned labeling substances can be used as one of several available alternatives of simultaneous markers in multiparameter bioaffinity assays at disposable oxide-covered aluminum electrodes. The main advantage of the present electrochemiluminescence generation method is that luminescent compounds having very different photophysics and chemistry can be simultaneously excited, thus providing good possibilities for internal standardization and multiparameter bioaffinity assays.

Heterogeneous oligonucleotide-hybridization assay based on hot electron-induced electrochemiluminescence of a rhodamine label at oxide-coated aluminum and silicon electrodes

“…Many common photoluminescent and chemiluminescent luminophores have been detected this way, examples including luminol and its derivatives [10,11], Ru(bpy) 3 2+ [12,13], fluorescein and eosin [14], SYBR (R) Green I [15], coumarine dyes [16], Rhodamine B [17] and terbium chelates [18,19]. The most sensitive HECL luminophores so far are terbium labels, which can be detected down to femtomolar concentration [18,19].…”

Cathodic electrochemiluminescence of lucigenin at disposable oxide-coated aluminum electrodes

“…In previous studies [22][23][24][25][26], we have demonstrated that many kinds of luminophores can be excited by cathodic pulse-polarization at conductor/insulator/electrolyte (C/I/E) tunnel junction electrodes e.g. oxide-coated aluminum, silicon and magnesium electrodes.…”

“…In practice, cathodic reductions may be produced simultaneously by heterogeneously transferred electrons from the bottom of the conduction band of the insulating film, via the surface states of the insulating film and by presolvated hot and hydrated electrons [25]. Meanwhile, strongly oxidizing species such as sulfate and hydroxyl radicals can be cathodically generated from purposely-added coreactants or form dissolved oxygen [22,23,25,33,34]. In addition, F + -centers existing in oxide film of C/I/E electrodes may act as oxidants [2,23,33].…”

“…General ECL excitation routes for luminophores based on our cathodic pulse polarization method have been observed to be reduction-initiated oxidative excitation (red-ox) or oxidation-initiated reductive excitation (ox-red) pathways in which the luminophores are excited by the cathodically generated species at the oxide film/electrolyte interface by successive one-electron transfer steps normally resulting in the luminophore in its original oxidation state but now in its singlet or triplet excited state [22][23][24][25][26]. However, sometimes the ECL mechanism is based on the decomposition of the luminophore [22].…”

Determination of Uric Acid by Chemiluminescence Measurement Using Tris(2,2'-bipyridine)ruthenium(II)-Octylphenylpolyglycol Ether System

“…Therefore, it is being widely used as a useful tool in a chemical analysis. Up to now, a continuous flow injection, [4][5][6][7][8][9][10][11][12] liquid chromatography [13][14][15][16][17] and capillary electrophoresis (CE) [18][19][20][21] have been mainly connected with the optical system. A very good selectivity and a very low detection limit could be accomplished with these kinds of connections.…”