Photoelectric Bi₂S₃ Nanoparticle/Ti₃C₂T_x Nanosheet Heterojunction for Promotion of Nerve Cell Growth

Bismuth sulfide (Bi 2 S 3 ) enabled us to transform light signals into electrical signals via the photoelectric effect, which exhibited tremendous prospects on constructing wireless electrical stimulation for accelerating nerve regeneration. However, too rapid recombination of photogenerated electron–hole pairs weakened its photocurrent. Herein, the Bi 2 S 3 /Ti 3 C 2 T x heterojunction was synthesized by in situ growth of Bi 2 S 3 nanoparticles on Ti 3 C 2 T x nanosheets and then mixed with poly- l -lactic acid (PLLA) powder to fabricate the Bi 2 S 3 /Ti 3 C 2 T x -PLLA conduit. At the heterojunction interfaces, Ti 3 C 2 T x with a more positive Fermi energy level could form interfacial potential difference with Bi 2 S 3 to promote electron–hole pair separation. Meanwhile, Ti 3 C 2 T x with excellent conductivity could provide channels for photogenerated electron transmission, thus facilitating the generation of the photocurrent. Photoluminescence and electrochemical impedance spectroscopy analysis indicated that electron–hole pair separation and electron transfer were enhanced. As a consequence, under near-infrared light radiation, the output photocurrent of Bi 2 S 3 /Ti 3 C 2 T x -PLLA was increased from 0.48 to 1.43 μA compared to that of Bi 2 S 3 -PLLA. The enhanced photocurrent effectively promoted the differentiation of rat pheochromocytoma (PC12) into functional neurons by upregulating extracellular Ca 2+ influx. Therefore, the above results demonstrated that this work provided a new perspective for wireless electrical stimulated nerve regeneration.