An Aptamer‐based Self‐Catalytic Colorimetric Assay for Carcinoembryonic Antigen

Abstract

We report a visualization assay for carcinoembryonic antigen (CEA). The assay was prepared based on target‐specific recognition, aptamer‐based DNAzyme self‐catalysis, and colorimetric reaction. Aptamer of CEA was gathered at the surface of magnetic beads for sandwiched co‐conjugate when CEA was added. The second aptamer (Apt2) on the beads was folded into G‐quadruplex by KCl to make G‐quadruplex‐hemin DNAzyme with hemin. Apt2‐based DNAzyme catalyzed H2O2‐mediated oxidation of 3,3′,5,5′‐tetramethylbenzidine, resulting in color changes and significant increase in absorption intensity at 450 nm (ΔA450nm). Yellow products can be observed with naked eyes when over 1.0 ng/mL CEA was added and there was a linear correlation between ΔA450 nm and CEA concentrations in the range of 0.1–8.0 ng/mL with the detection limit of 0.06 ng/mL. The proposed method was then used to determine CEA in human serum from healthy people and tumor patients, revealing a correlation with data from the electrochemiluminescent immunoassay. Owing to its simplicity, selectivity, and low‐cost, this method is a promising candidate for detecting CEA and clinical diagnosis of cancer.

A fluorescent aptasensor for highly sensitive and selective detection of carcinoembryonic antigen based on upconversion nanoparticles and WS2 nanosheets

“…Compared with the reported homogeneous aptasensor methods (Table S1†), the sensitivity of this proposed aptasensor based on UCNPs is at least one order of magnitude lower than that of the UCNP-based FRET aptasensor 16–18 as well as some other reported methods including using aptamers for determination of CEA. 32–36 Furthermore, the LOD of the developed aptasensor is far lower than the threshold value in healthy human serum (5 ng mL −1 ). 33 The significant improvement in the performance of the aptasensor based on UCNPs and WS 2 nanosheets was largely due to the superquenching fluorescence ability of WS 2 nanosheets toward UCNPs.…”