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Herzog G.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment | Beni V.,Linköping University
Analytica Chimica Acta | Year: 2013

In this article, a comprehensive overview of the most recent developments in the field of stripping voltammetry at regular micro-interfaces (both solid-liquid and liquid-liquid interfaces) is presented. This review will report on the most conventional arrays of metallic micro-electrodes but also on the rapidly growing field of electrochemistry at arrays of micro-interfaces between two immiscible electrolyte solutions (μITIES). The main fabrication methods, together with some design considerations and diffusion phenomena at such interfaces are discussed. Main applications of micro-interface arrays are presented including heavy metals detection at micro-electrode arrays and detection of organic molecules (amino acids, vitamins, peptides and drugs) at the μITIES. Stripping analysis at micro-interface arrays is suitable for the detection of analytes in several real media including water, soil extracts and biological fluids (blood and saliva) with high specificity, sensitivity (detection limits of nM, ppb level) and reliability. Stripping analysis at μITIES and micro-electrode arrays are two complementary approaches that have the advantages of being cost effective, simple to use and easily adaptable to field measurement. © 2013 Elsevier B.V.

Vila N.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment | Ghanbaja J.,CNRS Jean Lamour Institute | Aubert E.,CNRS Laboratory of Crystallography, Nuclear Magnetic Resonance and Modelling | Walcarius A.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment
Angewandte Chemie - International Edition | Year: 2014

One key challenge in inorganic mesoporous films is the development of oriented mesostructures with vertical channels, and even more challenging is their functionalization while maintaining accessible the selected surface groups. Combining the electrochemically assisted deposition of ordered and oriented azide-functionalized mesoporous silica with alkyne-azide click chemistry enables such nanostructured and vertically aligned hybrid films to be obtained with significant amounts of active organic functional groups, as illustrated for ferrocene and pyridine functions. A good level of mesostructural order was obtained, namely up to 40 % of organosilane in the starting sol. The method could be applied to a wide variety of functional groups, thus offering numerous new opportunities for applications in various fields. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Duval J.F.L.,University of Lorraine | Gaboriaud F.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment
Current Opinion in Colloid and Interface Science | Year: 2010

Electrokinetic phenomena, such as electrophoresis, are valuable tools for determining the interfacial (double layer) properties of colloidal particles. The theoretical formalisms employed to interpret electrokinetic data (electrophoretic mobility) were initially derived for the restrictive case of hard (non-permeable) particles with the electrokinetic potential as unavoidable primary variable. In this paper, we underline the inadequacy of such models for addressing the electrostatic and hydrodynamic characteristics of microbes like bacteria, viruses or yeast cells. These bioparticles are characterized by heterogeneous, soft, permeable interphases formed with the outer electrolytic medium, which requires advanced electrokinetic analyses where the concept of zeta-potential must be abandoned. We review the progresses made in the measurement and analysis of interphasial properties of bioparticles under electrokinetic conditions. In particular, emphasis is given on the necessity to couple appropriately interpreted electrokinetics with other physico-chemical measurements (e.g. issued from AFM imaging/force spectroscopy) and microbiological techniques (genetic manipulation of microbes). Using such a combination, a clear connection between complex interphase properties of microbes and e.g. their propensity to adhere onto charged surfaces should be achieved. © 2009 Elsevier Ltd. All rights reserved.

Walcarius A.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment
Analytical and Bioanalytical Chemistry | Year: 2010

Nano- and/or macrostructuring of electrode surfaces has recently emerged as a powerful method of improving the performances of electrochemical devices by enhancing both molecular accessibility and rapid mass transport via diffusion, by increasing the electroactive surface area in comparison to the geometric one, and/or by providing confinement platforms for hosting suitable reagents. This brief overview highlights how template technology offers advantages in terms of designing new types of porous electrodes-mostly based on thin films, and functionalized or not-and discusses their use in analytical chemistry via some recent examples from the literature on electrochemical sensors and biosensors. © 2009 Springer-Verlag.

Walcarius A.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment
Electroanalysis | Year: 2015

A review (350 references) is given to the interest of mesoporous materials for designing electrochemical sensors. After a brief summary of the implication of template-based ordered mesoporous materials in electrochemical science, the various types of inorganic and organic-inorganic hybrid mesostructures used to date in electroanalysis and the corresponding electrode configurations are described. The various sensor applications are then discussed on the basis of comprehensive tables and some representative illustrations. The main detection schemes developed in the field are (volt)amperometric sensing subsequent to preconcentration and electrocatalytic detection. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Walcarius A.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment
TrAC - Trends in Analytical Chemistry | Year: 2012

The past few years have seen an explosion in the use of ordered mesoporous carbon and, to lesser extent, templated macroporous carbon, as novel materials to design nanostructured electrodes devoted to sensing and biosensing. These materials offer attractive features that can be exploited in electrochemistry [e.g., good electronic conductivity, great porosity (high specific surface area, large pore volume and size) and widely open ordered structure]. After a brief presentation of these materials (template synthesis, characterization, properties and uses) and the ways to attach them to electrode surfaces (including their basic electrochemical behavior), we review their interest for electroanalytical purposes. We pay particular attention to applications in the fields of preconcentration electroanalysis, electrocatalysis, potentiometry and electrochemical biosensing, and to discussing the advantages of such templated porous carbons over other related nanostructured carbon materials. © 2012 Elsevier Ltd.

Walcarius A.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment
Chemical Society Reviews | Year: 2013

Ordered mesoporous materials prepared by the template route have attracted increasing interest from the electrochemists community due to their plenty of unique properties and functionalities that can be effectively exploited in electrochemical devices. This review will cover the whole field of the intersection between electrochemistry and ordered mesoporous materials. The latter are either electronically insulating (silica and some other metal oxides, as well as silica-based organic-inorganic hybrid materials), semi-conducting (metal oxides), or conducting (metals, carbons). The three main intersection areas are: (1) the development/use of electrochemical methods to characterize the properties of mesoporous materials (i.e., charge and mass transfer processes); (2) the generation of mesostructured solids by electro-assisted deposition using appropriate templates; and (3) the application of these novel materials for electrochemical purposes. The most common devices to date are based on a bulk composite or thin film configuration and the resulting electrodes modified with such mesoporous materials have been successfully applied in various fields, including mainly electrochemical sensing and biosensing as well as energy conversion and storage (620 references). © The Royal Society of Chemistry 2013.

Walcarius A.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment | Mercier L.,Laurentian University
Journal of Materials Chemistry | Year: 2010

A review with ca. 400 references is provided dealing with the use of mesoporous silica and organically-modified silica-based materials for removal of inorganic and organic pollutants from aqueous solutions. After having briefly discussed the interest of functionalized mesoporous silica for environmental remediation purposes, the various synthetic methods to prepare such nanoengineered adsorbents are described. Then, their application to the removal of heavy metal species, toxic anions, radionuclides, and a wide range of organic pollutants is presented in a comprehensive way with the help of extensive tables and some illustrating figures. © 2010 The Royal Society of Chemistry.

Quiles F.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment
Biomacromolecules | Year: 2012

Glycogen is mainly found as the principal storage form of glucose in cells. Many bacteria are able to synthesize large amounts of glycogen under unfavorable life conditions. By combining infrared spectroscopy, single molecule force spectroscopy (SMFS) and immuno-staining technique, we evidenced that planktonic P. fluorescens (Pf) cells are also able to produce glycogen as an extracellular polymeric substance. For this purpose, Pf suspensions were examined at 3 and 21 h of growth in nutritive medium (LB, 0.5 g/L). The conformation of the extracellular glycogen, revealed through its infrared spectral signature, has been investigated by SMFS measurements using Freely Jointed Chain model. The analysis of force versus distance curves showed over growth time that the increase of glycogen production was accompanied by an increase in glycogen contour lengths and ramifications. These results demonstrated that the production of extracellular bacterial glycogen can occur even if the cells are not subjected to unfavorable life conditions.

Abe Y.,CNRS Laboratory of Physical Chemistry and Microbiology for the Environment
Biofouling | Year: 2011

Atomic force microscope techniques and multi-staining fluorescence microscopy were employed to study the steps in drinking water biofilm formation. During the formation of a conditioning layer, surface hydrophobic forces increased and the range of characteristic hydrophobic forces diversified with time, becoming progressively complex in macromolecular composition, which in return triggered irreversible cellular adhesion. AFM visualization of 1 to 8 week drinking water biofilms showed a spatially discontinuous and heterogeneous distribution comprising an extensive network of filamentous fungi in which biofilm aggregates were embedded. The elastic modulus of 40-day-old biofilms ranged from 200 to 9000 kPa, and the biofilm deposits with a height >0.5 μm had an elastic modulus <600 kPa, suggesting that the drinking water biofilms were composed of a soft top layer and a basal layer with significantly higher elastic modulus values falling in the range of fungal elasticity.

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