Rambutan-Like Magnetic Nanozyme Modified with Wheat Germ Agglutinin Enhances Lateral Flow Immunoassay for...

Detecting respiratory bacteria and viruses quickly and accurately under field conditions still faces huge challenges. Here, we developed a rambutan-like magnetic nanozyme (Fe-DAu@Ir-WGA) by coating Fe₃O₄ particles with multiple layers of 5 nm Au@Ir nanoparticles (NPs) to provide magnetic enrichment capability and numerous three-dimensional catalytic sites while applying wheat germ agglutinin (WGA) on the outer layer as a broad-spectrum recognition molecule for glycoproteins from respiratory microorganisms. The Fe-DAu@Ir-WGA probe exhibits highly efficient universal enrichment capability for bacteria and viruses (capture efficiency >90%), while effectively eliminating various matrix interferences in complex samples, thereby improving the sensitivity, reliability, and universality of the current nanozyme lateral flow immunoassay (LFA). The developed Fe-DAu@Ir-WGA-LFA can simultaneously detect respiratory bacteria (Streptococcus pneumoniae and Legionella pneumophila) and respiratory virus (SARS-CoV-2) within 38 min, achieving limits of detection of 4 cells/mL for bacteria and 1.8 pg/mL for virus. This represents at least a 555-fold increase in sensitivity compared to traditional AuNP-based LFA and approximately a 116-fold increase compared to an enzyme-linked immunosorbent assay. The practicality of the proposed assay was validated by testing various complex real-world samples and 32 clinical respiratory samples, showcasing its significant potential for broad-spectrum detection of pathogens in clinical and field settings.