Construction of an electrochemiluminescence immunosensor based on a pre-concentration enhanced mechanism for ultrasensitive detection of CEA.

Carcinoembryonic antigen (CEA) is an essential biomarker for colorectal cancer screening and prognostic assessment, and its reliable quantification is crucial for early diagnosis and subsequent disease monitoring. In this work, a β-cyclodextrin/zeolitic imidazolate framework-8@SiO2 (CDZS-1) composite was selected as the carrier for Ru(bpy)32+, while CuO nanoparticles (CuO NPs) were introduced as co-reaction accelerators to fabricate a highly sensitive ECL immunosensor. The sensor exhibits the following advantages: (1) CDZS-1 offers a large specific surface area and high porosity, it features hierarchical porosity containing micropores and mesopores, allowing efficient loading of Ru(bpy)32+. (2) CDZS-1 can preconcentrate the co-reactant tri-n-propylamine (TPrA) through hydrophilic-hydrophobic interactions and confine the local concentration of Ru(bpy)32+/TPrA, thereby improving reaction efficiency and notably enhancing ECL emission. (3) CuO NPs, recognized for good biocompatibility and catalytic performance, were applied as probes to label the secondary antibody, which further strengthens the ECL signal. Experimental results confirmed that the sensor maintains a linear response toward CEA across 1.0 × 10-4 ng mL-1 to 80 ng mL-1, with a limit of detection (LOD) down to 27.5 fg mL-1. This ECL immunoassay shows substantial potential for clinical diagnosis and therapeutic evaluation of colorectal cancer, offering a promising analytical approach for accurate CEA quantification.