Commercialized rapid immunoanalytical tests for determination of allergenic food proteins: an overview

Food allergies have become an important health issue especially in industrialized countries. Undeclared allergenic ingredients or the presence of “hidden” allergens because of contamination during the food production process pose great health risks to sensitised individuals. The EU directive for food labelling lists allergenic foods that have to be declared on food products by the manufacturers. The list includes gluten-containing cereals, crustaceans, eggs, fish, peanuts, soybeans, milk, various nuts (e.g. almond, hazelnut, and walnut, etc.), celery, mustard, sesame seeds, lupin, and molluscs. Reliable methods for detection and quantification of food allergens are needed that can be applied in a fast and easy-to-use manner, are portable, and need only limited technical equipment. This review focuses on the latest developments in food allergen analysis with special emphasis on fast immunoanalytical methods such as rapid enzyme-linked immunosorbent assays (ELISA), lateral-flow immunochromatographic assays (LFA) and dipstick tests. Emerging technologies such as immunochemical microarrays and biosensors are also discussed and their application to food allergen analysis is reviewed. Finally, a comprehensive overview of rapid immunochemical test kits that are currently available commercially is given in tabular form.     

Ni3S2 Supported on Porous Ball‐milled Silicon,a Highly Selective Electrochemical Sensor for Glucose Determination

In this work, an electrochemical sensor based on Ni₃S₂ nanoparticles supported on porous ball‐milled silicon was fabricated for measuring glucose. At first, the glassy carbon electrode (GCE) surface was modified by Ni₃S₂ nanoparticles supported on a porous ball‐milled silicon substrate. To characterize the modified electrode, N₂ adsorption‐desorption isotherms and BHJ, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), elemental mapping and X‐ray diffraction (XRD) were used. In the following, the effective parameters on the sensor response such as pH, NaOH concentration, catalyst concentration, applied potential, and rotational speed of the electrode were optimized using cyclic voltammetric (CV) and hydrodynamic amperometric methods. Under the optimal conditions, the calibration curve was plotted using the hydrodynamic amperometric method. Three linear regions were obtained from 0.5–134, 134–1246, and 1246–3546 μM, with a detection limit of 0.2 μM for glucose. Finally, the proposed method was used for measuring glucose levels in human blood serums.     

Synthesis and characterization of Co(II), Ni(II), Zn(II) and Cu(II) complexes with a new tetraazamacrocyclic Schiff base ligand containing a piperazine moiety: X-ray crystal structure determination of the Co(II) complex

Two macrocyclic Schiff base ligands, L¹ [1+1] and L² [2+2], have been obtained in a one-pot cyclocondensation of 1,4-bis(2-formylphenyl)piperazine and 1,3-diaminopropane. Unfortunately, because of the low solubility of both ligands, their separation was unsuccessful. In the direct reaction of these mixed ligands (L¹ and L²) and the appropriate metal ions only [CoL¹(NO₃)]ClO₄, [NiL¹](ClO₄)₂, [CuL¹](ClO₄)₂ and [ZnL¹(NO₃)]ClO₄ complexes have been isolated. All the complexes were characterized by elemental analyses, IR, FAB-MS, conductivity measurements and in the case of the [ZnL¹(NO₃)]ClO₄ complex with NMR spectroscopy.     

Redox control of a ring-opening polymerization catalyst

The activity of an yttrium alkoxide complex supported by a ferrocene-based ligand was controlled using redox reagents during the ring-opening polymerization of L-lactide. The oxidized complex was characterized by X-ray crystallography and (1)H NMR, XANES, and M?ssbauer spectroscopy. Switching in situ between the oxidized and reduced yttrium complexes resulted in a change in the rate of polymerization of L-lactide. Synthesized polymers were analyzed by gel permeation chromatography. Polymerization of trimethylene carbonate was also performed with the reduced and oxidized forms of an indium alkoxide complex. The indium system showed the opposite behavior to that of yttrium, revealing a metal-based dependency on the rate of polymerization.     

Syntheses and Crystal Structures of Two 3D Lead(II) Coordination Polymers with Isonicotinic Acid N‐Oxide and Pseudohalides

Two novel 3D lead(II)‐azido and ‐thiocyanato coordination polymers with isonicotinate acid N‐oxide (INO) as the coligand were synthesized and characterized by elemental analysis, IR, and ¹H NMR spectroscopy and were also studied using X‐ray crystallography technique. These complexes have the formulas [Pb(INO)(NCS)]_n ( 1 ) and [Pb(INO)(N₃)(H₂O)]_n ( 2 ).     

Wall slip and melt fracture of poly(lactides)

The wall slip and melt fracture behaviour of several commercial polylactides (PLAs) as well as their rheological properties under shear and extensional have been investigated. The PLAs have had weight-average molecular weights in the range of 10⁴–10⁵ g/mol and studied in the temperature range of 160–200°C. The solution properties and linear viscoelastic behaviour of melts indicate linear microstructure behaviour. PLAs with molecular weights greater than a certain value were found to slip, with the slip velocity to increase with decrease of molecular weight. The capillary data were found to agree well with linear viscoelastic envelope once correction for slip effects was applied. The onset of melt fracture for the high molecular weight PLAs was found to occur at about 0.2 to 0.3 MPa, depending on the geometrical characteristics of the dies and independent of temperature. Addition of 0.5 wt.% of a polycaprolactone (PCL) into the PLA that exhibits melt fracture was found to be effective in eliminating and delaying the onset of melt fracture to higher shear rates. This is due to significant interfacial slip that occurs in the presence of PCL.     

(Homo) Flatness of posets on poideal extensions

We consider pomonoids , where G is a pogroup and I is a poideal of S and show that if an S-poset is principally weakly flat, (weakly) flat, po-flat, (principally) weakly po-flat, (po-) torsion free or satisfies Conditions (P), (P _E ), (P _w ), (PWP), (PWP) _w , (WP) or (WP) _w as an I ¹-poset, then it has these properties as an S-poset. We also show that an S-poset which is free, projective or strongly flat as an I ¹-poset may not generally have these properties as an S-poset.     

A numerical technique for solving fractional variational problems by Müntz–Legendre polynomials

This paper presents an efficient approximate method for solving a class of fractional variational problems (FVPs). The fractional derivatives are described in the Caputo sense. In the our method, we use the Müntz–Legendre orthonormal basis and the properties of Rayleigh–Ritz method for fractional calculus to reduce FVPs to solve a system of algebraic equations which solved using Newton’s iterative method. Also, an estimation of the error is given in the sense of Sobolev norms. The illustrative examples are provided to demonstrate the applicability and simplicity of the new technique.     

The molecular diversity scope of 4-hydroxycoumarin in the synthesis of heterocyclic compounds via multicomponent reactions

Molecular Diversity - 4-Hydroxycoumarins are some of the most versatile heterocyclic scaffolds and are frequently applied in the synthesis of various organic compounds. 4-Hydroxycoumarin-based...