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J Hazard Mater ; 401: 123794, 2021 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-33113737


In this work, an ultrasensitive and selective electrochemiluminescence (ECL) aptasensor with Au-tetrahedral aptamer nanostructure (Au-TAN) for acetamiprid detection was developed, which employed luminescence property of luminol and hydrogen peroxide (H2O2) as a co-reactant to apply the prepared Au-TAN to the luminescence systems. Au-TAN was prepared to modify an electrode surface via an Au-S bond to form a stable tetrahedral nanostructure. Fixed on the surface of the working electrode, Au-TAN could not only enhance the function of the aptamer but also boost the sensing performance. At the same time, Au nanoparticles (AuNPs) of the Au-TAN could also catalyze H2O2, thereby enhancing the luminescence performance of this aptasensor. The pH of the buffer solution, the concentration of H2O2 and the concentration of Au-TAN were optimized. Under the optimal conditions, the aptasensor had a detection limit of 0.0576 pM (S/N = 3), which was lower than those of other aptasensors for acetamiprid detection. Moreover, the weak alkaline environment explored in the experiment could expand its application range. Above all, the proposed method presented a high accuracy and sensitivity.

Artigo em Inglês | MEDLINE | ID: mdl-33161490


Broad-spectrum antibodies can effectively recognize substances with similar structures and have broad application prospects in field rapid detection. In this study, broad-spectrum antibodies (Abs) against organophosphorus pesticides (OPs) were used as sensitive recognition elements, which could effectively recognize most OPs. Gold nanoparticles (AuNPs) have good biocompatibility. It combined with Abs to form a gold-labeled probe (AuNPs-Abs), which enhances the effective binding of antibodies to nanomaterials. Prussian blue (PB) was added to electrodeposition solution to enhance the conductivity, resulting in superior electrochemical performance. The AuNP-Abs-PB composite film was prepared by electrodeposition on the electrode surface to improve the anti-interference ability and stability of the immunosensor. Under the optimal experimental conditions, the immunosensor had a wide detection range (IC20-IC80: 1.82 × 10-3-3.29 × 104 ng/mL) and high sensitivity. Most importantly, it was simple to be prepared and could be used to detect multiple OPs.

Sensors (Basel) ; 20(22)2020 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-33217912


Immunoassay has the advantages of high sensitivity, high specificity, and simple operation, and has been widely used in the detection of mycotoxins. For several years, time-resolved fluorescence immunochromatography (TRFIA) paper-based sensors have attracted much attention as a simple and low-cost field detection technology. However, a traditional TRFIA paper-based sensor is based on antibody labeling, which cannot easily meet the current detection requirements. A second antibody labeling method was used to amplify the fluorescence signal and improve the detection sensitivity. Polystyrene fluorescent microspheres were combined with sheep anti-mouse IgG to prepare fluorescent probes (Eu-IgGs). After the probe fully reacted with the antibody (Eu-IgGs-Abs) in the sample cell, it was deployed on the paper-based sensor using chromatography. Eu-IgGs-Abs that were not bound to the target were captured on the T-line, while those that were bound were captured on the C-line. The paper-based sensor reflected the corresponding fluorescence intensity change. Because a single molecule of the deoxynivalenol antibody could bind to multiple Eu-IgGs, this method could amplify the fluorescence signal intensity on the unit antibody and improve the detection sensitivity. The working standard curve of the sensor was established under the optimum working conditions. It showed the lower limit of detection and higher recovery rate when it was applied to actual samples and compared with other methods. This sensor has the advantages of high sensitivity, good accuracy, and good specificity, saving the amount of antibody consumed and being suitable for rapid field detection of deoxynivalenol.

Sci Total Environ ; 712: 136410, 2020 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-32050375


In order to solve the problem that the sensor cannot be reused due to the passivation of the electrode surface, a refreshable electrochemical aptasensor based on a hydrophobic electrode and a magnetic nanocomposite had been developed. Therein, the hydrophobic electrode was formed by modifying a screen-printed carbon electrode (SPCE) with polydimethylsiloxane (PDMS), which could avoid adsorption of molecules on the electrode surface due to its hydrophobicity. Combined with aptamer (Apt), the synthesized graphene oxide-ferroferric oxide (GO-Fe3O4) was used as a magnetic catcher to capture specific organophosphorus pesticides (OPs), which could be removed to the working area of SPCE with a magnet for electrochemical detection. The performance analysis of hydrophobic electrode showed that the SPCE could be used twice. When the electrochemical signals of Apt/GO-Fe3O4 and OPs/Apt/GO-Fe3O4 were recorded using the same SPCE, the current differences between them were directly related to the concentrations of OPs. Through the contrast test between the spiked vegetable samples and the OPs standard solutions, it was found that the OPs concentrations could be qualitatively evaluated by comparing the current differences. At the same time, the characteristic of collecting target with magnetic catcher was helpful for detecting OPs with a low concentration. Therefore, the refreshable aptasensor provided a huge potential to small molecule target evaluation.