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 degrees 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.