A Comprehensive Review on Chemically Modified Chitosan: Recent Advances in Multifaceted Applications and Future Perspectives

ABSTRACT Chitosan is a natural biopolymer derived from chitin, and it has received significant attention due to its remarkable physicochemical properties, biocompatibility, biodegradability, antioxidant, antimicrobial, and antimutagenic activity. In various fields such as biomedicine, agriculture, food packaging, water treatment, and cosmetics, this versatile polymer has found extensive applications. But it has some drawbacks related to solubility, stability, and functionality. To solve the problem of chitosan, novel modification techniques have expanded to make new derivatives like chitosan gallate, etc. In the biomedical domain, chitosan and its derivatives are widely utilized in drug delivery systems, wound healing, and tissue engineering due to their ability to enhance cell adhesion, proliferation, and controlled drug release. It also acts as an anticancer and antitumour agent. In the agriculture and food sector, it functions as an antimicrobial and film‐forming agent to improve food packaging, as well as to enhance shelf life and food safety. In water treatment, it acts as an effective adsorbent for heavy metals and dyes, addressing environmental concerns. Recent advancements in nanotechnology have further expanded the potential of chitosan and its derivatives by enabling the development of bionanocomposites and nanoparticles with improved functionality. This review critically examines the current state of research on chitosan and its novel derivatives, focusing on its synthesis, modification techniques, and multifaceted applications. Additionally, this review can provide valuable insights, promote innovation, and support the adoption of chitosan‐based applications in various industries, and ensure its contribution to science, sustainability, and technological advancement. Despite significant progress, challenges remain in standardization, in vivo validation, scalability, and long‐term safety assessment. Future research should focus on green synthesis routes, multifunctional nanoplatforms, and translational studies to accelerate the industrial and clinical adoption of chitosan‐based technologies.