Polymer-engineered MXenes for electrochemical sensors and biosensing

Two-dimensional (2D) MXenes have rapidly emerged as one of the most promising materials for electrochemical sensors and biosensors owing to their high electrical conductivity, hydrophilic surfaces, large specific surface area, and versatile surface chemistry. However, their practical implementation remains limited by rapid oxidation, interlayer restacking, chemical instability, biofouling, and insufficient long-term operational reliability. Polymer engineering has appeared more than just a simple stabilization strategy, by tailoring MXene interfaces, regulating charge transport, enhancing structural stability, improving biomolecule immobilization, suppressing nonspecific adsorption, and optimizing electrochemical sensing performance. This review establishes a polymer-engineering framework that correlates polymer design, interface engineering, physicochemical properties, sensing mechanisms, device performance, and practical implementation through structure–property–performance relationships. Polymer integration strategies, i.e ., physical blending, surface functionalization, in situ and ex situ polymerization, layer-by-layer (LBL) assembly, and electrospinning are critically compared together with the functional roles of conductive, biocompatible, antifouling, molecularly imprinted, redox-active, and stimuli-responsive polymers. The review further evaluates advantages, limitations, and application-specific trade-offs associated with these engineering strategies across biomedical diagnostics, environmental monitoring, food safety, wearable and implantable devices, point-of-care systems, and advanced integrated sensing platforms. Finally, the remaining challenges associated with long-term stability, reproducibility, standardization, scalable manufacturing, clinical validation, and commercialization are critically discussed, and future opportunities are highlighted to provide a practical roadmap for the rational design and translation of next-generation polymer-engineered MXene electrochemical sensors and biosensors.