Functional Chitosan Nanocomposites for Enhanced Electrochemical Sensing: A Comprehensive Review

Chitosan has emerged as a multifunctional biopolymer widely exploited in electrochemical sensing due to its unique physicochemical properties, including biocompatibility, film-forming capacity, protonated amino groups, and strong affinity for metal ions and biomolecules. These intrinsic characteristics enable efficient electrode modification, enhanced analyte adsorption, and immobilization of enzymes, nanoparticles, and 2D materials. In recent years, integrating chitosan with conductive nanostructures, such as carbon nanomaterials, metal oxides, metallic nanoparticles, and layered 2D materials, has significantly enhanced sensor performance, providing high sensitivity, selectivity, stability, and low detection limits across a broad range of analytes. This review presents an updated overview of chitosan’s roles in electrochemical sensing, including its functionalization techniques, electron transfer mechanism, and analyte identification. Key applications, such as biomolecule detection, heavy-metal monitoring, environmental pollutant analysis, pharmaceuticals, and emerging wearable sensing platforms, are discussed. Finally, current challenges and future research directions are highlighted to support the development of next-generation chitosan-based electrochemical sensors.