A Co-Reactive Immunosensor Based on Ti3C2Tx MXene@TiO2–MoS2 Hybrids Promoting luminol@Au@Ni–Co NCs Electrochemiluminescence for CYFRA 21–1 Detection

The construction of assays is capable of accurately detecting cytokeratin-19 (CYFRA 21-1), which is critical for the rapid diagnosis of nonsmall cell lung cancer. In this work, a novel electrochemiluminescence (ECL) immunosensor based on the co-reaction promotion of luminol@Au@Ni-Co nanocages (NCs) as ECL probe by Ti₃C₂T_x MXene@TiO₂-MoS₂ hybrids as co-reaction accelerator was proposed to detect CYFRA 21-1. Ni-Co NCs, as a derivative of Prussian blue analogs, can be loaded with large quantities of Au NPs, luminol, and CYFRA 21-1 secondary antibodies due to their high specific surface area. To further improve the sensitivity of the developed ECL immunosensor, Ti₃C₂T_x MXene@TiO₂-MoS₂ hybrids were prepared by in situ growth of TiO₂ nanosheets on highly conductive Ti₃C₂T_x MXene, and MoS₂ was homogeneously grown on Ti₃C₂T_x MXene@TiO₂ surfaces by the hydrothermal method. Ti₃C₂T_x MXene@TiO₂-MoS₂ hybrids possess excellent catalytic performance on the electro-redox of H₂O₂ generating more O₂^·- and obtaining optimal ECL intensity of the luminol/H₂O₂ system. Under the appropriate experimental conditions, the quantitative detection range of CYFRA 21-1 was from 0.1 pg mL^-1 to 100 ng mL^-1, and the limit of detection (LOD) was 0.046 pg mL^-1. The present sensor has a lower LOD with a wider linear range, which provides a new analytical assay for the early diagnosis of small-cell-type lung cancer labels.