Label-free differential chemiluminescent immunosensor based on magnetic nanoparticles CuFeO@ABEI-GNPs with dual catalytic sites.

Background: Cancer has become one of the main causes of death globally. The level of tumor markers in serum is correlated with the occurrence of cancer. Carcinoembryonic antigen (CEA) is the most commonly utilized tumor marker for cancer detection. Recently, various analytical technologies have been reported to detect biomarkers. However, developing a simple, sensitive, and noninvasive approach for CEA detection remains challenging in cancer diagnosis. Consequently, there is an urgent need for researchers to carry out innovative approaches for CEA detection.

Result: In this work, copper ferrite nanoparticles (CuFeO NPs) with excellent dispersity and fascinating magnetism have been successfully synthesized. To get CuFeO@ABEI-GNPs, ABEI-gold NPs (ABEI-GNPs) were generated on the surface of CuFeO NPs by using N-(4-Aminobutyl)-N-ethylisoluminol (ABEI) as a mild reduction reagent to reduce chloroauric acid tetrahydrate (HAuCl·4HO). The CuFeO@ABEI-GNPs exhibited a superior chemiluminescence (CL) performance compared with CuFeO@ABEI NPs, which was attributed to the synergistic catalysis effects of CuFeO NPs and GNPs. Interestingly, two unique CL emission peaks were observed in the kinetic curve of CuFeO@ABEI-GNPs. Furthermore, it was found that the kinetic curve could be regulated by the pH of hydrogen peroxide (HO) and a possible CL mechanism was proposed. Owing to the favorable CL properties of CuFeO@ABEI-GNPs, a label-free differential immunosensor was fabricated for CEA monitoring using the intensity difference between CL-1 and CL-2. The developed immunosensor exhibited a wide linear range from 0.1 to 5000 pg/mL, and a low detection limit of 0.05 pg/mL.

Significance And Novelty: The immunosensor was capable of determining CEA in real samples with simple operation, high accuracy, and good sensitivity. This study introduces a novel approach for developing CL functionalized materials, which have broad application potential in bioassays. The proposed differential method could serve as a novel tool for determining CEA in the diagnosis of clinical cancer.