La communication électronique au sein de nano-objets adsorbés

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Methylene blue phosphoramidite for DNA labelling

We thank Oceane Clabaux and Alexandre Escoffier for their contribution to the work.International audienceWe report the first synthesis of a methylene blue (MB) phosphoramidite derivative suitable for DNA solid-phase synthesis. The electrochemical and optical properties of the resulting MB modified oligonucleotides were confirmed. This new molecule is an important breakthrough in the design of new probes labelled with MB

Electron transfer rates in an adsorbed C60-porphyrin dyad

International audienceAssociation of C60 and porphyrin entities to build light harvesting systems is a promising alternative for future photovoltaic devices. Herein, we determine the electron transfer rates in a C60-porphyrin dyad anchoredonto a gold ultramicroelectrode via the porphyrin core. Similar rates are observed for both redox entities, suggesting a tilt of the molecules allowing an efficient through-space communication between C60 and the electrod

Highly sensitive electrochemical biosensor for bisphenol A detection based on a diazonium-functionalized boron-doped diamond electrode modified with a multi-walled carbon nanotube-tyrosinase hybrid film (vol 74, pg 830, 2015)

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Highly sensitive electrochemical biosensor for bisphenol A detection based on a diazonium-functionalized boron-doped diamond electrode modified with a multi-walled carbon nanotube-tyrosinase hybrid film (vol 74, pg 830, 2015)

International audienceno abstrac

Synthesis and electroactivated addressing of ferrocenyl and azido-modified stem-loop oligonucleotides on an integrated electrochemical device

International audienceWe report a strategy to address stem-loop oligonucleotides on a gold surface in order to develop a robust and ultra-sensitive integrated electrochemical DNA sensor. Probe immobilization relies on the potential-assisted copper-catalyzed alkyne-azide cycloaddition. Firstly, a tetrathiol-hexynyl derivative was used to introduce alkyne functions onto the electrode surface. This anchor has proved its robustness in conditions used for the " click " reaction and in wet storage. Then, different ferrocenyl and azido-modified stem-loop oligonucleotides were synthesized using the solid-phase synthesis technique and their immobilization was studied. Hybridization assays with the DNA target were performed in a complex medium by cyclic voltammetry. The detection sensitivity achieved by our functionalized electrodes was significantly increased, as a detection limit of 10 fM was determined. We also demonstrated that grafting of the stem-loop oligonucleotides via the electroactivated " click " reaction was specific to the gold surface on a microfabricated electro chemical device for the Lab-on-Chip application that fully integrates Au working microelectrodes, Pt counter and Ag reference electrodes.

Do molecular conductances correlate with electrochemical rate constants? Experimental insights.

International audienceWe measured single-molecule conductances for three different redox systems self-assembled onto gold by the STMBJ method and compared them with electrochemical heterogeneous rate constants determined by ultrafast voltammetry. It was observed that fast systems indeed give higher conductance. Monotonous dependency of conductance on potential reveals that large molecular fluctuations prevent the molecular redox levels to lie in between the Fermi levels of the electrodes in the nanogap configuration. Electronic coupling factors for both experimental approaches were therefore evaluated based on the superexchange mechanism theory. The results suggest that coupling is surprisingly on the same order of magnitude or even larger in conductance measurements whereas electron transfer occurs on larger distances than in transient electrochemistry

Robust Electrografting on Self-Organized 3D Graphene Electrodes

International audienceA self-organized three-dimensional (3D) graphene electrode processed by pulsed laser deposition with thermal annealing is reported. This substrate shows great performance in electron transfer kinetics regarding ferrocene redox probes in solution. A robust electrografting strategy for covalently attaching a redox probe onto these graphene electrodes is also reported. The modification protocol consists of a combination of diazonium salt electrografting and click chemistry by means of Cu I-catalyzed alkyne–azide cycloaddition. Our modification strategy applied to 3D graphene electrodes was analyzed by means of atomic force microscopy, scanning electron microscopy, Raman spectroscopy, cyclic voltammetry, and X-ray photoelectron spectroscopy (XPS). For XPS chemical surface analysis, special attention was paid to the distribution and chemical state of iron and nitrogen in order to highlight the functionalization of the graphene-based substrate by electrochemically grafting a ferrocene derivative. Dense grafting was observed, offering 4.9×10 –10 mol cm –2 surface coverage and showing a stable signal over 22 days. The electrografting was performed in the form of multilayers, which offers higher ferrocene loading than a dense monolayer on a flat surface. This work opens highly promising perspectives for the development of self-organized 3D graphene electrodes with various sensing functionalities

DC nitrogen plasma assisted Femtosecond Pulsed Laser Deposition of Carbon-Nitrogen alloy for environmental analytical Microsystems: thin films characterization and in situ plume analysis

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