Enhanced Mechanical Properties and Sensing Performance of MXene-Based Dual-Crosslinked Hydrogel via EGCG Coating and Dynamic Covalent Bond

Abstract

MXenes hold great promise for flexible sensors due to their outstanding electrical and mechanical properties. However, their practical application in aqueous environments is often compromised by oxidation susceptibility. Here, epigallocatechin gallate (EGCG), a naturally derived compound is introduced, as a protective coating for Ti₃C₂T_x MXene nanosheets. The catechol groups in EGCG form strong hydrogen bonds with MXene, significantly enhancing its oxidation resistance in aqueous environments for up to 40 days. By incorporating EGCG-coated MXene (MXene@EGCG) to form a dual-crosslinked hybrid network, a tough hydrogel with exceptional properties, including enhanced compressibility (>95%), high compressive strength (5.43 MPa), minimal residual strain (<1%), and rapid recovery within seconds is developed. Furthermore, the hydrogel exhibits superior sensing capabilities with a compressive gauge factor exceeding 10 and a stretch gauge factor of up to 3.72. This well-designed structure also endows it a low degree of hysteresis in compressive sensing. In vitro experiments confirm its great biocompatibility, desired self-adhesion properties, and practical utility as a sensing platform. This approach pioneers a versatile and transformative strategy for enhancing MXene stability and engineerability, unlocking new possibilities for fabricating high-performance hydrogel-based sensors capable of effectively sensing dynamic strains, which may find broad applications in the fields of multifunctional bioelectronics.