Amperometric aptasensor for carcinoembryonic antigen based on a reduced graphene oxide/gold nanoparticles modified electrode

We report the construction of a novel amperometric aptasensor for the highly specific detection of carcinoembryonic antigen (CEA). The sensing interface was assembled by electrodeposition of reduced graphene oxide (rGO) and gold nanoparticles (AuNPs) on a carbon screen-printed electrode (SPE) and further functionalization with a biotin and thiol-modified anti-CEA DNA hairpin aptamer. The sensing approach relies on the specific recognition of CEA by the folded aptamer, causing unfolding of the DNA hairpin structure and unmasking the biotin residues at the aptamer chain. Further incubation with a sptreptavidin-peroxidase conjugate allows the amperometric detection of the cancer biomarker. This aptasensor was able to detect CEA in the broad range from 20 pg mL−1 to 2 μg mL−1 (112 fM–11 μM) with a detection limit of 16 pg mL−1 (90 fM). The aptasensor also showed high reproducibility, specificity and stability, and was successfully validated in diluted human serum samples.