Piezoelectric Polarization Enhanced Photogenerated Carrier Separation of Bi₂S₃–BaTiO₃ Nanostructure-Based Photoelectric Poly-L-lactic Acid Scaffold for Stimulating Cell Growth

Bismuth sulfide (Bi 2 S 3 ) could respond to near-infrared light to generate photocurrent, demonstrating tremendous potential in constructing self-powered electrical stimulation to accelerate bone regeneration. Nevertheless, the facile recombination of electron–hole pairs undermined its photoelectric performance. Herein, a sea-buckthorn-like nanostructured Bi 2 S 3 –BaTiO 3 was synthesized by loading BaTiO 3 nanoparticles onto Bi 2 S 3 nanorods through a self-assembly method and then integrated into poly- L -lactic acid (PLLA) powders to fabricate PLLA/Bi 2 S 3 –BaTiO 3 scaffolds. Piezoelectric BaTiO 3 would deform under stress to produce instantaneous polarization, which triggered positive and negative charges presented on the relative surfaces of BaTiO 3 . Thus, the photogenerated electrons and holes of Bi 2 S 3 would be, respectively, transferred to the positive and negative charged surfaces of BaTiO 3, thereby achieving the electron–hole separation. Results revealed that under ultrasonic irradiation, the photoluminescence peak intensity of Bi 2 S 3 –BaTiO 3 was significantly reduced compared with that of Bi 2 S 3, confirming the improved electron–hole pair separation. Accordingly, the photocurrent of Bi 2 S 3 –BaTiO 3 was increased by approximately 1.4 times in comparison with that of Bi 2 S 3 . The enhanced photocurrent effectively promoted cell proliferation and differentiation by upregulating alkaline phosphatase expression, enhancing calcium nodule deposition, and promoting cellular Ca 2+ influx. Consequently, this work provided a perspective for establishing a self-powered electrical stimulated scaffold for bone repair.