Peroxygenase based sensor for aromatic compounds

We report on the redox behaviour of the peroxygenase from Agrocybe aegerita (AaeAPO) which has been electrostatically immobilized in a matrix of chitosan-embedded gold nanoparticles on the surface of a glassy carbon electrode. AaeAPO contains a covalently bound heme-thiolate as the redox active group that exchanges directly electrons with the electrode via the gold nanoparticles. The formal potential E ° ′ of AaeAPO in the gold nanoparticles-chitosan film was estimated to be −(286 ± 9) mV at pH 7.0. The heterogeneous electron transfer rate constant (ks) increases from 3.7 in the scan rate range from 0.2 to 3.0 V s−1 and level off at 63.7 s−1.Furthermore, the peroxide-dependent hydroxylation of aromatic compounds was applied to develop a sensor for naphthalene and nitrophenol. The amperometric measurements of naphthalene are based on the indication of H2O2 consumption. For the chitosan-embedded gold nanoparticle system, the linear range extends from 4 to 40 μM naphthalene with a detection limit of 4.0 μM (S/N = 3) and repeatability of 5.7% for 40 μM naphthalene.