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Characterization of home-made graphite/PDMS microband electrodes for amperometric detection in an original reusable glass-NOA®-PDMS electrophoretic microdevice
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - J.Gouyon F.d’Orlyé S.Griveau F.Bedioui A.Varenne
ELSEVIER - 329 135164 - https://dx.doi.org/10.1021/acs.langmuir.9b02031 - 2020
A new dismountable and reusable microchip for electrophoretic separation coupled to amperometric detection was developed. For this purpose, a new home made three-microbands electrode system was developed and microfabricated based on screen-printing for the inclusion of graphite/polydimethylsiloxane (C-PDMS) composite in microchannels down to 30 μm width. The composition of the composite as well as the fabrication methodology were optimized for an easy handling and an optimized electrochemical behavior. The electrochemical characterization of this composite material was first performed in bulk format (disc-shaped electrode, 6 mm diameter). It was then transposed to the micrometric scale for its integration in an original glass-NOA81®-PDMS microfluidic device allowing for reversible sealing. The microband electrodes were characterized by scanning electron microcopy and cyclic voltammetry, illustrating a good control of the microelectrode width. Then, the analytical performances of the C-PDMS composite microelectrodes were evaluated using Ru(NH3)63+ and FcMeOH as model electroactive molecules. The electrophoretic separation and quantitation of Ru(NH3)63+ were then performed in a background electrolyte made of hydrochloric acid and sodium chloride, leading to a LOD and a LOQ of 3.4 μmol L−1 and 11.3 μmol L−1, respectively. The re-openable NOA-based microdevice permits to regenerate the electrode surface by simply repositioning the microband on a new spot, allowing for robust analysis in a reusable system.
Hydrogel Matrix-Grafted Impedimetric Aptasensors for the Detection of Diclofenac
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - G. S. Kassahun, S. Griveau, S. Juillard, J. Champavert, A. Ringuedé, B. Bresson, Y. Tran, F. Bedioui, and C. Slim
Langmuir - 36(4) 827–836 - https://dx.doi.org/10.1021/acs.langmuir.9b02031 - 2020
Driven by the growing concern about the release of untreated emerging pollutants and the need for determining small amounts of these pollutants present in the environment, novel biosensors dedicated to molecular recognition are developed. We have designed biosensors using a novel class of grafted polymers, surface-attached hydrogel thin films, on conductive transducers as a biocompatible matrix for biomolecule immobilization. We showed that they can be dedicated to the molecular recognition of diclofenac (DCL). The immobilization of the aptamer onto surface-attached hydrogel thin films by covalent attachment provides a biodegradable shelter, providing the aptamer with excellent environments to preserve its active and functional structure while allowing the detection of DCL. The grafting of the aptamer is obtained using the formation of amide bonds via the activation of carboxylic acid groups of the poly(acrylic acid) hydrogel thin film. For improved sensitivity and higher stability of the sensor, a high density of the immobilized aptamer is enabled. The aptamer-modified electrode was then incubated with DCL solutions at different concentrations. The performances of the aptasensor were investigated by electrochemical impedance spectroscopy. The change in charge-transfer resistance was found to be linear with DCL concentration in the 30 pM to 1 μM range. The detection limit was calculated to be 0.02 nM. The improvement of the limit of detection can be mainly attributed to the three-dimensional environment of the hydrogel matrix which improves the grafting density of the aptamer and the affinity of the aptamer to DCL.
Physicochemical Characterization of Phthalocyanine-Functionalized Quantum Dots by Capillary Electrophoresis Coupled to a LED Fluorescence Detector
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Ramírez-García G, d'Orlyé F, Nyokong T, Bedioui F, Varenne A
Methods in Molecular Biology (Clifton, N.J.) - 2000 373-385 - DOI: 10.1007/978-1-4939-9516-5_23 - 2019
Capillary zone electrophoresis (CZE) complemented with Taylor Dispersion Analysis-CE (TDA-CE) was developed to physicochemically characterize phthalocyanine-capped core/shell/shell quantum dots (QDs) at various pH and ionic strengths. An LED-induced fluorescence detector was used to specifically detect the QDs. The electropherograms and taylorgrams allowed calculating the phthalocyanine-QDs (Pc-QDs) ζ-potential and size, respectively, and determining the experimental conditions for colloidal stability. This methodology allowed evidencing either a colloidal stability or an aggregation state according to the background electrolytes nature. The calculated ζ-potential values of Pc-QDs decreased when ionic strength increased, being well correlated with the aggregation of the nanoconjugates at elevated salt concentrations. For the same reason, the hydrodynamic diameter of Pc-QDs increased with increasing background electrolyte ionic strength. The use of electrokinetic methodologies has provided insights into the colloidal stability of the photosensitizer-functionalized QDs in physiologically relevant solutions and, thereby, its usefulness for improving their design and applications for photodynamic therapy.
VEGF (Vascular Endothelial Growth Factor) Functionalized Magnetic Beads in a Microfluidic Device to Improve the Angiogenic Balance in Preeclampsia
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Laura Trapiella-Alfonso, Lucile Alexandre, Camille Fraichard, Kelly Pons, Simon Dumas, Lucie Huart, Jean-François Gaucher, Marylise Hebert-Schuster, Jean Guibourdenche, Thierry Fournier, Michel Vidal, Isabelle Broutin
Hypertension - 74 145-153 - DOI: 10.1007/978-1-4939-9516-5_23 - 2019
Preeclampsia is a hypertensive pregnancy disease associated with a massive increase in sFlt-1 (soluble form of the vascular endothelial growth factor 1) in the maternal circulation, responsible for angiogenic imbalance and endothelial dysfunction. Pilot studies suggest that extracorporeal apheresis may reduce circulating sFlt-1 and prolong pregnancy. Nonspecific apheresis systems have potential adverse effects because of the capture of many other molecules. Our concept is based on a specific and competitive apheresis approach using VEGF (vascular endothelial growth factor) functionalized magnetic beads to capture sFlt-1 while releasing endogenous PlGF (placental growth factor) to restore a physiological angiogenic balance. Magnetic beads were functionalized with VEGF to capture sFlt-1. Experiments were performed using PBS, conditioned media from human trophoblastic cells, and human plasma. The proof of concept was validated in dynamic conditions in a microfluidic device as an approach mimicking real apheresis. Magnetic beads were functionalized with VEGF and characterized to evaluate their surface ligand density and recognition capabilities. VEGF-coated magnetic beads proved to be an efficient support in capturing sFlt-1 and releasing PlGF. In static conditions, sFlt-1 concentration decreased by 33±13%, whereas PlGF concentration increased by 27±10%. In dynamic conditions, the performances were improved, with 40% reduction of sFlt-1 and up to 2-fold increase of free PlGF. The sFlt-1/PlGF ratio was reduced by 63% in the plasma of preeclamptic patients. Apheresis was also associated with VEGF release. A ligand-based approach using VEGF-coated beads is an effective approach to the capture of sFlt-1 and the release of endogenous PlGF. It offers new perspectives for the treatment of preeclampsia.
Advances on non-invasive physically triggered nucleic acid delivery from nanocarriers
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Hai Doan Do, Brice Martin Couillaud, Bich-Thuy Doan, Yohann Corvis, Nathalie Mignet
Review - 138 3-17 - DOI: 10.1016/j.addr.2018.10.006 - 2018
Nucleic acids (NAs) have been considered as promising therapeutic agents for various types of diseases. However, their clinical applications still face many limitations due to their charge, high molecular weight, instability in biological environment and low levels of transfection. To overcome these drawbacks, therapeutic NAs should be carried in a stable nanocarrier, which can be viral or non-viral vectors, and released at specific target site. Various controllable gene release strategies are currently being evaluated with interesting results. Endogenous stimuli-responsive systems, for example pH-, redox reaction-, enzymatic-triggered approaches have been widely studied based on the physiological differences between pathological and normal tissues. Meanwhile, exogenous triggered release strategies require the use of externally non-invasive physical triggering signals such as light, heat, magnetic field and ultrasound. Compared to internal triggered strategies, external triggered gene release is time and site specifically controllable through active management of outside stimuli. The signal induces changes in the stability of the delivery system or some specific reactions which lead to endosomal escape and/or gene release. In the present review, the mechanisms and examples of exogenous triggered gene release approaches are detailed. Challenges and perspectives of such gene delivery systems are also discussed.
Clickable-Zwitterionic Copolymer Capped-Quantum Dots for in Vivo Fluorescence Tumor Imaging
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Laura Trapiella-Alfonso, Thomas Pons , Nicolas Lequeux , Ludovic Leleu, Juliette Grimaldi, Mariana Tasso, Edward Oujagir, Johanne Seguin, Fanny d'Orlyé, Christian Girard, Bich-Thuy Doan,
ACS Appl. Mater. Interfaces - 10-20 17107–17116 - doi.org/10.1021/acsami.8b04708 - 2018
In the last decades, fluorescent quantum dots (QDs) have appeared as high-performance biological fluorescent nanoprobes and have been explored for a variety of biomedical optical imaging applications. However, many central challenges still exist concerning the control of the surface chemistry to ensure high biocompatibility, low toxicity, antifouling, and specific active targeting properties. Regarding in vivo applications, circulation time and clearance of the nanoprobe are also key parameters to control the design and characterization of new optical imaging agents. Herein, the complete design and characterization of a peptide-near-infrared-QD-based nanoprobe for biomedical optical imaging is presented from the synthesis of the QDs and the zwitterionic-azide copolymer ligand, enabling a bio-orthogonal coupling, till the final in vivo test through all the characterization steps. The developed nanoprobes show high fluorescence emission, controlled grafting rate, low toxicity, in vitro active specific targeting, and in vivo long circulating blood time. This is, to our knowledge, the first report characterizing the in vivo circulation kinetics and tumor accumulation of targeted zwitterionic QDs.
The enzyme-like catalytic activity of cerium oxide nanoparticles and its dependency on Ce3+ surface area concentration
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - V. Baldim, F. Bedioui, N. Mignet, I. Margaillc and J.-F. Berret
ACS Appl. Mater. Interfaces - 10 6971-6980 - doi.org/10.1039/C8NR00325D - 2018
Cerium oxide nanoparticles are known to catalyze the decomposition of reactive oxygen species such as the superoxide radical and hydrogen peroxide. Herein, we examine the superoxide dismutase (SOD) and catalase (CAT) mimetic catalytic activities of nanoceria and demonstrate the existence of generic behaviors. For particles of sizes 4.5, 7.8, 23 and 28 nm, the SOD and CAT catalytic activities exhibit the characteristic shape of a Langmuir isotherm as a function of cerium concentration. The results show that the catalytic effects are enhanced for smaller particles and for the particles with the largest Ce3+ fraction. The SOD-like activity obtained from the different samples is found to superimpose on a single master curve using the Ce3+ surface area concentration as a new variable, indicating the existence of particle independent redox mechanisms. For the CAT assays, the adsorption of H2O2 molecules at the particle surface modulates the efficacy of the decomposition process and must be taken into account. We design an amperometry-based experiment to evaluate the H2O2 adsorption at nanoceria surfaces, leading to the renormalization of the particle specific area. Depending on the particle type the amount of adsorbed H2O2 molecules varies from 2 to 20 nm−2. The proposed scalings are predictive and allow the determination of the SOD and CAT catalytic properties of cerium oxide solely from physicochemical features.
The enzyme-like catalytic activity of cerium oxide nanoparticles and its dependency on Ce3+ surface area concentration
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Oliveira R, Sella C, Souprayen C, Ait-Yahiatene E, Slim C, Griveau S, Thouin L, Bedioui F
Electrochimica Acta - 286 365-373 - DOI10.1016/j.electacta.2018.07.158 - 2018
The detection of reactive oxygen and nitrogen species is of utmost importance in several pathological situations. Indeed, these reactive species are biomarkers of oxidative stress and their real-time monitoring is crucial to adapt medical treatments. We report here on the electrochemical detection of nitric oxide (NO center dot) in the presence of hydrogen peroxide (H2O2). The detection was performed by using different sensing microdevices involving either static solutions in wells or flowing solutions in microfluidic channels. Furthermore, an original strategy was proposed to further enhance the selectivity of NO center dot detection at Pt/poly(eugenol) modified platinum electrodes by designing a dual-electrode microfluidic device based on a pre-electrolysis of interfering species including H2O2 at an upstream electrode prior to NO center dot detection. (C) 2018 Elsevier Ltd. All rights reserved.
Electrochemical Behavior of Stainless Steels for Sudomotor Dysfunction Applications
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Fethi Bedioui Abdulghani Ismail Sophie Griveau
ELSEVIER - 12 42-50 - DOI : 10.1016/j.coelec.2018.04.014 - 2018
Electrochemical detection of nitric oxide using different electrode materials and strategies exploded after the discovery of nitric oxide as important biological messenger. S-nitrosothiols (RSNOs), which result from interaction of NO with peptides and proteins, were shown to be important pools of NO that interfere in different physiological and pathological conditions. This lead to development of several decomposition methods to detect RSNOs electrochemically. This mini-review summarizes the beginning and the current investigations in electrochemical methods to detect NO and RSNOs. Indeed, it describes the latest trends to detect NO and RSNO using microfluidic technologies coupled to electrochemistry and discuss the future of NO and RSNOs detection.
Integrated microfluidic device for the separation, decomposition and detection of low molecular weight S-nitrosothiols
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Gerson F Duarte-Junior, Abdulghani Ismail, Sophie Griveau, Fanny d'Orlyé , José Alberto Fracassi da Silva, Wendell K T Coltro, Fethi Bedioui , Anne Varenne
Analyst - 144(1) 180-185 - doi: 10.1039/c8an00757h - 2018
S-nitrosothiols (RSNOs) are very important biomolecules that play crucial roles in many physiological and physiopathological processes. They act as NO-donors and are candidates for future medicines. Their identification and quantitation are therefore important for biomedical applications. One, two or more RSNOs can then be combined to design a drug and therefore, the quantification of each is important to establish an acceptable quality control process. Till date, miniaturized devices have been used to detect RSNOs based on their total quantitation without a preceding separation step. This study reports on an original and integrated microdevice allowing for the successive electrokinetic separation of low molecular weight RSNOs, their decomposition under metal catalysis, and their quantitation by amperometric detection of the produced nitrite in the end-channel arrangement, leading to their quantitation in a single run. For this purpose, a commercial SU-8/Pyrex microfluidic system was coupled to a portable and wireless potentiostat. Different operating and running parameters were optimized to achieve the best analytical data, allowing for an LOD equal to 20 μM. The simultaneous separation of S-nitrosoglutathione and S-nitrosocysteine was successfully obtained within 75 s. The proposed methodology using SU-8/Pyrex microfluidic devices opens new possibilities to investigate future drug candidates for NO-donors.
In vitro distinction between proinflammatory and antiinflammatory macrophages with gadolinium-liposomes and ultrasmall superparamagnetic iron oxide particles at 3.0T
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Wassef Khaled, Joao Piraquive , Benjamin Leporq , Jing Hong Wan , Simon A Lambert 1, Nathalie Mignet , Bich-Thuy Doan , Sophie Lotersztajn , Philippe Garteiser , Bernard E Van Beers
J Magn Reson Imaging - 49(4) 1166-1173 - doi: 10.1002/jmri.26331 - 2018
Background: Inflammation involves a heterogeneous macrophage population, for which there is no readily available MR assessment method.

Purpose: To assess the feasibility of distinguishing proinflammatory M1 and antiinflammatory M2 macrophages at MRI enhanced with gadolinium liposomes or ultrasmall superparamagnetic iron oxide particles.

Study type: In vitro.

Specimen: We employed cultured RAW macrophages. M0 macrophages were polarized with lipopolysaccharide (LPS) or interleukin-4 (IL-4), resulting in M1 or M2 macrophages. The macrophages were incubated with gadolinium (±rhodamine) liposomes or iron oxide particles and cell pellets were prepared for MRI.

Field strength/sequence: Transverse relaxation rates and quantitative susceptibility were obtained at 3.0T with multiecho turbo spin echo and spoiled gradient echo sequences.

Assessment: MRI results were compared with confocal microscopy, flow cytometry, and expression of endocytosis, M1 and M2 genes.

Statistical tests: Mann-Whitney and Kruskal-Wallis tests were performed.

Results: Higher transverse relaxation rates and susceptibility were observed in M1 than in M2 and M0 macrophages (P < 0.01 both with liposomes and USPIO) and significantly different susceptibility in M2 and M0 macrophages (P < 0.01 both with liposomes and USPIO). These MRI results were confirmed at confocal microscopy and flow cytometry. LPS macrophages displayed M1 gene expression, whereas IL-4 macrophages showed M2 polarization and lower endocytosis gene expression rates.

Data conclusion: These in vitro results show that it is feasible to distinguish between proinflammatory M1 and antiinflammatory M2 macrophages according to their level of contrast agent uptake at MRI.

Level of evidence: 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:1166-1173.

Keywords: gadolinium liposomes; macrophage imaging; macrophage phagocytosis; magnetic resonance imaging of inflammation; quantitative susceptibility mapping; ultrasmall iron oxide particles.
In Vivo Evaluation of Magnetic Targeting in Mice Colon Tumors with Ultra-Magnetic Liposomes Monitored by MRI
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Thébault C, Ramniceanu G, Michel A, Beauvineau C, Girard C, Seguin J, Mignet N, Ménager C, Doan BT
Molecular Imaging and Biology - 21(2) 269-278 - DOI: 10.1007/s11307-018-1238-3 - 2018
PURPOSE:The development of theranostic nanocarriers as an innovative therapy against cancer has been improved by targeting properties in order to optimize the drug delivery to safely achieve its desired therapeutic effect. The aim of this paper is to evaluate the magnetic targeting (MT) efficiency of ultra-magnetic liposomes (UML) into CT26 murine colon tumor by magnetic resonance imaging (MRI). PROCEDURES:Dynamic susceptibility contrast MRI was applied to assess the bloodstream circulation time. A novel semi-quantitative method called %I0.25, based on the intensity distribution in T2*-weighted MRI images was developed to compare the accumulation of T2 contrast agent in tumors with or without MT. To evaluate the efficiency of magnetic targeting, the percentage of pixels under the intensity value I0.25 (I0.25 = 0.25(Imax - Imin)) was calculated on the intensity distribution histogram. RESULTS:This innovative method of processing MRI images showed the MT efficiency by a %I0.25 that was significantly higher in tumors using MT compared to passive accumulation, from 15.3 to 28.6 %. This methodology was validated by ex vivo methods with an iron concentration that is 3-fold higher in tumors using MT. CONCLUSIONS:We have developed a method that allows a semi-quantitative evaluation of targeting efficiency in tumors, which could be applied to different T2 contrast agents.
Electrochemical behavior of electrode materials (nickel and stainless steels) for sudomotor dysfunction applications : a review
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Fethi Bedioui Virginie Lair Sophie Griveau Armelle Ringuedé José Zagal Michel Cassir
Chimie analytique - - DOI : 10.1002/elan.201800439 - 2018
This is an overview of the electrochemical characterization of nickel and stainless steel as electrodes in medical devices for the early diagnosis of small fiber neuropathy that originates from type-2 diabetes or cystic fibrosis. The electrical current responses obtained during the clinical tests are related to the amount of chloride present on the sweat. Stainless steel electrodes are now used to replace nickel because this later not only presents problems with chloride sensitivity but its contact with skin can cause possible allergic reactions for some patients. For the above reasons, several types of stainless steels were studied. It was shown that some of them perform well and have lower costs than Ni electrodes. We discuss the state of the art of the electrochemical studies conducted with nickel and steels under physiological or biomimetic conditions and discuss the advantages of a particular steel over the others depending on the conditions, especially chloride concentration.
AGuIX ® from bench to bedside-Transfer of an ultrasmall theranostic gadolinium-based nanoparticle to clinical medicine
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - François Lux, Vu Long Tran, Eloïse Thomas, Sandrine Dufort , Fabien Rossetti , Matteo Martini, Charles Truillet, Tristan Doussineau, Guillaume Bort, Franck Denat, Frédéric Boschetti, Goran Angelovski, Alexandre Detappe, Yannic
Br J Radiol - 92(1093) 20180365 - doi: 10.1259/bjr.20180365 - 2018
AGuIX® are sub-5 nm nanoparticles made of a polysiloxane matrix and gadolinium chelates. This nanoparticle has been recently accepted in clinical trials in association with radiotherapy. This review will summarize the principal preclinical results that have led to first in man administration. No evidence of toxicity has been observed during regulatory toxicity tests on two animal species (rodents and monkeys). Biodistributions on different animal models have shown passive uptake in tumours due to enhanced permeability and retention effect combined with renal elimination of the nanoparticles after intravenous administration. High radiosensitizing effect has been observed with different types of irradiations in vitro and in vivo on a large number of cancer types (brain, lung, melanoma, head and neck…). The review concludes with the second generation of AGuIX nanoparticles and the first preliminary results on human.
Binding parameters between an aptamer and its target by frontal analysis continuous microchip electrophoresis (FACMCE): a comprehensive study of buffer composition and thermal treatment in the case of lysozyme
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - M. Girardot, H-Y. Li, S. Descroix, A. Varenne
Chromatographia - 76 305-312 - DOI: 10.1007/s10337-012-2346-x - 2013
An original and simple methodology based on microchip electrophoresis (MCE) in a continuous frontal analysis mode (named frontal analysis continuous microchip electrophoresis, FACMCE) was developed for the simultaneous determination of the binding parameters, i.e. ligand-site dissociation constant (k(d)) and number of binding sites on the substrate (n). This simultaneous determination was exemplified with the interaction between an aptamer and its target. The selected target is a strongly basic protein, lysozyme, as its quantification is of great interest due to its antimicrobial and allergenic properties. A glass microdevice equipped with a fluorescence detection system was coated with hydroxypropylcellulose, reducing the electroosmotic flow and adsorption onto the channel walls. This microdevice allowed the continuous electrokinetic injection of a mixture of fluorescently labelled aptamer and non-labelled lysozyme. By determining the concentration of the free fluorescently labelled aptamer thanks to its corresponding plateau height, mathematical linearization methods allowed to determine a k(d) value of 48.4±8.0 nM, consistent with reported results (31 nM), while the average number of binding sites n on lysozyme, never determined before, was 0.16±0.03. These results seem to indicate that the buffer nature and the SELEX process should influence the number and affinity of the binding sites. In parallel it has been shown that the binding between lysozyme and its aptamer presents two sites of different binding affinities.
Aptamer-conjugated nanoparticles: Preservation of targeting functionality demonstrated by microchip electrophoresis in frontal mode
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - M. Girardot, F. d'Orlye, S. Descroix, A. Varenne.
Analytical Biochemistry - 435 150-152 - PMID:23333271 - 2013
Aptamer-conjugated nanoparticles (Apt-NPs) are increasingly being developed for biomedical purposes and especially for diagnosis and therapy. However, there is no quantitative study of the targeting functionality of such grafted aptamers compared with free aptamers. Thus, we report the first determination of binding parameters for Apt-NP/target complexes, thanks to a continuous frontal analysis in a microchip electrophoresis format (named FACMCE), based on a methodology previously developed by our group. As a model system, the targeting ability of a lysozyme-binding aptamer conjugated to fluorescent maghemite nanoparticles was evaluated and showed evidence that the conjugation does not alter the affinity of this aptamer.
Electrokinetic characterization of superparamagnetic nanoparticle–aptamer conjugates: design of new highly specific probes for miniaturized molecular diagnostics
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - M. Girardot, F. d'Orlye, A. Varenne
Anal. Bioanal. Chem - 406(4) :1089-98 - DOI:10.1007/s00216-013-7265-7 - 2013
With the view of designing new nanoparticle (NP)-aptamer conjugates and proving their suitability as biorecognition tools for miniaturized molecular diagnostics, new maghemite-silica core-shell NP-aptamer conjugates were characterized for the first time in terms of grafting rate and colloidal stability under electrophoretic conditions using capillary electrophoresis. After the grafting rate (on the order of six to 50) of the lysozyme-binding aptamer had been estimated, the electrophoretic stability and peak dispersion of the resulting oligonucleotide-NP conjugates were estimated so as to determine the optimal separation conditions in terms of buffer pH, ionic strength and nature, as well as temperature and electric field strength. The effective surface charge density of the NPs was close to zero for pH lower than 5, which led to some aggregation. The NPs were stable in the pH range from 5 to 9, and an increase in electrophoretic mobility was evidenced with increasing pH. Colloidal stability was preserved at physiological pH for both non-grafted NPs and grafted NPs in the 10-100 mM ionic strength range and in the 15-60 °C temperature range. A strong influence of the nature of the buffer counterion on NP electrophoretic mobility and peak dispersion was evidenced, thus indicating some interactions between buffer components and NP-aptamer conjugates. Whereas an electric field effect (50-900 V cm(-1)) on NP electrophoretic mobility was evidenced, probably linked to counterion dissociation, temperature seems to have an appreciable effect on the zeta potential and aptamer configuration as well. This information is crucial for estimating the potentialities of such biorecognition tools in electrophoretic systems.
Red blood celles decorated with functionalized core-shell magnetic nanoparticles : elucidation of the adsorption mechanism
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - T. D. Mai, F. D’Orlyé, C. Menager, A. Varenne, M. Siaugue
Chem. Comm. - 49(47) :5393-5 - DOI:10.1039/c3cc41513a. - 2013
The decoration of red blood cells (RBCs) with aminated and carboxylated core-shell magnetic nanoparticles (CSMNs) was studied and elucidated. It was demonstrated that only aminated CSMNs could decorate the RBCs and their adsorption interaction is mainly ruled by electrostatic attraction between the positively charged amino groups on CSMNs and the abundant sialic acid groups on the outer surface of RBCs.
Surface functionalization of COC microfluidic materials by plasma and click chemistry processes
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - Y. Ladner, F. D’orlye, C. Perrard, B. Da Silva, C. Guyon, M. Tatoulian, S. Griveau, F. Bedioui & A. Varenne
Plasma Process - 10(11) :959-69 - DOI:10.1002/ppap.201300066 - 2013
A robust method for COC surfaces functionalization was developed for the first time by plasma polymerization. 1-bromopropane in the vapor phase allowed the formation of a brominated deposit on COC surfaces, which stability, homogeneity and chemical nature were evaluated for different experimental conditions. The analysis of vapor phase was achieved by mass spectrometry to control brominated precursor fragmentation. Following nucleophilic exchange in the presence of NaN3 to convert the brominated surface to azide-bearing surface, these modified COC were further functionalized with a fluorescent alkyne, via the copper-catalyzed azide–alkyne cycloaddition reaction, i.e. “click” reaction. Surface modifications were characterized by water contact angle measurement, ellipsometry, electrochemical microscopy, XPS, IR and fluorescence microscopy. This new process was proved to be efficient and stable in time up to 7 days.
Horseradish peroxidase nanopatterned electrodes by click chemistry: Application to the electrochemical detection of paracetamol
Laboratoire Synthèse Electrochimie Imagerie et Systèmes Analytiques - D. Quinton, A. Maringa, S. Griveau, T. Nyokong & F. Bedioui
Electrochemistry Communications - 31 :112-5 - https://doi.org/10.1002/elan.201300030 - 2013

33 publications.