Polyrotaxane Crosslinked Self-Healing Hydrogels for Switchable Bioadhesion

As an effective alternative to suture in wound closure, tissue adhesives often need to have excellent biocompatibility and suitable bioadhesion. To achieve long-term adhesion on moist tissue, polyrotaxane (PR) crosslinked self-healing hydrogels have been prepared by the introduction of dynamic borate bonds between PR bearing phenylboronic acid moieties (PR-PBA) and dopamine grafted poly(vinyl alcohol) (PVA-DOP). Synthesis of these precursor polymers PR-PBA and PVA-DOP is quite simple and the hydrogels combine dynamic borate bonds with the sliding motion of the phenylboronic acid moieties on PR. The sliding nature of the crosslinking points along the axle in the PR is thought to enhance the mechanical properties and adhesion ability of the resultant hydrogels. Meanwhile, catechol groups on dopamine units have been protected by borate bonds under alkaline conditions to avoid oxidation, and they then are released to react with various functional groups on tissue surface to ensure the switchable tissue adhesion. The self-healing test and adhesion of hydrogels on pigskin demonstrate the ability to restore the original performance after repeated strain cycles and maintain strong tissue adhesion. The components of these hydrogels have satisfying biocompatibility. These results indicate that these self-healing hydrogels have great potentials in tissue adhesion.