Light-Responsive Ag ₄₄ –Templated Silver Nanoparticles for Targeted Antibacterial Therapy: Harnessing Size-Dependent Synergistic Action Mechanisms

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 Ag 44 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/cm 2 ) synergistically enhanced antibacterial efficacy >10-fold, reducing MIC values to 2 μg/mL through: (i) Ag + release from the Ag 44 @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.