MXene Bimetallic\nCoating Synergistic Enhanced Colorimetric-Raman\nDual Signal-Based Immunochromatographic Assay for Advancing Detection\nPerformance

Herein, a three-dimensional thin film-like multifunctional\nMXene\nbimetallic coating material (Ti<sub>3</sub>C<sub>2</sub>@Au–Ag)\nwith strong color intensity, high surface-enhanced Raman scattering\n(SERS) activity, and strong antibody affinity (1.00 × 10<sup>8</sup> M<sup>–1</sup>) was prepared. It was the first time\nthat Ti<sub>3</sub>C<sub>2</sub>@Au–Ag-based colorimetric-SERS\ndual-signal immunochromatographic assay (ICA) was developed for the\ndetection of dexamethasone, achieving the limits of detection of 0.0089,\n0.14, and 0.084 μg/kg for milk, beef, and pork in colorimetric\nmode and 0.0015, 0.060, and 0.075 μg/kg in SERS mode. It was\nup to 200-fold more sensitive than the reported ICAs. The recoveries\nwere 82.0%–112.6%, and the coefficients of variation were 1.4%–13.7%.\nThe Ti<sub>3</sub>C<sub>2</sub>@Au–Ag-ICA was verified by LC–MS/MS\nin the application on 30 real samples with a correlation coefficient\ngreater than 0.98. This study can provide efficient theoretical and\npractical value for the development of a colorimetric-SERS dual-signal\nimmunoassay platform.