François Boué

François Boué
French National Centre for Scientific Research | CNRS · Institut de Chimie (INC)

PhD

About

282
Publications
26,650
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9,159
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Introduction
Biopolymers, polymers, polyelectrolytes, complexes with nanoparticles, nanocomposites Recently : digestion(food), cellulose, conjugated polymers. Radiation scattering techniques (X Rays, neutron, Small Angle Scattering, light scattering) , imaging (microscopy, UV microscopy, electronic microscopy, neutron), rheology. Numerical simulation. Working presently a lot on digestion.
Additional affiliations
January 1977 - April 2013
French National Centre for Scientific Research
Position
  • Managing Director
Description
  • Laboratoire Léon Brillouin dedicated to neutron scattering around the Orphée neutron reactor.

Publications

Publications (282)
Chapter
Many studies focused on gastric motility require the use of synthetic tracers to map the motion of content. Our study instead takes advantage of an unusual MRI acquisition protocol, combined with multi-objective optimised clustering to map the motion of food (peas, a natural ‘tracer’) in a human stomach. We chose NSGA-II to optimise the starting po...
Preprint
Full-text available
We address the issue of structure changes of a canola protein gel (as a solid food model) during gastrointestinal digestion. We present a method for synchrotron Small-Angle X-ray Scattering analysis of the digestion of a gel in a capillary. Scanning the capillary allows tracking the digestion under diffusion of enzymatic juices. The fitting paramet...
Article
Full-text available
Purpose: Numerous studies, including our previous work with lemon juice, have reported that low-pH meals reduce the glycemic response to starchy foods. However, the underlying mechanism is not yet understood. Tea, for its polyphenol content, has also been investigated. The main objective of this research was to concurrently study gastric emptying,...
Article
We studied rheology and nanostructures (by small angle neutron scattering) of heat-set canola seed protein gels, containing cruciferin and napin, prepared at pH 8 and pH 11. We focused on gastric and intestinal digestion of ten mm pieces, mimicking human gastro-intestinal tract. Stronger gels, prepared at pH 11 (above the IEP, isoelectric points, o...
Article
Full-text available
Scattering studies of milk and milk products, which are highly relevant food products on the global market, are often utilized and reported in literature to investigate and understand the subtle microscopic structural differences between dairy samples. These structural features determine the physical properties and ultimately the texture of milk pr...
Article
Full-text available
PurposeThe inhibition of enzymes that hydrolyze starch during digestion could constitute an opportunity to slow down the release, and ultimately the uptake, of starch-derived glucose. Simple dietary approaches consisting in pairing starch-rich foods with beverages that have the capacity to inhibit such enzymes could be an effective and easily imple...
Article
The determination of intrinsic chain stiffness of conjugated polymers is challenging, in particular, for scattering techniques because of their strong light absorption and structural instability due to the complicated intra-/intermolecular interactions. In this work, the chain conformation and aggregation formation of a high charge mobility donor-a...
Preprint
Full-text available
Various studies have shown that food structure has an impact on digestion kinetics. We focus here on the effects of gastric and intestinal enzymes (in-vitro digestion) on two canola seed storage proteins, napin and cruciferin. To monitor structure effect we conducted experiments on gels of these proteins at different pHs, yielding different structu...
Article
Full-text available
We study for the first time the structure of stable finite size clusters (i.e., colloidal molecules) obtained by self-assembly of cationic gold nanoparticles (i.e., atoms) mediated by a flexible polyanion. We reveal with non-denaturizing techniques a striking structural transition from 1D small chains of 12 gold nanoparticles (AuNPs) with a self-av...
Article
We show here how the nature of various divalent cations M2+ (Ca2+, Zn2+ or Fe2+) influences the structure and mechanical properties of ionotropic polygalacturonate (polyGal) hydrogels designed by the diffusion of cations along one direction (external gelation). All hydrogels exhibit strong gradients of polyGal and cation concentrations, which are s...
Article
Various studies have shown that food structure has an impact on digestion kinetics. We focus here on the effects of gastric and intestinal enzymes (in-vitro digestion) on two canola seed storage proteins, napin and cruciferin. To monitor structure effect we conducted experiments on gels of these proteins at different pHs, yielding different structu...
Article
Full-text available
The chain conformation in sulfonated polystyrene PSSNa of a degree of sulfonation 0.34 ≤ f ≤ 1, i.e., of various hydrophobicity, is followed in mixtures of water and increasing content of tetrahydrofuran (THF), a good solvent of the hydrophobic polystyrene moieties (which improves the solvent quality of the mixture). This is achieved by measuring t...
Article
Quantitative ultrasound (US) techniques have an attractive potential for the non-invasive and real-time characterization of the structural and mechanical properties of food. The objective of the present study is to unravel the determinants of the variations of US properties during sol-gel transition of emulsion filled gels of agar and gelatin, due...
Article
A novel time-lapse synchrotron deep-UV microscopy methodology was developed that made use of the natural tryptophan fluorescence of proteins. It enabled the monitoring in situ of the microstructural changes of protein gels during simulated gastric digestion. Two dairy gels with an identical composition, but differing by the coagulation mode, were s...
Article
Agricultural resources give us food but also potential sources of feedstocks for the chemical industry. As demand from the growing human population rises, the food industry and the chemical industry face similar problems of scaling operations while sourcing the largest possible amount of at least reasonable-quality raw materials. Food is composed o...
Article
The development of non-invasive methods is critical for a better understanding of the biomechanical phenomena involved in the dynamic mechanisms of food texture perception during oral processing. The aim of the present study is to investigate in vitro the potential of a quantitative ultrasound device in order to monitor the mechanical properties of...
Article
Quantitative Ultrasound techniques are good candidates for the in situ and real-time mechanical characterization of tongue-food-palate system, and thus to improve the understanding of the determinants of texture perception of food. Different model foods (consisting in gels and emulsion filled gels composed of agar and/or gelatin) have been designed...
Article
Foams are multiscale materials that have an enormous number of uses. As the relevant structural length-scales span from a few nanometres up to millimetres a number of characterisation methods need to be combined to obtain the full material structure. In this review we explain how foams can be explored using Small Angle Neutron Scattering (SANS). We...
Chapter
Full-text available
Many different nanosized objects or structures can be present in food, as occurring in different areas of matter, in particular soft matter, of which food can be considered a small field. Amorphous synthetic silica (SAS) has mostly developed in the agricultural domain for food, while its use is rising for biotech. Nano-world is a rich exploration f...
Article
Full-text available
We investigate by SANS and SAXS the structure of semi dilute aqueous hydrophobic quenched polyelectrolyte solutions, in which we can vary independently the hydrophobicity and the chemical/electrostatic charge fraction (above the Manning condensation threshold 36%). Such a de-correlation is the original point of the work, reached using statistical t...
Poster
Gastric digestion is the result of physical disintegration, acidic hydrolysis and enzymatic reactions leading to the release of nutrients which are absorbed in the upper intestinal tract. Protein is one of the essential macro‐nutrient and can be eaten in a great variety of forms (solubilized, cross‐linked, in their native or denatured states). Cont...
Preprint
We aim at combining high coercivity magnetic nanowires in a polymer matrix in a view to fabricate rare--earth free bonded magnets. In particular, our aim is to fabricate anisotropic materials by aligning the wires in the polymer matrix. We have explored the different parameters of the fabrication process in order to produce a material with the best...
Preprint
Aggregation of nanoparticles of given size $R$ induced by addition of a polymer strongly depends on its degree of rigidity. This is shown here on a large variety of silica nanoparticle self-assemblies obtained by electrostatic complexation with carefully selected oppositely charged bio-polyelectrolytes of different rigidity. The effective rigidity...
Article
Aggregation of nanoparticles of given size R induced by addition of a polymer strongly depends on its degree of rigidity. This is shown here on a large variety of silica nanoparticle self-assemblies obtained by electrostatic complexation with carefully selected oppositely charged biopolyelectrolytes of different rigidity. The effective rigidity is...
Article
Full-text available
Scattering functions of sodium sulfonated polystyrene (NaPSS) star-branched polyelectrolytes with high sulfonation degrees were measured from their salt-free aqueous solutions, using the Small Angle Neutron Scattering (SANS) technique. Whatever the concentration c, they display two maxima. The first, of abscissa q1*, is related to a position order...
Article
Neutron reflectivity has been used to investigate the effect of shear on the conformation of hydrogenated polystyrene chains end-grafted on a silicon wafer and covered by a deuterated polystyrene melt, in the grafting regime where the grafted chains at equilibrium extend in the bulk up to their radius of gyration. An experimental setup has been bui...
Presentation
The gastric digestion comprises three phases: physical disintegration, chemical breakdown and nutrient release. Controlling food proteins gelation conditions leads to the formation of particles with specific structural features that change protein digestibility. The development of foods with specific proteolysis rates allows their fit to different...
Article
Full-text available
The question of the influence of nanoparticles (NP) on chain dimensions in polymer nanocomposites (PNC) has been treated mainly through the fundamental way using theoretical or simulation tools and experiments on well-defined model PNC. Here we present the first experimental study about the influence of NP on the polymer chain conformation for PNC...
Article
Full-text available
Nano-hybrid hydrogels were prepared by cross-linking polymerization of N,N-dimethylacrylamide (DMA) within a dispersion of silica nano-particles. Working at constant polymer/water ratio, the mechanical properties of hydrogels can be finely tuned by changing either the level of covalent cross-linker and/or the amount of particles that act as physica...
Article
We study for the first time the structure of stable finite size clusters (i.e. colloidal molecules) obtained by self-assembly of cationic gold nanoparticles (i.e. atoms) mediated by a flexible polyanion. We reveal with non denaturizing techniques a striking structural transition from 1D small chains of 12 gold nanoparticles (AuNPs) with a self-avoi...
Article
Full-text available
Aggregates - a phenomenon still not understood, as well as pearl necklace-like chain conformation in aqueous solutions of hydrophobic polyelectrolyte are addressed here, using treatment by an organic solvent. The second appear to be at equilibrium in water, the first appear to be metastable, and surprisingly associated with higher zero shear viscos...
Article
We report a complete analysis of model silica/styrene-butadiene rubber (SBR) nanocomposites including a direct and quantitative correlation between the filler structure and the mechanical reinforcement. We compared two different ways of sample processing: a solvent casting route with well-defined colloidal silica and the manufacturing process of in...
Article
Full-text available
We aim at combining high coercivity magnetic nanowires in a polymer matrix in a view to fabricate rare-earth free bonded magnets. In particular, our aim is to fabricate anisotropic materials by aligning the wires in the polymer matrix. We have explored the different parameters of the fabrication process in order to produce a material with the best...
Article
Full-text available
We report on the structure of whey protein aggregates formed by a short heating coupled to shear at high temperatures (80-120) and neutral pH in scale-up processing conditions, using gel filtration chromatography, light scattering, small angle neutron scattering, and cryogenic transmission electron microscopy. The results are interpreted in terms o...
Article
Full-text available
Aggregatesa phenomenon still not understoodas well as the pearl-necklace-like chain conformation in aqueous solutions of hydrophobic polyelectrolytes are addressed here, using treatment by an organic solvent. The second appear to be at equilibrium in water. The first appear to be metastable, and surprisingly associated with higher zero shear visc...
Article
Full-text available
Magnetic interactions in aggregates of polyol-synthesized cobalt nanowires are studied by delta M plots. Negative delta M values are obtained as expected for magnetostatic coupling between physically isolated nanowires, without exchange interactions. Very weak interactions (down to delta M = -0.05) are achieved by alignment and dispersion into poly...
Article
Full-text available
The maximum magnetic performance which can be expected from elongated single domain particle based permanent magnets is assessed. The results are derived using micromagnetic calculations to model the behavior of large bundles of aligned nanowires. In particular, we discuss the cases of Co and Fe nanowires and their packing fraction dependence of co...
Article
The dynamic of confined polystyrene in nanoparticles was investigated in particles as small as 42 nm in the close packed morphology. The relaxation time was extracted from the dynamic of closure of voids between close packed particles. The particles deform under the effect of the surface tension energy (polystyrene/air), and the deformation is prob...
Article
Full-text available
We explore the mechanisms of association between neutral xyloglucan chains extracted from tamarind seeds using a dissolution process based on the use of a solvent with a chaotropic character. Meso-scale structures involving a few chains are evidenced and monitored by static light scattering and low-shear viscosity experiments as a function of the x...
Article
We present an investigation of the swelling dynamics of end-grafted hydrogenated polystyrene (h-PS) chains confined between a solid substrate and a deuterated polystyrene (d-PS) melt, based on neutron reflectometry experiments. The segment density profile of the grafted chains was measured for different annealing times. The kinetics of relaxation w...
Article
Full-text available
of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.
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The electrostatic complexation between model negatively charged silica nanoparticles (NPs) with radius R 10 nm and chitosan, a natural polyelectrolyte bearing positive charges with a semi-rigid backbone of a persistence length of Lp 9 nm, was studied by a combination of SANS, SAXS, light scattering, and cryo-TEM. In this system, corresponding to Lp...
Article
Full-text available
The advances in new technologies have prompted the need for functional systems smaller than the gyration radius of polymer chains. Thus, understanding how nanoconfinement affects polymer properties has been the focus of a lot of research for over a decade. Polystyrene in particular has been reported to be strongly affected when nanoconfined as a th...
Article
Full-text available
Surfactants, which are molecules bearing a hydrophobic part and a hydrophilic part, are widely used in many daily life products (detergent, cosmetic, pharmaceutical...) because of their foaming properties. Indeed, they spontaneously go to the interface between air and water, which stabilizes the thin water films surrounding air bubbles to obtain fo...
Article
Full-text available
We investigate in this paper the influence of the improvement of the solvent quality on the structure and the viscous properties of solutions of an hydrophobic polyelectrolyte, poly(styrene-co-sodium styrene sulfonate) : PSS. The solvent used is a mixture of water and an organic solvent, THF, which is also slightly polar. We use Small Angle Neutron...
Article
Full-text available
Surfactants, which are molecules bearing a hydrophobic part and a hydrophilic part, are widely used in many daily life products (detergent, cosmetic, pharmaceutical. . .) because of their foaming properties. Indeed, they spontaneously go to the interface between air and water, which stabilizes the thin water films surrounding air bubbles to obtain...
Article
Full-text available
We show by combining small-angle X-ray scattering (SAXS) and cryo-transmission electron microscopy (cryo-TEM) that anionic silica nanoparticles (SiNPs) assemble into well-defined 1D cluster when mixed with a dilute solution of semiflexible chitosan polycation. The nanorods are stable in excess of SiNPs and composed of 10 SiNPs well-ordered into str...
Preprint
Ultrastable foams with an optimal foamability have been obtained using hydroxyl fatty acids tubes. The stabilization results from the adsorption of monomers at the air-water interface preventing coalescence and coarsening and from the presence of tubes in the Plateau borders limiting the drainage. Upon heating, tubes transit to micelles, which indu...
Article
Full-text available
We study by Small Angle Neutron Scattering (SANS) the structure of Hyaluronan -Lysozyme complexes. Hyaluronan (HA) is a polysaccharide of 9 nm intrinsic persistence length that bears one negative charge per disaccharide monomer (Mmol = 401.3 g/mol); two molecular weights, Mw = 6000 and 500 000 Da were used. The pH was adjusted at 4.7 and 7.4 so tha...
Article
Full-text available
We describe the synthesis of macromolecular amphiphiles of various molar masses containing well-defined hydrophobic groups incorporating urea moieties. All compounds have the same proportion of associative hydrophobic groups and solubilising POE chains. However, a strong influence of both the number of associative groups per chain and the polydispe...
Article
Full-text available
The behavior at the air/water interface of multilamellar tubes made of the ethanolamine salt of the 12-hydroxy stearic acid as a function of the temperature has been investigated using Neutron Reflectivity. Those tubes are known to exhibit a temperature tunable diameter in the bulk. We have observed multilamellar tubes adsorbed at the air/water int...
Article
The phenylurea moiety is a ubiquitous synthon in supramolecular chemistry because it contains strong complementary hydrogen bonding groups and is synthetically very accessible. Here we investigate the possibility to strengthen self-association by conformational preorganization of the phenylurea moiety. In fact, we show that it is possible to strong...
Article
Full-text available
The use of agricultural resources for industrial purposes will undoubtedly be one of the major challenges of the 21 century, either from the energetic point of view by the progressive replacement of fossil fuels or with respect to non-energy uses by making available new organic “biosynthons” to the chemicals industry. In such a context, we demonstr...
Article
Full-text available
In this paper we report the influence of biopolymer folding on nanoparticle spatial distribution in two typical bio-nanocomposite hydrogels. These systems consist of negatively charged nanosized fillers (polyoxotungstate clusters and silica particles, 2.2 nm and 23.0 nm in diameter, respectively) dispersed at low volume fractions in a positively ch...
Article
We report on the influence of parameters controlling filler dispersion and mechanical reinforcement in model nanocomposites. We elaborate a series of nanocomposites and present a structural characterization of silica dispersion in polymer matrix for several particle sizes and polymer matrices, at all relevant scales, by coupling Small Angle X-ray S...
Article
Full-text available
Smart foams: Ultrastable foams with an optimal foamability are obtained using hydroxy fatty acids tubes. The stabilization results from the adsorption of monomers at the air-water interface and from the presence of tubes in the plateau borders. Upon heating, tubes transform to micelles, leading to foam destabilization and thus to the first foams to...