Highly Sensitive Amperometric Biosensors Based on Oxidases and CeCu Nanoparticles Coupled with Porous Gold

Metallic nanoparticles potentially have wide practical applications in various fields ofscience and industry. In biosensorics they usually act as catalysts (nanozymes, NZ) and/or mediators in electron transfer. In our present work we describe the development of amperometric biosensors (ABSs) based on oxidases and nanoparticles of CuCe (nCuCe). nCuCe was synthesized chemically from the correspondent salts and Na₂S as a reducing agent. nCuCe, being a very active peroxidase (PO) mimetic, was used here as a hydrogen peroxide sensing platform for oxidase-based ABSs. Using glucose oxidase (GO), alcohol oxidase (AO), methylamine oxidase (AMO), L-arginine oxidase (ArgO), and nCuCe as PO-like NZ (for GO, AO, AMO and ArgO-based ABSs) and as electro-active mediator (for laccase-based ABS), the biosensors on glucose, primary alcohols, methyl amine, L-arginine and catechol, respectively, were constructed and characterized. Enzymes were isolated from the correspondent over-producing cells according to the methods, proposed by the authors earlier. The developed mono-enzyme ABSs exhibited improved analytical characteristics in comparison with the correspondent bi-enzyme ABSs, which contained natural PO. Including electrodeposit nanoporous gold (npAu) in chemosensing layer on graphite electrode (GE), allows to additionally increase sensitivity of the constructed ABSs twice due to the increased and advanced surface. As an example, the bioelectrodes, containing laccase/GE, laccase/nCuCe/GE and laccase/nCuCe/npAu/GE had the sensitivities, respectively, 2300, 5055 and 9280 A·M⁻¹·m⁻². The proposed laccase-based ABSs were successfully tested on the samples of pharmaceuticals and food products for analysis of phenolic compounds.