Light-Responsive Ag₄₄-Templated Silver Nanoparticles for Targeted Antibacterial Therapy: Harnessing Size-Dependent...

Silver nanoparticles (Ag NPs) have garnered significant attention in biomedical and optoelectronic applications due to their localized surface plasmon resonance and antimicrobial properties. However, the aqueous-phase synthesis of structurally homogeneous Ag NPs with precise dimensional control remains challenging, particularly for achieving scalable antibacterial efficacy. Herein, we report a green strategy using atomically precise Ag₄₄ nanoclusters as nucleation templates to produce monodisperse Ag NPs (3-250 nm) with narrow polydispersity (<3% deviation) and tunable surface charge (-39 to -56 mV). Systematic evaluation revealed a strong inverse size-efficacy correlation (3-50 nm range), where Staphylococcus aureus (G⁺) exhibited heightened sensitivity. These NPs further demonstrated size-dependent antibacterial activity against both S. aureus and E. coli. Mechanistic studies indicate that enhanced surface oxidation states in smaller NPs facilitate bacterial membrane disruption. Crucially, blue light irradiation (450 nm, 0.3 mW/cm²) synergistically enhanced antibacterial efficacy >10-fold, reducing MIC values to 2 μg/mL through: (i) Ag⁺ release from the Ag₄₄@Ag core-shell structure; (ii) plasmon-mediated ROS generation; and (iii) photoenhanced surface reactivity. This multimechanistic antibacterial platform outperforms conventional Ag NPs, while the template-guided synthesis offers a sustainable paradigm for precision nanomaterials with tailored functionalities in photonic medicine and nanoelectronics.