Mxene-Based Glucose Biosensor: Strong Dependence of Exfoliation Method on Performance

Abstract

Over the last few years, the class of 2D materials has been expanded by a novel and uprising collection of early transition metal carbides known as MXenes. MXenes are synthesized via the selective etching of ‘A’ layers from their layered, ternary parent compounds, MAX phases, whereby M corresponds to early d-transition metal, A denoting a Group 13 or 14 main group sp-element, and X being either carbon or nitrogen. MXenes uniquely combine the metallic-like conductivity acquired from their parent counterparts, MAX phases and the hydrophilic nature of their surface terminating functional groups. The outstanding mechanical, chemical, physical and electrical properties of MXenes make them promising candidates for a myriad of applications, such as supercapacitors, catalysts and sensors. Inspired by the remarkable properties proffered by MXenes, we set forth to probe the feasibility of integrating MXene into a second-generation electrochemical glucose biosensor. Herein, MXenes were synthesized from their parent Ti3AlC2 MAX phase through two routes; (1) etching with 40% hydrofluoric acid (HF) (2) etching with 40% HF followed by subsequent delamination with 40% TBAOH, named Ti3C2-HF and Ti3C2-HF/TBA respectively. The heterogeneous electron transfer (HET) capabilities of these materials were examined and the superior material with the smallest peak-to-peak separation, pristine Ti3C2-HF/TBA, was then utilized to develop a glucose biosensor. Chronoamperometric measurements performed show that the proposed biosensing system displays high selectivity and remarkable electrocatalytic activity towards the detection of glucose. The glucose detection range spans over wide linear ranges of 50-27,750 µM and the proposed biosensor possesses a low limit of detection of 23.0 μM. The findings reported herein conceptually proves that pristine MXenes could be applied towards the development of biosensors and pave ways for future developments of highly selective and sensitive electrochemical biosensors for biomedical and food sampling applications.