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 Ti3C2Tx 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, Ti3C2Tx MXene@TiO2–MoS2 hybrids were prepared by in situ growth of TiO2 nanosheets on highly conductive Ti3C2Tx MXene, and MoS2 was homogeneously grown on Ti3C2Tx MXene@TiO2 surfaces by the hydrothermal method. Ti3C2Tx 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.