De-lei Li,Xi Zhang,Yuchan Ma,Yan Deng,Rong Hu,Yunhui Yang
A novel aptasensor for ultrasensitive and rapid detection of ochratoxin A (OTA) was developed using a metal–organic framework (MOF) as the signal unit. In this work, a MOF was utilized as the signal probe. The signal probe differs from traditional probes; the signal of the cadmium ions (Cd2+) from the MOF can be directly detected without acid dissolution and preconcentration, greatly simplifying the detection steps and reducing the detection time. Moreover, the MOF contains large amounts of Cd2+ ions, which could provide high electrochemical signals. Our report is the first time using an MOF as the electrochemical signal probe for an aptasensor application. A gold nanoparticle (Au NP)-doped molybdenum disulfide (MoS2) nanocomposite was employed as an immobilized matrix for the sensor because of its high electronic conductivity. Under the optimized experimental conditions, an ultrasensitive aptasensor for the detection of OTA exhibited a wide linear range of 0.05–100 ng mL−1 with a low detection limit (LOD) of 10 pg mL−1 OTA (at 3σ). With these merits, this stable, simple, low-cost, sensitive and selective electrochemical aptasensor shows promise for applications in environmental monitoring.
Ailing Lei,Mingda Li,Siqi Zhuo,Qianjin Li,Jianlin Li
Ochratoxin A (OTA) with high toxicity is widely present in agricultural products, posing an enormous threat to human and animal health. Thus, simple, rapid, sensitive and selective detection of OTA is highly necessary. Herein, we have developed a new label-free fluorescence and naked-eye detection platform for ochratoxin A based on the interaction between OTA-antiparallel G-quadruplex(G4)/crystal violet (CV). CV and OTA aptamer could form a G4 structure with high fluorescence intensity. When OTA was present in the G4/CV mixture, it replaced CV and bound to the OTA aptamer, and then the fluorescence of the mixture remarkedly quenched. The interaction among OTA and G4/CV had been revealed by fluorescence, ultraviolet and circular dichroism (CD) spectra. The detection process could be performed by naked-eye and could be completed within 10 min. The established method showed 0.1–1000 ng/mL linear detection range with 0.07 ng/mL limit of detection (LOD). The recovery rates in cereal samples were in the range of 76–105%. Compared with the classical ELISA, the recovery rates and the detected concentration of OTA in the naturally contaminated cereal samples were consistent. The new method can provide a simple, rapid and cost-effective, label-free and naked-eye detection of OTA with high specificity, good repeatability and high precision.
Ochratoxin A (OTA) is a highly toxic mycotoxin with nepHrotoxicity, hepatotoxicity, and carcinogenicity. It poses a long-term threat to the health of humans and animals. Although screen printed electrodes (SPE) with aptamer functionalization provide promising detection capabilities, their applications are limited by inherent weak electrochemical signals, prompting the need for signal amplification strategies. In this study, tetrahedral DNA clusters (TDCs) were prepared as aptamer probes for OTA, and an aptamer-based electrochemical sensing method for OTA was established for signal amplification. Multiple single-stranded DNA (ssDNA) were designed to self-assemble into tetrahedral DNA nanostructure (TDN) through base complementarity, with the OTA aptamer attached to one vertex. Additional ssDNA strands were further utilized to extend TDNs at the three remaining vertices, forming a DNA tetrahedral cluster. The method had a linear range of 1 pg/mL to 100 ng/mL (LOD = 1 pg/mL) for detecting OTA, with excellent specificity and satisfactory recovery rate in feed samples
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