A near-infrared-activated heterostructure endowed nerve scaffold with electrical stimulation and antibacterial performance

The weak tissue inducibility and easy implantation infection are still challenges confronted to tissue scaffold. Bismuth sulfide (Bi2S3) possessed favorable photoelectric, photothermal, and photodynamic properties not only enabling to response near-infrared light to generate electrical signals to promote nerve growth but also simultaneously produces reactive oxygen species (ROS) and heat to kill bacteria, which emerges as a promising alternative. However, the easy recombination of electron-hole weakens its photocurrent and ROS generation. Herein, Bi2S3/Ag3PO4 heterostructures are prepared by in situ growing Ag3PO4 on Bi2S3 and then mixed with poly-L-lactic acid powder to fabricate scaffolds by selective laser sintering. Due to the different Fermi levels of Bi2S3 and Ag3PO4, the photogenerated electrons of Bi2S3 transferred to the conduction band of Ag3PO4. Meanwhile, the heterojunction impeded the backflow of electrons, which efficiently achieved electron-hole pair separation. Results indicate that the photocurrent and ROS generated by the scaffold was enhanced. The improved photocurrent effectively induces stem cells to differentiate into nerve cells through up-regulating Ca2+ concentration and neural-specific markers Nestin expression. The produced ROS, photothermal, and Ag+ can synergistically kill bacteria. Ultimately, the scaffold exhibited excellent antimicrobial efficiency with 90.59 % and 91.45 % against E. coli and S. aureus, respectively. This strategy provides a new perspective to realize the integrated preparation of nerve scaffolds with electrical stimulation and antibacterial performance.