Chitosan, a renewable, non-toxic, and natural cationic polyelectrolyte, can be combined with many anionic polyelectrolytes (such as sodium alginate, hyaluronic acid, xylan, and gelatin) via electrostatic forces to form chitosan-based polyelectrolyte composites under certain conditions. This review summarizes various methods of preparing chitosan-based polyelectrolyte composites and analyzes their applications in clinical medicine and agriculture, as well as pharmaceutical, tissue, food, environmental, and textile engineering fields. The future development direction and potential of chitosan-based polyelectrolytes are also discussed.

Rapid control of heavy hemorrhaging is critical to save the life of injured individuals. Herein, we developed a novel hemostat employing chitosan-based microspheres, which was prepared by sequential microemulsion of chitosan solution, sol-gel phase transition, and surface modification by 3, 4-dihydroxyhydrocinnamic acid (HCA). HCA-modified chitosan microspheres (CSMS-HCA) displayed a porous structure, with a high specific surface area (~211.3 m²/g), accelerating their rapid absorption of blood and concentrating red cells and platelets. The CSMS-HCA exhibited much better in vitro and in vivo hemostatic efficacy than porous chitosan microspheres did. Such a rapid hemostat in the form of microspheres is highly effective in treating deep and irregular wounds, owing to easy accessibility to injured sites.