Bis(2,2'-bipyridil)Copper(II) Chloride Complex: Tyrosinase Biomimetic Catalyst or Redox Mediator?

Milan Sýs,Miroslav Novák,Granit Jashari,Amir M Ashrafi,Lukáš Richtera,Vojtěch Adam,Atripan Mukherjee

doi:10.3390/ma14010113

Abstract

In this article, construction of amperometric sensor(s) based on screen-printed carbon electrodes covered by thin layers of two types of carbon nanomaterials serving as amplifiers, and containing [Cu(bipy)2Cl]Cl∙5H2O complex is reported. Their performance and biomimetic activity towards two selected neurotransmitters (dopamine and serotonin) was studied mainly using flow injection analysis (FIA). The important parameters of FIA such as working potential, flow rate, and pH were optimized. The mechanism of the catalytic activity is explained and experimentally confirmed. It reveals that presence of hydrogen peroxide plays a crucial role which leads to answer the title question: can presented complex really be considered as a tyrosinase biomimetic catalyst or only as a redox mediator?

Highlights

IntroductionTransition metals play the key role in several biological processes including electron transfer, and catalysis as the active site of the proteins and enzymes [4]
Jashari, G.; Adam, V.; Ashrafi, A.M.; Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Department of Chemistry and Biochemistry, Mendel University in Brno, CZ-613 00 Brno, Czech Republic; Central European Institute of Technology, Brno University of Technology, 612 00 Brno, Czech Republic
multi-walled carbon nanotubes (MWCNTs) and Reduced graphene oxide (rGO) can be defined as electrically conductive nanomaterials with large specific surface areas

Summary

Introduction

Transition metals play the key role in several biological processes including electron transfer, and catalysis as the active site of the proteins and enzymes [4]. Due to their catalytic properties, the metal complexes were used in modification of the electrodes applied in electroanalytical determinations, where reducing of the overpotential required for the reduction or oxidation of the target analyte is desired [5]. An analyte which is reduced (oxidized) slowly at the bare electrode at high magnitude of the cathodic (anodic) potential, undergoes electrochemical reduction (oxidation) at lower potential magnitude resulting in higher sensitivity and better selectivity [7,8]

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