A Review on MXene and MXene-Based Composites for Advanced Biosensing and Bioimaging: Progress, Challenges, and Future Perspectives.

Recently, the growth of two-dimensional (2D) materials has opened innovative paths in nanobiotechnology, and MXenes have emerged as leading candidates owing to their superior physicochemical performance and functional adaptability. MXenes, a family of transition metal carbides, nitrides, and carbonitrides, reveal excellent electrical conductivity, large surface area, tuneable surface chemistry, hydrophilicity, and exceptional biocompatibility. These unique features make them highly attractive for biosensing and bioimaging applications. This review systematically abridges the recent advancements in MXene and its composites for biosensor development, containing electrochemical, optical, wearable, and flexible biosensors for the revealing of biomolecules, pathogens, cancer biomarkers, and glucose. The role of surface functionalization, hybridization with polymers, metal nanoparticles, carbon-based nanomaterials, and biomolecules in enhancing sensitivity, selectivity, and stability is critically deliberated. Moreover, the application of MXene composites in bioimaging approaches such as fluorescence imaging, photoacoustic imaging, magnetic resonance imaging (MRI), and multimodal imaging is explored, emphasizing their photothermal conversion efficiency and contrast development competences. Various challenges associated with long-term stability, oxidation resistance, toxicity, and large-scale production were also addressed, along with future perspectives for clinical translation and next-generation smart biomedical platforms. Overall, MXene-based materials clamp significant potential to transform biosensing and bioimaging techniques via multifunctional and integrated diagnostic systems.