Label-Free and Highly-Sensitive Detection of Ochratoxin A Using One-Pot Synthesized Reduced Graphene Oxide/Gold Nanoparticles-Based Impedimetric Aptasensor

Abstract

Ochratoxin A (OTA) primarily obtained by the genera aspergillus and penicillium, is one of the toxic substances for different organs and systems of the human body such as the kidney, liver, neurons and the immune system. Moreover, it is considered to cause tumors and fetal malformation even at a very low concentration. Fast and sensitive assay for detection of OTA at ultralow levels in foods and agricultural products has been an increasing demand. In this study, a new label-free electrochemical biosensor based on three-dimensional reduced graphene oxide/gold nanoparticles/aptamer for OTA detection was constructed. The 3D-rGO/Au NPs nanocomposites were firstly synthesized using a one-pot hydrothermal process under optimized experimental conditions. The 3D-rGO/Au NPs with considerable particular surface area and outstanding electrical conductivity was then coated on a glass carbon electrode to provide tremendous binding sites for -SH modified aptamer via the distinctive Au–S linkage. The presence of OTA was specifically captured by aptamer and resulted in electrochemical impedance spectroscopy (EIS) signal response accordingly. The constructed impedimetric aptasensor obtained a broad linear response from 1 pg/mL to 10 ng/mL with an LOD of 0.34 pg/mL toward OTA detection, highlighting the excellent sensitivity. Satisfactory reproducibility was also achieved with the relative standard deviation (RSD) of 1.393%. Moreover, the proposed aptasensor obtained a good recovery of OTA detection in red wine samples within the range of 93.14 to 112.75% along with a low LOD of 0.023 ng/mL, indicating its applicability for OTA detection in real samples along with economical, specific, susceptible, fast, easy, and transportable merits.

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

“…The 3D-rGO/AuNPs nanocomposites were synthesized through a one-pot hydrothermal reduction process according to our previous article [15]. Briefly, 20 mg of GO nanosheets were dissolved in 10 mL of water under ultrasonic treatment for 2 h to form 2 mg/mL of GO suspension.…”

“…The mixture was then centrifuged and the supernatant was collected as the original stock solution. It was found that the original stock solution of real samples possessed a huge matrix effect [15,31], resulting in false results. Thus, the rice and oat sample stock solutions were diluted 10-fold for accurate electrochemical analysis.…”

“…Specific electrochemical electrodes such as glassy carbon electrodes (GCEs) [11,12], carbon paste electrodes (CPEs) or graphite pencil electrodes [13,14] have been used to develop the electrochemical aptasensor of OTA detection. For instance, our previous work demonstrated a label-free aptasensing device based on 3D-rGO/AuNPs-modified GCEs to achieve the sensitive and selective determination of OTA [15]. The aptasensor exhibits an ultrasensitive limit of detection (LOD) of 0.34 pg/mL with good reproducibility.…”

Carbon-Based Nanocomposite Smart Sensors for the Rapid Detection of Mycotoxins

“…The 3D-rGO/Au NPs were synthesized using a one-pot method coated on a glassy carbon electrode, providing a large binding site for the -SH-modified aptamer through unique Au-S connections. Yasmin and colleagues used electrochemical impedance spectroscopy (EIS) for testing and showed a linear response from 1 pg/mL to 10 ng/mL with a limit of detection (LOD) of 0.34 pg/mL for OTA detection in red wine samples [34]. The plentiful presence of carboxyl groups in the CQDs provided strong bonding of aptamers on the surface of CQDs with π-π interactions [35].…”