1. A label-free electrochemical magnetic aptasensor based on exonuclease III-assisted signal amplification for determination of carcinoembryonic antigen.
- Author
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Li X, Weng C, Wang J, Yang W, Lu Q, Yan X, Sakran MA, Hong J, Zhu W, and Zhou X
- Subjects
- Carcinoembryonic Antigen chemistry, DNA, Single-Stranded chemistry, Gold chemistry, Humans, Immobilized Nucleic Acids chemistry, Limit of Detection, Magnetite Nanoparticles chemistry, Nucleic Acid Amplification Techniques, Aptamers, Nucleotide chemistry, Biosensing Techniques methods, Carcinoembryonic Antigen blood, Electrochemical Techniques methods, Exodeoxyribonucleases chemistry
- Abstract
A novel label-free and exonuclease III (Exo III)-assisted signal amplification electrochemical aptasensor was constructed for the determination of carcinoembryonic antigen (CEA) via magnetic field-induced self-assembly of magnetic biocomposites (Fe
3 O4 @Au NPs-S1-S2-S3). The magnetic biocomposites were acquired by modifying double-stranded DNA (S1-S2-S3) on the surface of Fe3 O4 @Au nanoparticles (Fe3 O4 @Au NPs). Among them, Fe3 O4 @Au NPs were used as carriers for magnetic separation, thiolated single-stranded DNA (S1) provided signal sequence, CEA aptamer (S2) worked as a recognition element, and complementary strand (S3) was used to form double strands. In the presence of CEA, S2 bonded with CEA competitively; the exposed S1 could not be cleaved since Exo III was inactive against ssDNA. The G-quadruplex/hemin complexes finally formed with the existence of K+ , and the high electrochemical signal of G-quadruplex/hemin complexes was recorded by differential pulse voltammetry (DPV) at -โ0.6 V. Conversely, in the absence of CEA, dsDNA was cleaved from the 3' blunt end by Exo III; the disappearance of G-rich sequence blocked the generation of the signal. This method exhibited good selectivity and sensitivity for the determination of CEA; the linear range was from 0.1 to 200 ng mL-1 and the limit of detection was 0.4 pg mL-1 . Graphical abstract.- Published
- 2020
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