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The discovery of aptamers for aflatoxin B1 (AFB1), one of toxic carcinogens, has allowed to develop aptamer-based sensors and assays for aflatoxin. In this work, we reported a direct fluorescence anisotropy (FA) assay for investigation of aptamer-AFB1 binding and detection of AFB1 with the aptamer having single tetramethylrhodamine (TMR) label on a specific site. From a series of labeling sites of...
Aflatoxin B1 (AFB1) is one of highly toxic mycotoxins and a known human carcinogen. The frequent contamination of AFB1 in food products and large health risk of AFB1 have raised global concerns. Sensitive detection of AFB1 is of vital importance and highly demanded. Herein, we reported a competitive horseradish peroxidase (HRP)-linked aptamer assay for AFB1, combining the advantages of aptamer for...
We developed an aptamer-based competitive fluorescence anisotropy (FA)/fluorescence polarization (FP) assay for adenosine triphosphate (ATP). Different from the traditional fluorescence polarization immunoassays for small molecules, here DNA aptamer against ATP was used as affinity ligand, and tetramethylrhodamine (TMR) labeled ATP served as fluorescent tracer. The binding between TMR-labeled ATP...
In this paper, near-infrared (NIR) light emitting L-noradrenaline functionalized CdSeTe QDs (NA-CdSeTe) were synthesized and applied to the biosensing of urea. When the pH value of NA-CdSeTe solution was adjusted from neutral to alkalinity, the noradrenaline on the surface of QDs would turn to quinone, which triggered the fluorescence quenching of NA-CdSeTe probe due to the charge transfer interactions...
Here we describe a thrombin-linked aptamer assay (TLAA) for protein by using thrombin as an enzyme label, harnessing enzyme activity of thrombin and aptamer affinity binding. TLAA converts detection of specific target proteins to the detection of thrombin by using a DNA sequence that consists of two aptamers with the first aptamer binding to the specific target protein and the second aptamer binding...
In this study, surface-functionalized nitrogen-doped graphene was prepared with 1, 3, 6, 8-pyrenetetrasulfonic acid tetrasodium salt in a simple way. The characteristics of the material were demonstrated by UV–vis absorption spectra, X-ray photoelectron spectroscopy, and electrochemical experiments. Then, the glassy carbon electrode was modified by the functionalized nitrogen-doped graphene and hexadecyltrimethylammonium...
In this paper, a facile and sensitive biocompatible biosensor based on Nafion/choline oxidase/manganese dioxide composite film was developed for the determination of choline chloride. Manganese dioxide (MnO2) nanoparticles, possessing the advantages of large specific surface areas, good hydrophilicity, great permeability as well as excellent biocompatibility, were synthesized in-situ at the surface...
A novel artificial receptor 1 containing the indolocarbazole-NH moieties as the recognition sites exhibited high selectivity and sensitivity toward F− over other typical anionic species in DMSO solution. Upon addition of F− into the solution, receptor 1 showed a remarkable ratiometric shift of the fluorescence maximum from 535 to 590nm, and also a prominent color change from light yellow to orange,...
Two C 2 -symmetrical hexaazatriphenylene (HAT) derivatives, 2,3-diphenyl-6,7,10,11-tetra(pyridin-2-yl)dipyrazino[2,3-f:2′,3′-h]quinoxaline (1) and 2,3,6,7-tetraphenyl-10,11-di(pyridin-2-yl)dipyrazino[2,3-f:2′,3′-h]quinoxaline (2), were designed and synthesized by the condensation reaction of 1,2-diamines and 1,2-diketones. Both compounds 1 and 2 exhibit sensitive, ratiometric and colorimetric...
Human neutrophil elastase (HNE) is a multifunctional serine protease, involved in infection defense, inflammatory process regulation, and physiopathological processes of several diseases. We developed aptamer-capture based assays for human neutrophil elastase with different substrates and solid supports to meet different demands, such as simplicity, sensitivity, and high throughput. Aptamers against...
A new ditopic ion pair receptor 1 containing two biindole moieties and a bis-benzocrown ether unit shows a remarkable color switching (ON- and -OFF) function induced by anion (F − ) and cation (K + ) recognition. The ditopic receptor 1 binds in a cooperative fashion to HSO 4− in the presence of 1·K + and acts as a selective ditopic receptor to recognize ion pairs...
In this work, a highly selective sample cleanup procedure that combining molecular imprinting technique (MIT) and solid phase extraction (SPE) was developed for the isolation of domoic acid (a fascinating marine toxin) from seafood samples. The molecular imprinting polymer (MIP) for domoic acid was prepared using 1,3,5-pentanetricarboxylic acid as the template molecule instead of domoic acid. 4-Vinyl...
The interactions of brilliant cresyl violet (BCV) with herring sperm DNA in γ-cyclodextrin (γ-CD) supramolecular system were studied by UV-vis absorption spectroscopy and cyclic voltammetry (CV). Both UV-vis absorption and CV data show that the interaction of BCV with DNA depends on the concentration ratio of BCV to DNA (R), the initial concentration of BCV and γ-CD. The binding constants of BCV monomer,...
In this paper, a highly selective sample cleanup procedure combining molecular imprinting and solid-phase extraction (MI-SPE) was developed for the isolation of melamine in dairy products. The molecularly imprinted polymer (MIP) was prepared using melamine as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linking monomer. The melamine...
The electrochemistry of dopamine (DA) was studied by cyclic voltammetry at a glassy carbon electrode modified by a gel containing multi-walled carbon nanotubes (MWNTs) and room-temperature ionic liquid of 1-octyl-3-methylimidazolium hexafluorophosphate (OMIMPF 6 ). The thickness of gel on the surface of the electrode has to be controlled carefully because the charging currents increase with...
A new sequential injection analysis (SIA) method of an electrokinetic flow analysis (EKFA) system for the determination of nitrite-nitrogen is presented in this paper. The proposed system mainly consisted of an electroosmotic pump, two solenoid valves and a spectrophotometer etc. All the pump and valves were controlled by a personal computer automatically. The determination method of nitrite-nitrogen...
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