Sandwich-like electrochemiluminescence aptasensor based on dual quenching effect from hemin-graphene nanosheet and enzymatic biocatalytic precipitation for sensitive detection of carcinoembryonic antigen

A new and simple sandwich-like electrochemiluminescence (ECL) aptasensor for carcinoembryonic antigen (CEA) assay was fabricated based on the dual quenching effect from hemin-graphene (H-rGO) nanosheet and enzymatic biocatalytic precipitation (BCP) on the Au-CdS nanocomposites-based ECL system. In this aptasensor platform, flower-like spherical Au-CdS nanocomposites were used as ECL luminophores and exhibit a strong ECL signal. The rGO nanosheet was used as a supporter to immobilize hemin molecules via pi-pi stacking interactions. Due to the steric hindrance and quenching effect of rGO, the ECL intensity decreased by the construction of the sandwich CEA aptamer I (NH2-DNA)-CEA-aptamer II (H-rGO-aptamer II) mode. In the process of BCP, the ECL intensity further decreased because the hemin with intrinsic peroxidase-like catalytic activity could oxidize the 4-chloro-l-naphthol (4-CN) to produce an insoluble precipitation on the sensor. Using this dual quenching strategy, the prepared aptasensor exhibits a linear range from 0.8 pg/mL to 4 ng/mL and a detection limit of 0.28 pg/mL. This ECL aptasensor has simple design and undemanding in operation and was utilized to determine the content of CEA in complex samples with recoveries of 95.0% to 115.8%. Moreover, no any chemical modification of aptamer was required, suggesting that the proposed ECL aptasensor could be applied for the detection of diverse proteins just by altering the aptamer sequence. (C) 2017 Elsevier B.V. All rights reserved.