Surface Engineering of MXenes for Biomedical Uses: Functionalization Strategies and Application Trends

MXenes, a class of 2-dimensional transition metal carbides and nitrides, have emerged as highly versatile materials in the biomedical field because of their high electrical conductivity, hydrophilicity, large surface-area-to-mass ratio, and compositional versatility. Despite their promise, the inherent instability in physiological environments, lack of inherent biological activity, and potential toxicity remain major challenges limiting their biomedical applications. To address these issues, a wide range of surface engineering strategies have been developed, including covalent and noncovalent functionalization with various biomolecules, biomedical polymers, and nanomaterials. Specifically, the surface modification of MXene is intended to improve biostability and biocompatibility, and confer specific biological functions for applications in tissue engineering, biosensing, antibacterial therapy, and multimodal bioimaging. This review provides a comprehensive overview of the recent advances in MXene functionalization in the biomedical field. Based on their mechanisms and biomedical functions, we categorized the functionalization strategies and proposed key design principles for the development of next-generation MXene-based therapeutic and diagnostic platforms.