Electromagnetic induction drives electron-hole separation in optoelectronic nerve conduit to accelerate nerve repair

Bismuth sulfide (Bi2S3), as a photoelectric material, could convert light signals to electrical signals and thus hold tremendous promise in constructing wireless electrical stimulation to accelerate nerve regeneration. However, the easily recombination of electrons and holes weakened the electrical stimulation effect. Herein, a core-shell Bi2S3@PPy nanorod was prepared via in-situ hydrothermal polymerization of conductive polypyrrole (PPy) on Bi2S3, and then blended into poly-L-lactic acid powder to fabricate nerve conduit by laser additive manufacturing. Under the rotating magnetic field, the conductive Bi2S3@PPy in the conduit could cut the magnetic inductance line to generate induced electromotive force, which could drive the electron and hole of Bi2S3 moved to the opposite direction and thereby achieving their efficient separation. Results indicated that the enhanced electron-hole separation boosted the generation of photocurrent, with an output current of 7.5 μA, significantly higher than the photocurrent under light irradiation (5.0 μA) and the induced current under magnetic field (2.5 μA). The immunofluorescent staining demonstrated that the enhanced photocurrent could up-regulate the expression of neuronal marker Nestin and GFAP. Moreover, the Ca2+ intracellular influx was improved, which manifested that the differentiation of BMSCs into neurons was provoked. Overall, this work might provide a potential wireless electrical stimulation strategy for accelerating nerve repair.