Immunomagnetic microbeads for screening with flow cytometry and identification with nano-liquid chromatography mass spectrometry of ochratoxins in wheat and cereal

Multi-analyte binding assays for rapid screening of food contaminants require mass spectrometric identification of compound(s) in suspect samples. An optimal combination is obtained when the same bioreagents are used in both methods; moreover, miniaturisation is important because of the high costs of bioreagents. A concept is demonstrated using superparamagnetic microbeads coated with monoclonal antibodies (Mabs) in a novel direct inhibition flow cytometric immunoassay (FCIA) plus immunoaffinity isolation prior to identification by nano-liquid chromatography–quadrupole time-of-flight-mass spectrometry (nano-LC-Q-ToF-MS). As a model system, the mycotoxin ochratoxin A (OTA) and cross-reacting mycotoxin analogues were analysed in wheat and cereal samples, after a simple extraction, using the FCIA with anti-OTA Mabs. The limit of detection for OTA was 0.15 ng/g, which is far below the lowest maximum level of 3 ng/g established by the European Union. In the immunomagnetic isolation method, a 350-times-higher amount of beads was used to trap ochratoxins from sample extracts. Following a wash step, bound ochratoxins were dissociated from the Mabs using a small volume of acidified acetonitrile/water (2/8 v/v) prior to separation plus identification with nano-LC-Q-ToF-MS. In screened suspect naturally contaminated samples, OTA and its non-chlorinated analogue ochratoxin B were successfully identified by full scan accurate mass spectrometry as a proof of concept for identification of unknown but cross-reacting emerging mycotoxins. Due to the miniaturisation and bioaffinity isolation, this concept might be applicable for the use of other and more expensive bioreagents such as transport proteins and receptors for screening and identification of known and unknown (or masked) emerging food contaminants

Modelling of adhesion effect in friction of viscoelastic materials

A model is suggested for the analysis of the combined effect of viscoelastic properties of bodies and adhesive interaction between their surfaces in sliding. The model is based on the solution of the contact problem for a 3D wavy surface sliding on the boundary of a viscoelastic foundation taking into account the molecular attraction in the gap between the bodies. The influence of adhesion on the contact stress distribution, real contact area and hysteretic friction force is analyzed

RABBIT'S PORTAL VEIN EMBOLISATION METHODS

There are a huge of number people with liver tumors. The main method of treatment of this pathology is surgery, in some cases, impossible without prior stimulation of liver regeneration. For these purposes in recent years increasingly used embolization and/or chemoembolization of liver vessels. One of the most common ways - portal vein embolization (PVE). Identification of the benefit - risk ratio for PVE agents is very actually aim of studies in preclinical fields. The aim of this study was to evaluate the methods of administration of the microspheres in the portal vein of the rabbit. As means embolic microspheres used a polyvinyl alcohol with a size 0,1÷0,3 mm. In the course of this work was reproduced method of rabbit’s PVE