Ternary Prussian blue nanozymes with synergistic multimetallic catalysis enable ultrasensitive lateral flow immunoassay for respiratory syncytial virus diagnosis

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in infants and children, and early and accurate diagnosis is crucial for its effective treatment and disease management. Here, we developed a nanozyme-enhanced lateral flow immunoassay (LFIA) that employed a newly generated monoclonal antibody against the conserved RSV nucleocapsid (N) protein. The platform was based on a ternary metal–organic framework nanozyme composed of iron, cobalt, and nickel ions, which exhibited synergistically enhanced peroxidase-like activity. This nanozyme efficiently catalyzed the oxidation of 3,3′ -diaminobenzidine, producing a colorimetric signal on the LFIA strip for visual detection. Due to the catalytic enhancement, the assay achieved a detection limit of 5 pg/mL for recombinant RSV N protein. For live RSV, the biosensor demonstrated a detection threshold of 10^0.875 TCID50/mL, representing a 1000-fold sensitivity improvement over AuNP-based LFIA. Moreover, the strip demonstrated high specificity and no cross-reactivity with other viruses. Owing to its simplicity, speed, and efficiency, the developed LFIA offers a robust point-of-care solution for RSV diagnosis. This platform holds great potential for clinical screening and early detection of viral infections, underscoring its value in future pandemic preparedness and respiratory disease surveillance.