Janus-Structured Poly(Lipoic Acid-co-Caffeic Acid) Patch for Asymmetric Underwater Adhesion in Sutureless Gastric...

Bioadhesives for internal organ repair suffer from weak underwater adhesion, poor mechanical compatibility and indiscriminate tissue adhesion. Herein, we report the synthesis of poly(lipoic acid-co-caffeic acid) (poly(LA-CA)) exhibiting tunable adhesive and mechanical properties according to the polymer configuration. By copolymerization of caffeic acid, thermal polymerization of lipoic acid yields branched copolymer of poly(LA-CA), which is viscous and highly adhesive in wet conditions, while radical polymerization initiated by ammonium persulphate produces elastic and non-adhesive linear poly(LA-CA). Robust asymmetrically adhesive Janus patch is then fabricated by coating a branched poly(LA-CA) layer on a linear copolymer substrate. The patch demonstrates combined performances, particularly showing universal, tough, and sustained adhesion in various environments, together with antioxidant, anti-inflammatory and antibacterial properties. Using the Janus poly(LA-CA) patch, gastric perforations of as large as 1 cm in diameter are cured in Bama miniature pigs without suturing. The sutureless treatment simultaneously prevents postoperative adhesion and gastric fluid leakage, resulting in 100% survival of the animals, superior to conventional suture repair method. The poly(LA-CA) material is promising for soft tissue injury repair with high clinical translation potential.