Label-Free and Ultrasensitive Electrochemiluminescent Immunosensor Based on Novel Luminophores of Ce₂Sn₂O₇ Nanocubes

In this research article, a novel and simple label-free electrochemiluminescence (ECL) immunosensor using cerium stannite (Ce₂Sn₂O₇) nanocubes as brand-new ECL emitters has been suggested for the first time. Ce₂Sn₂O₇ nanocubes prepared by a simple hydrothermal method displayed bright ECL emission, promising biocompatibility, low noxiousness, and perfect stability. On comparison of ECL and photoluminescence (PL) spectra, a surface-state mechanism was proposed to be involved in the ECL emission. After aminofunctionalization with 3-aminopropyltriethoxysilane (APTES), Ce₂Sn₂O₇ could be decorated with gold nanoparticles through Au–NH₂ covalent linkage, which yielded Au@Ce₂Sn₂O₇ nanocomposites and further enhanced the ECL emission. To confirm the proposed immunosensor feasibility, carcinoembryonic antigen (CEA) was employed as an exemplary analyte. Based on the abovementioned points, our fabricated immunosensor improved the ECL performance to CEA concentrations in a linear range of 0.001–70 ng/mL with a low limit of detection of 0.53 pg/mL (S/N = 3). With outstanding stability, reproducibility, and specificity, this method is expected to be an innovative one for sensitive analyses of CEA and other biomarkers in real samples.