Study on the enhancement of electrochemiluminescence of luminol-H2O2 system by sulphonated cobalt(II) phthalocyanine

The main aim of this paper is to explore a new label for electrochemiluminescence (ECL) bioassays. Tetra-substituted sulphonated cobalt(II) (CoTSPc) acting as a mimetic peroxidase of horseradish peroxidase was first found to be able to catalyze the ECL reaction of luminol-H2O2 at a glass carbon electrode. CoTSPc also retained its ECL catalytic activity when it was conjugated to BSA. Moreover, the enhanced ECL intensity of the luminol-H2O2 system at pH 7.4 was proportional to the amount of target bovine serum albumin (BSA). The spectrum characteristics of CoTSPc-BSA conjugate was examined. The effects of the pH, reaction medium of the solution, the concentration of luminal, H2O2 and the electrochemical scanning mode were also investigated. Although refinements in the technique are still necessary before it can be used in practice, a new ECL probe for protein, CoTSPc, has been preliminarily developed.