Laser-Induced Graphene Arrays-Based Three-Phase Interface Enzyme Electrode for Reliable Bioassays

Abstract

Electrochemical oxidase biosensors have been widely applied in healthcare, environmental measurements and the biomedical field. However, the low and fluctuant oxygen levels in solution and the high anodic detection potentially restrict the assay accuracy. To address these problems, in this work, we constructed a three-phase interface enzyme electrode by sequentially immobilizing H2O2 electrocatalysts and an oxidase layer on a superhydrophobic laser-induced graphene (LIG) array substrate. The LIG-based enzyme electrode possesses a solid–liquid–air three-phase interface where constant and sufficient oxygen can be supplied from the air phase to the enzymatic reaction zone, which enhances and stabilizes the oxidase kinetics. We discovered that the enzymatic reaction rate is 21.2-fold improved over that of a solid–liquid diphase system where oxygen is supplied from the liquid phase, leading to a 60-times wider linear detection range. Moreover, the three-phase enzyme electrode can employ a cathodic measuring principle for oxidase catalytic product H2O2 detection, which could minimize interferences arising from oxidizable molecules in biofluids and increase the detection selectivity. This work provides a simple and promising approach to the design and construction of high-performance bioassay systems.

Laser-Scribed Graphene for Human Health Monitoring: From Biophysical Sensing to Biochemical Sensing

“…LSG-based electrochemical enzymatic biosensors have garnered widespread attention for their excellent specificity and capability for real-time and continuous monitoring. The reaction occurs between the substrate molecule and the immobilized enzyme, facilitating electron exchange with the LSG electrode and generating a measurable current signal ( Figure 8 A) [ 62 ]. LSG serves as an ideal carrier material because its porous 3D interconnected network structure enhances electron transfer behavior by providing a large surface area and shortening the diffusion distance of substrate molecules within the interior of the electrode.…”

Laser-induced graphene trending in biosensors: understanding electrode shelf-life of this highly porous material

“…However, we implicitly followed the uncontroversial assumption that electrochemical sensors benefit from high wettability. However, the lab of Feng Xinjian is experienced with hydrophobic electrodes and recently created an enzyme sensor based on superhydrophobic LIG [ 41 ]. Higher oxygen supply from air pockets inside the hydrophobic LIG resulted in a 20 times higher reaction rate of the oxidase enzyme and 60 times wider linear detection range of their H 2 O 2 sensor.…”

Engineering a Hollow Carbon Sphere‐Based Triphase Microenvironment for Enhanced Enzymatic Reaction Kinetics and Bioassay Performance

“…To resolve the oxygen deficiency issue, substantial efforts have been devoted to constructing oxygen-rich biosensors with solid-liquid-air triphase interfaces based on superhydrophobic substrates such as carbon paper, [12,13] metaloxide semiconductor nanowire arrays, [14][15][16] polymer matrix, [17] and so on. [18,19] Nevertheless, the construction of these triphase enzymatic reaction interfaces involves just loading the oxidase layer onto the superhydrophobic substrates, resulting in a two-dimensional solid-liquid-air triphase interface. Due to the restricted triphase contact area at such a plane boundary, the oxidase-catalyzed reaction kinetics can be boosted only in the outermost portion of the oxidase layer, while the bulk of oxidase away from the gas phase is still oxygen deficient due to the sluggish diffusion of oxygen.…”