Orchestrating Asymmetric Surface Functionalities on Hydrogel Stamps where Adhesion Meets Lubrication

Bioadhesives applied on human organs are promising soft implants for interventional diagnostics and therapeutics. However, the conventional bioadhesive interfaces on organs typically lack apical-basal polarity 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 asymmetric surface functionalities on a tough yet biodegradable polysaccharide-peptide-derived hydrogel platform, mimicking the functions of a ciliated columnar epithelium enabled by its adhesive basal surface and defensive apical ciliated surface. The resulting hydrogel bioadhesive serves as a “stamp” with a polyacrylic acid-functionalized adhesive side, facilitating instant and robust adhesion on wet tissues within 1 min via body liquid-removing mechanisms and Ca²⁺-assisted complexation. The back side is functionalized with hyaluronic acid, demonstrating an outstanding biolubrication performance (coefficient of friction of ∼0.038 in the synovial fluid). The hydrogel stamp can also be integrated with biosensing and drug encapsulation/release functions for diagnostics and therapeutics. Our strategy devises a new path to simultaneously enable reliable wet tissue adhesion and reproduce the characteristics of original tissues, with useful insights into designing bioactive interfaces for broad biomedical applications.