Electrochemistry of Biosystems
Linking Glucose Oxidation to Luminol-based Electrochemiluminescence using bipolar Electrochemistry
Asymmetric Modification of TiO2 Nanofibers with Gold by Electric-Field-Assisted Photochemistry
Stimuli-responsive microgels for electrochemiluminescence amplification

A. Sauret, E. C. Barney, A. Perro, E. Villermaux, H. A. Stone and E. Dressaire 

Applied Physics Letters 2014, 105, 074101 

We report on a microfluidic method that allows measurement of a small concentration of largecontaminants in suspensions of solid micrometer-scale particles. To perform the measurement, we flowthe colloidalsuspension through a series of constrictions, i.e., a microchannel of varying cross-section. We show and quantify the role of large contaminants in the formation of clogs at a constriction and the growth of the resulting filter cake. By measuring the time interval between two clogging events in an array of parallel microchannels, we are able to estimate the concentration of contaminants whose size is selected by the geometry of the microfluidic device. This technique for characterizing colloidalsuspensions offers a versatile and rapid tool to explore the role of contaminants on the properties of thesuspensions.

 

D. Tarus, E. Hachet, L. Messager, B. Catargi, V. Ravaine, R. Auzély-Velty

Macromol. Rapid. Commun. 2014, 35, 2089 -2095

Dynamic covalent hydrogels are facilely prepared from biocompatible polysaccharides in physiological conditions by the formation of phenylboronate ester cross-links. This is based on the simple mixing of carboxylate-containing polysaccharides (i.e., hyaluronic acid or carboxymethylcellulose) modified with phenylboronic acid and maltose moieties according to mild coupling reactions performed in aqueous solution. The formation of dynamic networks based on reversible boronic-ester cross-links is demonstrated by analyzing their rheological behavior. This study shows that these gels can adapt their structure in response to chemical stimuli such as variations in pH or addition of glucose and self-heal.

2015-3

 

 

H. Sopha, J. Roche, I. Švancara, A. Kuhn

Anal.Chem. 2014, 86, 10515–10519

In this contribution, a wireless method for the electrolytic sampling of heavy metals at special bismuth-modified particles is presented. For the first time, glassy carbon beads were asymmetrically modified with bismuth using bipolar electrochemistry. The resulting chemically asymmetric beads, so-called Janus particles, could be employed for the wireless electroaccumulation of heavy metal ions in the bismuth film. The qualitative and quantitative aspects of this concept have been studied by using anodic stripping voltammetry with Cd2+ and Pb2+ as the model ions. Different experimental and instrumental parameters have been optimized, among others the concentration of Bi3+ ions, the deposition conditions for the bismuth-film, and the accumulation time of the target heavy metals.The developed concept could be applied to the transfer of heavy metal ions from a solution into a confined space without need to electrically connect the collector (electrode), thus representing an interesting new approach for trace metal analysis in small volumes.2014-22

P. Masse, E. Sellier, V. Schmitt, and V. Ravaine

Langmuir, 2014, 30 (49), pp 14745–14756

The importance of electrostatics on microgel adsorption at a liquid interface is studied, as well as its consequence on emulsion stabilization. In this work, poly(N-isopropylacrylamide) (pNIPAM) microgels bearing different numbers of charges and various distribution profiles are studied, both in solution and at the oil–water interface of emulsion drops. Charged microgels are compared to neutral ones, and electrostatic interactions are screened by adding salt to the aqueous solution. In solution, electrostatics has a significant impact on microgel swelling, as induced by the osmotic pressure exerted by mobile counterions in the gel network. At the interface of drops, microgels pack in a hexagonal array, whose lattice parameter is independent of the number of charges and range of electrostatic interactions. Microgel morphology and packing are ruled only by the adsorption of the pNIPAM chain at the interface. Conversely, decreasing the charge density of microgels by the protonation of the carboxylic groups leads to unstable emulsions, possibly as a result of the impact of hydrogen bonding on microgel deformability.

2015-2

J. Roche, S. Carrara, J. Sanchez, J. Lannelongue, G. Loget, L. Bouffier, P. Fischer, A. Kuhn
Sci. Rep. 2014, 4, 6705

Miniaturized structures that can move in a controlled way in solution and integrate various functionalities are attracting considerable attention due to the potential applications in fields ranging from autonomous micromotors to roving sensors. Here we introduce a concept which allows, depending on their specific design, the controlled directional motion of objects in water, combined with electronic functionalities such as the emission of light, sensing, signal conversion, treatment and transmission. The approach is based on electric field-induced polarization, which triggers different chemical reactions at the surface of the object and thereby its propulsion. This results in a localized electric current that can power in a wireless way electronic devices in water, leading to a new class of electronic swimmers (e-swimmers).

2014-21

Zeste de Science du CNRS


jeudi 15 février 2018
Après son communiqué de presse paru en octobre dernier, le CNRS vient de mettre en ligne une vidéo de vulgarisation pour expliquer le principe de l'électrochimie bipolaire appliquée à la mise en mouvement de polymères conducteurs. Vous pouvez la consulter en cliquant sur l'image ci-dessous !

Communiqué de presse du CNRS - Des plastiques qui dansent


mercredi 11 octobre 2017
De nouveaux types d’actionneurs à base de polymères conducteurs ont été publiés dans la revue Angewandte Chemie et viennent de faire l'objet d'un communiqué de presse du CNRS. L’originalité de l'approche réside dans le déclenchement d'une déformation réversible d’un plastique à distance par voie électrochimique. Ce processus, qui exploite le principe de l'électrochimie bipolaire, se déroule sans aucune connexion physique et permet d’actionner plusieurs objets... Read More...

Communiqué de presse du CNRS - Semi-conducteurs Janus


lundi 24 juillet 2017
Dans le cadre d'une collaboration avec des scientifiques thaïlandais (centre VISTEC à Rayong et Kasetsart University à Bangkok), notre équipe vient de mettre au point un nouveau procédé permettant de synthétiser des particules "Janus" semi-conductrices qui pourraient trouver application dans le domaine de la catalyse, et notamment celui de la photolyse de l’eau. Les résultats de ces travaux ont été publiés dans la revue Angewandte Chemie et viennent de faire l'objet d'un... Read More...

Financement ERC pour Alexander Kuhn


mercredi 3 mai 2017
Alexander KUHN vient d'obtenir un financement de l'ERC pour une durée de 5 ans ! L'objectif global du projet, intitulé ELECTRA, est de proposer des stratégies jusqu'à présent inexplorées et polyvalentes, basées sur l'utilisation non-conventionnelle de phénomènes électrochimiques, pour générer une asymétrie dans des systèmes chimiques à différentes échelles de longueur.... Read More...

Distinguished Fellow


lundi 11 janvier 2016
The French Chemical Society has selected Alexander Kuhn as one of its new distinguished fellows. The official ceremony will be held in May 2016 in Paris. Congratulations!