A near-infrared-activated heterostructure endowed nerve scaffold with electrical stimulation and anti-bacteria

The weak tissue inducibility and easy implantation infection are still challenges confronted to tissue scaffold. Bismuth sulfide (Bi 2 S 3 ) 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, Bi 2 S 3 /Ag 3 PO 4 heterostructures are prepared by in-situ growing Ag 3 PO 4 on Bi 2 S 3 , and then mixed with poly- L -lactic acid powder to fabricate scaffolds by selective laser sintering. Due to the different Fermi level of Bi 2 S 3 and Ag 3 PO 4 , the photogenerated electrons of Bi 2 S 3 transferred to the conduction band of Ag 3 PO 4 . Meanwhile, the heterojunction impeded the backflow of electrons, which efficiently achieved electron-hole pair separation. Results indicate 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 Ca 2+ 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.