Amperometric immunoassay for the carcinoembryonic antigen by using a peroxidase mimic consisting of palladium nanosphere
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ORIGINAL PAPER
Amperometric immunoassay for the carcinoembryonic antigen by using a peroxidase mimic consisting of palladium nanospheres functionalized with glutathione-capped gold nanoparticles on graphene oxide Zhaoling Tan 1 & Linlin Cao 2 & Yuying Yang 1 & Qin Yan 1 & Qing Liu 1 & Wen Zhang 2 & Pingping Zhao 3 & Yueyun Li 1 & Daopeng Zhang 1 Received: 26 March 2019 / Accepted: 7 September 2019 # Springer-Verlag GmbH Austria, part of Springer Nature 2019
Abstract A composite nanoenzyme was used in a sandwich-type electrochemical immunoassay for the carcinoembryonic antigen (CEA). Hierarchically porous palladium nanospheres (Pd NPs) were functionalized with glutathione-capped gold nanoparticles (G-Au NPs) and then loaded onto graphene oxide (GO) to obtain a peroxidase mimicking nanoenzyme of type GO-supported G-Au/Pd. The composite can catalyze the oxidation of the substrate tetramethylbenzidine (TMB) by H2O2 to give blue-colored oxidized TMB within only 20 s. This strong peroxidase activity, good conductivity and high specific surface area of the material make it a useful label for secondary antibodies (Ab2) for the detection of CEA. The cotton-like electrodeposited gold nanoparticles with good electrical conductivity were used to immobilize primary antibody (Ab1). The amperometric immunoassay has a detection range that extends from 10 fg·mL−1 to 100 ng·mL−1 at a working potential of −0.4 V with addition of 5 mmol·L−1 H2O2 as electrochemically active substrate, and the detection limit is as low as 3.2 fg·mL−1 (S/N = 3). Keywords Nanoenzymes . Sandwich-type electrochemical immunosensor . GO supported G-Au/Pd . CEA . Signal amplification
Introduction Carcinoembryonic antigen (CEA) with a molecular weight of about 200 kDa, has been related to colorectal cancer and conZhaoling Tan and Linlin Cao contributed equally to this work. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00604-019-3799-5) contains supplementary material, which is available to authorized users. * Qing Liu [email protected] 1
School of Chemistry and Chemical Engineering, Shandong University of Technology, Zibo 255049, People’s Republic of China
2
Department of Clinical Laboratory, Zibo Central Hospital, Zibo 255036, People’s Republic of China
3
College of Chemical and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266510, People’s Republic of China
sidered as a biomarker for breast tumors and ovarian carcinoma. The content of CEA for normal people is about 2.5– 5.0 ng·mL−1, which will increase once the tumor appears [1]. The earlier a cancer is discovered, the better your chances of cure [2]. There are various methods to detect CEA, such as enzyme-linked immunosorbent assay [3], mass spectrometric [4], chemiluminescent [5], photoelectrochemical immunoassay [6] and electrochemical immunosensor [7]. Among all of these methods, electrochemical immunosensors with low detection limits, high sensitivity, good selectivity and stability have shown broad prospects
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