Thermoreversible Tissue Adhesion with Hydrogel Through a Topological Entanglement Approach

Achieving thermoreversible adhesion between hydrogel and living tissues in a facile way is challenging. Existing strategies bring difficulty to the chemical design and synthesis of hydrogels. Herein, an approach to achieve tough thermoreversible tissue adhesion with hydrogel is proposed, which uses a polymer solution with heat-induced sol-gel transition as the interfacial polymer matrix, with no chemical design required for the hydrogel network. When the interfacial polymer matrix is introduced to the interface of the hydrogel and living tissues, it can gelate in situ within the substrate networks under a temperature stimulus, and topologically entangle with the preexisting networks of the substrates, which generates a strong adhesion. By triggering with another temperature stimulus, the newly formed network dissociates to realize an easy detachment. Thermoreversible adhesion is demonstrated between polyacrylamide hydrogel and various porcine tissues as examples, and the mechanism of this adhesion strategy is studied by varying various influence factors. A theoretical model that can fit and predict the effects of different parameters on the adhesion energies is also established. This adhesion strategy based on topological entanglement among a thermoreversible polymer system and the substrates may broaden the achieving methods of thermoreversible tissue adhesion.