Fast Detection of Pathogenic <em>Escherichia coli</em> from Chicken Meats

Food is a means to sustain and enjoy life, but it is also a medium for microbial contamination, causing disease and death. Fruits, vegetables, meat, and water are the common sources of contamination. Escherichia coli is one of the most frequent Pathogenic Bacteria responsible for food poisoning and food-related infections. E. coli infection causes severe bloody diarrhea, abdominal cramps, and occasional vomiting. In the present study, electrochemical impedance spectroscopy (EIS), surface plasmon resonance (SPR), and physisorption techniques were evaluated to decrease sample preparation time and to improve the sensitivity and specificity for the detection of low levels of pathogenic Escherichia coli in frozen chicken meat. The electrical and optical properties of the immobilized anti-E. coli antibody were studied. Moreover, the developed biosensor was used for E. coli detection in inoculated frozen chicken meat

Conception et réalisation de matériaux biofonctionnels pour des dispositifs capteurs impédimétriques

La biofonctionnalisation est une étape clé pour la réalisation du biocapteur et donc pour l'obtention de bonnes performances analytiques. Deux procédures de fonctionnalisation de la surface d'or ont été étudiées par mesure d'impédance. Nous avons, en premier lieu, formé sur l'électrode d'or une monocouche auto-assemblée mixte de 1,2 dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-(biotinyl) (biotinyl-PE) et d'acide 16-mercaptohexadecanoique (MHDA). L'immobilisation de l'anticorps sur la couche SAM est assurée par la neutravidine qui avec ces quatre sites peut relier les biotines immobilisées sur la surface d'or avec celle de l'anticorps biotinylé. Deux couples anticorps-antigène : Biotinyl-antiHemoglobine/Hemoglobine et Biotinyl-Fab fragment K47/Atrazine ont été détectés. La deuxième procédure celle de l'immobilisation d'une couche des particules magnétiques marquées par la streptavidine en appliquant un champ magnétique de 300 mT.The biofonctionnalisation is a key step for the realization of the biosensor and thus for obtaining good analytical performances. Two procedure of fonctionnalization of the gold surface were studied by impedance spectroscopy. Initially, we formed on the gold electrode a mixed self-assembled monolayer consisting of 1,2 dipalmitoyl-Sn-glycero-3-phosphoethanolamine-N-(biotinyl) (biotinyl-EP) and acid 6-mercaptohexadecanoic (MHDA). The tethered neutravidin was used the biotin sites present in the mixed monolayer, with those associated to the biotinyl-antibody. Two antibody-antigen system : Biotinyl-antiHemoglobine/Hemoglobine and Biotinyl-Fab K47/Atrazine fragment were detected. Second procedure that of the immobilization of a layer of the magnetic particles marked by the streptavidine by applying magnetic fields of 300 mT.LYON-Ecole Centrale (690812301) / SudocSudocFranceF

A disposable immunomagnetic electrochemical sensor based on functionalised magnetic beads on gold surface for the detection of atrazine

Texte complet sur : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TG0-4JXY3WV-2&_user=884697&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000047341&_version=1&_urlVersion=0&_userid=884697&md5=b1ab409a4909cb7275ff74f51204f9d0International audienceA disposable immunomagnetic electrochemical sensor involving magnetic particles was developed and applied for the detection of atrazine. The sensor was based on a magnetic monolayer of magnetic particles coated with streptavidin, formed on a gold electrode after application of a magnetic field. The magnetic monolayer was characterized using faradaic impedance spectroscopy, cyclic voltammetry and atomic force microscopy (AFM) techniques. The magnetic monolayer formation leads to an important change in constant phase element due to a change in thickness. AFM images show that the magnetic monolayer is formed and is very dense. The atrazine interacts with biotinyl-Fab fragment K47 and the immunoreaction was characterized by impedance spectroscopy. A decrease in electron transfer resistance was observed which could be attributed to rearrangements in the magnetic monolayer. This approach leads to a sensitive detection of atrazine, acting as an antigen, with a good linear response in the range 10-600 ng/ml

Impedance biosensing using phages for bacteria detection: Generation of dual signals as the clue for in-chip assay confirmation

In the present work, we compare the use of antibodies (Ab) and phages as bioreceptors for bacteria biosensing by Electrochemical Impedance Spectroscopy (EIS). With this aim, both biocomponents have been immobilised in parallel onto interdigitated gold microelectrodes. The produced surfaces have been characterised by EIS and Fourier Transform Infra-Red (FTIR) Spectroscopy and have been applied to bacteria detection. Compared to immunocapture, detection using phages generates successive dual signals of opposite trend over time, which consist of an initial increase in impedance caused by bacteria capture followed by impedance decrease attributed to phage-induced lysis. Such dual signals can be easily distinguished from those caused by non-specific adsorption and/or crossbinding, which helps to circumvent one of the main drawbacks of reagentless biosensors based in a single target-binding event. The described strategy has generated specific detection of E. coli in the range of 1E4 - 1E7 CFU mL-1 and minimal interference by non-target Lactobacillus. We propose that the utilization of phages as capture biocomponent for bacteria capture and EIS detection allows in-chip signal confirmation.Peer reviewe

Study and Modelling of Optocouplers Ageing

Full text on : http://jase.esrgroups.org/issue12008.htmInternational audienceOptocoupler is a coupling component used commonly in feedback control loop circuits for power supply equipment. Its high failure risk causes in most cases the breakdown of the whole equipment. In this work, the wear-out process of this component is studied and a special attention to the most significant parameters variation is paid. Different types of accelerated endurance tests under high temperature; high current and other types are applied to some batches of optocoupler samples in order to determine the best fault signature of the components. An accurate analytical model for the ageing of optocouplers is proposed. This model is based on microscopic analysis of physical phenomena at the semiconductor part of the component. Finally, results obtained with the proposed model are compared to experimental results. Thus the model can bi used to optimize working conditions of optocouplers and improve their lifetime and as a result the reliability of the whole power supply

Immobilization of specific antibody on SAM functionalized gold electrode for rabies virus detection by electrochemical impedance spectroscopy

International audienceThe rabies constitutes one of the most dangerous viruses causing many death cases every year. Each year approximately 55,000 people die of rabies, with high percentage of children. High percentages (99%) of the registered cases were in Asia and Africa. In order to fight this dangerous disease, many techniques are usually used for diagnostic but are usually complex, heavy, expensive, difficult to implement, requiring high-qualified personnel, and this is a necessity of developing new detection process. In this work, we describe the development of an immunological sensor based on functionalized gold electrode allowing rabies antigen detection. The biosensor is based on the immobilization of specific rabies antibodies onto functionalized gold microelectrode. The affinity interaction of the immobilized antibody with the specific antigen can be measured with low limit detection and with a good reproducibility with impedance spectroscopy. The non-specific interaction has been tested using the Newcastle antigen. (c) 2007 Elsevier B.V. All rights reserved

Evaluation of endothelial cell adhesion onto different protein/gold electrodes by EIS.

International audienceTo study cell attachment to biomaterials, several proteins such as fibronectin, collagen IV, heparin, immunoglobulin G, and albumin have been deposited onto polystyrene adsorbed on a self-assembled monolayer (silane or thiol) on glass or gold, respectively. The different steps of this multilayer assembly have been characterized by electrochemical impedance spectroscopy (EIS). These data are compared to those of adhesion rate, viability percentage, and cytoskeleton labeling for a better understanding of the cell adhesion process to each protein. All the proteins are endothelial cell adhering biomolecules but not with the same features. A linear relationship has been established between adhesion rate and resistance of the endothelial cell/protein interface for all negatively charged proteins

Adsorption Study of Congo Red Dye from Synthetic Wastewater at Different Concentrations Using Zinc Sulfide Nanoparticles

Zinc sulfide (ZnS) nanoparticles were fabricated using the chemical precipitation method. The X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM) techniques were used to investigate the structural parameters of the formed ZnS. The hexagonal crystal structure of the Zn and ZnS phases was formed. The average crystallite size of the ZnS phase is 10.3 nm, which is much smaller than that of the Zn phase (54.5 nm). Several frequencies and phonon modes were detected in the Raman scattering spectrum belonging to the ZnS nanoparticles. The synthesized ZnS nanoparticles were used as catalysts to eliminate the Congo red (CR) dye, with different concentrations, from synthetic wastewater. The impact of the CR dye concentration and shaking period on the adsorption of CR was thoroughly investigated, and various adsorption kinetic models were tested. After 3 h of shaking, the adsorption efficiency reached 26.01% for 40 mg/L CR dye and 27.84% for 20 mg/L CR dye. The adsorption capacities of the CR dye in the presence of ZnS are 16% and 9% for 40 and 20 mg/L, respectively. Based on the correlation factor, the intraparticle diffusion kinetic model was considered the best of the tested models

Chemically grafted of single-walled carbon nanotubes onto a functionalized silicon surface

This paper highlights some interesting results regarding the Single walled carbon nanotubes (SWCNTs) functionalized by carboxylic acid, which were dispersed with ultrasonic vibration and implanted using 3 aminopropyltriethoxysilane (APTES) solution on a porous pyramidal silicon (PPS) surface. The physical characterizations of the samples were studied by both Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Also, Fourier transform infrared spectroscopy (FTIR) has been carried out. First, SEM morphological observations reveals that nano pores dig into the sides of the micro pyramids and SWCNTs located throughout the area Si pyramidal structure. Second, AFM confirm the information ob tained by various other techniques such those of electron microscopy. Third, Fourier transform infrared spectroscopy (FTIR) analysis confirms the chemical bonding between the silicon and SWCNTs. Finally, a graphical abstract is proposed to describe the implantation steps of SWCNTs on the porous silicon (pSi) having pyramidal structure