Biowaste to biosensors: Comparative insights into chitosan-based nanocomposites for high-performance electrochemical...

Chitosan is a biopolymer, which can effectively use as an electrochemical sensing component, when combined with suitable nanomaterials. Its unique chemical structure, featuring amino and hydroxyl groups, enables effective filler dispersion, antifouling action, film-forming properties and analyte immobilization while offering sustainability. These distinct properties set chitosan apart from other polymers including cellulose, alginate, nafion, polyvinyl alcohol, and conducting polymers. This distinction makes chitosan an ideal matrix for synthesizing nanocomposites tailored for sensing applications. Percolation theory provides insight into the conductivity of nanocomposites formed by incorporating conductive fillers into insulating polymer matrix. The interplay between percolation theory and chitosan chain mobility provides valuable perception into the electrical properties of nanocomposite. This review explores the potential of chitosan-based nanocomposites in electrochemical sensing of diverse analytes, including biomolecules, heavy metal ions and pesticides. Begin with an overview of chemical structure of chitosan, the review discussing sources, properties and applications of chitosan. Further, specifically focused on the application of chitosan-based nanocomposite in electrochemical sensing. The review gives in depth discussion on chitosan-based nanocomposites and blends, classified based on the type of micro-/nano-reinforcing materials and conducting polymers. The promising micro-/nano-fillers, those showcasing their potential in electrochemical sensing including carbon-based nanomaterials, metal oxides, MXene, conducting polymers and metal organic frameworks (MOF) are discussed and compared their performance. Despite a plethora of reviews on chitosan as component in electrochemical sensing, a comprehensive overview of its applications in conjunction with diverse electroactive materials remain scarce. This tutorial review aims to bridge these gaps by presenting an integration of diverse fillers into chitosan and their capability on electrochemical detection of varieties of analytes for advanced biomedical, environmental and food processing applications.