Injectable, Water-Reinforceable, and Antibacterial Tissue Adhesive with Underwater Bioadhesion Capability

It is challenging for adhesives to adhere to tissues covered with body fluids as the hydration layer hinders adhesive/tissue interfacial interactions. Marine creature mussels can firmly adhere to underwater reefs by the coacervate adhesive composed of mussel foot proteins (Mfps). Inspired by these water-reinforceable Mfps extruded from byssus, an injectable and water-reinforceable tissue adhesive (WrITA) was developed in this work. It is composed of poly(acrylic acid-co-N-vinylpyrrolidone) (poly(AAc-co-NVP)), tannic acid conjugated poly(lipoic acid) (TA-c-PLA), and polyethylenimine. Upon contacting with water, hydrophobic PLA chains of TA-c-PLA in WrITA formed a self-associated cross-linking point, which induced contraction of the poly(AAc-co-NVP) network due to multiple hydrogen bonds between TA and poly(AAc-co-NVP) chains. In this process, the cohesive strength of the adhesive was enhanced, which could provide a tough base for durable underwater tissue adhesion. In underwater adhesion, the hydrophobic PLA chains could evict interfacial water to facilitate the interfacial adhesion via electrostatic interactions and hydrogen bonds. WrITA could form tight adhesion to the tissue in minutes. Its lap-shear adhesion strength reached 87 kPa after 3 min of curing but increased and remained at 100 kPa after 3 h on porcine skin underwater. In addition, its bursting pressure on porcine skin was up to 1912 mmHg. In addition to the strong underwater tissue adhesion, it also had superior antibacterial and antioxidant activity, as well as cytocompatibility. The easy-to-use and safe WrITA may meet the need for quick deployment underwater in diverse biomedical applications.