Photoelectric Bi2S3 Nanoparticle/Ti3C2Tx Nanosheet Heterojunction for Promotion of Nerve Cell Growth

Bismuth sulfide (Bi2S3) 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 Bi2S3/Ti3C2Tx heterojunction was synthesized by in situ growth of Bi2S3 nanoparticles on Ti3C2Tx nanosheets and then mixed with poly-l-lactic acid (PLLA) powder to fabricate the Bi2S3/Ti3C2Tx-PLLA conduit. At the heterojunction interfaces, Ti3C2Tx with a more positive Fermi energy level could form interfacial potential difference with Bi2S3 to promote electron–hole pair separation. Meanwhile, Ti3C2Tx 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 Bi2S3/Ti3C2Tx-PLLA was increased from 0.48 to 1.43 μA compared to that of Bi2S3-PLLA. The enhanced photocurrent effectively promoted the differentiation of rat pheochromocytoma (PC12) into functional neurons by upregulating extracellular Ca2+ influx. Therefore, the above results demonstrated that this work provided a new perspective for wireless electrical stimulated nerve regeneration.