Hofmeister effect driven dynamic-bond cross-linked dialdehyde xylan hydrogels with rapid response and robust mechanical properties for expanding stent

The biomedical field urgently needs for programmable stent materials with nontoxic, autonomous self-healing, injectability, and suitable mechanical strength, especially self-expanding characteristics. However, such materials are still lacking. Herein, based on gelatin and dialdehyde-functionalized xylan, we synthesized 3D-printable, autonomous, self-healing, and mechanically robust hydrogels with a reversible Schiff base crosslink network. The hydrogels exhibited excellent mechanical properties and automatic healing properties at room temperature. The solid mechanical properties originate from the Schiff base, hydrogen bonding interactions, and xylan nanoparticle reinforcement of the polymer networks. As a proof of concept, the Hofmeister effect enabled the hydrogel to contract in highly concentrated salt solutions. In contrast, the same hydrogel expanded and relaxed in dilute salt solutions (quick response within 10 s), showing ionic stimulus-response and excellent shape memory characteristics, which demonstrated that the prepared hydrogel could be used as self-expanding artificial vascular stents. In particular, good biocompatibility was confirmed by cytotoxicity and compatibility tests, and ex vivo arterial experiments further indicated the feasibility of these artificial vascular scaffolds (the expansion force reached 1.51 N). Combined with its ionic stimuli-responsive shape memory ability, the strong mechanical, self-healing, 3D-printable, and biocompatibility properties make this hydrogel a promising material for artificial stents in various biomedical applications.