Green and sustainable hydrogels based on quaternized chitosan to enhance wound healing

Hydrogel-based biomaterials applied as wound dressings provide the wound with a moist environment, which facilitates tissue regeneration through granulation and re-epithelialization. The inherent flexibility and adjustable architecture of hydrogels enables incorporation of cells, antimicrobial drugs, growth factors, and bioactive compounds, which leads to expediting wound contraction and enhancing the regeneration process. The utilization of natural polysaccharides, particularly chitosan, as a green and one of the most sustainable biomaterials among renewable resources, has been widely practised in wound healing because of its promising costeffectiveness, biocompatibility, and biodegradability. However, the challenge of limited solubility of chitosan at neutral or basic media (pH >= 6.5) has been pinpointed. The exploration of quaternary chitosan hydrogels was a big step to combat its low solubility through the contribution of a quaternary ammonium group that improves the hydrophilicity and additionally brings about antibacterial activity over a wide range of pH. This review summarizes the latest progress in using hydrogel dressings based on quaternized chitosan for wound regeneration, encompassing various aspects such as hemostasis, antibacterial activity, antioxidant properties, and overall wound healing efficacy. Furthermore, the present review addresses the existing challenges and proposes possible solutions to enlarge development avenues in pursue of optimizing wound regeneration performance of quaternized chitosan-based hydrogels in prospect.