Electrochemical mapping reveals direct correlation between heterogeneous electron-transfer kinetics and local density of states in diamond electrodes

Conducting carbon materials: A multi-microscopy approach shows that local heterogeneous electron-transfer rates at conducting diamond electrodes correlate with the local density of electronic states. This model of electroactivity is of considerable value for the rational design of conducting diamond electrochemical technologies, and also provides key general insights on electrode structure controls in electrochemical kinetic

La microscopie électrochimique à balayage (développement et applications)

Voulant se doter des outils les plus récents et les plus performant pour étudier la réactivité électrochimique locale de différents matériaux, le Laboratoire d'Electrochimie et Physico-chimie des Matériaux et des Interfaces (LEPMI) a décidé de se doter d'un microscope électrochimique à balayage (Scanning Electrochemical Microscopy ou SECM). Ce microscope à sonde locale avait été développé dès les milieu des années 1980 à partir des avancées scientifiques et techniques de la microscopie par effet tunnel et des ultra-microélectrodes.Le travail présenté porte sur la mise au point d'un dispositif de microscopie électrochimique à balayage, dispositif n'existant pas alors en France. Dans un premier temps, un procédé permettant de fabriquer des ultra-microélectrodes a, tout d'abord, été conçu. Dans un deuxième temps, une configuration de microscope ouverte et évolutive a été trouvée et mise au point. Dans un dernier temps, le microscope étant opérationnel, des expériences ont été menées sur en imagerie de réactivité de surface afin de définir les capacités de l'appareil. Puis, le microscope a servi à caractériser des électrodes de diamant plus ou moins dopé au bore et à procéder à des expériences de micro-fabrication (dépôt de cuivre et gravure sur arséniure de gallium dopé au zinc). Enfin, il a permis d'investiguer l'interface d'électrodes de diamant avec des molécules biologiques.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Using Scanning Electrochemical Microscopy to Determine the Doping Level and the Flatband Potential of Boron-Doped Diamond Electrodes

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Biotin grafting on boron-doped diamond

International audienceGrafting of biotin on top of a polycrystalline boron-doped diamond layer was achieved by surface oxidation followed by an esterification reaction and revealed by fluorescently labelled streptavidin

Nucleosides and ODN electrochemical detection onto boron doped diamond electrodes

International audienceBoron doped diamond (BDD) is a promising material for electroanalytical chemistry due mainly to its chemical stability, its high electrical conductivity and to the large amplitude of its electroactive window in aqueous media. The latter feature allowed us to study the direct oxidation of the two electroactive nucleosides, guanosine and adenosine. The BDD electrode was first activated by applying high oxidizing potentials, allowing to increase anodically its working potential window through the oxidation of CH surface groups into hydroxyl and carbonyl terminations. Guanosine (1.2 V vs. Ag/AgCl) and adenosine (1.5 V vs. Ag/AgCl) could then be detected electrochemically with an acceptable signal to noise ratio. The electrochemical signature of each oxidizable base was assessed using differential pulse voltammetry (DPV), in solutions containing one or both nucleosides. These experiments pointed out the existence of adsorption phenomena of the oxidized products onto the diamond surface. Scanning electrochemical microscopy (SECM) was used to investigate these adsorption effects at the microscopic scale. The usefulness of BDD electrodes for the direct electrochemical detection of synthetic oligonucleotides is also evidenced

Interfacing Boron Doped Diamond and biology: an insight on its use for bioanalytical applications

International audienceBoron doped diamond (BDD) films are promising materials for electroanalysis and bioelectroanalysis. This contribution gives a short review on BDD functionalization by chemical and biochemical entities and on the applications of BDD electrodes to electroanalysis of chemical compounds of biological interest. This review is illustrated by the developments on BDD interfaces in both these areas carried out in our group. BDD electrodes were prepared by means of microwave plasma-assisted CVD onto silicon substrate giving rise to H-terminated BDD films. Anodic polarization of BDD electrodes in aqueous media generates hydrophilic oxidized surfaces and extended electrochemical window in aqueous media. We took advantage of this enlarged electrochemical window together with the hydroxylated surface for the functionalization of BDD electrode surfaces with biomolecules and for bioelectroanalysis. We have designed a novel route of BDD functionalization using OH terminations of the anodized surface. The modification of the BDD surface with biotin groups will be presented here as biologically active model. Furthermore, as the anodic potential window of BDD increases upon electrochemical activation, 2′-deoxyguanosine (1.2 V vs. Ag/AgCl) and 2′-deoxyadenosine (1.5 V vs. Ag/AgCl) could be detected electrochemically with an acceptable signal to noise ratio. The electrochemical signature of each oxidizable base was assessed using differential pulse voltammetry (DPV). These experiments pointed towards adsorption of the oxidized products, which were investigated macroscopically by DPV and at the microscopic level by SECM (scanning electrochemical microscopy)