Taotao Feng,Xiuwen Qiao,Haining Wang,Zhao Sun,Chenglin Hong
In this article, a novel electrochemical immunosensor was proposed based on ferrocenecarboxylic acids (Fc-COOH) connected to the branched structure of an electrode surface for the detection of carcinoembryonic antigen (CEA). The electrode was first modified with multi-walled carbon nanotubes–chitosan (MWCNT–CS) complexes, and the MWCNT–CS coating contains active secondary reaction functional entities that could form covalent bonds with molecules containing carboxyl or aldehyde groups. A large number of Fc-COOH groups were connected to the branched structure of the electrode surface, and then the electrode was further modified with polydopamine (PDA) and gold nanoparticles (AuNPs), which not only provided a favorable microenvironment and increased the loading capacity of the biomolecules to maintain the activity of the immobilized biomolecules, but also enhanced the conductivity and charge-transport properties of the modified electrode. Under optimal conditions, the immunosensor showed a low limit of detection (0.002 ng mL−1) and a wide linear range (0.01–80 ng mL−1). With the merits of acceptable stability, high sensitivity, the wide linear range and the low detection limit, the new immunosensors show great potential in the field of analytical applications.
Huixiang Yan,Xiaodi Tang,Xudong Zhu,Yanbo Zeng,Xing Lu,Zhengzhi Yin,Yixia Lu,Yiwen Yang,Lei Li
Herein we report a sandwich-type electrochemical immunosensor for sensitive detection of cardiac troponin I (cTnI) using a new composite of carboxyl-terminated ionic liquid and helical carbon nanotubes (CIL-HCNTs) as platform and ferrocenecarboxylic acid (Fc-COOH) as signal label. The composite of CIL-HCNTs was prepared by a simple and convenient one-step ultrasound method and was then characterized by Fourier transform infrared spectroscopy, scanning electron microscope, cyclic voltammetry and chronocoulometry. CIL-HCNTs, possessing large surface area and high electrical conductivity, provide a good platform for anti-cTnI monoclonal antibody immobilization through the carboxyl groups of CIL-HCNTs. The Fc-COOH, as a signal label based on the oxidation process, was combined with the CIL-HCNT platform to construct the electrochemical immunosensor for cTnI determination. Under optimal conditions, the electrochemical immunosensor exhibited desirable performance for cTnI determination with a wide range of linearity from 0.01 to 60.0 ng mL −1 and a relatively low detection limit of 0.006 ng mL −1 . Importantly, the immunosensor showed excellent specificity and acceptable reproducibility as well as satisfactory reliability for human serum sample analysis.
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