Photothermal and Photodynamic Effects of g-C₃N₄ Nanosheet/Bi₂S₃ Nanorod Composites with Antibacterial Activity for Tracheal Injury Repair

Photodynamic antimicrobial therapy via producing ROS based on light-responsive nanoparticles has attracted worldwide attention because of the high selectivity and low side effects. However, biofilms and bacterial membranes provide a natural barrier to prevent the penetration of ROS, which impairs the photodynamic antibacterial efficiency of nanoparticles. Photothermal therapy is an effective strategy against biofilms and bacterial membranes because high temperature can destroy the biofilm structure and enhance the membrane permeability. Herein, Bi2S3 nanorods were anchored on the surface of zinc-doped g-C3N4 (ZnCN) nanosheets to construct a ZnCN-Bi2S3 nanocomposite; then, it was incorporated into poly-l-lactic acid and prepared into scaffolds by the selective laser sintering technology. Bi2S3 nanorods not only endowed the scaffold with an excellent photothermal property but also strengthened the photodynamic effect of ZnCN nanosheets after forming the nanocomposite. The results showed that this nanocomposite had a lower recombination rate of photogenerated electron–hole pairs and produced higher photocurrent compared to those of the g-C3N4 nanosheets and Bi2S3 nanorods. The scaffold destroyed the biofilm and elevated the bacterial membrane permeability significantly and finally achieved 98.5% antibacterial rate for Staphylococcus aureus and 96.3% antibacterial rate for Pseudomonas aeruginosa. Encouragingly, the scaffold could also promote chondrogenic differentiation because of the continuous release of Zn ions. The scaffold containing ZnCN-Bi2S3 nanocomposites possessed excellent antimicrobial and cartilage regeneration functions, which displayed great potential in treating tracheal injuries.