Label-free detection of gliadin food allergen mediated by real-time apta-PCR

Celiac disease is an immune-mediated enteropathy triggered by the ingestion of gluten. The only effective treatment consists in a lifelong gluten-free diet, requiring the food industry to tightly control the gluten contents of their products. To date, several gluten quantification approaches using antibodies are available and recommended by the legal authorities, such as Codex Alimentarius. However, whilst these antibody-based tests exhibit high sensitivity and specificity, the production of antibodies inherently requires the killing of host animals and is time-consuming and relatively expensive. Aptamers are structured single-stranded nucleic acid ligands that bind with high affinity and specificity to their cognate target, and aiming for a cost-effective viable alternative to the use of antibodies. Herein, we report the systematic evolution of ligands by exponential enrichment (SELEX)-based selection of a DNA aptamer against gliadin from a combinatorial DNA library and its application in a novel detection assay. Taking into account the hydrophobic nature of the gliadin target, a microtitre plate format was exploited for SELEX, where the target was immobilised via hydrophobic interactions, thus exposing aptatopes accessible for interaction with the DNA library. Evolution was followed using surface plasmon resonance, and following eight rounds of SELEX, the enriched DNA pool was cloned, sequenced and a clear consensus motif was identified. An apta-PCR assay was developed where competition for the aptamer takes place between the surface-immobilised gliadin and gliadin in the target sample, akin to an ELISA competitive format where the more target present in the sample, the less aptamer will bind to the immobilised gliadin. Following competition, any aptamer bound to the immobilised gliadin was heat-eluted and quantitatively amplified using real-time PCR, achieving a detection limit of approx. 2 nM (100 ng mL^?1). The specificity of the selected aptamer was demonstrated and no cross-reactivity was observed with streptavidin, bovine serum albumin or anti-gliadin IgG.

The analysis of alkyl-capped alcohol ethoxylates and alcohol ethoxycarboxylates from alcohol ethoxylates by atmospheric pressure chemical ionization mass spectrometry

Alcohol ethoxylates (AEs) are nonionic surfactants. They are industrially important compounds that have historically been difficult to analyze, with the best results to date achieved through derivatization (e.g., silylation) followed by analysis by gas chromatography/mass spectrometry (GC/MS). Recently, mass spectrometric techniques such as field desorption (FD), time-of-flight secondary ion mass spectrometry (TOF-SIMS), fast atom bombardment (FAB), electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) have been employed to analyze surfynol(R) 4xx. In an effort to produce low-cost alkyl-capped AEs and anionic detergents from AEs, a fast and reliable measure of the product yields and conversions from AEs is required in research. We found that the product yields and conversions from reactions of AEs, obtained by the employment of atmospheric pressure chemical ionization (APCI), were in good agreement with those obtained from proton nuclear magnetic resonance spectroscopy ((1)H-NMR). Therefore, APCI can be used as a validated tool for studying AE reactions. Mixtures that contain either silylated or unsilylated ethoxylates and/or carboxylates yield the same APCI mass spectra. Copyright -Copyright 1999 John Wiley & Sons, Ltd.     

Controlling the Reactivity of the [P8W48O184]40− Inorganic Ring and Its Assembly into POMZite Inorganic Frameworks with Silver Ions

The construction of pure‐inorganic framework materials with well‐defined design rules and building blocks is challenging. In this work, we show how a polyoxometalate cluster with an integrated pore, based on [P₈W₄₈O₁₈₄]^40? (abbreviated as {P₈W₄₈}), can be self‐assembled into inorganic frameworks using silver ions, which both enable reactions on the cluster as well as link them together. The {P₈W₄₈} was found to be highly reactive with silver ions resulting in the in situ generation of fragments, forming {P₉W₆₃O₂₃₅} and {P₁₀W₆₆O₂₅₁} in compound ( 1 ) where these two clusters co‐crystallize and are connected into a POMZite framework with 11 Ag⁺ ions as linkers located inside clusters and 10 Ag⁺ linking ions situated between clusters. Decreasing both the concentration of Ag⁺ ions, and the reaction temperature compared to the synthesis of compound ( 1 ), leads to {P₈W₅₁O₁₉₆} in compound 2 where the {P₈W₄₈} clusters are linked to form a new POMZite framework with 9 Ag⁺ ions per formula unit. Further tuning of the reaction conditions yields a cubic porous network compound ( 3 ) where {P₈W₄₈} clusters as cubic sides are joined by 4 Ag⁺ ions to give a cubic array and no Ag⁺ ions were found inside the clusters.     

Texture measurement of shaped material by impulse acoustic microscopy

All the microstructural parameters involved in metallurgical processes are difficult to determine directly on a shaped material. The aim of this paper is to use an impulse line-focus acoustic microscope (LFAM) as a non-destructive alternative to X-ray diffraction for measuring texture of slightly anisotropic materials. We apply it to characterize the rolling and annealing texture for tantalum sheets.     

Concept of multipole magnetic field rotation in ECRIS

The conventional type of magnetic well is formed by superposition of two types of magnetic field, axial bumpy field and radial multipole field. It is used to contain plasma that consists of neutrals, ions and electrons. These particles are in constant motion in the well and energetic electrons create plasma by violent collisions with neutrals and ions. The confined electrons are constantly heated by ECR technique in the presence of magnetic field. In this paper it has been shown theoretically that how the electron motion is influenced in terms of heating, containment and azimuthal uniformity of plasma, by the axial rotation of the multipole magnetic field [1,2]. Afterwards, the feasibility of achieving a rotating magnetic multipole field is discussed to some extent. And it is seen that it is not beyond the capability of the scientific community in the present scenario of the advanced technology. Presently, it can be achieved for lesser field and slightly larger size of the multipole electromagnet and can be used for improvement of the ECR ion source (ECRIS).     

Learning and forgetting on asymmetric,diluted neural networks

It is possible to construct diluted asymmetric models of neural networks for which the dynamics can be calculated exactly. We test several learning schemes, in particular, models for which the values of the synapses remain bounded and depend on the history. Our analytical results on the relative efficiencies of the various learning schemes are qualitatively similar to the corresponding ones obtained numerically on fully connected symmetric networks.     

Orienting the Pore Morphology of Core-Shell Magnetic Mesoporous Silica with the Sol-Gel Temperature. Influence on MRI and Magnetic Hyperthermia Properties

The controlled design of robust, well reproducible, and functional nanomaterials made according to simple processes is of key importance to envision future applications. In the field of porous materials, tuning nanoparticle features such as specific area, pore size and morphology by adjusting simple parameters such as pH, temperature or solvent is highly needed. In this work, we address the tunable control of the pore morphology of mesoporous silica (MS) nanoparticles (NPs) with the sol-gel reaction temperature (T_sg). We show that the pore morphology of MS NPs alone or of MS shell covering iron oxide nanoparticles (IO NPs) can be easily tailored with T_sg orienting either towards stellar (ST) morphology (large radial pore of around 10 nm) below 80 °C or towards a worm-like (WL) morphology (small randomly oriented pores channel network, of 3–4 nm pore size) above 80 °C. The relaxometric and magnetothermal features of IO@STMS or IO@WLMS core shell NPs having respectively stellar or worm-like morphologies are compared and discussed to understand the role of the pore structure for MRI and magnetic hyperthermia applications.     

Following the Reaction of Heteroanions inside a {W18O56} Polyoxometalate Nanocage by NMR Spectroscopy and Mass Spectrometry

By incorporating phosphorus(III)‐based anions into a polyoxometalate cage, a new type of tungsten‐based unconventional Dawson‐like cluster, [W₁₈O₅₆(HP^IIIO₃)₂(H₂O)₂]^8?, was isolated, in which the reaction of the two phosphite anions [HPO₃]^2? within the {W₁₈O₅₆} cage could be followed spectroscopically. As well as full X‐ray crystallographic analysis, we studied the reactivity of the cluster using both solution‐state NMR spectroscopy and mass spectrometry. These techniques show that the cluster undergoes a structural rearrangement in solution whereby the {HPO₃} moieties dimerize to form a weakly interacting (O₃PH???HPO₃) moiety. In the crystalline state the cluster exhibits a thermally triggered oxidation of the two P^III template moieties to form P^V centers (phosphite to phosphate), commensurate with the transformation of the cage into a Wells–Dawson {W₁₈O₅₄} cluster.     

Size segregation and particle velocity fluctuations in settling concentrated suspensions

We investigate the sedimentation of concentrated suspensions at low Reynolds numbers to study collective particle effects on local particle velocity fluctuations and size segregation effects. Experiments are carried out with polymethylmetacrylate (PMMA) spheres of two different mean diameters (190 and 25 μm) suspended in a hydrophobic index-matched fluid. Spatial repartitions of both small and large spheres and velocity fluctuations of particles are measured using fluorescently labelled PMMA spheres and a particle image velocimetry method. We also report measurements of the interstitial fluid pressure during settling. Experiments show that size segregation effects can occur during the sedimentation of concentrated suspensions of either quasi-monodisperse or bidisperse spheres. Size segregation is correlated to the organisation of the sedimentation velocity field into vortex-like structures of finite size. A loss of size segregation together with a significant decrease of the fluid pressure gradient in the bulk suspension is observed when the size of vortex-like structures gets on the order of the container size. However, the emergence of channels through the settling zone prevents a complete loss of size segregation in very concentrated suspensions.