Molybdenum disulfide-loaded multilayer AuNPs with colorimetric-SERS dual-signal enhancement activities for flexible immunochromatographic diagnosis of monkeypox virus.

The sudden outbreak of monkeypox in 2022 suggests the importance of developing a rapid but sensitive virus detection technology. Herein, we report a colorimetric/surface-enhanced Raman scattering (SERS) dual-signal co-enhanced immunochromatographic assay (ICA) for the flexible, ultrasensitive, and accurate detection of monkeypox virus (MPXV) in various complex samples. A thickness-controlled polyethyleneimine interlayer (1 nm) is coated onto two-dimensional molybdenum disulfide (MoS2) nanosheet to enable the electrostatic adsorption of two layers of dense 30 nm AuNPs, which not only improves colorimetric ability but also creates numerous efficient SERS hotspots. Moreover, the SERS activity of film-like dual-signal tag (MoS2@Au-Au) is drastically enhanced by combining the chemical enhancement effect of MoS2 sheets and the electromagnetic enhancement effect of Au-Au hotspots. The introduction of MoS2@Au-Au greatly broadens the application range of existing ICA methods, in which the colorimetric signal supports the quick identification of the target virus and the SERS signal allows the quantitative detection of MPXV with detection limits of as low as 0.2 and 0.002 ng/mL. Given its rapid detection ability (< 20 min), high accuracy in real samples (RSD < 9.89 %), and superior sensitivity than traditional AuNP-based colorimetric ICA (> 500 times), the proposed assay has great potential for field application.