FeS2/WS2 Heterostructure: A Promising Candidate for Mild-Temperature Photothermal Therapy with Enhanced Photodynamic Effect and Antibacterial Activity

FeS₂, a member of metal chalcogenide semiconductors, is a cheap and available material with distinguishable photothermal activity under light irradiation. However, its photodynamic properties have to be improved for practical phototherapy applications. Therefore, in this study, FeS₂/WS₂ p-n junctions, comprising varying amounts of WS₂, are synthesized using the simple hot injection method. Establishment of the heterostructure is verified using X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS) analysis. p-n junction formation is further validated via calculations based on ultraviolet-visible (UV–vis.) spectrophotometer and XPS data. Photothermal and photodynamic properties of the samples are examined considering various aspects. The FeS₂/WS₂ heterostructure provides a heating response above 50 °C with a high photothermal conversion efficiency of 52.6%. The reactive oxygen species (ROS) formation ability is observed to depend on the material concentration and O₂•^‾ is determined as the primary reactive oxygen species. The in vitro antibacterial activity of the samples is tested against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria as a function of material concentration. At all concentrations, the FeS₂/WS₂ heterostructure exhibits higher activity than that of FeS₂ nanoparticles. The efficiency of the sample against S. aureus and E. coli is calculated to be 100% and 99.4% respectively, at a low material concentration of 100 µg mL⁻¹.