Manganese dioxide (MnO₂) nanosheets have shown exciting potential in nanomedicine because of their ultrathin thickness, large surface area, high near-infrared (NIR) absorbance and good biocompatibility. However, the effect of MnO₂ nanosheets on bacteria is still unclear. In this study, MnO₂ nanosheets were shown for the first time to possess highly efficient antibacterial activity by using Salmonella as a model pathogen. The growth curve and surface plate assay uncovered that 125 μg/mL MnO₂ nanosheets could kill 99.2% of Salmonella, which was further verified by fluorescence-based live/dead staining measurement. Mechanism analysis indicated that MnO₂ nanosheet treatment could dramatically induce reactive oxygen species production, increase ATPase activity and cause the leakage of electrolytes and protein contents, leading to bacterial death. These results uncover the previously undefined role of MnO₂ nanosheets and provide novel strategies for developing antimicrobial agents.

Considering the increasing abundance of antibiotic-resistant bacteria, novel antimicrobial approaches need to be investigated. Photothermal therapy (PTT), an innovative noninvasive therapeutic technique, has demonstrated significant potential in addressing drug-resistant bacteria and bacterial biofilms. However, when used in isolation, PTT requires higher-temperature conditions to effectively eradicate bacteria, thereby potentially harming healthy tissues and inducing new inflammation. This study aims to present a comprehensive review of nanomaterials with intrinsic antimicrobial properties, antimicrobial materials relying on photothermal action, and nanomaterials using drug delivery antimicrobial action, along with their applications in antimicrobials. Additionally, the synergistic mechanisms of these antimicrobial approaches are elucidated. The review provides a reference for developing multifunctional photothermal nanoplatforms for treating bacterially infected wounds.