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The use of biochars (BCs) and activated carbons as a way of sequestering soil-bound pollutants such as chlordecone (CLD) is increasingly being studied. This study aims at assessing the impact of Sargassum BC/AC particle size and Sargassum BC amendment rate on CLD adsorption in Nitisol and in Andosol. Four different types of carbonaceous matrices were tested: Sargasso carbon activated by phosphoric acid (SargH

International audience; The effect of enzymatic modification of polysaccharides on the formed supramolecular structures was studied. Gum Arabic and chitosan were modified by covalent grafting of ferulic acid oxidation products so that they could establish new interactions such as π interactions. The stoichiometry of the interaction was studied by ITC measurements, as well as its strength and related thermodynamic parameters. These experiments were supported by Zeta potential and turbidity measurements and optical macroscopy observations. Grafting of phenolic compounds onto the polymers increased their ability to exhibit π-π stacking and π-cation interactions and led to the formation of various supramolecular structures. For native gum Arabic and chitosan assemblies, the stoichiometry value determined by ITC was consistent with optical microscopy, macroscopic observations and Zeta potential (around a molar ratio gum Arabic:chitosan of 3). The structures formed were coacervates. For the modified polymers, the optimal molar ratio determined by Zeta potential measurements (3.27) differed from the one determined by ITC (6.3). This meant the formation aggregates was not only due to electrostatic interactions but also to other type of interactions (new π-π stacking and π-cation interactions). It was concluded that by modifying the polymers, it was possible to control the supramolecular structures formed

The modification of gum Arabic with ferulic acid oxidation products was performed in aqueous medium, at 30 °C and pH 7.5, in the presence of Myceliophthora thermophila laccase as biocatalyst. First, this study aimed to investigate the structures of the oxidation products of ferulic acid that could possibly be covalently grafted onto gum Arabic. HPLC analyses revealed that this reaction produced several oxidation products, whose structures were investigated using LC-MS/MS analyses (liquid chromatography-mass spectrometry with mass fragmentation analyses) and NMR experiments. The chemical structure of one intermediate reaction product was fully elucidated as the 2-(4-hydroxy-3-methoxyphenyl)-4-[(4-hydroxy-3-methoxyphenyl) methylidene] cyclobutane-1, 3-dione, called by the authors cyclobutadiferulone. Secondly, this study aimed to locate the grafting of the oxidation products onto gum Arabic by performing several NMR experiments. This study did not determine how much and specifically which oxidation products were grafted but some of them were undeniably present onto modified gum Arabic, close to the glucuronic acid C5 carbon or close to the galactose C6 carbon.

High-quality graphene is an especially promising carbon nanomaterial for developing nanofluids for enhancing heat transfer in fluid circulation systems. We report a complete study on few layer graphene (FLG) based nanofluids, including FLG synthesis, FLG-based nanofluid preparation, and their thermal conductivity. The FLG sample is synthesized by an original mechanical exfoliation method. The morphological and structural characterization are investigated by both scanning and transmission electron microscopy and Raman spectroscopy. The chosen two-step method involves the use of thee nonionic surfactants (Triton X-100, Pluronic&reg, P123, and Gum Arabic), a commercial mixture of water and propylene glycol and a mass content in FLG from 0.05 to 0.5%. The thermal conductivity measurements of the three FLG-based nanofluid series are carried out in the temperature range 283.15&ndash, 323.15 K by the transient hot-wire method. From a modeling analysis of the nanofluid thermal conductivity behavior, it is finally shown that synergetic effects of FLG nanosheet size and thermal resistance at the FLG interface both have significant impact on the evidenced thermal conductivity enhancement.

Gum Arabic is a natural polysaccharide with valuable properties that enable its use in many industrial fields. Nevertheless, its application field may be enlarged to new properties. One way consists of the modification of the polysaccharide through an enzymatic process based on the oxidation of a phenolic compound. This work aims then to study the impact of the presence of ferulic acid oxidation products onto gum Arabic on its properties as its color, thermal properties, rheological and interfacial behaviors. For instance, modified gum Arabic powder underwent a change of color from white to orange and a glass transition was reported contrary to native gum. Though its rheological behavior did not change, its solubility decreased from 42.5 ± 2.6 to 10.6 ± 0.1% w/v. However, the amphiphilic behavior of functionalized gum Arabic seemed to be different from the one of native gum Arabic. For a given concentration, the surface tension of the modified polymer was lower (31.2 ± 0.8 mN m−1 for native gum Arabic against 52.5 ± 2.4 mN m−1 for the modified gum at 1% w/v). Finally, modified gum Arabic presented important antioxidant properties. The modification of gum Arabic with phenolic compounds appeared then as a promising way to produce a polysaccharide with new properties that could enlarge the field of its potential applications and could make it an interesting food ingredient.

International audience; Cocoa powders are highly subjected to caking, a phenomenon of solid particles agglomeration that impairs powder functionalities such as rehydration and flowing properties. This study aimed at identifying the main caking mechanisms occurring during storage of cocoa powders, according to their fat content and water activity, as well as storage temperature. The formation of caked powder was monitored at macroscopic scale by sieve analysis, showing that caking was significant only for fatty powders at 40 degrees C, in agreement with a caking mechanism controlled by fat melting. The similarity of results obtained at 0.2 and 0.7 water activity indicated that the humidity caking mechanism was not significant for these powders. Observations performed by TEM' evidenced the formation of fat bridges, confirming the occurrence of the fat melting mechanism. Then, solvent extraction techniques designed to quantify fat fractions permitted to highlight that storage caused the conversion of encapsulated fat into free fat. At temperatures sufficient to melt cocoa fat (40 degrees C), this newly formed free fat migrates toward cocoa particle surface, enhancing its fat coverage, hence making cocoa particle sticky and prone to cake. Finally, XPS analysis of the extreme surface of cocoa powders confirmed that two conditions should be met to trigger significant cocoa powder caking: high fat content and elevated storage temperature.

The interactions between gum Arabic (GA) and chitosan (CN) in solution have been investigated upon pH (4.5, 5.0 and 5.5) and temperature (5, 25 and 45 °C). Isothermal titration calorimetry (ITC) has been used to determine the thermodynamic parameters involved in the complex coacervation process between these two polymers. Zeta potential, turbidity measurements and optical microscopy were used as complementary methods to have a better understanding of the phenomenon at the origin of the self-assembly. Unlike data already published by authors, concerning the GA-CN coacervation model, a raise in temperature seemed to favor electrostatic interactions. The enthalpy became more favorable upon temperature, a phenomenon probably related to the availability of CN charges. A raise in temperature would lead to a compaction of CN, decreasing its steric hindrance during self-assembly. According to all experiments conducted in this study, the GA/CN interaction optimal molar ratio would be 4:1. However, this optimal ratio changed upon pH-temperature combinations. The results presented in this study should lead to a better understanding of the interactions between charged polymers and in the end, help in their application in the food, pharmaceutical and cosmetic industries.

In this study, a novel multi-scale drug encapsulation system, curcumin-Solid Lipid Nanoparticles (SLNs) loaded chitosan microparticles, has been formulated by combining biopolymer- and lipid-based drug delivery systems. Curcumin was loaded into phospholipids / Tween 80 stabilized shea butter SLNs (C-SLNs) using high shear homogenization – ultrasonication technique. Over than 99% of curcumin was entrapped into SLNs. In order to protect and to improve their stability, C-SLNs were encapsulated within chitosan microparticles (CS-C-SLNs) by ionotropic gelation using sodium tripolyphosphate (TPP) as a crosslinking agent. The final microparticles presented a thin size distribution centered on 21.6 ± 1.6 μm and were stable upon time in water. Differential scanning calorimetry and X-Ray diffraction revealed that the SLNs lipid structure was not affected by either curcumin or chitosan. These preliminary results showed that CS-SLNs microparticles can be a promising encapsulation system for hydrophobic compounds.

Curcumin interaction with micellar caseins (MC), Lactobacillus delbrueckii bulgaricus (Lb) and Streptococcus thermophilus (St) and its influence on the acid gelation were investigated. Epifluorescence microscopy evidenced the adsorption of curcumin on bacteria surfaces and its transfer from MC to bacteria. Fluorescence spectroscopy of curcumin and fluorescence quenching of caseins variations in presence of bacteria and MC were evaluated. The interaction between curcumin and St and Lb was confirmed due to the decrease of curcumin fluorescence intensity from 1.7 A.U to 1.20 A.U and to 1.40 A.U, respectively. The transfer of curcumin between MC and bacteria was confirmed. The curcumin interacted more with St than with Lb envelope with a fluorescence intensity decrease from 6.20 ± 0.02 A.U to 5.20 ± 0.08 A.U and to 4.60 ± 0.08 A.U, respectively. It also showed that St was more hydrophobic than Lb bacterial envelope leading curcumin to interact more with Streptococcus surface. Curcumin adsorption did not affect Lb and St growth nor its acidification rate of milk. The acid gelation study led to a typical gel yoghurt-like formation. For the first time, it was demonstrated that curcumin interacted with lactic bacteria without modifying its growth and milk acidic gelation property.

International audience; Despite various spectacular therapeutic properties, curcumin has low bioavailability mainly due to its poor solubility in water. In this paper, we encapsulated curcumin by nanoliposomes prepared from salmon purified phospholipid and coated with chitosan. Various techniques were used in order to study the interactions among phospholipid, chitosan and curcumin. FTIR results showed both electrostatic and hydrophobic interactions as well as hydrogen bonding between chitosan and phospholipid, while hydrophobic forces and hydrogen bonding dominated the interactions between curcumin and phospholipid as well as between curcumin and chitosan. Shear viscosity measurements demonstrated a flow behavior change from Newtonian to shear thinning after liposome coating. The increase/decrease stress ramp showed that the addition of chitosan layer decreased significantly the hysteresis loop area (thixotropic behavior) and therefore increased significantly the liposomal dispersion stability. The viscoelastic properties investigated by small-amplitude oscillatory shear rheology demonstrated improvement of mechanical stability after chitosan addition. Small-angle X-ray scattering experiments revealed that the liposome membrane structure was not affected by the chitosan layer or the encapsulated curcumin.

The encapsulation of curcumin in micellar caseins (MCs) and the production of powder were performed by spray-drying. Nearly 97% of the curcumin was retained and the yellow powder showed a typical high casein powder morphology. The hygroscopic properties were determined, slight differences reflected less available hydrophobic sites when curcumin was bound to casein, favoring interactions with water in curcumin-enriched MC powders. No difference was detected on the internal MC structure via SAXS. The antioxidant activity of doped-curcumin powder presented 88% of active curcumin. For 60 days at 40 °C storage, the antioxidant activity of curcumin measured by ABTS and FRAP assays was preserved with a percentage of 82 ± 2.0% and 84 ± 1.1%, respectively. Curcumin doped powders presented similar features to classical casein powders (rehydration and gelling abilities). It was demonstrated that curcumin encapsulation in MCs in its powder form helped in protecting its antioxidant activity without influencing the techno-functional properties of MCs. This study allowed the incorporation of curcumin via the MC matrix as an active food ingredient available in a powder state usable as classical milk powder in several food formulations.

We report here the synthesis of mesoporous silica materials from various fluorinated-based systems using as the inorganic precursor either sodium silicate solution or silicate ions produced from the dissolution of silica under basic conditions. The properties of the materials are compared with the ones of the mesostructures prepared from tetramethoxysilane as silica source. Results show that whatever the silica source, well-ordered hexagonal materials with a narrow pore size distribution are obtained. Nevertheless, the pH has a great influence on the properties of the recovered materials since it governs the interactions between the surfactant and the inorganic precursor and the pH range for which the hexagonal mesopore ordering is obtained, depends on the silica source. Using sodium silicate, hexagonal mesostructured materials with high specific surface area (≥800 m 2 /g) and narrow pore size distribution (4 nm) are recovered for pH from 0.3 to 5. It should be noted that the formation of organized mesoporous silica under acidic conditions with this precursor is barely reported in literature. Replacing sodium silicate by silica fumed, the pH range leading to a hexagonal mesopore ordering is reduced to 0.3–1.5. When the organosilane is used the ordered mesoporous materials are recovered regardless the pH. In addition in that case a better control of the self assembly between the surfactant and the silica species allows tuning the particles’ morphology. Under acidic conditions tetramethoxysilane gives rise to gyroids or toroids and favors the formation of submicrometer particles, while irregularly shaped particles are produced with sodium silicate or silica fumed under alkaline conditions. Results also show that neither the specific surface area, nor the cell parameter strongly depend on the silica precursor as long as the hexagonal structure is kept.

International audience; The surface of 11 wt.% fat cocoa particles was thoroughly investigated during a 2-month storage at 20 and 40 degrees C and at a(w) = 0.2. Surface fat migration was evidenced only for powders stored at 40 degrees C by X-ray Photoelectron Spectroscopy. This was confirmed by ToF-SIMS, which allowed visualizing bigger fat patches at the surface of 40 degrees C-stored powders. These observations emphasize that fat need to be under a melted form to move toward the surface during storage. However, an increase in the free fat content was observed at both 20 degrees C and 40 degrees C. These results suggest rearrangements of particle structure during storage; free fat being more accessible to solvents at both temperatures. Confirmation was done by Scanning and Transmission Electron Microscopy images. Free and encapsulated fat were also extracted and analyzed during storage and no significant difference in fatty acids distribution (C16, C18, C18:1, C18:2) was observed by gas chromatography.

Mesoporous silica materials have been prepared using aqueous solutions of hydrogenated-fluorinated surfactant mixtures. The phase behavior of the C18H35(OC2H4)10-C6F15C2H4(OC2H4)11OH [RH18(EO)10-RF6(EO)11] mixture in aqueous solution was first established at the temperature at which the silica source is added, i.e., 20 or 40 degrees C. We have delimited the different phase domains. Concerning the mesostructured silica, whatever the temperature at which the silica source is added, mesoporous material with a hexagonal array of their channel is formed via a cooperative templating mechanism (CTM), if the content of RF6(EO)11 in the surfactant mixture is lower than 50%. Moreover, when the silica source is added at 40 degrees C, the recovered materials exhibit a bimodal pore size distribution. The appearance of this bimodality has been related to the coexistence of hydrogenated micelles with fluorinated wormlike micelles. By contrast, the bimodality is not observed when the silica source is added at 20 degrees C.

International audience; In this study, the ability of micellar casein (MC) to interact with curcumin during acidification and to produce acid gel was investigated. Steady-state fluorescence spectroscopy of curcumin variation and fluorescence quenching of caseins upon binding with curcumin molecules were evidenced. Increasing the temperature from 20 to 35 degrees C enhanced MC-curcumin interactions as reflected by the increase in the binding constant from 0.6 +/- 0.3 x 10(4) to 6.6 +/- 0.6 x 10(4) M-1. From changes in entropy, enthalpy and Gibbs free energy, hydrophobic interactions were proposed as major binding forces. Static fluorescence MC quenching was demonstrated for the MC-curcumin complex during acidification. From pH 7.4 to pH 5.0, the binding site numbers varied in the range from 1.25 +/- 0.05 to 1.49 +/- 0.05 and the binding constant k(b) varied from 3.9 +/- 0.4 x 10(4) to 7.5 +/- 0.7 x 10(4) M-1. Small angle X-ray scattering profiles demonstrated that the MC internal structure was unchanged upon curcumin binding. The.-potential value of curcumin-doped MC indicated that curcumin did not modify the global charge of MC particles. Acid gelation studied by oscillation rheology and static multiple light scattering at 20 and 35 degrees C led to a similar behavior for native and curcumin-doped MC suspensions. For the first time, it was demonstrated that the colloidal and functional properties of MC were unchanged when doped with curcumin during acidification.

International audience; In the present work, shea butter solid lipid nanoparticles (SLN) were prepared by sonication using nonionic surfactants as stabilizers without organic solvent. The mixture design methodology enabled to control particles size from 50?nm to more than 1?µm according to the mixture composition. Then, curcumin, a natural polyphenol, has been encapsulated in nanoparticles with a wide range of diameters (50–230?nm) and the encapsulation efficiency has been related to the particles sizes. The bigger the nanoparticles, the lower the encapsulation efficiency. The lipid structure at non dispersed state and under SLN form has been studied by differential scanning calorimetry and X-ray diffraction. From the obtained results, encapsulated curcumin did not affect the lipid properties at the SLN state unlike at non dispersed state. The localization of the curcumin in the outer shell of the lipid nanoparticles explained the evolution of the encapsulation efficiency according to the nanoparticles size. Practical applications: Solid lipid nanoparticles (SLN) can be used for the delivery of both hydrophobic and hydrophilic drugs. Preparing such nanovectors with natural, non-expensive materials and easily available (i.e., shea butter) will promote their potential use in several applications like oral, parenteral, dermal or ocular delivery. Controlling the particles size from the formulation composition and also the drug loading from SLN properties is of main importance to optimize the use of SLN as colloidal carrier. Mixture design of experiments methodology allowed the control of shea butter solid lipid nanoparticles size upon system composition. The influence of SLN size on the encapsulation efficiency of curcumin was studied.

International audience; Abstract The experimental design methodology has been used to study the influence of the synthesis parameters on the properties of nanostructured mesoporous materials prepared using a fluorinated surfactant based system. In a first set of experiments, the surfactant concentration, the pH of the micellar solution and the hydrothermal treatment conditions (duration and temperature) have been related to the organization of the materials pore network studied by SAXS. From the obtained results, the parameters ranges have been reduced to investigate their effect on the textural properties (specific surface area, pore diameter and pore volume) and silanol groups of well-ordered 2D-hexagonal materials. Models are proposed and validated for the prediction of the specific surface area and the pore diameter.

The formation of two-dimensional (2D)-hexagonal (p6m) silica-based hybrid materials from concentrated micellar solutions (10 wt %) of two nonionic fluorinated surfactants, R(7)(F)(EO)(8) and R(8)(F)(EO)(9), is investigated in situ using synchrotron time-resolved small angle X-ray scattering (SAXS). The two surfactants form direct micelles with different structures prior to the silica precursor addition as demonstrated by SAXS and SANS. R(8)(F)(EO)(9) gives spherical micelles and R(7)(F)(EO)(8) more complex ones, modeled here as short wormlike micelles. The in situ SAXS experiments reveal that both surfactants form well-ordered 2D-hexagonal hybrid materials after the addition of the silica precursor, in coexistence with an excess of surfactant micelles. The structures of both 2D-hexagonal phases are compared just after precipitation, and it is found that more robust and larger silica walls are formed for R(8)(F)(EO)(9) than for R(7)(F)(EO)(8). This could explain why only the material obtained with R(8)(F)(EO)(9) is stable upon washing, as observed previously. Moreover, it is proposed that in both cases, only a part of the micelles interact with the silica oligomers and undergo structural modifications before forming the 2D-hexagonal mesophase. The obtained results are finally discussed in the more general framework of the templating mechanism for nonionic surfactants.

International audience; The mechanisms of formation of organically modified (phenyl, vinyl, and methyl) silica materials with cubic Pm3̅n and hexagonal p6m periodic mesostructures obtained in one step in the presence of the cetyltrimethylammonium bromide (CTA+B) surfactant are reported in this study. Understanding the way these complex materials form is difficult but undoubtedly necessary for controlling the material structure and its properties because of the combined presence of surface organic groups and large surface areas. Here, the mechanism of formation is clarified on the basis of the modeling of time-resolved in situ small angle X-ray scattering (SAXS) experiments, with a specific focus on the micelle evolution during material formation. Their fast self-assembly is followed for the first time with a quick temporal resolution of a few seconds using a third-generation synchrotron radiation source. To better understand the behavior of the complex organic-containing mesostructure, we perform a comparative study with the corresponding organo-free, isostructural materials obtained from three different surfactants (CTA+, CTEA+, and CTPA+) having a constant chain length (C16) and an increasing polar head volume (met-, et-, and prop-). Numerical modeling of SAXS data was crucial to highlighting a systematic sphere-to-rod micellar transition, otherwise undetected, before the formation of the 2D hexagonal phase in both organo-free and organo-containing systems. Then, two different pathways were found in the formation of the cubic Pm3̅n mesostructure: either an ordering transition from concentrated flocs of spherical micelles (from CTEA+ or CTPA+) for pure TEOS systems or a structural transformation from an intermediate 2D hexagonal mesophase in organosilane systems (from CTA+). Combining the comparison between organo-free and organo-containing systems with numerical modeling, we find that the hexagonal-to-cubic phase transition in the organically modified materials seems to be strongly influenced not only by the obvious presence of the organic group but also by the quicker and more massive condensation kinetics of silicate oligomers on the CTA+ micellar surface. Finally, quite unexpectedly, we find a wormlike-to-sphere micellar transition in the CTPA+ system.

A second generation of boron nitride-based porous materials has been synthesized by a double nanocasting process via a carbonaceous template as a medium starting from a zeolite. In the multistep pr...

In an attempt to answer the question if there is dependence between the pore ordering of the mesoporous silica, obtained through the cooperative template mechanism, and the shape of the micellar aggregates of the surfactant solutions, the micellar structures of two nonionic fluorinated surfactant based-systems are studied by SANS. By fitting the experimental spectra with theoretical models, the structural evolution of the molecular aggregates can be described, and some important parameters can be obtained, such as the water and eventually oil penetration into the surfactant film, the aggregation number, the area per polar head of the surfactant, and the surfactant chain conformations. We have shown that for the C(8)F(17)C(2)H(4)(OC(2)H(4))(9)OH system, the micelles are prolate spheroids. The increase of the surfactant concentration in water does not change the characteristics of the interfacial film, but the aggregation number raises and the particles become more elongated. By contrast, the experimental curves of C(7)F(15)C(2)H(4)(OC(2)H(4))(8)OH cannot be fitted considering a small particle model. However, progressive incorporation of fluorocarbon induces a change of size and shape of the globules, which become smaller and more and more spherical. Regarding the material mesopore ordering, it appears that the micelles that lead to hexagonal mesoporous silica materials are described with a model of quasi-spherical globules. On the contrary, when large micelles are found, only wormhole-like structures are obtained.

We report the immobilization of Rhizomucor miehei lipase (RmL) onto mesoporous silica materials, in particular the investigations concerning the effects of the level of silica condensation and of the pore size on the enzyme activity. The efficiency of the immobilization was revealed by FTIR spectroscopy. Infrared was also used to determine the quantity of adsorbed enzyme. Immobilization efficiency increased when the RmL concentration in the buffer solution was changed from 2 to 10 mg/mL. Nevertheless, while upon enzyme immobilization the mesopore ordering was sustained for the support recovered after hydrothermal treatment at 100 °C, a structure collapse occurred for the one prepared at 80 °C. The difference in behavior is attributed to the lower hydrothermal stability of this material, which reflects the lower level of silica condensation. The enzyme-containing mesostructured silica was effectively used to catalyze the model esterification reaction of lauric acid with 1-propanol, as the immobilized lipase retained its catalytic activity. A linear relationship was observed between the reaction rate and the amount of catalyst. RmL immobilized on mesoporous materials presented a satisfactory reusability, while the remaining activity of RmL after 4 months of storage was 47% of the initial one.

In this study, we have investigated the influence of the temperature during the synthesis on the hydrothermal stability of mesostructured silica prepared from a system based on nonionic fluorinated surfactant. Results obtained by SAXS, nitrogen adsorption–desorption analysis and infrared spectroscopy show that when the temperature is increased the hydrothermal stability of the recovered material is enhanced. Indeed, as soon as the treatment into boiling water begins, the structure of the sample synthesized at 80 °C is altered, while the material synthesized at 100 °C is very stable up to 24 h. This behavior has been attributed to a higher degree of silica condensation and to a decrease of both the number of silanol groups and the microporosity. A comparison of the characteristics of the materials obtained with both hydrogenated and fluorinated surfactants also evidences that the lather are more stable when treated with boiling water.

We have investigated the influence of the ratio between the volume of the hydrophilic head (VA) and the volume of the hydrophobic part (VB) of the surfactant on the mesopore ordering. To understand the difference of behavior we have performed a complete study dealing with fluorinated [Rm(F)(EO)n] and hydrogenated [Rm(H)(EO)n] surfactants. Their mixtures have also been taken into account. Here only the phase diagrams and the structural parameters of the liquid crystal phases of the mixed systems are reported. We have shown that the mutual or partial miscibility of the fluorinated and the hydrogenated surfactants depends on the number of oxyethylene units of each surfactant. To follow, various systems were used for the preparation of silica mesoporous materials via a cooperative templating mechanism (CTM). Results clearly reveal that VA/VB ratios in the range between 0.95 and 1.78 lead to the formation of well-ordered mesostructures. Wormhole-like structures are obtained for higher or lower values. Moreover, results show that from the VA/VB point of view, polyoxyethylene fluoroalkyl ether surfactants behave like their hydrogenated analogues.

In this study, we have shed some light on the relation between the position of the lower consolute boundary of various nonionic surfactants in water and the structure of the mesoporous silica materials synthesized from these surfactants-based systems. In the first part, the lower consolute boundary was shifted by adding salts. Depending on the features of the phase diagram, we have looked for either a salting out or a salting in effect. Mesoporous materials were prepared from a micellar solution of the investigated surfactants. Results clearly evidenced that the cooperative self-assembly mechanism is not favored if the lower consolute boundary is not shifted toward high temperatures. Moreover, the higher the difference between the phase separation temperature and the temperature at which the silica precursor is added to the surfactant solution, the better the mesopore ordering is. In the second part, this tendency has been confirmed by using a hydrogenated surfactant as additive.

This work deals with the design of a lipo-polysaccharidic system as a micrometric assembly between solid lipid nanoparticles (SLNs) and a biopolymer. The aim is to formulate a vector can: carry a hydrophobic active molecule, resist to gastric conditions, and allow a controlled release in specific conditions. Choosing the active molecule is carried on a polyphenol, curcumin, for its antioxidant and anti-inflammatory activities. Being hydrophobic, curcumin was encapsulated in shea butter nanoparticles, which is a natural lipid and solid at room temperature. Lipid nanocarriers are not resistant to gastric conditions; the nanoparticles have been included in a chitosan matrix in the form of a micrometric assembly controlled by electrostatic interactions. This natural polymer, positively charged due to the presence of amine groups, is resistant to attack by gastric enzymes and has specific interaction with the intestinal mucosa and in particular the mucin which can be useful as a carrier for curcumin in colon targeted drug delivery. The first part of this study focused on shea butter–curcumin system with the absence of chitosan. The effect of polyphenols on the lipid crystallization was studied. The influence of the composition of the ternary mixture (shea butter, surfactant, water) on the properties of the nanoparticles was then investigated by using the response surface methodology. This helped to control the size of SLNs and then to show the influence of particle size on the encapsulation efficiency of curcumin. The second part focuses on the assembling between the nanoparticles and chitosan. Micrometric particles were obtained through electrostatic interactions between SLNs encapsulated curcumin and chitosan, Ce travail porte sur la conception d'un système lipo-polysaccharidique sous forme d'un assemblage de taille micrométrique entre des nanoparticules lipidiques solides (SLNs) et un biopolymère. Le but est de formuler un vecteur pouvant : transporter un principe actif hydrophobe, résister aux conditions gastriques, et permettre un relargage contrôlé en conditions spécifiques. Le choix de la molécule active s'est porté sur un polyphénol, la curcumine, pour ses activités anti-oxydantes et anti-inflammatoires. Etant hydrophobe, la curcumine a été encapsulée dans des nanoparticules de beurre de karité qui est un lipide d'origine naturelle et solide à température ambiante. Les systèmes lipidiques ne résistant pas aux conditions gastriques, les nanoparticules ont été incluses dans une matrice de chitosane sous forme d'un assemblage micrométrique contrôlé par des interactions électrostatiques. Ce polymère naturel, chargé positivement grâce à la présence de groupements amines, résiste aux attaque des enzymes gastriques et présente des interactions spécifiques avec la muqueuse intestinale et notamment les mucines permettant ainsi un ciblage vers l'intestin et le côlon. La première partie de cette étude est focalisée sur le système beurre de karité-curcumine en absence de chitosane. L'effet du polyphénol sur la cristallisation du lipide a tout d'abord été étudié. L'influence de la composition du mélange ternaire (beurre de karité, tensioactif, eau) sur les propriétés des nanoparticules formées a ensuite été étudiée en utilisant la méthodologie des plans de mélanges. Cela a permis de contrôler la taille des SLNs formulées et de mettre ensuite en évidence l'influence de la taille des particules sur le taux d'encapsulation de la curcumine. La seconde partie est axée sur l'assemblage entre les nanoparticules et le chitosane. Des particules micrométriques ont ainsi été obtenues par interactions électrostatiques entre les SLNs encapsulant la curcumine et stabilisées par des phospholipides et le chitosane

This work deals with the design of a lipo-polysaccharidic system as a micrometric assembly between solid lipid nanoparticles (SLNs) and a biopolymer. The aim is to formulate a vector can: carry a hydrophobic active molecule, resist to gastric conditions, and allow a controlled release in specific conditions. Choosing the active molecule is carried on a polyphenol, curcumin, for its antioxidant and anti-inflammatory activities. Being hydrophobic, curcumin was encapsulated in shea butter nanoparticles, which is a natural lipid and solid at room temperature. Lipid nanocarriers are not resistant to gastric conditions; the nanoparticles have been included in a chitosan matrix in the form of a micrometric assembly controlled by electrostatic interactions. This natural polymer, positively charged due to the presence of amine groups, is resistant to attack by gastric enzymes and has specific interaction with the intestinal mucosa and in particular the mucin which can be useful as a carrier for curcumin in colon targeted drug delivery. The first part of this study focused on shea butter–curcumin system with the absence of chitosan. The effect of polyphenols on the lipid crystallization was studied. The influence of the composition of the ternary mixture (shea butter, surfactant, water) on the properties of the nanoparticles was then investigated by using the response surface methodology. This helped to control the size of SLNs and then to show the influence of particle size on the encapsulation efficiency of curcumin. The second part focuses on the assembling between the nanoparticles and chitosan. Micrometric particles were obtained through electrostatic interactions between SLNs encapsulated curcumin and chitosan, Ce travail porte sur la conception d'un système lipo-polysaccharidique sous forme d'un assemblage de taille micrométrique entre des nanoparticules lipidiques solides (SLNs) et un biopolymère. Le but est de formuler un vecteur pouvant : transporter un principe actif hydrophobe, résister aux conditions gastriques, et permettre un relargage contrôlé en conditions spécifiques. Le choix de la molécule active s'est porté sur un polyphénol, la curcumine, pour ses activités anti-oxydantes et anti-inflammatoires. Etant hydrophobe, la curcumine a été encapsulée dans des nanoparticules de beurre de karité qui est un lipide d'origine naturelle et solide à température ambiante. Les systèmes lipidiques ne résistant pas aux conditions gastriques, les nanoparticules ont été incluses dans une matrice de chitosane sous forme d'un assemblage micrométrique contrôlé par des interactions électrostatiques. Ce polymère naturel, chargé positivement grâce à la présence de groupements amines, résiste aux attaque des enzymes gastriques et présente des interactions spécifiques avec la muqueuse intestinale et notamment les mucines permettant ainsi un ciblage vers l'intestin et le côlon. La première partie de cette étude est focalisée sur le système beurre de karité-curcumine en absence de chitosane. L'effet du polyphénol sur la cristallisation du lipide a tout d'abord été étudié. L'influence de la composition du mélange ternaire (beurre de karité, tensioactif, eau) sur les propriétés des nanoparticules formées a ensuite été étudiée en utilisant la méthodologie des plans de mélanges. Cela a permis de contrôler la taille des SLNs formulées et de mettre ensuite en évidence l'influence de la taille des particules sur le taux d'encapsulation de la curcumine. La seconde partie est axée sur l'assemblage entre les nanoparticules et le chitosane. Des particules micrométriques ont ainsi été obtenues par interactions électrostatiques entre les SLNs encapsulant la curcumine et stabilisées par des phospholipides et le chitosane