Antibody conjugated Au/Ir@Cu/Zn-MOF probe for bacterial lateral flow immunoassay and precise synergistic antibacterial treatment

Staphylococcus aureus is one of the most prevalent threats to public health. Rapid detection with high sensitivity and targeted killing is crucial to curb its spread. Herein, a metal-bearing nanocomposite, consisting of a bimetallic nanoparticle and a metal-organic framework (Au/Ir@Cu/Zn-MOF) was constructed. Upon conjugation with anti-S. aureus antibody, this nanocomposite (Ab-Au/Ir@Cu/Zn-MOF) was exploited for its dual functions, i.e. as a reporting probe in a lateral flow immunoassay and a high efficiency antibacterial reagent. Benefiting from the enrichment of Au/Ir NPs by the Cu/Zn-MOF, the Au/Ir@Cu/Zn-MOF-based lateral flow immunoassay sensor exhibited a visual limit of detection of 103 CFU/mL, which was100 times more sensitive than Au/Ir-based sensor. Moreover, the Ab-Au/Ir@Cu/Zn-MOF probe possessed synergistic photothermal-chemodynamic bactericidal effect that specifically targeted against S. aureus. Under a co-treatment by H2O2 (0.4 mM) and 808 nm near infrared irradiation (1 W/cm2, 5 min), complete sterilization of 5 × 105-106 CFU/mL S. aureus was achieved at a nanocomposite concentration as low as 6.25 μg/mL. The superior antibacterial efficiency was attributable to the three-fold properties of the Ab-Au/Ir@Cu/Zn-MOF probe: (1) enhanced multi-enzyme mimicking activities that promote reactive oxygen species generation, (2) high photothermal activity (efficiency of 53.70%), and (3) bacteria targeting ability via the antibody coating. By changing the antibody, this nanocomposite can be tailored to target a wide range of bacteria species, for detection and for precise antibacterial treatment.