F. Pinaud, N. Sojic, V. Ravaine
L'Actualité Chimique, 2014, 390.
In the present work, redox thermoresponsive microgels bearing ruthenium complex were synthesized. Investigation of electrogenerated chemiluminescent properties shows an unexpected amplification up to two orders of magnitude at the volume phase transition. The origin of this phenomenon is explained by the decrease in the average distance between adjacent ruthenium complexes at the swell-collapse transition, which favors the annihilation process in the microgels. This general principle offers the opportunity to develop a new range of electrogenerated chemiluminescent biosensors based microgels.
J. Roche, E. Gianessi, A. Kuhn
Phys. Chem. Chem. Phys. 2014, 16, 21234-21236.
Here we report a new physico-chemical method based on bipolar electrochemistry for producing spherical metal beads with a well-controlled size. Applying an electric field to a low conductivity electrolyte containing metal beads leads to a polarization potential across the beads which triggers their electrodissolution. Under stirring, their size decreases gradually and results in a final population which is spherical and monodisperse. Furthermore, shapeless particles can see their spherical character increased to form isotropic objects. The process is versatile, self-limiting and produces beads of different final diameters depending on the applied potential. Finally, the removed material can be recycled at one of the feeder electrodes.
M. Ongaro, J. Roche, A. Kuhn, P. Ugo
Chem. Electro. Chem. 2014, 2048-2051
We present a new procedure for the site-specific deposition of metal on semiconductor nanofibers (NF). The semiconductor NFs are exposed to an external electric field while irradiated with UV light. This coupling allows the generation of excited electron–hole couples and drives them to the opposite extremities of the fibers where they can react with redox species in solution. We demonstrate here that, when both UV light and electric field are simultaneously applied, a metal deposit is formed at the cathodically polarized tip of the NF in a controlled way. Such an electric-field-assisted photochemical (EFAP) process is suitable for highly localized photodeposition of metals, leading to semiconductor Janus objects.
M. Sentic, S. Arbault, B. Goudeau, D. Manojlovic, A. Kuhn, L. Bouffier, N. Sojic
Chem. Commun. 2014, 50, 10202-10205.
An electrochemiluminescent (ECL) swimmer driven by bipolar electrochemistry is reported for enzymatic glucose sensing. The chemo-mechanical motion is induced by localized hydrogen bubble generation. The concomitant oxidation of the luminophore and of the enzymatically-produced NADH leads to ECL emission with a direct glucose-dependant light intensity. We demonstrate herein the local sensing and reporting of glucose in a concentration gradient explored by the ECL swimmer. Such a dynamic sensing approach combines in a synergetic way the wireless propulsion with the enzymatic selectivity using ECL as a readout method at the level of moving objects.
E. Suraniti, S. Ben-Amor, P. Landry, M. Rigoulet, E. Fontaine, S. Bottari, A. Devin, N. Sojic, N. Mano, S. Arbault
Angew. Chem. Int. Ed. 2014, 126, 6773-6776.
Mitochondria consume oxygen at the respiratory chain and convert redox energy into ATP. As a side process, they produce reactive oxygen species (ROS), which physiological activities still need to be understood. However, current analytical methods do not allow monitoring quantitatively and unambiguously mitochondrial ROS. We have developed electrochemical biosensors based on peroxidase-redox polymer-modified electrodes, providing a selective detection of H2O2 with nanomolar sensitivity, a linear response over 5 concentration-decades and fast response-time. The release of H2O2 by mitochondria was then monitored under phosphorylating or inhibited respiration conditions. We report the detection of two concomitant regimes of H2O2 release: large fluxes (hundreds of nM) under complex III-inhibition, and bursts of a few nanomolars immediately following mitochondria activation. These unprecedented bursts of H2O2 are assigned to the role of mitochondria as the hub of redox signaling in cells.
- Adsorption of Microgels at an Oil–Water Interface: Correlation between Packing and 2D Elasticity
- Imaging Redox Activity at Bipolar Electrodes by Indirect Fluorescence Modulation
- Electropolymerization of Polypyrrole by Bipolar Electrochemistry in an Ionic Liquid
- Straight-forward Synthesis of Ringed Particles