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GO-amplified fluorescence polarization assay for high-sensitivity detection of aflatoxin B1 with low dosage aptamer probe
摘要： Aflatoxin B1 (AFB1) is the most toxic mycotoxin of the aflatoxins (AFs) and shows carcinogenic, teratogenic and mutagenic effects in humans and animals. AFB1 is widely seen in cereal products such as rice and wheat. This research proposed a low-cost, high-sensitivity fluorescence polarization (FP) assay for detection of AFB1 using aptamer biosensors based on graphene oxide (GO). The aptamers labelled with fluorescein amidite (FAM) were adsorbed on the surface of GO through π–π stacking and electrostatic interaction, thus forming aptamer/GO macromolecular complexes. Under these conditions, the local rotation of fluorophores was limited and the system had a high FP value. When there was AFB1 in the system, aptamers were dissociated from the GO surface and combined with AFB1 owing to their specificity to form aptamer/AFB1 complexes. As a result, large changes were observed in the molecular weights of aptamers before, and after, the combination, therefore leading to the apparent changes in FP value. The results showed that when only 10 nM of aptamer was used, the changes in FP and the AFB1 concentration had a favourable linear relationship within 0.05 to 5 nM of AFB1, and the lowest detection limit (LOD) was 0.05 nM. In addition, the recoveries of rice sample extract ranged from 89.2% to 112%. The method is simple, highly sensitive, cost-efficient and shows potential application prospects.
关键词： Signal amplifier,Fluorescence polarization,Graphene oxide,Aptamer,Aflatoxin B1
更新于2025-09-23 15:22:29
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Photocatalytic Degradation of Aflatoxin B1 by activated carbon supported TiO2 catalyst
摘要： The photocatalytic efficiency of activated carbon supported TiO2 catalyst (AC/TiO2) for degradation of aflatoxin B1 (AFB1) under UV-Vis light was evaluated in this study. AC/TiO2 was prepared by simple hydrothermal synthesis and characterized by scanning electron micrograph (SEM), X-ray diffraction (XRD) and FT-IR. The various factors including catalyst dosage, pH value and light source affecting the degradation efficiency of AFB1 were also investigated. The higher degradation efficiency of AFB1 by AC/TiO2 composite (98 %) than bare TiO2 (76 %) were attributed to a higher surface area and enhanced visible light intensity by the synergy of AC and TiO2. The degradation process of AFB1 was fitted with the pseudo-first-order kinetic model. In addition, the catalyst can be easily separated from the solution and keep good activity. The hole (h+) and the hydroxyl radicals (?OH) were found to play an important role in the degradation of AFB1. These results demonstrated that AC/TiO2 possess synergy of high absorption capacity and photoactivity, thus supplying a simple, efficient and green approach for the degradation of AFB1.
关键词： AC/TiO2 catalyst,Photocatalytic Degradation,Aflatoxin B1
更新于2025-09-23 15:22:29
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Time-resolved fluorescent immunochromatographic assay-based on three antibody labels for the simultaneous detection of aflatoxin B <sub/>1</sub> and zearalenone in Chinese herbal medicines
摘要： A time-resolved fluorescent immunochromatographic assay (TRFICA) was successfully developed for the sensitive, simultaneous, and quantitative detection of aflatoxin B1 (AFB1) and zearalenone (ZEN) in Chinese herbal medicines. Eu-nanospheres (EuNPs) with unique optical properties increased the stability and sensitivity of the immunochromatographic assay. To obtain stable quantitative results, we applied a three-label system in which monoclonal antibodies for AFB1 and ZEN were conjugated to the EuNPs as detection probes on the test line (T line), and EuNP-labelled chicken IgY conjugates acted as the reference on the control line (C line). The fluorescence intensities of the T and C lines were recorded, and the T/C ratio was employed as the quantitative signal for the elimination of strip variation and matrix effects. The parameters that affected the TRFICA were optimised. Under optimal conditions, the established TRFICA gave good linear ranges from 0.60 μg/kg to 3.92 μg/kg for AFB1 and from 0.40 μg/kg to 1.28 μg/kg for ZEN. The limits of detection for AFB1 and ZEN were as low as 0.60 and 0.40 μg/kg, respectively, in Chinese herbal medicines Semen coicis, Rhizoma dioscoreae, and Platycodon grandiflorus, respectively. The average recoveries of the spiked samples were 73%–95% for AFB1 and 75.83%–90% for ZEN, both with a relative standard deviation of < 9.08%. The results of 15 actual samples detected by the developed TRFICA showed a satisfactory correlation with those of ultra-performance liquid chromatography tandem mass spectrometry. Therefore, the TRFICA is a simple, rapid, and sensitive approach to quantitatively detect mycotoxins in Chinese herbal medicines.
关键词： aflatoxin B1,time-resolved fluorescent immunochromatographic assay,zearalenone,Three antibody labels,Chinese herbal medicines
更新于2025-09-23 15:21:01
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Development of a ZnCdS@ZnS quantum dotsa??based label-free electrochemiluminescence immunosensor for sensitive determination of aflatoxin B1 in lotus seed
摘要： In this study, we designed a ZnCdS@ZnS quantum dots (QDs)–based label-free electrochemiluminescence (ECL) immunosensor for sensitive determination of aflatoxin B1 (AFB1). A Nafion solution assembled abundant QDs on the surface of a Au electrode as ECL signal probes, with specially coupled anti-AFB1 antibodies as the capturing element. As the reduction reaction between S2O8 2? in the electrolyte and QDs on the electrode led to ECL emission, the decreased ECL signals resulting from target AFB1 in the samples were recorded for quantification. We evaluated electrochemical impedance spectroscopy and ECL measurements along each step in the construction of the proposed immunosensor. After systematic optimization of crucial parameters, the ECL immunosensor exhibited a good sensitivity, with a low detection limit of 0.01 ng/mL for AFB1 in a wide concentration range of 0.05–100 ng/mL. Testing with lotus seed samples confirmed the satisfactory selectivity, stability, and reproducibility of the developed ECL immunosensor for rapid, efficient, and sensitive detection of AFB1 at trace levels in complex matrices. This study provides a powerful and universal analytical platform for a variety of analytes that can be used in broad applications for real-time analysis, such as food and traditional Chinese medicine safety testing, environmental pollution monitoring, and disease diagnostics.
关键词： Electrochemiluminescence immunosensor,Nafion,Lotus seed,Aflatoxin B1,ZnCdS@ZnS quantum dots,Label-free
更新于2025-09-23 15:19:57
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Comparative Study of Time-Resolved Fluorescent Nanobeads, Quantum Dot Nanobeads and Quantum Dots as Labels in Fluorescence Immunochromatography for Detection of Aflatoxin B1 in Grains
摘要： Label selection is an essential procedure for improving the sensitivity of fluorescence immunochromatography assays (FICAs). Under optimum conditions, time-resolved fluorescent nanobeads (TRFN), quantum dots nanobeads (QB) and quantum dots (QD)-based immunochromatography assays (TRFN-FICA, QB-FICA and QD-FICA) were systematically and comprehensively compared for the quantitative detection of aflatoxin B1 (AFB1) in six grains (corn, soybeans, sorghum, wheat, rice and oat). All three FICAs can be applied as rapid, cost-effective and convenient qualitative tools for onsite screening of AFB1; TRFN-FICA exhibits the best performance with the least immune reagent consumption, shortest immunoassay duration and lowest limit of detection (LOD). The LODs for TRFN-FICA, QB-FICA and QD-FICA are 0.04, 0.30 and 0.80 μg kg?1 in six grains, respectively. Recoveries range from 83.64% to 125.61% at fortified concentrations of LOD, 2LOD and 4LOD, with the coefficient of variation less than 10.0%. Analysis of 60 field grain samples by three FICAs is in accordance with that of LC-MS/MS, and TRFN-FICA obtained the best fit. In conclusion, TRFN-FICA is more suitable for quantitative detection of AFB1 in grains when the above factors are taken into consideration.
关键词： aflatoxin B1,immunochromatography,time-resolved fluorescent nanobeads,quantum dot nanobeads,quantum dot
更新于2025-09-23 15:19:57
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A multiplexed FRET aptasensor for simultaneous detection of mycotoxins with magnetically controlled graphene oxide/Fe3O4 as single energy acceptor?
摘要： Aflatoxin B1 (AFB1) and fumonisin B1 (FB1) are the most common mycotoxins and often coexist in agricultural products, which are known to be a toxic superposition and even carcinogenic effects on humans. We proposed a multiplexed fluorescence resonance energy transfer (FRET) aptasensor for simultaneous detection of mycotoxins with magnetically controlled graphene oxide (GO)/Fe3O4 as single energy acceptor. CdTe quantum dots emitting green (GQDs) and red (RQDs) fluorescence are modified by aptamers specifically for AFB1 and FB1 and used as dual energy donors. Compared with conventional FRET system based on GO quencher, GO/Fe3O4, a single energy acceptor, can not only quench the fluorescence of aptamer-modified GQDs and RQDs with different emission peaks simultaneously, but also be removed by effective magnetic separation to eliminate the interference of background. In the absence of GO/Fe3O4 nanocomposites, the aptamer modified GQDs and RQDs give off strong fluorescence under ultraviolet radiation. The fluorescence of GQDs and RQDs is quenched when GO/Fe3O4 nanocomposites is added to the system owing to the π–π stacking interaction between GO/Fe3O4 nanocomposites and GQDs- and RQDs-labeled aptamer. However, in the presence of AFB1 and FB1, the binding of aptamers to their specific targets will fold their single stranded structures and hinder the contact between base group in aptamers and GO/Fe3O4, which cause the fluorescence recovery of GQDs and RQDs. With the help of one step of magnetic separation, the supernatants can be collected for fluorescence analysis. After optimization of detection conditions, the developed method had a wider linear range of 10 pg mL?1–100 ng mL?1 for AFB1 and 50 pg mL?1–300 ng mL?1 for FB1 and showed no cross-reactivity with other closely related mycotoxins, respectively. The limit of detection for AFB1 and FB1 are calculated to be 6.7 and 16.2 pg mL?1 based on S/N=3. The detection of mycotoxins has been successfully realized in peanut samples and a new application field of FRET system is expected for various targets.
关键词： aptasensor,fluorescence resonance energy transfer,aflatoxin B1,fumonisin B1,simultaneous detection
更新于2025-09-11 14:15:04
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Ovalbumin antibody-based fluorometric immunochromatographic lateral flow assay using CdSe/ZnS quantum dot beads as label for determination of?T-2 toxin
摘要： This work describes an anti-ovalbumin antibody-based lateral flow immunoassay (LFI) for T-2 toxin. The antibody uses a coating antigen as a bifunctional element for universality and introduces preincubation to improve the detection limits of the method. T-2 toxin and ovalbumin-modified T-2 toxin competitively binds on the anti-T-2 toxin monoclonal antibody modified on CdSe/ZnS quantum dot beads during preincubation. The modified T-2 toxin acts as a bifunctional element that forms immuno complexes during preincubation and combines with anti-ovalbumin antibody coated in the test line through the ovalbumin terminal. Fluorescence is detected at 610 nm on the test zone following photoexcitation at 365 nm. It has a reverse dose-effect relationship with the amount of T-2 toxin. The calibration plot is linear in the 20–110 fg mL?1 T-2 toxin concentration range, and the limit of detection (LOD) is 10 fg mL?1, which is lower by 8-fold than that of the traditional LFI system (LOD 80 fg mL?1) and one order of magnitude than those of LFIs with labels of colloidal gold nanoparticles (LOD 150 fg mL?1) or fluorophores (LOD 190 ng mL?1). Universality was verified through aflatoxin B1 detection using the established ovalbumin antibody-based LFI system (LOD 10 fg mL?1). The performance of the method was compared with that of established systems and a commercial ELISA kit (LOD 360 fg mL?1).
关键词： Fluorometry,Bifunctional element,Calibration plot,Sensitivity,Limit of detection,Aflatoxin B1,Preincubation
更新于2025-09-11 14:15:04
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Aptamers Improving Fluorescence Anisotropy and Fluorescence Polarization Assays for Small Molecules
摘要： Nucleic acid affinity probes, such as aptamers, have been combined with fluorescence anisotropy (FA) / fluorescence polarization (FP) technology for the development of a diverse range of assays. Formation of a complex between a small fluorescent molecule and its binding partner usually increases the overall size of the fluorescent molecule and decreases its rate of rotation, resulting in increases in fluorescence anisotropy/polarization. Structure-switching of the fluorescently labeled aptamers arising from target binding can also affect molecular volume, local rotation of the fluorophore, and/or fluorescence lifetime, causing changes in anisotropy/polarization. Incorporation of the unique adsorptive properties of single-stranded nucleic acid aptamers on nanomaterials, hybridization of aptamers with complementary sequences, and the amplifiable ability of nucleic acid aptamers have broadened the applications of fluorescence anisotropy assays and enhanced their sensitivity. This review focuses on aptamer-based fluorescence anisotropy assays for the detection of small molecules, such as therapeutic drugs, environmental contaminants, natural toxins, and metabolites.
关键词： aptamer,adenosine triphosphate (ATP),nanomaterials,anisotropy,cocaine,nucleic acids,toxins,DNAzyme,polarization,aflatoxin B1,ochratoxin A (OTA),tyrosinamide
更新于2025-09-10 09:29:36
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Etching reaction-based photoelectrochemical immunoassay of aflatoxin B1 in foodstuff using cobalt oxyhydroxide nanosheets-coating cadmium sulfide nanoparticles as the signal tags
摘要： A new split-type photoelectrochemical (PEC) immunosensing platform was designed for sensitive detection of aflatoxin B1 (AFB1) in foodstuffs, coupling with enzymatic hydrolysate-triggered etching reaction of cobalt oxyhydroxide (CoOOH) on cadmium sulfide (CdS) nanoparticles-functionalized interface. Initially, the photosensitive electrode was prepared by coating CoOOH nanosheets on the surface of CdS nanoparticles to quench the photocurrent. Thereafter, a competitive-type enzyme immunoreaction was carried out on monoclonal anti-AFB1 antibody-conjugated magnetic bead by using alkaline phosphatase (ALP)-labeled bovine serum albumin-AFB1 (AFB1-BSA) conjugate as the competitor. With the formation of immunocomplex, the carried ALP hydrolyzed ascorbic acid 2-phosphate (AAP) into ascorbic acid (AA) and phosphate. The former ascorbic acid produced etched or dissolved CoOOH nanosheets into Co2+ ions, thus resulting in the exposure of CdS nanoparticles on the surface to enhance the photocurrent of the modified electrode. Under optimum conditions, the photocurrent decreased linearly with the increasing AFB1 concentration in the dynamic range of 0.01 – 10 ng mL-1, and the limit of detection was 2.6 pg mL-1. The precision of this method (expressed as RSD) was ± 8.6%. In addition, the accuracy was monitored by analyzing spiked food samples, and gave the well-matched results with the referenced ELISA method.
关键词： cobalt oxyhydroxide nanosheets,cadmium sulfide nanoparticles,aflatoxin B1,photoelectrochemical immunoassay,etching reaction
更新于2025-09-04 15:30:14