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

 

Clogging by sieving in microchannels: application to the detection of contaminants in colloidal suspensions
Friday, 08 April 2016
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...
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Readily Prepared Dynamic Hydrogels by Combining Phenyl Boronic Acid- and Maltose-Modified Anionic Polysaccharides at Neutral pH
Friday, 19 December 2014
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...
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Impact of Electrostatics on the Adsorption of Microgels at the Interface of Pickering Emulsions
Friday, 19 December 2014
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...
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Wireless Electrosampling of Heavy Metals for Stripping Analysis with Bismuth-Based Janus Particles
Wednesday, 19 November 2014
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...
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Wireless powering of e-swimmers
Tuesday, 21 October 2014
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...
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Stimuli-responsive microgels for electrochemiluminescence amplification
Tuesday, 07 October 2014
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...
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Physico-chemical Milling for controlled Size Reduction of Metal Beads
Thursday, 28 August 2014
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...
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Asymmetric Modification of TiO2 Nanofibers with Gold by Electric-Field-Assisted Photochemistry
Thursday, 31 July 2014
M. Ongaro, J. Roche, A. Kuhn, P. UgoChem. Electro. Chem. 2014, 2048-2051 We present a new procedure for the site-specific deposition of metal on semiconductor nanofibers (NF). The semiconductor NFs...
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Electrochemiluminescent Swimmers for Dynamic Enzymatic Sensing
Monday, 30 June 2014
M. Sentic, S. Arbault, B. Goudeau, D. Manojlovic, A. Kuhn, L. Bouffier, N. SojicChem. Commun. 2014, 50, 10202-10205. An electrochemiluminescent (ECL) swimmer driven by bipolar electrochemistry is...
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Monitoring Electrochemically the Early Events of Hydrogen peroxide Production by Mitochondria
Thursday, 22 May 2014
E. Suraniti, S. Ben-Amor, P. Landry, M. Rigoulet, E. Fontaine, S. Bottari, A. Devin, N. Sojic, N. Mano, S. ArbaultAngew. Chem. Int. Ed. 2014, 126, 6773-6776.Mitochondria consume oxygen at the...
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Electropolymerization of Polypyrrole by Bipolar Electrochemistry in an Ionic Liquid
Tuesday, 13 May 2014
S. Kong, O. Fontaine, J. Roche, L. Bouffier, A. Kuhn, D. ZigahLangmuir 2014, 30, 2973−2976 Bipolar electrochemistry has been recently explored for the modification of conducting micro- and...
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Adsorption of Microgels at an Oil–Water Interface: Correlation between Packing and 2D Elasticity
Friday, 25 April 2014
F. Pinaud, K. Geisel, P. Massé, B. Catargi, L. Isa, W. Richtering, V. Ravaine, V. SchmittSoft Matter, 2014, in press. The aim of this paper is to determine how microgels adsorb at a model...
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Imaging Redox Activity at Bipolar Electrodes by Indirect Fluorescence Modulation
Friday, 21 March 2014
Bouffier L., Doneux T., Goudeau B., Kuhn A.Anal. Chem. 2014, 86(8) 3708-3711. Bipolar electrochemistry (BPE) is nowadays well-known but relatively underexploited and still considered as...
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Site-Selective Synthesis of Janus-type Metal-Organic Framework Composites
Thursday, 06 March 2014
Yadnum S., Roche J., Lebraud E., Négrier P., Garrigue P., Bradshaw D., Warakulwit C., Limtrakul J., Kuhn A. Angew. Chem. Int. Ed. 2014, 126, 4082-4086. Herein, bipolar electrochemistry is applied in...
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Mapping the Electrogenerated Chemiluminescence Reactivity in Space: Mechanistic Insight into Model Systems Used in Immunoassays
Monday, 03 March 2014
Sentic, M., Milutinovic, M., Kanoufi, F., Manojlovic, D., Arbault S., Sojic, N.Chem. Sci. 2014, 5, 2568-2572. The remarkable characteristics of electrogenerated chemiluminescence (ECL) as a readout...
Enantioselective Recognition at Mesoporous Chiral Metal Surfaces
Wednesday, 19 February 2014
Wattanakit C., Bon Saint-Côme Y., Lapeyre V., Bopp P., Heim M., Yadnum S., Nokbin S., Warakulwit C., Limtrakul J., Kuhn A.Nature Comm. 2014, 5, article 3325. Chirality is widespread in natural...
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Straight-forward Synthesis of Ringed Particles
Thursday, 23 January 2014
Roche J., Loget G., Zigah D., Fattah Z., Goudeau B., Arbault S., Bouffier L., Kuhn A.Chem. Sci. 2014, 5, 1961-1966 Particles with sophisticated surface patterns have many potential applications...
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Impact of pNIPAM Microgel Size on their Ability to stabilize Pickering Emulsions
Wednesday, 22 January 2014
Destribats M., Lapeyre V., Sellier E., Varga I., Ravaine V., Schmitt V.Langmuir 2014, 30, 1768-1777. We study the influence of the particle size on the ability of poly(N-isoprolylacrylamide)...
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Asymmetrical Modification of Carbon Microfibers by Bipolar Electrochemistry in Acetonitrile
Friday, 10 January 2014
Ongaro M., Gambirasi A., Favaro M., Kuhn A., Ugo P.Electrochim. Acta 2014, 116, 421. This contribution presents the asymmetrical modification of carbon microfibers (CMF) with gold and polythiophene...
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Thiol-ene Clickable Hyaluronans: from Macro- to Nanogel
Wednesday, 25 December 2013
Hachet E., Sereni N., Pignot-Paintrand I., Ravaine V., Szarpak-Jankowska A., Auzély-Velty R.J. Coll. Interface Sci. 2014, 419, 52-55. The fabrication of hyaluronic acid (HA) nanogels using a...
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Enhanced Detection of Hydrogen Peroxide with Platinized Microelectrode Arrays for Analyses of Mitochondria Activities
Sunday, 01 December 2013
Ben-Amor S., Vanhove E., Sékli Belaïdi F., Charlot S., Colin D., Rigoulet M., Devin A., Sojic N., Launay J., Temple-Boyer P., Arbault S. Electrochimica Acta 2014, ASAP article Black...
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Electrochemical Transduction of DNA Hybridization at Modified Electrodes by using an Electroactive Pyridoacridone Intercalator
Thursday, 12 September 2013
Bouffier L., Wang B. S., Roget A., Livache T., Demeunynck M., Mailley P.Anal. Bioanal. Chem. 2014, 406(4), 1163-1172. A synthetic redox probe structurally related to natural pyridoacridones was...
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Optical Microwell Array for Large Scale Studies of Single Mitochondria Metabolic Responses
Sunday, 28 July 2013
Vajrala V. S., Suraniti E., Garrigue P., Goudeau B., Rigoulet M., Devin A., Sojic N., Arbault S.Anal. Bioanal. Chem. 2014, 406, 931-941. Forefront Paper Microsystems based on microwell arrays have...
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Lighting up Redox Propulsion with Luminol Electrogenerated Chemiluminescence
Monday, 08 July 2013
Bouffier L., Zigah D., Adam C., Sentic M., Fattah Z., Manojlovic D., Kuhn A., Sojic N.ChemElectroChem 2014, 1(1), 95-98. A blue-light-emitting swimmer driven by bipolar electrochemistry is reported...
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