Adaptive Control in Lubrication, Adhesion, and Hemostasis by Chitosan-Catechol-pNIPAM

Bio-inspired wet adhesives attract considerable attention in the biomedical field. However, achieving reversible and controllable wet adhesion still remains a challenging issue. In this study, we report a new thermo-responsive polysaccharide wet adhesive conjugate named Chitosan–Catechol–poly(N-isopropyl acrylamide) (Chitosan–Catechol–pNIPAM), where catechol, the wet adhesive moiety, and pNIPAM, the thermal responsive group, are chemically tethered to a chitosan backbone. The as-synthesized Chitosan–Catechol–pNIPAM presents a reversible sol–gel transition behavior when the temperature is cycled below and above the lower critical solution temperature (LCST, 35 °C), along with dynamic switching between lubrication and wet adhesion on various materials. Based on these excellent features, Chitosan–Catechol–pNIPAM can realize controllable attachment/detachment behavior over the skin through heating/cooling processes. Due to its good biocompatibility, the Chitosan–Catechol–pNIPAM coated syringe needles exhibit instant hemostasis after removing the needles from the punctured sites of mouse veins. Overall, the as-synthesized Chitosan–Catechol–pNIPAM is expected to be used as a new intelligent adhesive in various biomedical settings.