Precision-engineered magnetic/plasmonic heterodimers for naked-eye and photothermal mpox virus diagnostics

The global surge of mpox virus (MPXV) demands diagnostic tools that combine laboratory-grade accuracy with point-of-care simplicity. Here, we report an all-in-one lateral flow immunoassay (LFIA) leveraging precision-engineered Fe₃O₄-Au_shell heterodimers for dual-signal MPXV quantification via naked-eye readout and photothermal amplification. These monodisperse plasmonic-magnetic nanoparticles, synthesized through controlled seed-mediated heterodimerization, integrate magnetic enrichment, photothermal conversion, and tunable plasmonic resonance into a single architecture. The Fe₃O₄ core enables rapid magnetic separation, while the Au shell provides dual-mode LSPR colorimetry and NIR photothermal quantification. Magnetic separation eliminates preprocessing for direct analysis of untreated samples (e.g., blood, saliva), while photothermal amplification achieves 0.04 ng/mL sensitivity (125 × lower than visual detection). Dual-signal cross-verification ensures reliability: a 5 ng/mL naked-eye threshold supports rapid screening, complemented by photothermal linear quantification (1-1000 ng/mL, R² = 0.992) for precise viral load assessment. Validated with 100 % specificity against influenza and 93.3-98.5 % recovery in serum samples, this platform shows promising potential in point-of-care pathogens detection in resource-limited area.