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

Bismuth sulfide (Bi2S3) 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 Bi2S3–BaTiO3 was synthesized by loading BaTiO3 nanoparticles onto Bi2S3 nanorods through a self-assembly method and then integrated into poly-L-lactic acid (PLLA) powders to fabricate PLLA/Bi2S3–BaTiO3 scaffolds. Piezoelectric BaTiO3 would deform under stress to produce instantaneous polarization, which triggered positive and negative charges presented on the relative surfaces of BaTiO3. Thus, the photogenerated electrons and holes of Bi2S3 would be, respectively, transferred to the positive and negative charged surfaces of BaTiO3, thereby achieving the electron–hole separation. Results revealed that under ultrasonic irradiation, the photoluminescence peak intensity of Bi2S3–BaTiO3 was significantly reduced compared with that of Bi2S3, confirming the improved electron–hole pair separation. Accordingly, the photocurrent of Bi2S3–BaTiO3 was increased by approximately 1.4 times in comparison with that of Bi2S3. The enhanced photocurrent effectively promoted cell proliferation and differentiation by upregulating alkaline phosphatase expression, enhancing calcium nodule deposition, and promoting cellular Ca2+ influx. Consequently, this work provided a perspective for establishing a self-powered electrical stimulated scaffold for bone repair.