INTEGRATED MICROFLUIDIC DEVICE FOR DROPLET MANIPULATION

Droplets based microfluidic systems have a big potential for the miniaturization of processes for bioanalysis. In the form of droplets, reagents are used in discrete volume, enabling high-throughput chemical reactions as well as single-cell encapsulation. Microreactors of this type can be manipulated and applied in bio-testing. In this work we present a platform for droplet generation and manipulation by using dielectrophoresis force. This platform is an integrated microfluidic device with a dielectrophoresis (DEP) chip. The microfluidic device generates microdroplets such as water in oil emulsion

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 alpha-zearalenol (alpha-ZOL) (69%) recognition, while crossreactivities with alpha-zearalanol, zearalanone, beta-zearalenol and beta-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 mu g/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 mu g/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 alpha-ZOL)

Rapid method for qualitative detection of 2,4,6-trinitrotoluene in environmental water samples

A gel-based immunoassay that can be used for the detection of 2,4,6-trinitrotoluene (TNT) in water samples was developed. Four polyclonal antibodies were generated in chickens using TNT derivatives. The assay was based on the immunoaffinity preconcentration and immuno-enzyme analysis of TNT in the gel. The results of the assay, assessed by color development, were evaluated visually and also by using a flatbed scanner and subsequent digital processing of the scanned gel. The most sensitive color mode, parameter S (saturation, HSB mode), was used for the immunoassay optimization and evaluation of the results. The immunoassays with the best parameters were optimized and characterized. A cut-off level of 5 mu g TNT L-1 was reached for water samples. It was shown that tap and environmental water samples could be analyzed directly, without sample preparation and dilution. The developed test is acceptable for use in an on-site field test to provide rapid (about 15 min for six samples), qualitative and reliable results for making environmental decisions such as identifying "hot spots", monitoring of military and terrorist activities, and selecting of site samples for laboratory analysis

An immunochemical test for rapid screening of zearalenone and T-2 toxin

An immunochemically based test for noninstrumental simultaneous detection of zearalenone (ZEA) and T-2 toxin (T2) in feed was developed. The method combines clean-up of sample extract, pre-concentration of analytes by immunoextraction and immunodetection through the enzymatic reaction of horseradish peroxidase (HRP). The test is housed inside a standard 1-mL solid-phase extraction column and consists of three layers: two test layers (one for ZEA and another for T2) with immobilised specific antibodies and one control layer with bound anti-HRP antibodies. Feed extract was passed through an additional column with clean-up layer, which was disconnected after extract application. Total assay time was about 15 min for six samples and detection time was 4 min after chromogenic substrate application. Under optimised conditions a cut-off level for ZEA and T2 of 100 mu g/kg was established. Different feed types were analysed for ZEA and T2 contamination by the proposed method and results were confirmed by LC-MS/MS

Mechanism of dicarbonyl(2,4-pentanedionato)iridium(I) decomposition on iron surface and in gas phase: Complex experimental and theoretical study

The mechanism of thermal destruction of Ir(acac)(CO)2 as one of the most important MOCVD precursors for Ir coatings deposition was proposed on the footing of the in situ mass spectrometry analysis and quantum chemical modeling. Calculated structural parameters and vibrational spectra of Ir(acac)(CO)2 molecule were found to be in a fairly good agreement with the experimental data. Ir(acac)(CO)2 was found to unlikely decompose in the gaseous phase while its adsorption onto the iron surface leads to major structural distortions easing the bond cleavage, molecule decomposition with subsequent formation of iridium films