Disposable Electrochemical Aptasensor Based on Graphene Oxide-DNA Complex as Signal Amplifier towards Ultrasensitive Detection of Ochratoxin A

Abstract

Signal amplification is crucial in developing a reliable disposable screen-printed carbon electrodes (SPCEs)-based biosensor for analyte detection with a narrow detection window. This work demonstrated a novel label-free electrochemical aptasensor based on SPCEs for the ultrasensitive detection of ochratoxin A (OTA). The graphene oxide-DNA (GO-DNA) complex as a signal amplifier with easy preparation was investigated for the first time. The proposed aptasensor based on the SPCEs/GO/cDNA-aptamer/3D-rGO-AuNPs structure was formed through the hybridization of aptamer-linked 3D-rGO/AuNPs and its complementary DNA-linked GO (GO-cDNA). The presence of OTA was discerned by its specific aptamer forming a curled OTA-aptamer complex and releasing the GO-cDNA from the surface of SPCEs. The resulting OTA-aptamer complex hindered interfacial electron transfer on the sensing surface, leading to the decreased peak current. The GO-cDNA further amplified the peak current change. This electrochemical aptasensor showed a low limit of detection of 5 fg/mL as well as good reproducibility with the relative standard deviation (RSD) of 4.38%. Moreover, the detection result of OTA in the rice and oat samples was comparable with that of the enzyme-linked immunosorbent assay (ELISA) kit. In general, the OTA aptasensor used in this work with convenient preparation, low-cost, good selectivity, high sensitivity and acceptable reproducibility can be proposed as a reliable point-of-care (POC) technique for OTA determination.

Modern Electrochemical Biosensing Based on Nucleic Acids and Carbon Nanomaterials

“…Multiple similar biosensor’s construction, based on composites of Au nanomaterials with GO and reduced GO, have been used for the detection of other biomarker proteins [ 72 , 73 , 74 ] and small molecules [ 75 , 76 , 77 ]. In all cases, the introduction of nanomaterials was aimed at improving the rate of the electron transfer and developing the surface area, and thus, creating a greater number of receptor binding sites.…”

“…A very simple competitive aptasensor design for the detection of ochratoxin A was proposed in 2022 by Hu et al [ 76 ]. In this case, graphene derivatives played a dual role.…”

“… Working principle of competitive aptasensor labelled with graphene oxide-complementary DNA conjugates (GO-cDNA) for the electrochemical detection of ochratoxin A. Adapted with permission from Hu et al [ 76 ] (under the terms and conditions of the Creative Commons CC BY License 4.0). …”