Physiologically-Regulated Adhesion of Hydrogels for Wound Dressing

Adhesion is an essential function of wound dressing materials, which allows the close contact with skin surface. However, the dressing replacement inevitably causes the secondary damage to unhealed wound. A wound dressing material having physiologically-regulated adhesion is thus expected to avert the secondary damage to patients. Herein, we report a hydrogel by covalently introducing cationic moieties into an elastic network. The cationic moieties are capable of electron-withdrawing that promotes a strong electrostatic interaction with polar groups of protein (high electron cloud density) from the wound skin tissue, enabling the adhesion of hydrogel on the skin surface. With the tissue metabolism, the nucleophilic skin surface forms a lipid layer that gradually destroys the electrostatic interaction and weakens the interfacial affinity. The adhesion energy can be reduced from 60 to <10 J/m 2 in seven days, so that the dressing material can be removed from the wound area without bringing in the secondary damage. The cationic moieties also endow the hydrogel a high water swelling ratio, reaching 25200%, making it capable of absorption of a large amount of tissue exudate. In addition, the cationic moieties have an antibacterial effect that can decrease the infection possibility of the wound. The in-vivo tests demonstrate that the wound on a mouse back reaches physiological 100% healing after the hydrogel dressing treatment for 12 days. All results show that the introduction of cationic moieties makes the hydrogel more promising as a wound dressing.