4.6 Article

A switchable electrochemical hairpin-aptasensor for ochratoxin A detection based on the double signal amplification effect of gold nanospheres

Journal

NEW JOURNAL OF CHEMISTRY
Volume 46, Issue 9, Pages 4126-4133

Publisher

ROYAL SOC CHEMISTRY
DOI: 10.1039/d1nj05729d

Keywords

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Funding

  1. Qinglan Project
  2. Fundamental Research Funds for the Central Universities [2242020K40191]
  3. Postgraduate Research & Practice Innovation Program of Jiangsu Province [KYCX21_0163]

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A switchable electrochemical hairpin-aptasensor has been established for the detection of OTA in food samples. The sensor utilizes a hairpin-DNA as a signal switch and combines gold nanospheres and multiwalled carbon nanotubes to establish a support interface. Conjugated polymer-nanoparticle composites are used to label report DNA, forming a signal probe. The sensor offers a low detection limit and a wide monitoring range.
Ochratoxin A (OTA) is a ubiquitous food contaminant and can cause serious harm to human health. Herein, a switchable electrochemical hairpin-aptasensor for OTA detection was established. Hairpin-DNA (h-DNA) was designed as a signal switch consisting of an anti-OTA aptamer (OTA-apt) and complementary DNA (cDNA). Gold nanospheres (GNSs) were combined with multiwalled carbon nanotubes (MWCNTs) to establish a great support interface (MWCNTs/GNSs). Meanwhile, conjugated polymer-nanoparticle composites (POPD-GNSs) were prepared and utilized to label report DNA (rDNA), forming a signal probe (POPD-GNSs-rDNA). In the presence of OTA, a configuration change was triggered and switched on the h-DNA, leading to the exposure of cDNA, which is complementary with the rDNA. Therefore, POPD-GNSs-rDNA was introduced on the electrode and produced strong electrical signals (signal on). GNSs played the role of double signal amplification in the switchable electrochemical hairpin-aptasensor. Thus, a low limit of detection of 1 pg mL(-1) was obtained and the monitoring range was from 2 pg mL(-1) to 1 ng mL(-1). Moreover, the practicability and reliability of the constructed aptasensor was verified by detecting OTA in coffee samples. The satisfactory recovery demonstrates the potential application of this aptasensor in OTA monitoring for food security. This strategy is also applicable to the detection of other small molecule contaminants in food.

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