MXene Bimetallic Coating Synergistic Enhanced Colorimetric-Raman Dual Signal-Based Immunochromatographic Assay for Advancing Detection Performance

Herein, a three-dimensional thin film-like multifunctional MXene bimetallic coating material (Ti₃C₂@Au-Ag) with strong color intensity, high surface-enhanced Raman scattering (SERS) activity, and strong antibody affinity (1.00 × 10⁸ M^-1) was prepared. It was the first time that Ti₃C₂@Au-Ag-based colorimetric-SERS dual-signal immunochromatographic assay (ICA) was developed for the detection of dexamethasone, achieving the limits of detection of 0.0089, 0.14, and 0.084 μg/kg for milk, beef, and pork in colorimetric mode and 0.0015, 0.060, and 0.075 μg/kg in SERS mode. It was up to 200-fold more sensitive than the reported ICAs. The recoveries were 82.0%-112.6%, and the coefficients of variation were 1.4%-13.7%. The Ti₃C₂@Au-Ag-ICA was verified by LC-MS/MS in the application on 30 real samples with a correlation coefficient greater than 0.98. This study can provide efficient theoretical and practical value for the development of a colorimetric-SERS dual-signal immunoassay platform.