Orchestrating Asymmetric Surface Functionalities on Hydrogel Stamps where Adhesion Meets Lubrication

Bioadhesives applied on human organs are promising softimplantsfor interventional diagnostics and therapeutics. However, the conventionalbioadhesive interfaces on organs typically lack apical-basalpolarity to resemble the surface functions of original organ epithelia.To overcome the bioadhesive-induced dysfunction on treated organs,we have developed an innovative strategy via engineering asymmetricsurface functionalities on a tough yet biodegradable polysaccharide-peptide-derivedhydrogel platform, mimicking the functions of a ciliated columnarepithelium enabled by its adhesive basal surface and defensive apicalciliated surface. The resulting hydrogel bioadhesive serves as a "stamp"with a polyacrylic acid-functionalized adhesive side, facilitatinginstant and robust adhesion on wet tissues within 1 min via body liquid-removingmechanisms and Ca2+-assisted complexation. The back sideis functionalized with hyaluronic acid, demonstrating an outstandingbiolubrication performance (coefficient of friction of & SIM;0.038in the synovial fluid). The hydrogel stamp can also be integratedwith biosensing and drug encapsulation/release functions for diagnosticsand therapeutics. Our strategy devises a new path to simultaneouslyenable reliable wet tissue adhesion and reproduce the characteristicsof original tissues, with useful insights into designing bioactiveinterfaces for broad biomedical applications.