An Immunosensor Using Electroactive COF as Signal Probe for Electrochemical Detection of Carcinoembryonic Antigen

Two kinds of two-dimensional (2D) covalent-organic frameworks (COF) were used to construct a sandwich-type electrochemical immunosensor for a proof-of-concept study .Vinyl-functionalized COFTab-Dva could be linked with Ab1 by the thiol-eneclickreaction. Electroactive COFTFPB-Thi was modified with gold nanoparticles (AuNPs) to ensure the successful connection with Ab2 through Au-S bond. Meanwhile, electro-active COFTFPB-Thi was used to as signal probe to realize both the detection of carcinoembryonic antigen (CEA) and theamplification of detection signal. In detection process of thesandwich-type electrochemical immunosensor, glassy carbonelectrode (GCE) was modified with 2D COFTab-Dvafirst thenconnected with Ab1 by the thiol-eneclickreaction, next quantitative CEA was captured, followed by specificially capturing signalprobe of Ab2/AuNPs/COFTFPB-Thi where AuNPs acted as nanocarriers of Ab2 and COFTFPB-Thi served as the signalproducers. As the amount of CEA was increased, the amount of signal probe captured to the electrode was also increased, and the peak signal intensity of the redox reaction of COFTFPB-Thi was enhanced accordingly. Thus, the quantitative detection of CEAcould be realized according to the peak signal intensity of electroactive COFTFPB-Thi. The electrochemical immunosensor ownedwide detection range of 0.11 ng/mL-80 ng/mL, low detection limit of 0.034 ng/mL and good practicability. This study opens up anew revelation for quantitative detection of CEA using electroactive COF as enhanced signal probe.

Automated summary

Two-dimensional covalent-organic frameworks (COF) were used to construct a sandwich-type electrochemical immunosensor for the quantitative detection of carcinoembryonic antigen (CEA). The immunosensor exhibited a wide detection range and a low detection limit.