Highly Porous 3D Gold Enhances Sensitivity of Amperometric Biosensors Based on Oxidases and CuCe Nanoparticles

Abstract

Metallic nanoparticles potentially have wide practical applications in various fields of science and industry. In biosensorics, they usually act as catalysts or nanozymes (NZs) and as mediators of electron transfer. We describe here the development of amperometric biosensors (ABSs) based on purified oxidases, synthesized nanoparticles of CuCe (nCuCe), and micro/nanoporous gold (pAu), which were electro-deposited on a graphite electrode (GE). As an effective peroxidase (PO)-like NZ, nCuCe was used here as a hydrogen-peroxide-sensing platform in ABSs that were based on glucose oxidase, alcohol oxidase, methylamine oxidase, and L-arginine oxidase. At the same time, nCuCe is an electroactive mediator and has been used in laccase-based ABSs. As a result, the ABSs we constructed and characterized were based on glucose, methanol, methyl amine, L-arginine, and catechol, respectively. The developed nCuCe-based ABSs exhibited improved analytical characteristics in comparison with the corresponding PO-based ABSs. Additionally, the presence of pAu, with its extremely advanced chemo-sensing surface layer, was shown to significantly increase the sensitivities of all constructed ABSs. As an example, the bioelectrodes containing laccase/GE, laccase/nCuCe/GE, and laccase/nCuCe/pAu/GE exhibited sensitivities to catechol at 2300, 5055, and 9280 A·M−1·m−2, respectively. We demonstrate here that pAu is an effective carrier of electroactive nanomaterials coupled with oxidases, which may be promising in biosensors.

Nanomaterials as Redox Mediators in Laccase-Based Amperometric Biosensors for Catechol Assay

“…All solutions were prepared using ultrapure water. Laccase from Trametes zonatus was purified and characterized as described by us earlier [ 18 , 19 ].…”

“…In our previous work, the screening of fungi and mushroom cultures for their capability to synthesize laccase was carried out, the best producers of laccase were selected, the optimal conditions were estimated for cell cultivation to achieve the highest productivity of these enzymes, and novel laccase-based amperometric biosensors (ABSs) were proposed [ 18 , 19 ].…”

“…Among many recent advanced detection platforms, laccase-based biosensors are superior for their rapid, effective, and online use by in situ devices for the determination of phenolic compounds [ 19 , 20 , 21 , 22 , 23 ]. In enzyme-based biosensors, immobilization methods play a significant role.…”

“…In enzyme-based biosensors, immobilization methods play a significant role. Future potential has been proposed for novel achievements in laccase immobilization techniques (entrapment, adsorption, cross-linking, and covalent) on new nanocomposites, including electroactive nanomaterials for laccase-based biosensors [ 19 , 23 ].…”

“…Numerous nanostructured carriers have been developed to advance traditional enzyme immobilization strategies, including carbon nanotubes, graphene and its derivatives, nanoparticles, nanoflowers, and metal-organic frameworks with unique properties. These platforms for enzyme immobilization have a high surface-to-volume ratio, high surface area, robust chemical and mechanical stability, surface pendant functional groups, and outstanding electrical characteristics, resulting in a higher concentration and stabilization of the immobilized enzyme [ 3 , 12 , 19 , 20 , 21 ].…”