Engineering oxygen vacancies in scaffold for enhanced photodynamic antibacterial efficacy

Bismuth oxide (Bi2O3) displayed tremendous application prospects in the field of photodynamic antibacterial due to its favorable biocompatibility and high chemical stability. Notwithstanding, its antibacterial efficacy was constrained by the rapid electron-hole recombination and limited near-infrared absorption. Herein, oxygen vacancies-rich Bi2O3 nanoparticles were synthetized by sulfur-doping, and then introduced into a poly-l-lactide scaffold fabricated by laser additive manufacturing. On the one hand, the oxygen vacancies could serve as the electron capture center to promote the electron-hole separation. On the other hand, the localized electrons at the oxygen vacancies could adjust the energy band structure of Bi2O3 and thus expand the optical absorption to nearinfrared region. Photoelectrochemical results presented that with the introduction of oxygen vacancies, the Nyquist curve radius was significantly decreased and the photocurrent increased about fivefold, demonstrating the enhanced electron-hole separation efficiency. As a result, the reactive oxygen species (ROS) produced by the scaffold was remarkably boosted under near-infrared irradiation. Besides, the scaffold also exhibited favorable photothermal performance. With the synergistic effect of ROS and photothermal, the scaffold effectively killed bacteria by destroying bacterial membrane structure, triggering protein leakage and consuming glutathione. Finally, the scaffold exhibited antibacterial rates of 98.6 % and 98.2 % against E. coli and S. aureus, respectively.