Highly sensitive biosensor for the hydrogen peroxide determination by enzymatic triggering and amplification

A biosensor showing submicromolar sensitivity to hydrogen peroxide was developed utilizing recombinant Coprinus cinereus peroxidase (rCiP) and pyrroloquinoline quinone (PQQ)-dependent glucose dehydrogenase (GDH). High sensitivity of the biosensor was achieved by triggering an initiator conversion with peroxidase following the signal amplification by cyclic conversion of the mediator formed. As an initiator 1-, 2-naphthol or guaiacol were used. The sensitivity of the biosensor was dependent on an electrode potential and on an initiator used. At the electrode potential 0.2 V the biosensor sensitivity reached 1.1 μA/(μM cm 2) in the presence of 20 mM of glucose and 10 μM of 1-naphthol. If 2-naphthol or guaiacol were used as the initiator the sensitivity of biosensor was 46 or 35% in comparison to 1-naphthol, respectively. The comparison of electrochemical conversion of the initiators and oxidized products with the potential dependence of the biosensor response permitted to hypothesize that peroxidase catalysed quinone-like compounds’ formation. The amplification of the biosensor response was achieved by cyclic mediator conversion during the action of GDH.