Glucose Oxidase/Egg White Protein Microparticles with a Redox Mediator for Glucose Biosensors on a Screen-Printed Electrode and a Decomposable Electrode.

Glucose oxidase (GOx) is a typical model enzyme used to create biosensors. Exploring a strategy to prepare ready-to-use functional enzymatic microparticles combining GOx and food-based proteins offers compelling advantages. However, no reports exist on the integration of egg white materials to synthesize functional biorecognition particles with glucose oxidation catalytic functions for electrochemical biosensors. Here, we demonstrate functional microparticles combining egg white proteins, GOx, and 9,10-phenanthrenequinone (PQ). The egg white proteins crosslink to form three-dimensional scaffolds to accommodate GOx and redox molecules. The PQ mediator enhances electron transfer between the electrode surface and the GOx enzyme's flavin adenine dinucleotides. The functional microparticles are directly applied to the printed electrode. The performance of these microparticles is evaluated using a screen-printed carbon nanotube (CNT)-modified electrode coated with GOx/PQ/egg white protein microparticles. The analytical performance of the system exhibits a linear range of 0.125-40 mM, with a maximum current (Imax) and a Michaelis-Menten constant (Km) being 0.2 µA and 4.6 mM, respectively. Additionally, a decomposable electrode composed of CNTs and edible oil conjugated with functional enzyme microparticles is shown to undergo degradation under gastric conditions. Utilizing food-based proteins to accommodate enzymes and to create redox-active microparticles for catalyzing glucose oxidation offers advantages in developing affordable and degradable bioelectrodes. This concept holds promise for advancing biocompatible electrodes in biosensor and bioelectronics applications.

Redox-Mediated Gold Nanoparticles with Glucose Oxidase and Egg White Proteins for Printed Biosensors and Biofuel Cells.

Glucose oxidase (GOx)-based electrodes are important for bioelectronics, such as glucose sensors. It is challenging to effectively link GOx with nanomaterial-modified electrodes while preserving enzyme activity in a biocompatible environment. To date, no reports have used biocompatible food-based materials, such as egg white proteins, combined with GOx, redox molecules, and nanoparticles to create the biorecognition layer for biosensors and biofuel cells. This article demonstrates the interface of GOx integrated with egg white proteins on a 5 nm gold nanoparticle (AuNP) functionalized with a 1,4-naphthoquinone (NQ) and conjugated with a screen-printed flexible conductive carbon nanotube (CNT)-modified electrode. Egg white proteins containing ovalbumin can form three-dimensional scaffolds to accommodate immobilized enzymes and adjust the analytical performance. The structure of this biointerface prevents the escape of enzymes and provides a suitable microenvironment for the effective reaction. The bioelectrode's performance and kinetics were evaluated. Using redox-mediated molecules with the AuNPs and the three-dimensional matrix made of egg white proteins improves the transfer of electrons between the electrode and the redox center. By engineering the layer of egg white proteins on the GOx-NQ-AuNPs-mediated CNT-functionalized electrodes, we can modulate analytical performances such as sensitivity and linear range. The bioelectrodes demonstrate high sensitivity and can prolong the stability by more than 85% after 6 h of continuous operation. The use of food-based proteins with redox molecule-modified AuNPs and printed electrodes demonstrates advantages for biosensors and energy devices due to their small size, large surface area, and ease of modification. This concept holds a promise for creating biocompatible electrodes for biosensors and self-sustaining energy devices.