Non-Stoichiometric FeS2 nanoparticles as antibacterial agents with combined photothermal and photodynamic effect

In this study, non-stoichiometric FeS2 nanoparticles were synthesized via hot-injection method and evaluated as dual effect antibacterial agent. Non-stoichiometric FeS2 nanoparticles were achieved by altering the molar ratio of the precursors (i.e., Fe-source and S-source). X-ray photoelectron spectroscopy (XPS) analysis revealed that Fe/S ratio in the FeS2 nanoparticles were 1.012:2, 0.960:2, 0.905:2, and 0.900:2 for the samples with Fe-source to S-source ratios of 1/6, 1/8, 1/10, and 1/12, respectively. In the case of Fe/S: 0.900:2, the temperature increased up to about 53 degrees C (photothermal conversion efficiency: 52.6 %) in addition to reactive oxygen species (ROS) generation under 808 nm near-infrared (NIR) light irradiation. Based on the in vitro antibacterial activity tests, non-stoichiometric FeS2 nanoparticles exhibited promising antibacterial activity against Escherichia coli (98.00%) and Staphylococcus aureus (99.89%) due to the synergistic effects of ROS formation and hyperthermia. The non-stoichiometric FeS2 nanoparticles can be considered as high potential antibacterial material under NIR irradiation.