摘要：

Nanomaterials with antimicrobialproperties triggered by external stimuli appear to be a promisingand innovative substitute for the destruction of antibiotic-resistantsuperbugs as they can induce multiple disruptions in the cellularmechanism. This study demonstrates the use of squaraine (SQ) dye asthe photosensitive material, activated in the near-infrared tissue-transparenttherapeutic window. The dye has been covalently attached to the ZnOnanoparticle surface, forming ZnO-SQ nanohybrids. The formation ofthe nanohybrids is confirmed using Fourier transform infrared andother optical spectroscopic methods. The photoinduced interfacialelectron transfer process (as confirmed using the time-resolved fluorescencetechnique) from the excited state of SQ to the conduction band ofZnO is responsible for the greater reactive oxygen species (ROS) generationability of the nanohybrid. The production of photoactivated ROS (especiallysinglet oxygen species) by ZnO-SQ provides remarkable antimicrobialaction against clinically significant <named-content>Staphylococcusaureus</named-content>. Detailed investigations suggest synergisticinvolvement of cell membrane disruption and nanoparticle internalizationfollowed by photoinduced intracellular ROS generation, which resultin an unprecedented 95% bacterial killing activity by the nanohybrid.Moreover, the efficacy of the nanohybrid for disruption of bacterialbiofilms has been examined. The electron microscopic images suggestsignificant bacterial cell death following structural alteration andreduced adherence property of the biofilms. Nanodimension-driven greaterinternalization of ZnO-SQ followed by an improved dissolution of ZnOin an acidic environment of the biofilm as well as red-light-driveninterfacial charge separation and ROS generation improves the efficacyof the material for biofilm destruction. An artificial medical implantmimicking titanium sheets coated with ZnO-SQ depicts light-triggereddisruption in the adherence property of matured biofilms. The cytotoxicityand hemolysis assays show inherent biocompatibility of the photoactivenanohybrid. This study is notably promising for the treatment of life-threateningdrug-resistant infections and eradication of biofilms formed withinartificial implants.

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