An Injectable, Electroconductive Hydrogel/Scaffold for Neural Repair and Motion Sensing

Electroconductive hydrogels and scaffolds have great potential for strain sensing and in tissue engineering. Herein, we designed electroconductive self-healing hydrogels and shape-recoverable scaffolds with injectability, strain/motion-sensing ability, and neural regeneration capacity. The crosslinked network of hydrogels and scaffolds was synthesized and prepared under physiological conditions from N-carboxyethyl chitosan (CEC), a chitosan-modified polypyrrole (DCP) nanoparticle (similar to 40 nm), and a unique aldehyde-terminated difunctional polyurethane (DFPU) crosslinker. CEC was mixed with DCP by electrostatic interaction and then crosslinked with DFPU through a dynamic Schiff base reaction. Schiff base endowed the hydrogels with self-healing behavior, confirmed by rheological examinations. Shape-recoverable scaffolds were obtained by freeze-drying the hydrogels. These hydrogels and scaffolds showed injectability and conductivity (3-6 mS/cm), while the scaffolds also exhibited high water absorption and durable elasticity after repeated deformation. The hydrogels and scaffolds promoted the attachment, proliferation, and differentiation of neural stem cells (NSCs). The scaffolds had excellent strain/motion-sensing properties in vitro and ex vivo as well as biodegradability and biocompatibility in vivo. Moreover, the neural regeneration capacity of the conductive hydrogel or the cell-laden conductive hydrogel was demonstrated by the rescue of motor function (similar to 53 and similar to 80% functional recoveries, respectively) in the zebrafish brain injury model. These hydrogels and scaffolds are potential candidates for nerve repair and motion sensing.