Élaboration par électrodéposition en régime impulsionnel de revêtements de zinc sur acier

Des revêtements de zinc ont été élaborés en mode pulsé et continu. Des tests de corrosion ont été entrepris dans une solution agitée et aérée de NaCl (30 g/L) en utilisant un montage électrochimique classique à trois électrodes. La morphologie des revêtements a été caractérisée par des observations en microscopie électronique à balayage (MEB-FEG). Enfin, la diffraction des rayons X en mode symétrique a permis d’évaluer la structure et les principales orientations cristallographiques des dépôts

Elaboration d'une membrane polymérique incorporant la tridodecylamine pour la détection de l'acide orange 10

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A new HRP/catalase biosensor based on microconductometric transduction for nitrite determination

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Electrochemical Characterization of Enzymatic Impedimetric Biosensor Destined to Detect Organochlorine Pesticide: the Diclofop-methyl

Preservation of aquatic ecosystems requires early warning tools such as biosensors for in situ monitoring and continuously. Such tools can provide information about the nature of pollutants condition be designed to meet specific manner. This work proposes an impedimetric biosensor, using a bacterial enzyme (Condida Rugosa lipase) immobilized in an organic matrix composed of BSA (bovine serum albumin) and glutaraldehyde, capable of detecting organochlorine pesticides (Diclofop-methyl) state trace in aqueous media. Moreover, these measurements were carried out by varying a number of parameters characteristic of the system being studied in order to better define the role of the different elements involved in the development of the receiving part of the sensor as follows: Composition of the membrane, effect of temperature and the effect of the pH of the medium. The results show that the developed biosensor provides answers in an area of very low concentrations of the order of 5.99x10-14 - 5.88x10-3 g/L and a detection limit of 5.99x10-14 g/L for Diclofop-methyl. This biosensor detects the pollutant in a temperature range between 20 °C and 40 °C. We also studied the selectivity of the detection of the target substance in the presence of interfering with some heavy metals (cadmium, cobalt, zinc and lead) and other organophosphorus and organochlorines pesticide

Caractérisation d'un biocapteur enzymatique impédimétrique destiné à la détection d'un pesticide organochlore.

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A sensitive and selective thrombin impedimetric aptasensor based on tailored aptamers obtained by solid-phase synthesis

International audienceThe aim of the present work is to show the interest of a generic concept of aptamers directly obtained through a supported synthesis, using phosphoramidite synthons, for biosensor application. By that way, we were able to tailor the anchoring groups and specific spacers. The concept is validated on an impedimetric aptasensor for detection of thrombin. Two aptamer sequences, selected from literature (15 and 29 mers), were synthesized with a multi-thiol modification at one extremity. After their grafting on gold electrode, the faradic electrochemical impedance measurements allow the direct detection of thrombin in the range of 3-30 ng mL(-1) ancl 3-50 ng mL(- 1) for 15 meraptamer and 29 meraptamer respectively, with a detection limit of 3.1 ng mL(-1) (80 pmol/l) for both sequences. This study demonstrates that these aptasensors exhibit high sensitivity (higher sensitivity for 29 meraptamer), high selectivity (compared to a model protein, BSA), stability and reproducibilit

Development of a hexavalent chromium ISFET sensor with a polymeric membrane including tributylphosphate

International audienceThis paper presents a first report on chromium ISFET (ion-sensitive field effect transistor) based on a polymeric membrane (siloprene) including an ionophore (tributylphosphate) sensitive for hexavalent chromium. The sensor sensitivity as a function of the pH was studied; its value is minimum in a pH interval from 5.5 to 7.5. The sensitivity for hexavalent chromium was found to be 15 mV/Ioga(Cr6+) in the range of 10(-4) to 10(-2) M. The detection limit was found to be 10(-5) M. The studied interfering ions are Pb(II) and Cd(II) that do not represent a great perturbation upon the response for hexavalent chromium. (c) 2005 Elsevier B.V. All rights reserved

Comparative Study of Responses of Two Enzymatic Biosensors Based on Lipase from Candida rugosa and Porcine Pancreas for Detection of Diclofop-Methyl

International audienceThe objective of this study was to evaluate the immobilization of lipase on an organic matrix by reticulation method, aiming at its application in the detection of organochlorine pesticide. The biologically inactive protein of bovine serum albumin (BSA) and glutaraldehyde were used for immobilizing lipase from a microbial source ( Candida rugosa CRL ) and animal cells (porcine pancreatic lipase, PPL). Use of this immobilized preparation was extended to the realization of two different origins of a miniaturized enzymatic biosensors is presented for the electrochemical detection of a large range of organochlorine pesticide (diclofop-methyl) in phosphate buffer saline (PBS) were observed experimentally. The best responses of biosensor were obtained for PPL with a high sensitivity to organochlorine pesticide in the concentration range of 5.99*10-12 to 5.89*10-2g*L-1, whereas a linear response of CRL for diclofop-methyl was obtained. The lipase biosensors exhibits the advantage of a simple fabrication procedure, wide dynamic range and a lower detection limit (5.99*10-12 g*L-1 for diclofop-methyl). The impact of heavy metals as well as organophosphorous and other organochlorine pesticides was also studied