Charge gating-enhanced electrostatic targeting using quaternary-ammonium chitosan@metal organic framework for rapid...

Herein, we report a multifunctional quaternary-ammonium chitosan (QCS)@zeolitic imidazolate framework nanocapsules (RZFQ) capable of detecting E. coli and S. aureus down to ∼1 CFU/mL within 10 min and achieving over 99 % bactericidal efficiency at low concentrations (10-15 μg/mL). To achieve this, a novel strategy leveraging charge gating-enhanced electrostatic targeting and functional integration was developed for rapid bacterial detection and synergistic antibacterial therapy. Sensitive bacterial detection and high antibacterial activity of the composite were attributed to the enhanced surface affinity of RZFQ with bacteria by QCS wrapping. The encapsulated Fe₃O₄/rose bengal (RB) improved the light absorption and charge transfer. RZFQ exhibits significant antibacterial efficacy through the synergistic effects of chemodynamic therapy/photodynamic therapy (CDT/PDT). The RZFQ nanocapsules exhibited excellent detection sensitivity (10¹-10⁹ CFU/mL) and high bactericidal efficacy. Subsequently, an intelligent analytical system integrating a color reaction of 3,3',5,5'-tetramethylbenzidine (TMB) and a developed smartphone-based application was successfully developed to achieve high-throughput and on-site E. coli testing. This platform not only improves treatment accuracy but also provides a promising method for combating antibiotic resistance via targeted antibacterial agent delivery.