Tough polyacrylamide-tannic acid-kaolin adhesive hydrogels for quick hemostatic application.

Adhesive hydrogels for wet and dynamic tissues are important for biomedical applications in order to withstand cyclic loading such as in the case of hemorrhaging control on the curved skins and heart tissues. However, the fabrication of hydrogels with strong mechanical properties, high adhesion strength, and hemostatic efficiency remains a big challenge. Inspired by the great adhesive behavior of mussels and Arion subfuscus, novel adhesive and hemostatic polyacrylamide-tannic acid-kaolin (PAAm-TA-KA) hydrogels were reported in this work. The hydrogels displayed high strength and toughness due to their physical and chemical crosslinking structures. The abundant catechol groups on tannic acid endow the hydrogels with strong and durable adhesion strength of up to 500 kPa on porcine skin. When applied onto human skin, the hydrogels could be easily peeled off without leaving any remains and causing any damages. The kaolin nanoparticles incorporated in the PAAm-TA-KA hydrogels not only served as a physical crosslinking agent, but an activator of the blood clotting factor FXII for accelerating the formation of thrombus. The strong tissue adhesion and blood coagulant potential of the PAAm-TA-KA hydrogels imparted them high hemostatic efficiency. The free-standing, adhesive, tough, cytocompatible, and hemostatic hydrogels are highly promising for traumatic bleeding control materials.