Triple-crosslinked beta-cyclodextrin oligomer self-healing hydrogel showing high mechanical strength, enhanced stability and pH responsiveness

A novel self-healing hydrogel was prepared from a cationic beta-cyclodextrin oligomer allyl ether [C(beta CD-OM)AE] using a triple cross-linking strategy combining electrostatic interaction, host-guest complexation, and C-C bonds as the macrocrosslinker. Here, the C(beta CD-OM)AE@Ad gel was successfully prepared by polymerization of synthesized C(beta CD-OM)AE, 1-adamantyl acrylate, and acrylic acid. The triple cross-linked hydrogel shows multi-functionality of high mechanical strength, enhanced stability, cytocompatibility, pH responsiveness as well as self-healing ability. Based on the cooperative and synergetic forces of non-covalent and covalent bonds, the C(beta CD-OM)AE@Ad gel shows a high tensile strain up to 1,590%, and the self-healed gel could restore up to 84% of its initial length within 24 h. Furthermore, drug release in the hydrogel was controlled by the surrounding pH and slowly released. The present work reveals the cooperativity of multiple cross-links for a 3D structured polymeric material, and the developed self-healable hydrogel can possibly be applied in various biomedical applications.