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Enikő Krisch, Léa Messager, Benjámin Gyarmati, Valérie Ravaine, and András Szilágyi

Macromol. Mater. Eng. 2016, 301(3), 260–266

Nanogels loaded with fluorescent dextran as a model drug are synthesized by the oxidation induced cross-linking of water soluble redox responsive thiolated poly(amino acid) in miniemulsion without the introduction of any cross-linker molecule. Two types of high energy methods, namely, ultrasonication and high pressure homogenization (HPH), are compared. Dynamic light scattering and transmission electron microscopy measurements confirm that spherical nanogels in 100–150 nm diameter range are prepared successfully by HPH method. Size and surface charge of the nanogels can easily be controlled by environmental pH. The release of encapsulated drug is triggered by the degradation of nanogels in reducing environment due to the cleavage of disulphide bonds.

2015-20

Thibaut Divoux, Véronique Lapeyre, Valérie Ravaine, and Sébastien Manneville

Phys. Rev. E 2015, 92, 060301(R)

Flows of suspensions are often affected by wall slip, that is, the fluid velocity Vf in the vicinity of a boundary differs from the wall velocity Vw due to the presence of a lubrication layer. While the slip velocity Vs = abs (Vf - Vw) robustly scales linearly with the stress S at the wall in dilute suspensions, there is no consensus regarding denser suspensions that are sheared in the bulk, for which slip velocities have been reported to scale as a Vs = k.(S)p with exponents p inconsistently ranging between 0 and 2. Here we focus on a suspension of soft thermoresponsive particles and show that Vs actually scales as a power law of the viscous stress (S - Sc), where Sc denotes the yield stress of the bulk material. By tuning the temperature across the jamming transition, we further demonstrate that this scaling holds true over a large range of packing fractions Phi on both sides of the jamming point and that the exponent p increases continuously with Phi, from 1 in the case of dilute suspensions to 2 for jammed assemblies. These results allow us to successfully revisit inconsistent data from the literature and pave the way for a continuous description of wall slip above and below jamming.

L. Koefoed, K. Shimizu, S. U. Pedersen, K. Daasbjerg, A. Kuhn, and D. Zigah

RSC Adv., 2015, DOI: 10.1039/c5ra20156j

Bipolar electrochemistry (BPE) is widely used to trigger electrochemical reactions on conducting objects without direct electrical wiring. In this study a novel methodology is reported, which for the first allows simultaneous deposition of two different organic films at each end of a glassy carbon substrate (1 x 1 cm2). The approach is based on the use of an organic bifunctional molecule, which may be oxidatively and reductively electrografted at he same time. The reduction process goes through the diazonium group, while the oxidation proceeds via the primary amine. The double functinoalized plates are investigated by ellipsometry, cyclic voltammetry, condensation imaging, x-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry. Post-modification of one of the anchoring layers illustrates the versatility of the system, pointing to its potential use in fields going from molecular electronics to targeted drug delivery.

2015-17

Florent Pinaud, Romain Millereux, Pierre Vialar-Trarieux, Bogdan Catargi, Sandra Pinet, Isabelle Gosse, Neso Sojic, Valérie Ravaine

J. Phys. Chem. B, 2015, 119 (40), pp 12954–12961

Stimuli-responsive microgels with redox and luminescent resonance energy transfer (LRET) properties are reported. Poly(N-isopropylacrylamide) microgels are functionalized simultaneously with two models dyes: a derivative of tris(bipyridine) ruthenium complex and cyanine 5. Both moieties are chosen as a pair of luminophores with a spectral overlap for resonance energy transfer, where the ruthenium complex acts as a donor and the cyanine an acceptor. The effect of the temperature on the efficiency of the LRET of the microgels has been investigated and compared using either photoluminescence (PL) or electrochemiluminescence (ECL) as the excitation process. In PL, the synthesized microgels exhibit resonance energy transfer regardless of the swelling degree of the microgels. The transfer efficiency is a function of the donor–acceptor distance and can be tuned either by the swell–collapse phase transition or by the dye content in the microgel network. In ECL, the microgels emit light only at the wavelength of the ruthenium complex because the resonance energy transfer does not occur. Indeed, even within the microgel matrix, the cyanine dye is oxidized at the potential required for ECL generation, which impairs its emitting properties. Thus, both excitation channels (i.e., PL and ECL) show differential behavior for the resonance energy transfer processes.

2015-18

V. Badets, D. Duclos, D. Quinton, O. Fontaine, D. Zigah

Electrochimica Acta, 2015, doi:10.1016/j.electacta.2015.10.066

A dual gold-copper microelectrode (diameter 25 μm) was fabricated to be employed in a scanning electrochemical microscopy (SECM) configuration, and was used in feedback mode to both modify (write) and analyze (read) a substrate. This write-and-read procedure was performed on a glassy carbon electrode on which azide groups were introduced by electrochemical reduction of a diazonium salt. The copper part of the microelectrode was used to electrogenerate Cu(I) that catalyzed a “click” reaction between azide moieties on the surface and dissolved ethynylferrocene. This created a pattern of ferrocene moieties on the surface that was analyzed with the gold part of the microelectrode.

2015-16

 

Redox- and pH-Responsive Nanogels Based on Thiolated Poly(aspartic acid)
Monday, 25 July 2016
Enikő Krisch, Léa Messager, Benjámin Gyarmati, Valérie Ravaine, and András Szilágyi Macromol. Mater. Eng. 2016, 301(3), 260–266 Nanogels loaded with fluorescent dextran as a model drug are...
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Wall slip across the jamming transition of soft thermoresponsive particles
Monday, 25 July 2016
Thibaut Divoux, Véronique Lapeyre, Valérie Ravaine, and Sébastien Manneville Phys. Rev. E 2015, 92, 060301(R) Flows of suspensions are often affected by wall slip, that is, the fluid velocity Vf...
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Differential Photoluminescent and Electrochemiluminescent Behavior for Resonance Energy Transfer Processes in Thermoresponsive Microgels
Monday, 25 July 2016
Florent Pinaud, Romain Millereux, Pierre Vialar-Trarieux, Bogdan Catargi, Sandra Pinet, Isabelle Gosse, Neso Sojic, Valérie Ravaine J. Phys. Chem. B, 2015, 119 (40), pp 12954–12961...
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One-Step Preparation of Bifunctionalized Surfaces by Bipolar Electrografting
Wednesday, 30 December 2015
L. Koefoed, K. Shimizu, S. U. Pedersen, K. Daasbjerg, A. Kuhn, and D. Zigah RSC Adv., 2015, DOI: 10.1039/c5ra20156j Bipolar electrochemistry (BPE) is widely used to trigger electrochemical reactions...
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Original Dual Microelectrode: Writing and Reading a local click reaction with Scanning Electrochemical Microscopy
Thursday, 05 November 2015
V. Badets, D. Duclos, D. Quinton, O. Fontaine, D. Zigah Electrochimica Acta, 2015, doi:10.1016/j.electacta.2015.10.066 A dual gold-copper microelectrode (diameter 25 μm) was fabricated to be...
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Electrogenerated Chemiluminescence of Cationic Triangulene Dyes: Crucial Influence of the Core Heteroatoms
Thursday, 05 November 2015
C. Adam, A. Wallabregue, H. Li, J. Gouin, R. Vanel, S. Grass, J. Bosson, L. Bouffier, J. Lacour and N. Sojic. Chem. Eur. J., 2015, 21, 19243-19249. Trianguleniums are fascinating conjugated...
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Solid-State Bipolar Electrochemistry: Polymer-Based Light-Emitting Electrochemical Cells
Thursday, 05 November 2015
S. Chen, G. Wantz, L. Bouffier and J. Gao. ChemElectroChem, 2016, 3, 392-398. We present solid-state, polymer-based, light-emitting electrochemical cells incorporating bipolar electrodes (BPEs)...
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Guiding pancreatic beta-Cells to target Electrodes in a whole-cell Biosensor for Diabetes
Friday, 25 September 2015
E. Pedraza, A. Karajić, M. Raoux, R. Perrier, A. Pirog, F. Lebreton, S. Arbault, J. Gaitan, S. Renaud, A. Kuhn, J. Lang Lab Chip, 2015, 15, 3880–3890 We are developing a cell-based bioelectronic...
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The EChemPen: A Guiding Hand To Learn Electrochemical Surface Modifications
Wednesday, 23 September 2015
M. Valetaud, G. Loget, J. Roche, N. Hüsken, Z. Fattah, V. Badets, O. Fontaine, D. Zigah. J. Chem. Educ., 2015, 92 (10), pp 1700–1704. The Electrochemical Pen (EChemPen) was developed as an...
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Bipolar Electrografting on the Inner Wall of Carbon Nanotubes
Wednesday, 23 September 2015
C. Kumsapaya, J. Limtrakul, A. Kuhn, D. Zigah, C. Warakulwit. ChemElectroChem, 2016, 3, 410-414. Vertically aligned carbon nanotubes were grown over the inner wall of the pores of an anodic aluminum...
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Single-Step Screening of the Potential Dependence of Metal Layer Morphologies Along Bipolar Electrodes
Monday, 07 September 2015
G. Tisserant, J. Gillion, J. Lannelongue, Z. Fattah, P. Garrigue, J. Roche, D. Zigah, B. Goudeau, A. Kuhn and L. Bouffier.  ChemElectroChem, 2016, 3, 387-391. The preparation of surface...
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Enantioselective Recognition of DOPA by mesoporous Platinum imprinted with Mandelic acid
Friday, 24 July 2015
T. Yutthalekha, C. Warakulwit, J. Limtrakul, A. Kuhn Electroanalysis, 2015, Special Issue Advanced Materials, in press Chiral imprinted mesoporous platinum was electrochemically synthesized in the...
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Bottom-up Generation of Miniaturized Coaxial Double Electrodes with tunable Porosity
Friday, 24 July 2015
A. Karajić, S. Reculusa, M. Heim, P. Garrigue, S. Ravaine, N. Mano, A. Kuhn Adv. Mater. Interfaces, 2015, in press We report the bottom-up design of a fully integrated and miniaturized...
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3D electrogenerated chemiluminescence: from surface-confined reactions to bulk emission
Thursday, 11 June 2015
M. Sentic, S. Arbault, L. Bouffier, D. Manojlovic, A. Kuhn and N. Sojic.   Chem. Sci., 2015, 6, 4433-4437.   Among luminescence techniques, electrogenerated chemiluminescence (ECL) provides...
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Synthesis of conducting asymmetric hydrogel particles showing autonomous motion
Thursday, 28 May 2015
A. Srinivasan, J. Roche, V. Ravaine and A. KuhnSoft Matter, 2015, 11, 3958-3962 In the present work, we introduce a new approach for the synthesis of asymmetric particles made from electrically...
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Shearforce Positioning of Nanoprobe Electrode Arrays for Scanning Electrochemical Microscopy Experiments
Tuesday, 12 May 2015
C. Adam, F. Kanoufi, N. Sojic and M. Etienne. Electrochim. Acta, 2015, in press. Shearforce detection was applied to the controlled positioning of nanotip arrays at air/solid and liquid/solid...
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Generation of Metal Composition Gradients by Means of Bipolar Electrodeposition
Wednesday, 18 March 2015
G. Tisserant, Z. Fattah, C. Ayela, J. Roche, B. Plano, D. Zigah, B. Goudeau, A. Kuhn and L. Bouffier.  Electrochim. Acta, 2015, 179, 276-281. Bipolar electrochemistry is an unconventional...
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Effects of 50 Hz Magnetic Fields on Gap Junctional Intercellular Communication in NIH3T3 Cells
Wednesday, 18 February 2015
Y. Percherancier, B. Goudeau, R. Charlet de Sauvage, F. Poulletier de Gannes, E. Haro, A. Hurtier, N. Sojic, I. Lagroye, S. Arbault, and B. Veyret Bioelectromagnetics, 2015, 36, 4, 287-293. The...
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Synthesis of Multivalent Silica Nanoparticles combining both Enthalpic and Entropic Patchiness
Friday, 16 January 2015
C. Hubert, C. Chomette, A. Désert, M. Sun, M. Treguer, S. Mornet, A. Perro, E. Duguet, S. Ravaine Faraday Discuss., 2015, 181, 139-146 Silica particles with a controlled number of entropic patches,...
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Linking Glucose Oxidation to Luminol-based Electrochemiluminescence using bipolar Electrochemistry
Wednesday, 10 December 2014
V. Eßmann, D. Jambrec, A. Kuhn, W. Schuhmann Electrochem. Comm. 2015, 50, 77–80. The range of potential analytes for bipolar electrochemistry can be significantly extended by modification of...
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