Supramolecular Enzymatic Labeling for Aptamer Switch-Based Electrochemical Biosensor

Abstract

Here we report a novel labeling strategy for electrochemical aptasensors based on enzymatic marking via supramolecular host–guest interactions. This approach relies on the use of an adamantane-modified target-responsive hairpin DNA aptamer as an affinity bioreceptor, and a neoglycoconjugate of β-cyclodextin (CD) covalently attached to a redox enzyme as a labeling element. As a proof of concept, an amperometric aptasensor for a carcinoembryonic antigen was assembled on screen-printed carbon electrodes modified with electrodeposited fern-like gold nanoparticles/graphene oxide and, by using a horseradish peroxidase-CD neoglycoenzyme as a biocatalytic redox label. This aptasensor was able to detect the biomarker in the concentration range from 10 pg/mL to 1 ng/mL with a high selectivity and a low detection limit of 3.1 pg/mL in human serum samples.

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“…186 As such, these probes are often deposited together with backfilling and passivating molecules such as alkanethiol chains 187 (e.g., 3-mercapto-1-propanol, 6-mercapto-1-hexanol, and 11-mercapto-1-undecanol), polyethylene glycol, bovine serum albumin, and casein. [188][189][190] In addition, linkers such as trithiols can promote the stability of the self-assembled monolayers on the electrode (Fig. 4a: (ii)).…”