A Janus Hydrogel Wet Adhesive for Internal Tissue Repair and Anti‐Postoperative Adhesion

Abstract

Despite rapid development of adhesive hydrogels, the typical double-sided adhesives fail to adhere to wet tissues and concurrently prevent postoperative tissue adhesion, thus severely limiting their applications in repair of internal tissues. Herein, a negatively charged carboxyl-containing hydrogel is gradiently, electrostatically complexed with a cationic oligosaccharide by a one-sided dipping method to form a novel Janus hydrogel wet adhesive whose two-side faces demonstrate strikingly distinct adhesive and nonadhesive properties. The lightly complexed surface demonstrates instant robust adhesion to various wet biological tissues even under water since the phase separation induced by electrostatic complexation increases the hydrophobicity and water drainage capacity. Intriguingly, the highly complexed surface is non-adhesive due to complete neutralization of carboxyls in the hydrogels. The Janus hydrogel can be used to replace traditional sutures to treat gastric perforation of rabbits. Animal experiment outcomes reveal that one side of the Janus hydrogel is firmly glued to the stomach tissue, and other side facing outward can efficiently prevent the postoperative adhesion. Molecular simulation elucidates the importance for selecting cationic polymer species. It is believed that gradient polyelectrolyte complexation establish a new direction to create Janus adhesives for internal tissue/organ repair and simultaneous prevention of post-operative adhesion.

Recent progress in polymer hydrogel bioadhesives

“…At present, in addition to excellent adhesion properties, tissue adhesives used in clinics also need to prevent postoperative adhesions. Liu et al 115 used a one‐side dip coating method to electrostatically compound a negatively charged carboxyl‐containing hydrogel with cationic oligosaccharides in a gradient to form a novel poly( N ‐acryloyl 2‐glycine) cationic chitooligosaccharide Janus (PACG‐COS‐J) hydrogel wet adhesive that exhibited significantly different adhesive and non‐adhesive properties on each side. The lightly complexed surface exhibits instant firm adhesion to various wet biological tissues even under water, because the phase separation caused by electrostatic complexation increases hydrophobicity and drainage capacity.…”

Hydrogel tapes for fault-tolerant strong wet adhesion

“…After gradually forming covalent linkages, the hydrogel tapes show an increased adhesion strength of ~1268 J m -2 , outperforming many reported bioadhesives. [50][51][52][53][54][55] We further demonstrate the feasibility of using the hydrogel tapes as tissue sealants and adhesives for soft and implantable devices both in vitro and in vivo. Finally, we show that the hydrogel tapes are biocompatible, degradable and suitable for various biomedical applications.…”

A long-term retaining molecular coating for corneal regeneration

“…However, in the GelNB-4 treated group, there is an extra peak appearing at 400.0 eV. A large amount of C N bonds formed on the tissue after treatment with UV-activated GelNB-4 indicating that Schiff bases formed at the interface between GelNB-4 coating and tissue [ 43 ].…”