Capacitive-Coupling-Responsive Hydrogel Scaffolds Offering Wireless In Situ Electrical Stimulation Promotes Nerve Regeneration

Electrical stimulation (ES) has shown beneficial effects in repairing injured tissues. However, current ES techniques that use tissue-traversing leads and bulky external power suppliers have significant limitations in translational medicine. Hence, exploring noninvasive in vivo ES to provide controllable electrical cues in tissue engineering is an imminent necessity. Herein, a conductive hydrogel with in situ electrical generation capability as a biodegradable regeneration scaffold and wireless ES platform for spinal cord injury (SCI) repair is demonstrated. When a soft insulated metal plate is placed on top of the injury site as a wireless power transmitter, the conductive hydrogel implanted at the injury site can serve as a wireless power receiver, and the capacitive coupling between the receiver and transmitter can generate an alternating current in the hydrogel scaffold owing to electrostatic induction effect. In a complete transection model of SCI rats, the implanted conductive hydrogels with capacitive-coupling in situ ES enhance functional recovery and neural tissue repair by promoting remyelination, accelerating axon regeneration, and facilitating endogenous neural stem cell differentiation. This facile wireless-powered electroactive-hydrogel strategy thus offers on-demand in vivo ES with an adjustable timeline, duration, and strength and holds great promise in translational medicine. Because of the capacitive coupling configuration, the electrostatic induction response of the chitosan/gelatin/black phosphorus conductive hydrogel implanted in the spinal cord injury lesion site can offer in situ electrical stimulation without any external metal stimulation electrodes and percutaneous electrical wirings. The capacitive coupling of high-frequency electrical field between hydrogel receiver and insulated metal patch transmitter can generate alternating current flowing in the hydrogel scaffold.image