Controllable γ-radiation synthesis of conductive polymer-shelled AgNPs nanocomposites with enhanced antibacterial and antibiofilm activities.

Antimicrobial resistance poses an escalating threat to global health, driving demand for non-antibiotic strategies. Silver nanoparticles (AgNPs) and antimicrobial blue light (aBL) phototherapy have emerged as potent modalities: AgNPs offer broad-spectrum, multi-targeted action with low propensity for resistance, while aBL enables localized, light-triggered bacterial inactivation via endogenous photosensitizers and induced reactive oxygen species. Seeking to integrate these advantages, we developed poly(3,4-ethylenedioxythiophene) (PEDOT): poly (sodium 4-styrenesulfonate) (PSS)-shelled AgNPs (PP-AgNPs) via a green, radiation-induced reduction route and systematically elucidated their controlled synthesis and antimicrobial performance. PEDOT:PSS is a blend of two distinct polymers, conductive PEDOT and non-conductive PSS. Specifically, we identify absorbed dose and EDOT monomer concentration as key levers governing nucleation, growth, and composite architecture. Optimal conditions (9 kGy, 1 mM EDOT) afford uniformly dispersed PP-AgNPs (11.0 ± 9.7 nm) with stable PEDOT:PSS coating. Structural analyses show that the shell improve colloidal storage stability and interfacial functionality through electrostatic and coordination interactions, while preserving the silver crystalline phase. Additionally, PP-AgNPs display pronounced, dose-dependent antibacterial activity, achieving MICs of 0.5 mg/L against Staphylococcus aureus and 0.25 mg/L against Pseudomonas aeruginosa, and disrupting mature biofilms of both strains (∼85% biomass reduction at 60 mg/L). SEM imaging reveals direct membrane and cell-wall damage with irreversible morphological collapse. Although no significant synergy with blue light was observed under the tested conditions, the PEDOT shell imparts intrinsic photoelectrical responsiveness, suggesting a feasible path to photo-assisted antimicrobial optimization. This platform unites scalable, green synthesis with tunable nanocomposite design, offering a versatile foundation for next-generation, non-antibiotic antibiofilm therapies.