TY - JOUR T1 - Electrochemical sandwich aptasensor for the carcinoembryonic antigen using graphene quantum dots, gold nanoparticles and nitrogen doped graphene modified electrode and exploiting the peroxidase-mimicking activity of a G-quadruplex DNAzyme. AU - Shekari,Zahra, AU - Zare,Hamid R, AU - Falahati,Ali, Y1 - 2019/07/13/ PY - 2019/01/25/received PY - 2019/06/02/accepted PY - 2019/7/15/entrez PY - 2019/7/16/pubmed PY - 2020/3/26/medline KW - Biomarker KW - CEA KW - Electroreduction KW - Hemin–G–quadruplex · KW - Hydrogen peroxide SP - 530 EP - 530 JF - Mikrochimica acta JO - Mikrochim Acta VL - 186 IS - 8 N2 - A sandwich-type electrochemical aptasensor has been constructed and applied for sensitive and selective detection of the carcinoembryonic antigen (CEA). The surface of a glassy carbon electrode (GCE) was first modified with nitrogen-doped graphene and then gold nanoparticles and graphene quantum dots electrodeposited on it to obtain an architecture of type GQD/AuNP/NG/GCE. In the next step, the CEA-binding aptamer was immobilized on the modified GCE. Hemin intercalates in the amino-modified hemin aptamer to form a hemin-G-quadruplex (hemin-G4) DNAzyme. The amino modified CEA aptamer II is connected to hemin-G4 by glutaraldehyde (GA) as a linker to produce CEAaptamerII/GA/hemin-G4 (=ApII/GA/DNAzyme). Through a sandwich mode, the ApII/GA/DNAzyme bioconjugates are captured on the modified GCE. Subsequently, the hemin-G4 acts as peroxidase-mimicking DNAzyme and rapidly catalyzes the electroreduction of hydrogen peroxide. The quantitative determination of CEA was achieved by differential pulse voltammetry, best at a working potential of around -0.27 V vs. Ag/AgCl. Under optimized conditions, the assay has a linear response in the 10.0 fg mL-1 to 200.0 ng mL-1 CEA concentration range and a lower detection limit of 3.2 fg mL-1. Graphical abstract Schematic presentation of a sandwich-type electrochemical aptasensor based on nitrogen doped graphene (NG), gold nanoparticles (AuNPs) and graphene quantum dots (GQDs) modified glassy carbon electrode, and the hemin-G4 DNAzyme for femtomolar detection of the carcinoembryonic antigen. SN - 1436-5073 UR - https://www.unboundmedicine.com/medline/citation/31302781/Electrochemical_sandwich_aptasensor_for_the_carcinoembryonic_antigen_using_graphene_quantum_dots_gold_nanoparticles_and_nitrogen_doped_graphene_modified_electrode_and_exploiting_the_peroxidase_mimicking_activity_of_a_G_quadruplex_DNAzyme_ DB - PRIME DP - Unbound Medicine ER -