Near-Infrared Light-Triggered Photothermal-Pyroelectric Scaffold Offering Wireless Electrical Stimulation Accelerates Nerve Repair

Although electrical stimulation had considerable potential for accelerating nerve repair, its future application was confined by the need for an external power supply and a limited range of action. Herein, a nerve scaffold with wireless electrical stimulation and cell recruitment function was constructed by incorporating polyethylenimine (PEI)-modified reduced graphene oxide (rGO) into a pyroelectric polyvinylidene fluoride (PVDF) scaffold fabricated via the laser additive manufacturing technique. Once irradiated with near-infrared light (NIR), rGO dispersed in the PVDF matrix could form numerous micro/nanoscaled thermal gradient fields through the photothermal conversion effect. These thermal gradient fields could further induce PVDF to spontaneously polarize and release surface charges, thereby achieving wireless electrical stimulation. More importantly, the positively charged amino groups on PEI could recruit negatively charged cells to the scaffold by electrostatic interactions, thus realizing better electrical stimulation. The qPCR results and upregulated neuronal markers Tuj, GFAP, and Nestin demonstrated that the generated electrical stimulation could effectively induce bone marrow mesenchymal stem cells to differentiate into neurons. Further mechanisms revealed that the enhanced cell differentiation was mainly attributed to electrical stimulation promoting calcium influx by opening gated calcium ion channels. In summary, this work holds great promise for the treatment of nerve repair.