Ti3C2Tx MXene/Graphene/AuNPs 3D porous composites for high sensitivity and fast response glucose biosensing

Glucose oxidase (GOx) is one of the typical enzymes widely used in glucose sensors. In recent years, novel nanomaterials have been developed to immobilize the enzyme, which is of great importance for the development of biosensors. Here we constructed 3D porous Ti3C2Tx MXene/Graphene/AuNPs (MGA) composites by a simple mixing-freeze-drying and self-reduction process. The abundant hydrophilic groups on the surface of Ti3C2Tx MXene nanosheets endow the MGA composites with highly hydrophilic microenvironment. The 3D porous composites provide a more open structure and promote the entry of GOx into the internal pores, which may enhance the stable immobilization and retention of GOx in the film. The unique electrocatalytic properties and synergistic effects between AuNPs and Ti3C2Tx MXene/Graphene are used to further enhance the electron transport in the 3D porous composites and reduce the redox potential. The MGA/GOx glucose sensor shows linear current in the range of glucose concentration from 2 μM to 0.4 mM and 0.4 mM to 6 mM, with sensitivities of 169.49 μA/(mM·cm2) and 34.13 μA/(mM·cm2) respectively, showing high sensitivity at low concentrations. The detection limit of glucose sensor reaches 2 μM and the response time is less than 3 s. This sensor can be applied to the detection of glucose in human sweat.