Catalytic MXCeO for enzyme based electrochemical biosensors: Fabrication, characterization and application towards a wearable sweat biosensor.

Two-dimensional (2D) layered materials that integrate metallic conductivity, catalytic activity and the ability to stabilize biological receptors provide unique capabilities for designing electrochemical biosensors for large-scale detection and diagnostic applications. Herein, we report a multifunctional MXene-based 2D nanostructure decorated with enzyme mimetic cerium oxide nanoparticle (MXCeO) as a novel platform and catalytic amplifier for electrochemical biosensors, specifically targeting the detection of oxidase enzyme substrates. We demonstrate enhanced catalytic efficiency of the MXCeO for the reduction of hydrogen peroxide (HO) and its ability to immobilize oxidase enzymes, such as glucose oxidase, lactate oxidase and xanthine oxidase. The designed biosensors exhibit high selectivity, stability, and sensitivity, achieving detection limits of 0.8 μM HO, 0.49 μM glucose, 3.6 μM lactate and 1.7 μM hypoxanthine, when the MXCeO and their respective enzymes were used. The MXCeO was successfully incorporated into a wearable fabric demonstrating high sensitivity for lactate measurements in sweat. The unique combination of MXenes with CeO offers excellent conductivity, catalytic efficiency and enhanced enzyme loading, demonstrating potential of the MXCeO as a catalytically active material to boost efficiency of oxidase enzyme reactions. This design can be used as a general platform for increasing the sensitivity of enzyme based biosensors and advance the development of electrochemical biosensors for a variety of applications.