Université PSL



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Red blood cells decorated with functionalized core–shell magnetic nanoparticles: elucidation of the adsorption mechanism
Thanh Duc Mai, Fanny d’Orlye, Christine Ménager, Anne Varenne and Jean-Michel Siaugue
Chem. Comm. - -49 5393—95 - DOI: 10.1039/C3CC41513A - 2013
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
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
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
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
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
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
D. Quinton, A. Maringa, S. Griveau, T. Nyokong & F. Bedioui
Electrochemistry Communications - 31 :112-5 - https://doi.org/10.1002/elan.201300030 - 2013
Electrochemical DNA-biosensors : two-electrode set up well adapted for miniaturized devices
M. Lazerges, V. T. Tal, P. Bigey, D. Scherman & F. Bedioui
Sensors & Actuators - B 182 :510-513 - DOI:10.1016/j.snb.2013.02.098 - 2013
The proof of concept of a DNA-biosensor based on a two-electrode electrochemical setup and using a microelectrode as working electrode, well adapted for detection in microliter samples and miniaturization, is presented herein. A 23-base DNA-probe self-assembled monolayer was first formed onto a 50 μm-diameter gold surface. The microelectrode extremity was then immersed in a 50 μL DNA-target solution drop itself deposited onto a 2 mm-diameter gold counter electrode. Transduction occurs via long-range electron transfer, which is enhanced subsequently to hybridization, due to DNA-base π-stacking. Single mismatch detection of this first prototype was matched at room temperature in the nanomolar range without any optimization.
Electrografted nanostructured platforms for click chemistry
Cernat A., Griveau S., Martin S., Lacroix JC., Farcau M., Sandelescu R., Bedioui F.
Electrochemistry Communications - 23 :141-4 - DOI:10.1016/j.elecom.2012.07.014 - 2012
We report on the combination of nanosphere lithography, electrodeposition and click chemistry to produce nanostructured surfaces with improved number of anchored molecules. Our strategy was developed here for the immobilization of ferrocene at glassy carbon electrode, both used as models. The nanostructuration of the surface was obtained by adsorption of 900 nm-diameter polystyrene nanosphere followed either by electropolymerization of N-(10-azidodecyl)pyrrole or by electrografting of 4-azidobenzenediazonium. In the case of poly-N-(10-azidodecyl)pyrrole, the AFM analysis of the surface after electropolymerization and removal of the nanospheres show the formation of a patterned film with holes separated of ˜900 nm. In the case of 4-azidobenzenediazonium, the electrografting proceeds similarly to bare surfaces, but with a decrease of reduction peak intensity due to the partial coverage of the electrode surface with insulating nanospheres. For both modified surfaces, the immobilization of ferrocene by copper(I) catalyzed azide-alkyne cycloaddition was clearly evidenced by cyclic voltammetry. The evaluation of the surface coverage shows that the nanostructuration leads to larger specific area for the chemical anchorage of ferrocene. Finally this procedure produces versatile functionalization of conductive materials used in various applications.
Carbon nanotubes and metalloporphyrins and metallophthalocyanines-based materials for electroanalysis
Zagal JH., Griveau S., Santander-Nelli M., Gutierrez Granados S., Bedioui F.
J. Porph. Phthal. - 16 :713-40 - DOI:10.1142/S1088424612300054 - 2012
We discuss here the state of the art on hybrid materials made from single (SWCNT) or multi (MWCNT) walled carbon nanotubes and MN4 complexes such as metalloporphyrins and metallophthalocyanines. The hybrid materials have been characterized by several methods such as cyclic voltammetry (CV), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and scanning electrochemical microscropy (SECM). The materials are employed for electrocatalysis of reactions such as oxygen and hydrogen peroxide reduction, nitric oxide oxidation, oxidation of thiols and other pollutants.

19 publications.