Application of a new anti-zearalenone monoclonal antibody in different immunoassay formats

Monoclonal antibodies against zearalenone (ZEA) were raised in mice according to the hybridoma technology and applied in different immunochemical techniques. More specifically, three formats based on the competitive direct enzyme immunoassay principle were developed: an enzyme-linked immunosorbent assay (ELISA), a flow-through gel-based immunoassay column and a flow-through membrane-based immunoassay. In ELISA, the 50% inhibitory concentration (IC50) was 0.8 ng/mL, and the limit of detection for ZEA standard solutions was 0.1 ng/mL. The antibodies showed a high ZEA (100%) and α-zearalenol (α-ZOL) (69%) recognition, while cross-reactivities with α-zearalanol, zearalanone, β-zearalenol and β- zearalanol were 42%, 22%, <1% and <1%, respectively. For standard solutions, a cut-off level at 10 ng/mL could be established for the gel- and membrane-based enzyme immunoassays. Assay time of both non-instrumental tests was 25 min for 10 samples. By including a simple sample extraction procedure, the methods were applied to wheat with IC50s in ELISA of 80 and 120 μg/kg (dilution up to 5% and 15% (v/v) of wheat matrix, respectively). The cut-off level of the gel- and membrane-based immunoassays was established at 100 μg/kg. Potentials and limitations of the developed methods were compared. The possible application for multi-mycotoxin analysis of the ELISA method based on a single monoclonal antibody was investigated. Therefore, principal component analysis and partial least squares regression data modelling were used to separate the immunoassay responses of two cross-reactants (ZEA and α-ZOL).      

Moment Analysis in Non-Linear Frontal-Elution and Elution Chromatography

Analytical formulae are presented for the statistical moments of an output chromatographic curve for non-linear distribution isotherms at a very narrow feed band (“elution chromatography”). Non-linear “frontal-elution chromatography”, i.e., the case of a very wide feed band, is also considered. The analytical expressions characterize the position and the width of sorption and desorption boundaries of the output curve. The column length at which a constant configuration of the sorption (or desorption) boundary is attained is dependent in the curvature of the isotherm and on the plate height. The results have been confirmed experimentally.     

Modeling the contact wear fracture of a two-layer basement

We develop a method for calculating the kinetics of fatigue fracture of a two-layer elastic basement by a periodic system of indenters sliding on the surface and modeling the surface microroughness. The method is based on solving the contact problem for a periodic system of indenters and a two-layer elastic basement, determining the internal stresses with friction forces taken into account, and constructing the damage function in the two-layer basement. We calculate the kinetics of the fatigue fracture of the surface layer (the coating) and find the characteristics of the process depending on the strength and mechanical properties of the coating and basement materials, the loading and geometric characteristics of the system, and the friction coefficient.     

Modeling the influence of the coating deposition technology on the contact interaction characteristics

For a multilayer elastic half-space, we consider an axisymmetric loading model taking into account damage on the interface between the layers. The influence of intermediate layers arising in various coating technologies on the contact and internal stresses occurring in the coating and the substrate under elastic indentation conditions is studied for relatively rigid and nonrigid coatings.     

Pyrene sensitized phosphorescence enhanced by the heavey atom effect in the water-heptane-sodium dodecyl sulfate-pentanol microemulsion

The influence of the external TI⁺ “heavy” ion on the singlet and triplet excited states of the pyrene and Trypaflavine molecules solubilized in the water-heptane-sodium dodecyl sulfate-pentanol microemulsion was studied. The triplet-triplet (T-T) energy transfer in the system Trypaflavine (donor)-pyrene (acceptor) and the sensitized phosphorescence of pyrene were first observed in the microemulsion containg Tl⁺ ions. The quenching rate constants of the excited states of the luminophores by Tl⁺ ions were calculated. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1529–1532, September, 2000.     

The wear contact problem with partial slippage

A method of analysing the variation in the stress state and shape of wearable bodies, subjected to the action of an oscillating shear load with partial slippage of the surface in the contact area is proposed. The method is based on the introduction of two time scales: the time of a single cycle of variation in the shear load and the time corresponding to a specified number of cycles. To estimate the shape variation of the surface due to wear a linear relation between the wear rate and the contact pressure and velocity of relative slippage is used. Cases of complete or partial removal of the wear particles from the friction zone are considered. As an example, the kinetics of the variation in the stress state in the contact of an elastic indentor, having a flat base and rounded edges, with an elastic half-space of the same material, is investigated. Analytical expressions for calculating the asymptotic values of the stresses and shape of the worn surface are obtained.     

New approach to quantitative analysis of benzo[a]pyrene in food supplements by an immunochemical column test

A quantitative immunochemical rapid test for sensitive determination of benzo[a]pyrene (BAP) as a model analyte was developed making use of a handheld reader for results evaluation. The covalent immobilization of antibodies to different Sepharose gels, i.e., CNBr-activated Sepharose 4B and CNBr-activated Sepharose 4 Fast Flow was compared with adsorption to a polyethylene support. The lowest limits of detection (LOD) were 4 ng L⁻¹ and 40 ng L⁻¹, respectively, using optimized assay conditions. The developed test was applied to food supplements (garlic, black radish and maca), including a pretreatment procedure. LOD of 9 ng kg⁻¹ and linear range of 13-80 ng kg⁻¹ were obtained. Results of BAP determination in naturally contaminated samples were confirmed by high-performance liquid chromatography coupled to fluorescence detection and a good correlation was achieved. We suggest that the developed test format can be used to quantitative detection of the low molecular weight analytes, such as mycotoxins, pesticides, other pollutants in food and environmental samples.