Facile Preparation of Cu₂Se Nanosheets as Dual-Functional Antibacterial Agents

The spread of antibiotic-resistance poses a great threat, making it a growing need to develop other antibacterial strategies and therapeutics. Recently, owing to their excellent physicochemical properties, copper chalcogenides have received extensive attention as photothermal agents. However, most reports are focused on Cu_2-S nanoparticles, whereas very few water-dispersible Cu_2-Se nanomaterials have been reported due to their difficult preparation process. Herein, water-dispersible and biocompatible cuprous selenide nanosheets (Cu₂Se NSs) were synthesized by a simple anion exchange method starting from cuprous oxide nanorods (Cu₂O NRs), which could also help avoid any environmental pollution caused by the organic solvent used during synthesis. The obtained Cu₂Se NSs showed strong absorption in the second near-infrared window (NIR II) with a good photothermal conversion efficiency as high as ∼61.16%, outstanding among the previously reported NIR II photothermal agents. Interestingly, using Staphylococcus aureus and Escherichia coli as model pathogens, these Cu₂Se NSs possess an intrinsic bacteriostatic effect and could inhibit the growth of both bacteria species. Furthermore, both the fluorescent-based microscopy and the bacterial morphology analysis using a scanning electron microscope have demonstrated that incubation of both species of bacteria with Cu₂Se NSs under laser irradiation (1064 nm) would lead to complete disruption of the bacterial cell wall. Our work presents a facile method to prepare water-dispersible Cu₂Se NSs-, which could serve as highly efficient dual-functional antibacterial agents.