Poly-o-aminophenol as laccase mediator and influence of enzyme on the polymer electrodeposition
|Barbara Pałys 1, Monika Marzec 1, Jerzy Rogalski 2|
1. Warsaw University, Department of Chemistry, Pasteura 1, Warsaw 02-093, Poland
Applicability of poly-o-aminophenol (POAP) as redox mediator for fungal laccase is investigated and compared with other conducting polymer matrices. Laccase has been entrapped by means of electrochemical polymerization carried out in the solution containing monomer and enzyme. The obtained layers have been characterized by cyclic voltammetry in deaerated and oxygen saturated solutions, as well as by spectroscopic methods. The activity of enzyme has been verified by the standard test using syringaldazine.
Laccase immobilized in POAP matrix catalyses oxygen reduction without any additional mediators. POAP is able to mediate the electron transfer between the enzyme active site and the electrode surface similarly to poly-o-phenylenediamine which has been studied previously . Similar electrocatalytic currents are observed, but the oxygen reduction potential is shifted by as much 0.4 V towards positive direction making POAP the promising candidate for application as material for bio-fuel cell cathodes.
The role of laccase in electrodeposition of POAP has been explored. It was found that the polymer layers obtained during the enzyme entrapment procedure are significantly thicker comparing to POAP layers obtained in absence of enzyme. Furthermore, laccase facilitates formation of longer polymer chains as revealed by UV/VIS absorption spectra. Raman experiments indicate that molecular structures of POAP layers electrodeposited with and without enzyme are similar.
The monomer belongs to typical laccase substrates. Addition of laccase to the o-aminophenol solution causes immediate formation of brownish soluble oligomers. After few hours brown precipitate becomes visible. The precipitate is composed from long polymer chains as revealed by spectroscopic results. POAP formed by laccase contains nanostructures. Its morphology differs from typical polymer samples synthesized chemically or electrochemically. Consequently, application of laccase as polymerization initiator might be manner of controlling the morphology of polymer samples.
 B. Palys, A. Bokun, J. Rogalski, Electrochim. Acta 52 (2007) 7075
Presentation: Short communication at SMCBS'2009 International Workshop, by Barbara Pałys
See On-line Journal of SMCBS'2009 International Workshop
Submitted: 2009-08-28 13:35 Revised: 2009-10-29 14:53