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The timely detection of infectious pathogen is critical in clinical early diagnosis and treatment of infectious diseases. Plasmonic enzyme-linked immunosorbent assay (ELISA), by means of enzyme-mediated growth or aggregation of AuNPs, has received considerable attention because it allows a naked-eye detection of target in very low numbers. In this work, a dual-signal amplified plasmonic ELISA combined the high loading capacity of magnetic beads with the establishing stimulation effect of zinc ion has been developed to detect RSV as a model pathogen based on alkaline phosphatase-triggered dispersion of aggregated AuNPs. In ideal conditions, the proposed immunoassay can conveniently distinguish the concentration of RSV in a range of 0.1–30 pg/mL. In addition, the limit of detection of RSV of this immunoassay exceeds that of conventional ELISA by about 50 times. The high sensitivity makes this approach a good alternative to existing colorimetric immunoassays for pathogen detection. [ABSTRACT FROM AUTHOR]

Highlights: [•] We report a solution-based MEF sensing platform. [•] Metallic surface-dye distance is controlled by changing the thickness of silica shell. [•] Dual-aptamer was involved to recognize distinct binding epitopes of the same target. [•] Ag@Si NPs was used as an excellent probe for darkfield light scattering imaging. [ABSTRACT FROM AUTHOR]