Recent progress on stimuli-responsive chitosan-based biomaterials as drug carriers

As a natural polysaccharide, chitosan has gained increasing attention as a versatile matrix for developing carriers in drug delivery due to its biocompatibility, biodegradability, and modifiable functional groups. Stimuli-responsive strategies have been extensively investigated to achieve controlled and on-demand drug release by exploiting pathological cues, exhibiting significant potential for precision medicine. This review summarizes recent advances in chitosan-based drug delivery carriers with diverse responsive mechanisms, including pH-, redox-, enzyme-, and reactive oxygen species-responsive systems, as well as multi-stimuli responsive platforms. The design principles, underlying mechanisms, and therapeutic outcomes of these systems are discussed. Finally, the review highlights the challenges that hinder clinical translation and outlines future directions to optimize chitosan-based delivery systems for precision medicine.