Probing the structural stability of R-phycocyanin under pressure.

The red macroalgae Porphyra, commonly known as Nori, is widely used as food around the world due to its high nutrient content, including the significant abundance of colored phycobiliproteins (PBPs). Among these, R-phycocyanin (R-PC) stands out for its vibrant purple color and numerous bioactive properties, making it a valuable protein for the food industry. However, R-PC's limited thermal stability necessitates alternative processing methods to preserve its color and bioactive properties.

Destructuration of Canola Protein Gels during In Situ Gastrointestinal Digestion Studied by X-ray Scattering.

We are studying the destructuration of canola protein gels, as a solid food model, during in situ gastrointestinal digestion using synchrotron small-angle X-ray scattering (SAXS). Digestion of two gels, prepared by heating pH 8 and pH 11 solutions, was carried out by diffusion of enzymatic juices into the gel from the top of the capillary and monitored for several tens of hours. Very similar time evolutions of SAXS curves occur at different positions of the gel in the capillary, with a delay determined by the distance from the surface initially in contact with the digestive juice.

Self-adhesion of uncrosslinked poly(butadiene--acrylonitrile), nitrile rubber, an inhomogeneous and associative polymer.

Nitrile rubber (, NBR) is a crosslinked copolymer of butadiene and acrylonitrile that finds widespread use in the automotive and aerospace industry as it sustains large, reversible deformations while resisting swelling by petrochemical fuels. We recently demonstrated that this material has a drift in composition due to the difference in reactivity between acrylonitrile and butadiene monomers during emulsion copolymerisation. Thus, although NBR is often thought of as a random copolymer, it does experience thermodynamic driving forces for self-assembly and kinetic barriers for processing like those of block copolymers.

Electroactive Bi-Functional Liquid Crystal Elastomer Actuators.

Liquid crystal elastomers (LCEs) with promising applications in the field of actuators and soft robotics are reported. However, most of them are activated by external heating or light illumination. The examples of electroactive LCEs are still limited; moreover, they are monofunctional with one type of deformation (bending or contraction).

In Situ Monitoring of Block Copolymer Self-Assembly via Solvent Exchange through Controlled Dialysis with Light and Neutron Scattering Detection.

Solution self-assembly of amphiphilic block copolymers (BCs) is typically performed by a solvent-to-water exchange. However, BC assemblies are often trapped in metastable states depending on the mixing conditions such as the magnitude and rate of water addition. BC self-assembly can be performed under near thermodynamic control by dialysis, which accounts for a slow and gradual water addition.

The effects of biliverdin on pressure-induced unfolding of apomyoglobin: The specific role of Zn ions.

Apomyoglobin (apoMb), a model protein in biochemistry, exhibits a strong propensity to bind various ligands, which makes it a good candidate as a carrier of bioactive hydrophobic drugs. The stability of its hydrophobic pocket determines its potential as a carrier of bioactive compounds. High pressure (HP) is a potent tool for studying protein stability, revealing the specific role of hydrophobic cavities in unfolding.

Exploring and strengthening the potential of R-phycocyanin from Nori flakes as a food colourant.

This study aimed to purify, characterise and stabilise the natural food colourant, R-phycocyanin (R-PC), from the red algae Porphyra spp. (Nori). We purified R-PC from dried Nori flakes with a high purity ratio (A/A ≥ 3.

Structure of proteins under pressure: Covalent binding effects of biliverdin on β-lactoglobulin.

High pressure (HP) is a particularly powerful tool to study protein folding/unfolding, revealing subtle structural rearrangements. Bovine β-lactoglobulin (BLG), a protein of interest in food science, exhibits a strong propensity to bind various bioactive molecules. We probed the effects of the binding of biliverdin (BV), a tetrapyrrole linear chromophore, on the stability of BLG under pressure, by combining in situ HP small-angle neutron scattering (SANS) and HP-UV absorption spectroscopy.

Large hybrid Polymer/Lipid Unilamellar vesicle (LHUV) at the nanoscale: An insight into the lipid distribution in the membrane and permeability control.

Membrane structuration of Large Hybrid Unilamellar Polymer/Lipid Vesicle (LHUV) is an important parameter on the optimization of their properties and thus their valuation in various fields. However, this kind of information is hardly accessible. In this work, we will focus on the development of LHUV obtained from the self-assembly of diblock poly(dimethylsiloxane)-b-poly(ethylene oxide) (PDMS-b-PEO) of different molar masses combined with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) at 15% and 25% w/w content.

Fluorescent polymer cubosomes and hexosomes with aggregation-induced emission.

Fluorescent polymer cubosomes and hexosomes with aggregation-induced emission (AIE) were prepared from amphiphilic block copolymers PEG--PTPEMA where the hydrophobic block PTPEMA was a polymethacrylate with tetraphenylethene (TPE) as the AIE side group. Four highly asymmetric block copolymers with hydrophilic block weight ratio ≤ 20% were synthesized. Cubosomes and hexosomes with strong fluorescence emission were obtained by nanoprecipitation of polymers with < 9% in dioxane/water and THF/water systems.

Direct Access to Polysaccharide-Based Vesicles with a Tunable Membrane Thickness in a Large Concentration Window via Polymerization-Induced Self-Assembly.

Polymersomes are multicompartmental vesicular nano-objects obtained by self-assembly of amphiphilic copolymers. When prepared in the aqueous phase, they are composed of a hydrophobic bilayer enclosing water. Although such fascinating polymeric nano-objects have been widely reported with synthetic block copolymers, their formation from polysaccharide-based copolymers remains a significant challenge.

Effect of Ligands on HP-Induced Unfolding and Oligomerization of β-Lactoglobulin.

To probe intermediate states during unfolding and oligomerization of proteins remains a major challenge. High pressure (HP) is a powerful tool for studying these problems, revealing subtle structural changes in proteins not accessible by other means of denaturation. Bovine β-lactoglobulin (BLG), the main whey protein, has a strong propensity to bind various bioactive molecules such as retinol and resveratrol, two ligands with different affinity and binding sites.

Effect of the microstructure of n-butyl acrylate/N-isopropylacrylamide copolymers on their thermo-responsiveness, self-organization and gel properties in water.

Hypothesis: Polymer composition, microstructure, molar mass, architecture… critically affect the properties of thermoresponsive polymers in aqueous media.

Experiments: The behaviour of n-isopropylacrylamide and n-butyl acrylate-based copolymers of variable composition and structure (statistical, diblock or triblock) was studied in solution at different temperatures and concentrations with turbidimetry measurements, differential scanning calorimetry, electronic microscopy, rheology and scattering experiments.

Findings: This study illustrates how it is possible through chemical engineering of the microstructure of amphiphilic thermoresponsive polymers to modulate significantly the self-assembly, morphological and mechanical properties of these materials in aqueous media.

On the Origin of the Anomalous Behavior of Lipid Membrane Properties in the Vicinity of the Chain-Melting Phase Transition.

Biomembranes are key objects of numerous studies in biology and biophysics of great importance to medicine. A few nanometers thin quasi two-dimensional liquid crystalline membranes with bending rigidity of a few kT exhibit unusual properties and they are the focus of theoretical and experimental physics. The first order chain-melting phase transition of lipid membranes is observed to be accompanied by a pseudocritical behavior of membrane physical-chemical properties.

Large and Giant Unilamellar Vesicle(s) Obtained by Self-Assembly of Poly(dimethylsiloxane)--poly(ethylene oxide) Diblock Copolymers, Membrane Properties and Preliminary Investigation of their Ability to Form Hybrid Polymer/Lipid Vesicles.

In the emerging field of hybrid polymer/lipid vesicles, relatively few copolymers have been evaluated regarding their ability to form these structures and the resulting membrane properties have been scarcely studied. Here, we present the synthesis and self-assembly in solution of poly(dimethylsiloxane)--poly(ethylene oxide) diblock copolymers (PDMS--PEO). A library of different PDMS--PEO diblock copolymers was synthesized using ring-opening polymerization of hexamethylcyclotrisiloxane (D3) and further coupling with PEO chains via click chemistry.

Self-Assembly of PEG--PTMC Copolymers: Micelles and Polymersomes Size Control.

Poly(ethylene glycol)--poly(trimethylene carbonate) PEG--PTMC diblock copolymers were synthesized with five different PTMC degrees of polymerization ( = 38, 96, 144, 170, 332) and their self-assembly properties in water were studied using a manual nanoprecipitation procedure. We confirmed that the copolymer's hydrophilic weight fraction () is controlling nanoparticles morphology. We determined that the PEG--PTMC with ≈ 17% is the optimal hydrophilic fraction for the stabilization of well-defined unilamellar vesicles with a membrane thickness of δ ≈ 14.

Embedding of superparamagnetic iron oxide nanoparticles into membranes of well-defined poly(ethylene oxide)-block-poly(ε-caprolactone) nanoscale magnetovesicles as ultrasensitive MRI probes of membrane bio-degradation.

The present study reports the preparation of poly(ethylene oxide)-block-poly(ε-caprolactone) (PEO-b-PCL) polymer vesicles via a nanoprecipitation method and the loading of two different size hydrophobically coated ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles (a magnetic core size of 4.2 nm and 7.6 nm) into the membrane of these nanovesicles, whose thickness was measured precisely by small angle neutron scattering (SANS).

A high pressure cell using metallic windows to investigate the structure of molecular solutions up to 600 MPa by small-angle neutron scattering.

We report on a high pressure (HP) cell designed for the determination of the structure of molecular solutions by small-angle neutron scattering (SANS). The HP cell is fitted up with two thick metallic windows that make the device very resistant under hydrostatic pressures up to 600 MPa (or 6 kbar). The metallic windows are removable, offering the possibility to adapt the HP cell to a given study with the pressure desired on an appropriate spatial range to study the structure of various molecular solutions by SANS.

Versatile oligo(ethylene glycol)-based biocompatible microgels for loading/release of active bio(macro)molecules.

The present study aims in the understanding of the effect of oligo(ethylene glycol)-based biocompatible microgels inner structure on the encapsulation/release mechanisms of different types of cosmetic active molecules. For that, multi-responsive microgels were synthesized using three types of cross-linkers: ethylene glycol dimethacrylate (EGDMA), oligo(ethylene glycol) diacrylate (OEGDA) and N,N-methylenebisacrylamide (MBA). The inner morphology of the microgels synthesized was studied by H-nuclear magnetic resonance (H NMR) and small-angle neutron scattering (SANS) techniques and no effect of cross-linker type on microgel microstructure was observed in the case of analysing purified microgel dispersions.

Self-Assembly of Stimuli-Responsive Biohybrid Synthetic- b-Recombinant Block Copolypeptides.

The synthesis and original thermoresponsive behavior of hybrid diblock copolypeptides composed of synthetic and recombinant polypeptides are herein reported. A thermoresponsive recombinant elastin-like polypeptide was used as a macroinitiator to synthesize a range of poly( l-glutamic acid)- block-elastin-like polypeptide (PGlu- b-ELP) diblock copolypeptides with variable PGlu block lengths. Their temperature-triggered self-assembly in water and in phosphate-buffered saline (PBS) was investigated at the macroscopic scale using complementary techniques such as turbidimetry, dynamic and static light scattering, small-angle neutron scattering, and at the molecular scale by H NMR and circular dichroism (CD).

Comb-Like Fluorophilic-Lipophilic-Hydrophilic Polymers for Nanocapsules as Ultrasound Contrast Agents.

Imaging the enhanced permeation and retention effect by ultrasound is hindered by the large size of commercial ultrasound contrast agents (UCAs). To obtain nanosized UCAs, triblock copolymers of poly(ethylene glycol)-polylactide-poly(1 H,1 H,2 H,2 H-heptadecafluorodecyl methacrylate) (PEG-PLA-PFMA) with distinct numbers of perfluorinated pendant chains (5, 10, or 20) are synthesized by a combination of ring-opening polymerization and atom transfer radical polymerization. Nanocapsules (NCs) containing perfluorooctyl bromide (PFOB) intended as UCAs are obtained with a 2-fold increase in PFOB encapsulation efficiency in fluorinated NCs as compared with plain PEG-PLA NCs thanks to fluorous interactions.

PEGylated nanocapsules of perfluorooctyl bromide: Mechanism of formation, influence of polymer concentration on morphology and mechanical properties.

PEGylated nanocapsules containing a liquid core of perfluorooctyl bromide (PFOB) were formulated by an emulsion-evaporation process to be further used as ultrasound contrast agents (UCAs). In an attempt to modulate their acoustic response, related to their shell thickness-to-radius ratio, the initial concentration of polymer was varied in the formulation. Indeed, thinner shells may lead to higher echogenicity.

The role of solvent swelling in the self-assembly of squalene based nanomedicines.

Squalene based nanoparticles obtained via nanoprecipitation are promising candidates as efficient anti-cancer drugs. In order to highlight their preparation process and to facilitate further clinical translation, the present study enlightens the paramount role of the solvent in the formation of these nanomedicines. Three different squalene-based nanoparticles, i.

Probing structure in submicronic aqueous assemblies of emulsified microemulsions and charged spherical colloids using SANS and cryo-TEM.

The spatial distribution of charged spherical colloids when used as stabilizers of phytantriol-based emulsified microemulsions (EME, L2 symmetry group) is investigated. The coverage of the lipid-based mesophases by the colloids is monitored using small-angle neutron scattering (SANS) in contrast matching conditions and visualized using cryogenic transmission electron microscopy (cryo-TEM) imaging. The results demonstrate that, despite the stability of the emulsion droplets, very few colloids are ever found on the droplets.

Polymersome shape transformation at the nanoscale.

Polymer vesicles, also named polymersomes, are valuable candidates for drug delivery and micro- or nanoreactor applications. As far as drug delivery is concerned, the shape of the carrier is believed to have a strong influence on the biodistribution and cell internalization. Polymersomes can be submitted to an osmotic imbalance when injected in physiological media leading to morphological changes.