Didier Lairez

Didier Lairez
Atomic Energy and Alternative Energies Commission | CEA

About

91
Publications
14,709
Reads
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2,526
Citations
Additional affiliations
January 2017 - present
Atomic Energy and Alternative Energies Commission
Position
  • Researcher
September 1993 - present
Atomic Energy and Alternative Energies Commission
Position
  • Researcher
January 1991 - September 1993
Atomic Energy and Alternative Energies Commission
Position
  • Researcher

Publications

Publications (91)
Preprint
Full-text available
Even today, the concept of entropy is perceived by many as quite obscure. The main difficulty is analyzed as being fundamentally due to the subjectivity and anthropocentrism of the concept that prevent us to have a sufficient distance to embrace it. However, it is pointed out that the lack of coherence of certain presentations or certain preconceiv...
Article
Full-text available
When a lipid membrane approaches a material/nanomaterial, nonspecific adhesion may occur. The interactions responsible for nonspecific adhesion can either preserve the membrane integrity or lead to its disruption. Despite the importance of the phenomenon, there is still a lack of clear understanding of how and why nonspecific adhesion may originate...
Article
Full-text available
The myelin sheath—a multi-double-bilayer membrane wrapped around axons—is an essential part of the nervous system which enables rapid signal conduction. Damage of this complex membrane system results in demyelinating diseases such as multiple sclerosis (MS). The process in which myelin is generated in vivo is called myelination. In our study, we in...
Article
It remains a great experimental challenge to obtain quantitative information on the polyelectrolyte (PE) behavior confined in charged nanoporous materials. Here, we propose an original approach using transverse streaming potential measurements (TSPMs), an efficient technique providing information on the electrical surface properties of nanoporous m...
Article
The exact resolution function of the transfer vector for the HERMÈS reflectometer at the Laboratoire Léon Brillouin is calculated as an example of a neutron time-of-flight spectrometer with a double-disk chopper. The calculation accounts for the wavelength distribution of the incident beam, the tilt of the chopper axis, collimation and gravity, wit...
Article
The binding of imidazolium salts to cucurbit[8]uril, CB[8], triggers a step-wise self-assembly process with semiflexible polymer chains and crystalline nanostructures as early- and late-stage species, respectively. In such a process, which involves the crystallization of the host–guest complexes, the guest plays a critical role in directing self-as...
Preprint
Full-text available
The exact resolution function in transfer vector for the reflectometer HERM\`ES at Laboratoire L\'eon Brillouin is calculated as an example of neutron time-of-fligh spectrometer with double-disk chopper. Calculation accounts for wavelength distribution of the incident beam, tilt of the chopper axis, collimation and gravity, without approximation of...
Article
Full-text available
During evaporative drying of a colloidal dispersion, the structural behavior at the air-dispersion interface is of particular relevance to the understanding of the consolidation mechanism and the final structural and mechanical properties of the porous media. The drying interface constitutes the region of initial drying stress that, when accumulate...
Article
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Nanoparticles (NPs) homogeneously covered with polymer chains or with chains of two different polymers segregated in distinct domains (“Janus” particles) possess remarkable features. Their unique colloidal properties can be finely tuned by the grafted polymers while the characteristics of the nano-core remain unaffected. Herein, a simple and robust...
Article
The formation of supported lipid bilayers (SLB) on hydrophilic substrates through the method of unilamelar vesicle fusion is used routinely in a wide range of biophysical studies. In an effort to control and better understand the fusion process on the substrate, many experimental studies employing different techniques have been devoted to the eluci...
Article
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Ionic Liquids (ILs) are a specific class of molecular electrolytes characterized by the total absence of co-solvent. Due to their remarkable chemical and electrochemical stability, they are prime candidates for the development of safe and sustainable energy storage systems. The competition between electrostatic and van der Waals interactions leads...
Article
As opposed to piezo-ceramics (i.e PZT), flexibility and robustness characterize piezoelectric polymers. The main advantage of a piezoelectric polymer, such as Poly (vinylidene fluoride) (PVDF), is an electric power generation under large reversible elastic deformation. Starting from polarized PVDF, we have shown that, despite the fact that irradiat...
Article
Full-text available
The transport of molecules in confined media is subject to entropic barriers. So theoretically, asymmetry of the confinement length may lead to molecular ratchets with entropy as the only driving force for the biased transport. We address experimentally this question by performing alternative ionic current measurements on electrolytes confined in n...
Article
Full-text available
Conical nanopores can theoretically work as molecular funnel based on an entropic ratchet mechanism. This may allow to rectify ionic current in case anions and cations widely differ in size. We address experimentally this question by performing cyclic voltammetry on electrically neutral conical nanopores ("track-etched" membranes at the isoelectric...
Article
Phenol-functionalized MWCNTs were prepared by specially synthesized "wet chemistry" process. TEM images revealed that the produced carbon nanotubes are of high purity having diameter from 20 to 45. nm and length 2-3. μm. In order to optimize the utilization of MWCNTs for the preparation of mixed matrix composite materials a thorough characterizatio...
Article
To study the impact of the size and the structure of the nano-assembly on the drug/particle association, determining the intrinsic partition coefficient, in order to better master the encapsulation and release properties of the carrier. An experimental methodology is proposed to characterize the drug/nanoparticle association by mean of a partition...
Article
Full-text available
The effects of the thermoelastic and piezoelectric strain exerted by an active polymer matrix on a Ni nanowire (NW) are studied at the nanoscale by measuring the inverse magnetostriction of single-contacted Ni NWs. The reorientation of the magnetization is measured by anisotropic magnetoresitance. In the absence of strain, the Ni NW exhibits a typi...
Article
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Abstract In a cylindrical magnetic nanowire, a magnetic domain wall (DW) can move along the wire when an applied magnetic field or a spin-polarized current is applied. We show that in a magnetic device composed of two conical nanowires connected by a nanosized constriction, a DW can be trapped and detrapped. The magnetoreistance and the relaxation...
Article
Herein we report the photocontrol of the CB[8] mediated supramolecular polymerization of azobenzene-containing monomers. The CB[8] polymers have been characterized both in solution and in the solid state. These host-guest complexes can be reversibly switched between high thermostable photostationary states. Moreo...
Article
Full-text available
We address the problem of antimicrobial peptides that create pores in lipid bilayers, focusing on voltage-temperature dependence of pore opening. Two novel experiments (voltage clamp with alamethicin as an emblematic representative of these peptides and neutron reflectivity of lipid monolayer at solid-water interface under electric field) serve to...
Article
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We report circular dichroism measurements on the helix-coil transition of poly(L-glutamic acid) in solution with polyethylene glycol (PEG) as a crowding agent. The PEG solutions have been characterized by small angle neutron scattering and are well described by the picture of a network of mesh size ξ, usual for semi-dilute chains in good solvent. W...
Article
The optical properties of a series of gold nanoparticles (D ≈ 2.3–8 nm) grafted with a stabilizing polymer with a wide range of chain lengths (Mw ≈ 6.5K–29.5K) have been studied quantitatively in different dielectric solvents. Mie–Drude dipolar theory was applied to model the localized surface plasmon resonance (SPR) peak position, as well as the p...
Article
Full-text available
In the present study, [bmim][PF6] ionic liquid (IL) was introduced into the pores of two ordered mesoporous silicas (MCM-41 and SBA-15) having different pore sizes by means of two different processes: a) with physical imbibition from a methanol solution under high vacuum and b) by chemically immobilising the IL with silanisation of the pore surface...
Poster
Tissues and organs are formed by specialized cells and by extracellular matrix (ECM) organized in 3-dimensional (3D) structure. ECM is a mix of various components, mainly of proteins. ECM remodeling is a physiological and pathological phenomenon (Raeber et al 2005). During tumor dissemination, invasive cells must liquefy the matrix to invade other...
Article
Small-angle neutron scattering (SANS), contrast-matching SANS, and nitrogen adsorption have been utilized to investigate the confined ionic liquid (IL) [bmim][PF(6)] phase in ordered mesoporous silica MCM-41 and SBA-15. The results suggest that the pores of SBA-15 are completely filled with IL whereas a small fraction of the pore volume, the pore "...
Article
Full-text available
Track-etched functionalized nanoporous β-PVDF membrane electrodes, or functionalized membrane electrodes (FMEs), are electrodes made from track-etched, poly(acrylic acid) (PAA) functionalized nanoporous β-poly(vinylidene fluoride) (β-PVDF) membranes with thin porous Au films sputtered on each side as electrodes. In order to form the β-PVDF nanoporo...
Article
Full-text available
Using neutron reflectivity together with an appropriate electrochemical cell, we have studied the effects of transverse electric field on the Bovine Serum Albumin (BSA) monolayer initially adsorbed at the interface of the aqueous solution and a conductive doped-silicon wafer. Depending on the sign of the initial potential, a second layer is adsorbe...
Article
Full-text available
Angiogenesis plays a critical role in tumor growth. This phenomena is regulated by numerous mediators such as vascular endothelial growth factor (VEGF). CBO-P11, a cyclo-peptide, has proven to specifically bind to receptors of VEGF and may be used as targeting ligand for tumor angiogenesis. We herein report the design of novel nanoparticles conjuga...
Article
Small-angle neutron scattering proved that molecules in aqueous solutions of pyridine, 2-methylpyridine and 2,6-dimethylpyridine form clusters. The clusters are dynamic aggregates consisting of hydrogen-bonded water-amine complexes. Strengthening of the hydrogen bonds between water and amine molecules due to the methyl groups in the ortho position...
Article
Full-text available
We report voltage-clamp measurements through single conical nanopore obtained by chemical etching of a single ion track in polyimide film. Special attention is paid to the pink noise of the ionic current (i.e., 1/f noise) measured with different filling liquids. The relative pink-noise amplitude is almost independent of concentration and pH for KCl...
Article
Full-text available
Voltage-clamp measurements on lipid bilayers at the onset of peptide attacks before pore formation are reported. With four different peptides [alamethicin, melittin, and two synthetic peptides of the leucine (L)-lysine(K) copolymers (LK series)], correlations of conductivity fluctuations slowly decay over four decades in time. This slow dynamics is...
Article
The supramolecular organization of particles composed of heteroxylans (HX) and synthetic lignin (dehydrogenation polymer, DHPs) was studied by light scattering (LS), atomic force microscopy (AFM), and fluorescent probes. Results from static and quasi-elastic light scattering indicate a dense core surrounded by a soft corona. Such organization is al...
Article
Full-text available
The main characteristics of the very small angle neutron scattering spectrometer (VSANS) under construction at the Laboratoire Léon Brillouin are a multibeam pinhole collimator converging onto an image plate detector. By combining tiny collimation (diaphragms of around 1 or 2 mm in diameter) with the small pixel size of the detector (0.15 × 0.15 mm...
Article
Full-text available
Poly(vinylidene fluoride) (β-PVDF) nanoporous membranes are obtained by heavy ion irradiation and track etching leading to cylindrical pores. Pores diameter measured by scanning electron microscopy and small angle neutron scattering lies in the 20–50nm range. Electron paramagnetic resonance study gives evidence that radicals still remains in PVDF m...
Article
Full-text available
Enzyme-catalyzed gel degradation is inherently controlled by diffusion of enzymes in the gel. We report kinetics measurements on the gelatin-thermolysin system, varying solvent viscosity as well as gel and enzyme concentrations. Scaling relations and reduced variables are proposed which are shown to account for the experimental results. Finally, we...
Article
Full-text available
We study the electrophoretic blockades due to entries of partially unfolded proteins into a nanopore as a function of the concentration of the denaturing agent. Short and long pore blockades are observed by electrical detection. Short blockades are due to the passage of completely unfolded proteins, their frequency increases as the concentration of...
Article
Full-text available
Small-angle neutron scattering has been successfully used since the 1970s. As a general rule, methods to extract the useful signal from that received by the detector are well known and give good results. At the Laboratoire Léon Brillouin, for example, these methods have been employed for a long time. However, the data reduction software has been ch...
Article
Full-text available
T4 DNA semi-dilute entangled solutions submitted to high shear rates show a region of weak dependence of the steady-state shear stress on the shear rate. For the highest concentration studied, this region extends over two decades of shear rate, and a plateau of shear stress is observed over one decade. The concentration dependence of the lower boun...
Article
Full-text available
La diffusion de neutrons aux petits angles (DNPA) permet de sonder les propriétés statiques de la matière sur une échelle spatiale allant de quelques dixièmes à quelques dizaines de nanomètres. Cette technique est ainsi particulièrement bien adaptée à l'étude des macromolécules en solution. Il est possible d'accéder à des grandeurs moyennes qui car...
Article
In order to mimic the first steps of lignification, pectin/synthetic lignin (dehydrogenation polymers (DHPs)) interactions were investigated using reconstructing approaches. In artificially lignified bacterial cellulose(BC)/pectin composites, DHP nodules display a more dispersed distribution than in BC mats. Occurrence of covalent linkages between...
Article
Full-text available
Coniferyl alcohol was polymerized in pectin solution in order to mimic the lignification that is the final step of biosynthesis of plant cell wall. Dehydrogenated polymers (DHP = coniferyl alcohol polymers = synthetic lignin) interact with pectin to form hydrophobic clusters as monitored by pyrene fluorescence spectroscopy. The structure of these c...
Article
Full-text available
A model for the gel degradation by an enzyme, where the gel is schematized as a cubic lattice, and the enzyme as a random walker, that cuts the bond over which it passes was studied. The model was found to undergo a reverse random percolation which, for low density enzymes falls within a universality class different from random percolation. The cha...
Article
Enzyme-catalyzed proteolysis of gelatin gels has been studied. We report a gel degradation rate varying as the square of the enzyme concentration. The diffusion motion of enzymes in the gel has been measured by two-photon fluorescence correlation spectroscopy and identified as being anomalously slow. These experimental results are discussed from a...
Article
Full-text available
Small-angle neutron scattering experiments were performed on dilute solutions of a high molecular weight protein (fibronectin, M = 580 kg/mol) in four cases: native conditions; unfolded state obtained by a denaturing agent (urea); and two badly refolded (or collapsed) states obtained by progressive elimination of the denaturing agent in salt-contai...
Article
Fibronectin structural reorganization induced by temperature has been investigated by Fourier-transform infrared (FT-IR) spectroscopy and light-scattering experiments. At 20 degrees C, from resolution enhanced by FT-IR spectra, 43% of beta sheet, 31% of turn and 26% of unordered structures were estimated. Static and quasi-elastic light-scattering r...
Article
Fibronectin structural reorganization induced by temperature has been investigated by Fourier-transform infrared (FT-IR) spectroscopy and light-scattering experiments.At 20 °C, from resolution enhanced by FT-IR spectra, 43% of β sheet, 31% of turn and 26% of unordered structures were estimated. Static and quasi-elastic light-scattering results do n...
Article
The use of spherical probe particles to investigate the viscoelastic properties of polymer solutions has been suggested for a long time. We present, in this paper, an analysis of quasi-elastic light scattering results from latex probe particles during gelation of a gelatin solution. We show that by focusing on the short-time and long-time behavior...
Article
We have studied by quasi-elastic light scattering the aggregation of hen egg-white lysozyme upon salt addition. Our results show that these aggregates are fractal, in agreement with the results reported in the literature, and that they do not display any fluctuation of internal concentration. Lysozyme aggregates are rigid at the time scale consider...
Article
Full-text available
We report a quasielastic light scattering study of the dynamics of large latex probe particles (R=225 nm) in gelatin solution undergoing gelation. We show that by focusing on the short-time and long-time behavior of the autocorrelation function, it is possible to simply interpret out data in terms of the divergence of the viscosity and emergence of...
Article
We monitored the cell-free solubilization of extracellular matrix and fibronectin gels, catalyzed by exogenous proteinases. The corresponding measurements could not be interpreted according to usual proteinase kinetics. The observation that this experimental system did not consist in surface but in bulk degradation and appeared specific to gel subs...
Article
Full-text available
Water confined in nonionic fluorocarbon reverse micelles was investigated through mid-infrared spectroscopy (OH stretching and bending modes), in combination with quasielastic light scattering data. The characteristic OH stretching band is seen to exhibit significant changes upon decreasing water core size. An analysis in terms of three different l...
Article
Full-text available
Aggregation of methylcellulose in aqueous dilute solution is studied by light and small angle neutron scattering. For temperature T<293.15K, the free chains adopt a swollen conformation. For T>313.15K, a slow aggregation kinetics occurs. At qRg<1, the association number is found to vary as Rg3. However at qRg>1, the scattered intensity decreases as...
Article
Fibronectin is a multifunctional glycoprotein (molecular mass, M = 530 kg/mol) of the extra cellular matrix (ECM) having a major role in cell adhesion. In physiological conditions, the conformation of this protein still remains debated and controversial. Here, we present a set of results obtained by scattering experiments. In "native" conditions, t...
Article
Full-text available
The aggregation of hen egg-white lysozyme upon salt addition was studied by quasi-elastic light scattering. Our results agree with the fractal structure of the aggregates already reported in the literature. However, we also demonstrate that these aggregates are rigid, since they do not display any fluctuation of internal concentration. Such a r...