Ultrasmall FeS₂ Nanoparticles‐Decorated Carbon Spheres with Laser‐Mediated Ferrous Ion Release for Antibacterial Therapy

Abstract

Recent progress in nanotechnology and the ancient use of sulfur in treating dermatological disorders have promoted the development of nano-sulfides for antimicrobial applications. However, the variable valences and abundant forms of nano-sulfides have complicated investigations on their antibacterial activity. Here, carbon nanospheres (CNSs) with decoration of ultrasmall FeS₂ nanoparticles (CNSs@FeS₂ ) is synthesized, and their antibacterial ability and mechanism are explored. The CNSs@FeS₂ released Fe²⁺ and sulfur ions simultaneously through dissolution and disproportionation. In vitro study indicated that the released Fe²⁺ killed bacteria by increasing the oxidative state of bacterial surfaces and intracellular molecules. Importantly, the released sulfur exhibited a protective effect on Fe²⁺ , ensuring the stable existence of Fe²⁺ to continuously combat bacteria. Moreover, the carbon shells of CNSs@FeS₂ not only prevented the aggregation of FeS₂ but also accelerated the release of Fe²⁺ through photothermal effects to achieve synergistic hyperthermia/Fe²⁺ therapy. In vivo experiments indicated that treatment with CNSs@FeS₂ resulted in a marked reduction in bacterial number and improvement in survival in an acute peritonitis mouse model, and antibacterial wound experiments demonstrated high efficacy of CNSs@FeS₂ -enabled synergistic hyperthermia/Fe²⁺ therapy. Thus, this study clarifies the antibacterial mechanism of FeS₂ and offers a synergetic therapeutic platform with laser-mediated Fe²⁺ release for antibacterial applications.