Hot electron-induced electrochemiluminescence of calcein and calcein-Tb(III) complex at disposable oxide-covered aluminum and polyvinyl butyral-carbon black/metal composite electrodes in aqueous solutions

: Kalle Salminen, Päivi Grönroos, Harri Härmä, Sakari Kulmala

Publisher: PERGAMON-ELSEVIER SCIENCE LTD

: 2018

Electrochimica Acta

: ELECTROCHIMICA ACTA

: ELECTROCHIM ACTA

: 266

: 212

: 219

: 8

: 0013-4686

DOI: https://doi.org/10.1016/j.electacta.2018.02.016

Hot electron-induced electrochemiluminescence (HECL) of calcein and calcein-Tb(III) complex was generated at oxide-covered aluminum electrode during cathodic pulse polarization. The excitation of calcein as a molecule or as a ligand is based on subsequent one-electron oxidation and reduction steps by oxidizing radicals and solvated electrons. During HECL excitation of calcein-Tb(III) solution a reaction product of the calcein is formed that also enables the photoexcitation of Tb(III) via the formed ligand derivative by ligand-sensitized mechanism. The determination of low concentrations of calcein with aluminum electrodes was complicated by a relatively strong background electroluminescence originating from the Al2O3-layer. Polyvinyl butyral-carbon black composite electrodes coated on brass were fabricated to solve this problem and a fifty-fold lower background emission was obtained for these novel composite electrodes in comparison to that of oxide-covered 99.9% pure aluminum electrodes. The obtained detection limits were 3.2.10(-10) M for calcein and 6.4.10(-9) M for calcein-Tb(III) at the present composite electrodes. These species could potentially be utilized as electrochemiluminescent labels in bioaffinity assays. (C) 2018 Elsevier Ltd. All rights reserved.

Calcein, Carbon paste electrodes, Electrochemiluminescence, Hot electron electrochemistry, Lanthanide luminescence