Study on the Mechanism of Black Phosphorus Nanosheets Loading Sr2+ Used in Photothermal Antibacterial Treatment

Bacterial infections seriously affect the health of patients and their incidence is very high. Photothermal therapy has shown promising prospects in the treatment of bacterial infections as it can effectively kill bacteria and reduce inflammation. Black phosphorus (BP) is an emerging nanoparticle that can generate heat under the action of near-infrared light, it can safely and effectively kill bacteria through photothermal therapy. In this experiment, black phosphorus was used as a photothermal agent to kill bacteria and strontium ions were loaded onto BP to enhance its stability and antibacterial performance. BP was obtained by liquid phase exfoliation and Sr2+ was loaded onto the surface of BP by electrostatic interaction. BP-Sr was synthesized via electrostatic interactions and characterized using various techniques. The cytocompatibility of BP-Sr was evaluated by CCK8 assay and live/dead staining which showed no significant cytotoxicity with a concentration not exceed 50 μg/mL. Meanwhile, the antibacterial effects showed 99% of bacteria died after 10 min under the action of a 2 W/cm2 laser and the structure of bacteria was destroyed. Finally, the transcriptomic results suggest that bacteria death may be related to membrane destruction, metabolic disorders, and transport damage. HE staining and Gram staining also showed that inflammation was significantly alleviated after laser treatment. These findings propose a great solution for bacterial infection and also enrich the theoretical framework supporting the application of BP-Sr in the field of antibiosis.