[Research progress in the response mechanisms and applications of pH-responsive chitosan-based drug delivery systems]

The pH-responsive drug delivery systems represent a significant topic of intense research in precision medicine. As a natural amino polysaccharide, chitosan possesses excellent biocompatibility, degradability, and inherent pH-responsive properties, making it as an ideal carrier material for such systems. This paper systematically reviews the recent research progress in pH-responsive chitosan-based drug delivery systems. It begins by elucidating the influences of key parameters such as chitosan chemical structure, deacetylation degree, and molecular weight, and how they affect material properties. The pH-responsive mechanisms of both pure and its composite chitosan systems are then analyzed. Subsequently, the design concepts, preparation methods, and drug release characteristics of various carrier types, including nanoparticles, hydrogels, Pickering emulsions, and multifunctional composite systems, are summarized. Furthermore, their applications in intravenous targeted therapy, oral drug delivery, wound healing, and local treatment are outlined. Finally, current challenges hindering clinical translation are discussed with a particular focus on issues like insufficient in vivo stability and difficulties in large-scale production. This discussion provides a valuable reference for the optimized design and future clinical application of pH-responsive chitosan-based drug delivery systems.