Amperometric Biosensors Based on Recombinant Bacterial Laccase CotA for Hydroquinone Determination

In this study, stable CotA laccase from Bacillus subtilis 168 was adsorbed on electrode modified with a thiol graphene-gold nanoparticle (thGP-AuNPs) nanocomposite film. The novel bacterial laccase biosensor was employed for quantitative detection of hydroquinone (HQ) and the electrochemical properties of this laccase biosensor were investigated. The results indicate that the immobilized CotA shows great oxidation activity towards HQ in the presence of oxygen and the biosensor shows linear electrocatalytic activity in the concentration range from 1.6 to 409.6 μM, with a detection limit of 0.3 μM. Further, the CotA modified electrode, when compared to fungal laccase-modified biosensors, shows better alkaline stability (retaining approximately 80 % and 70 % of response current at pH 8 and 9, respectively) and reusability (retaining ∼87 % of response current after 100 days). The development of this new kind of laccase on a biosensor will offer a novel tool for substance detection applications in hostile environments, especially for industrial pollutants.