Boronate Affinity-Assisted Electrochemically Controlled ATRP for Ultrasensitive Electrochemical Aptasensing of Carcinoembryonic Antigen
As an acidic glycoprotein, carcinoembryonic antigen (CEA) is of great value as a broad-spectrum tumor marker in the differential diagnosis and surveillance of malignant tumors. In this work, we report an electrochemical aptasensor for the ultrasensitive and highly selective detection of CEA, taking advantage of the dual amplification by the boronate affinity-assisted electrochemically controlled atom transfer radical polymerization (BA-eATRP). Specifically, the BA-eATRP-based electrochemical aptasensing of CEA involves the capture of target antigens by nucleic acid aptamers, the covalent crosslinking of ATRP initiators to CEA antigens via the selective interactions between the phenylboronic acid (PBA) group and the cis-diol group of the monosaccharide residues, and the collection of the ferrocene (Fc) reporters via the eATRP of ferrocenylmethyl methacrylate (FcMMA). As CEA is decorated with hundreds of cis-diol groups, the BA-based crosslinking can result in the labeling of each CEA with hundreds of ATRP initiators; furthermore, the eATRP of FcMMA results in the surface-initiated growth of long-chain ferrocenyl polymers, leading to the tethering of each ATRP initiator-conjugated site with hundreds to thousands of Fc reporters. Such that, the BA-eATRP can result in the efficient labeling of each CEA with a plenty of Fc reporters. Under the optimized conditions, the BA-eATRP-based strategy enables the highly selective aptasensing of CEA at a concentration as low as 0.34 pg·mL−1, with a linear range of 1.0−1,000 pg·mL−1. Besides, this aptasensor has been successfully applied to the quantitative analysis of CEA in human serum. The BA-eATRP-based electrochemical aptasensor is cost-effective and simple in operation, holding broad application prospect in the ultrasensitive and highly selective detection of CEA.