Characterization of graphite electrodes modified with laccases from Trametes hirsuta and Cerrena unicolor and their use for flow injection amperometric determination of some phenolic compounds

Abstract

Fungal laccases from Trametes hirsuta and Cerrena unicolor were immobilized on spectroscopic graphite electrodes using physical absorption. The laccase-modified graphite electrodes were mounted as the working electrodes into a wall jet flow through an electrochemical cell and then used for flow injection amperometric determination of different phenolic compounds of relevance both for environmental and clinical analysis. At optimum conditions for determination of catechol serving as a model compound, the output response signals of the laccase-modified electrodes were recorded as the result of injections of 50 μL of solutions with different phenolic substrates into the carrier citrate buffer solution with a working potential of −50 mV vs. Ag|AgCl. Statistical aspects were applied and the Michaelis–Menten constants evaluated were correlated to the chemical structure of the investigated phenolic compounds.

Keywords:

• Biosensors
• Flow injection
• Amperometry
• Laccase
• Phenols

Acknowledgements

The authors thank the Swedish Research Council (VR), the Swedish International Development Cooperation Agency (SIDA, 348-2003-4947) and the European Community (ICA2-CT-2000-10050) for financial support. The Swedish Institute (SI) is acknowledged for the support of a postdoctoral fellowship for B.H.