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Researchers showed that microplastics from our waste are dispersed in water by proteins adsorbed to their surface. This discovery opens the way to low-tech strategies for collecting them. Plastic waste scattered in nature breaks up into invisible particles of micrometric or nanometric size. Because scientists do not yet know their physical and chemical properties and their biological interactions, they cannot fully assess the environmental impact of this diffuse pollution. In nature, microplastics quickly become coated with molecules of biological origin. How do these biomolecules modify their behaviour? To find out, research teams from CEA, IMMM, UPC, and Soleil Synchrotron in France, have studied microplastics in water to understand the role of the protein corona on their stability. The most persistent microplastics in the environment, polyethylene and polypropylene (5 and 10 µm in diameter), were chosen for this study. In the absence of proteins, buoyancy and capillary forces tend to gather the microplastics towards the surface ('creaming') and very few particles remain in solution. In the presence of proteins, hydrophobic microplastics become hydrophilic and can diffuse in water. In addition, this protein corona prevents agglomeration and stabilises microplastics suspensions in water. Taking advantage of this effect, size fractions of stabilized microplastics could be prepared for toxicological screening using a protein corona formed with a well-known protein, serum albumin. Alternatively, it is also possible to destabilise the protein corona surrounding the microplastics, either by adding a salt, which induces protein precipitation, or by heating, which results in protein aggregation. In both cases, 95% of the microparticles were removed from water by creaming after 24 hours. Heat treatment could be used to purify water to make it drinkable, where industrial depollution facilities are lacking

A new methodology is presented to covalently graft polyisoprene from natural or recycled rubber on hydroxylated and silicon-containing surfaces. For this purpose, we first synthesized novel functional telechelic oligomers from natural rubber, bearing a hydroxyl group at one chain end and a silane group at the other, which allowed their direct tethering on silicon-based and other materials. As alternative approach, we also synthesized bi-functional telechelic oligomers with a ketone and an aldehyde end-moieties and they reacted selectively with surface amino groups, introduced via a pre-functionalization step using commercial amino-alkoxysilanes. A high glass surface coverage density was reached and the oligoisoprenes free chain-ends were converted to acrylate functions, to possibly grow more polymer or to engage a photopolymerization process with other bio-based acrylate-terminated telechelic oligoisoprenes, in order to obtain thick films. In this way, ultra-thin oligomer layers, copolymer brushes, as well as grafted films and bulk materials were formed and characterized at sub-nanometer resolution using X-rays Reflectivity. A strong covalent grafting of polyisoprene coatings was achieved and resisted to long immersions in water and aggressive organic solvents under strong mechanical agitation. The robust molecular, thin films, and bulk sheathings are versatile polymeric constituents and represent a new family of sustainable coatings.

International audience; The continuous production of drug delivery systems assisted by microfluidics has drawn a growing interest because of the high reproducibility, low batch-to-batch variations, narrow and controlled particle size distributions and scale-up ease induced by this kind of processes. Besides, microfluidics offers opportunities for high throughput screening of process parameters and the implementation of process characterization techniques as close to the product as possible. In this context, we propose to spotlight the GALECHIP concept through the development of an instrumented microfluidic pilot considered as a Galenic Lab-on-a-Chip to formulate nanomedicines, such as lipid nanocapsules (LNCs), under controlled process conditions. In this paper we suggest an optimal rational development in terms of chip costs and designs. First, by using two common additive manufacturing techniques, namely fused deposition modelling and multi-jet modelling to prototype customized 3D microfluidic devices (chips and connectors). Secondly, by manufacturing transparent Silicon (Si)/Glass chips with similar channel geometries but obtained by a new approach of deep reactive ion etching (DRIE) technology suitable with in situ small angle X-ray scattering characterizations. LNCs were successfully produced by a phase inversion composition (PIC) process with highly monodispersed sizes from 25 nm to 100 nm and formulated using chips manufactured by 3D printing and DRIE technologies. The transparent Si/Glass chip was also used for the small angle X-ray scattering (SAXS) analysis of the LNC formulation with the PIC process. The 3D printing and DRIE technologies and their respective advantages are discussed in terms of cost, easiness to deploy and process developments in a GALECHIP point of view.

We describe a bottom-up surface functionalization to design hybrid molecular coatings that tether biomembranes using wet chemistry. First, a monolayer was formed by immersion in a NH2-Ar-SO3H solution, allowing aryldiazonium salt radicals to spontaneously bind to it via strong C bonding. After formation of the air-stable and dense molecular monolayer (–Ar-SO3H), a subsequent activation was used to form highly reactive –Ar-SO2Cl groups nearly perpendicular to the monolayer. These can bind commercial surfactants, PEGylated oligomers and other inexpensive molecules via their -OH, -COOH, or -NH2 chain end-moieties, to build hybrid coatings. Metal and oxidized chromium, semi-conductor n-doped silicon (111), are the substrates tested for this protocol and the aromatic organic monolayers formed at their surface are characterized by X-ray photoelectron spectroscopy (XPS). XPS reveals unambiguously the presence of C–Cr and C–Si bonds, ensuring robustness of the coatings. Functional sulfur groups (–SO3H) cover up to 6.5×10−10 mol cm−2 of the silicon interface and 4.7×10−10 mol cm−2 of the oxidized chromium interface. These surface concentrations are comparable to the classic values obtained when the prefunctionalisation is driven by electrochemistry on conductors. Tethered lipid membranes formed on these coatings were analyzed by neutron reflectivity at the interface of functionalized n-doped silicon substrates after immersion in a solution of lipid vesicles and subsequent fusion. Results indicate a rather compact hybrid coating of Brij anchor-harpoon molecules that maintain a single lipid bilayer above the substrate, on top of a hydrated PEO cushion.

International audience; The choice of materials used in the chip fabrication is crucial in microfluidics. They are selected and adapted depending on the available production techniques and associated processes, the involved characterization and measurement methods, the physical and chemical experimental conditions, and the cost. Here, we propose a versatile approach using a combination of epoxy materials to fabricate manually resealable and reusable (>40 times) microfluidic chips which demonstrate numerous potentialities: good chemical resistance, optical (visible and X-ray) transparency, biocompatibility, capability to undergo in average 2.9 bar of liquid pressure, or integration of high aspect ratio (>1500) channels. It thus represents a promising alternative for prototyping in a large panel of applications and fundamental studies.

В роботі розглянуто сенсор бета-лактоглобуліну з удосконаленою методикою вимірювання. Як основного алергену молока. Бета-лактоглобулін (БЛГ) використовується як основний біомаркер для аналізу коров’ячого молока. Запропоновано структуру сенсора з нанокристалічним оксидом церію в якості підзатворного діелектрика та удосконаленим методом вимірювання. Він полягає в використанні мікропотокової системи, що забезпечує постійний об’єм досліджуваної речовини для динамічного аналізу білка бета-лактоглобуліну - основного алергену молока. Запропонований сенсор був виготовлений на основі іон-селективного польового транзистора з польовим ефектом (IСПT) з p-каналом. Транзистор був виготовлений на кремнієвій пластині, легованій фосфором (n-тип), питомий опір 4,5 Ом/m^2, орієнтацією (111) та товщиною 450 мкм. В роботі проаналізовано вплив освітленості на результати експерименту та ступінь очищення поверхні датчика між кожним вимірюванням. Оскільки існуючий метод ІФА занадто довгий (1,5 години), а запропонований спосіб дозволяє виявити наявність бета-лактоглобуліну протягом декількох хвилин. Отримані результати відкривають перспективи використання запропонованих сенсорних та методів у технологіях виробництва дієтичних продуктів та експрес-аналізу. Запропонований підхід дозволяє аналізувати динамічні характеристики біосенсора з точки зору характерних рівнів сигналу ІСПТ на початку і у кінці часового інтервалу, що дає можливість оцінювати ступінь десорбції білка з поверхні. Це, у свою чергу, свідчить про властивості сенсора щодо відновлюваності та можливості його повторного використання. Отримані результати щодо впливу освітлення на відгук сенсора свідчать про необхідність поміщати робочу область сенсора у світлонепроникний бокс. Запропонована методика дозволяє здійснювати вимірювання рівнів бета-лактоглобуліну у широкому діапазоні змін рН розчину. Достатньо малий час детектування білка бета-лактоглобуліну і можливість динамічного аналізу білка на основі запропонованої структури біосенсора відкриває перспективи його використання у технологіях виготовлення дієтичних продуктів харчування та експрес-аналізу. In this article sensor with improved measurement technique for the detection of milk allergens was developed. β-lactoglobulin (BLG) protein was used as the biomarker for cow milk detection. The structure of the sensor with nanocrystalline cerium oxide is proposed with an advanced measurement method, which consists of using a micro-flow system to provide a constant volume of the substance to be tested for the dynamic analysis of the beta-lactoglobulin protein, the major milk allergen. The influence of illumination on the experiment and the degree of cleaning of the sensor surface between each measurement are analyzed. Because the existing ELISA method is too long (1.5 hours), and the proposed method allows to identify the presence of beta-lactoglobulin in a few minutes. В роботе рассмотрено сенсор бета-лактоглобулина с усовершенствованной методикой измерения как основного аллергена молока. Бета-лактоглобулин (БЛГ) используется в качестве основного биомаркера для анализа качества коровьевого молока. Предложено структуру сенсора с нанокристалическим оксидом церия в качестве подзатворного диэлектрика та усовершенствованным методом измерения. Этот метод состоит в использовании микропоточной системы для обеспечения постоянного объема исследуемого вещества для динамического анализу белка бета-лактоглобулина - основного аллергена молока. Также проведено исследования влияния уровня освещения на результаты эксперимента та степень очистки поверхности сенсора между каждым измерением. Существующий ИФА метод требует много времени для проведения одного экспериментавалим (1,5 час.), а предложена методика позволяет идентифицировать наличие бета-лактоглобулина всего лишь за несколько минут.

International audience; Plastic debris are classified as a function of their size and recently a new class was proposed, the nanoplastics. Nano-sized plastics have a much greater surface area to volume ratio than larger particles, which increases their reactivity in aquatic environment, making them potentially more toxic. Only little information is available about their behavior whereas it crucially influences their toxicity. Here, we used dynamic light scattering (DLS) to explore the influence of environmental factors (fresh- and saltwater, dissolved organic matter) on the behavior (surface charge and aggregation state) of three different nano-polystyrene beads (50 nm), with (i) no surface functionalization (plain), (ii) a carboxylic or (iii) an amine functionalization. Overall, the positive amine particles were very mildly affected by changes in environmental factors with no effect of the salinity gradient (from 0 to 653 mM) and of a range 1–30 μg.L−1 and 1–10 μg.L−1 of organic matter in artificial seawater and ultrapure water, respectively. These observations are supposedly linked to a coating specificity leading to repulsive mechanisms. In contrast, the stability of the negatively charged carboxylic and plain nanobeads was lost under an increasing ionic strength, resulting in homo-aggregation (up to 10 μm). The increase in organic matter content had negligible effect on these two nanobeads. Analysis performed over several days demonstrated that nanoplastics formed evolving dynamic structures detected mainly with an increase of the homo-aggregation level. Thus, surface properties of given polymers/particles are expected to influence their fate in complex and dynamic aquatic environments.

Commercial surfactants, which are inexpensive and abundant, were covalently grafted to flat and transparent electrodes, and it appears to be a simple functionalization route to design biomembrane sensors at large-scale production. Sparsely tethered bilayer lipid membranes (stBLM) were stabilized using such molecular coatings composed of diluted anchor-harpoon surfactants that grab the membrane with an alkyl chain out of a PEGylated-hydrogel layer, which acts as a soft hydration cushion. The goal of avoiding the synthesis of complex organic molecules to scale up sensors was achieved here by grafting nonionic diblock oligomers (Brij58 = C xH2 x+1(OCH2CH2) nOH with x = 16 and n = 23) and PEO short chains ((OCH2CH2) nOH with n = 9 and n = 23) from their hydroxyl (-OH) end-moiety to a monolayer of -Ar-SO2Cl groups, which are easy to form on electrodes (metals, semiconducting materials, ...) from aryl-diazonium salt reduction. A hybrid molecular coating on gold, with scarce Ar-SO2-Brij58 and PEO oligomers, was used to monitor immobilization and fusion kinetics of DOPC small unilamellar vesicles (SUV) by both quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) techniques. Using flat and transparent thin chromium film electrodes, we designed biosensors to couple surface sensitive techniques for membranes, including X-ray reflectivity (XRR), atomic force microscopy (AFM) with subnanometer resolution, and optical microscopy, such as fluorescence recovery after photobleaching measurements (FRAP), in addition to electrochemistry techniques (cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS)). The advantages of this biomembrane-sensing platform are discussed for research and applications.

This paper presents the synthesis and biological activity of a new antimicrobial material based on natural rubber derived building blocks and an organic antibacterial monomer, covalently bound to the polymer network. This investigation focused on the synthesis of an original acrylate monomer bearing an organic biologically active moiety (a guanidinium group) and in its co-polymerization in presence of telechelic acrylate oligomers, prepared from polyisoprene. The cross-linked films obtained have been characterized by InfraRed Spectroscopy, contact angle, and thermal analyses. It was shown that no-leaching of the bioactive monomer occurred and that the material resisted to long water immersions. Polyisoprene coatings prepared from pure acrylate oligoisoprenes also showed a weak antimicrobial activity that was drastically increased by integrating the guanidinium monomer. Biological tests carried out with three strains of pathogenic bacteria (Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis) proved the strong activity of the coatings.

Well-defined high molar mass poly(1,4-butadiene)-g-poly(e-caprolactone) (PBu-g-PCL) graft copolymers were prepared through the grafting-from route by the combination of ring-opening metathesis polymerization (ROMP) and organocatalyzed ring-opening polymerization (ROP). The synthesis route relies on the ROMP of cis-4-benzyloxymethyl-3-hydroxymethylcyclobutene initiated by ruthenium-based Grubbs’ catalysts followed by organocatalyzed ROP of e-caprolactone initiated by the hydroxyl side groups of the backbone using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as the catalyst. The reported strategy provides PBu-g-PCL having a strictly poly(1,4-butadiene) backbone with the highest molar mass reported up to now (Mn > 106 g mol–1). Self-assembling properties of the resulting PBu-g-PCL graft copolymer were investigated using small-angle X-ray scattering (SAXS) in toluene solution and in the solid state.

International audience; Marine plastic pollution is a major environmental issue. Given their ubiquitous nature and small dimensions, ingestion of microplastic (MP) and nanoplastic (NP) particles and their subsequent impact on marine life are a growing concern worldwide. Transfers along the trophic chain, including possible translocation, for which the hazards are less understood, are also a major preoccupation. Effects of MP ingestion have been studied on animals through laboratory exposure, showing impacts on feeding activity, reserve depletion and inflammatory responses, with consequences for fitness, notably reproduction. However, most experimental studies have used doses of manufactured virgin microspheres that may not be environmentally realistic. As for most ecotoxicological issues, the environmental relevance of laboratory exposure experiments has recently been debated. Here we review constraints and priorities for conducting experimental exposures of marine wildlife to microplastics based on the literature, feedback from peer reviewers and knowledge gained from our experience. Priorities are suggested taking into account the complexity of microplastics in terms of (i) aggregation status, surface properties and interactions with organic and inorganic materials, (ii) diversity of encountered particles types and concentrations, (iii) particle bioavailability and distribution in experimental tanks to achieve reproducibility and repeatability in estimating effects, and (iv) strict experimental procedures to verify the existence of genuine translocation. Relevant integrative approaches encompass a wide spectrum of methods from -omics to ecophysiological approaches, includingmodeling, are discussed to provide novel insights on the impacts of MP/NP on marine ecosystems from a long-term perspective. Knowledge obtained in this way would inform stakeholders in such a way as to help them mitigate impacts of the micro- and nano-plastic legacy.

International audience; There has been an intense research effort in the last decades in the field of biofouling prevention as it concerns many aspects of everyday life and causes problems to devices, the environment, and human health. Many different antifouling and antimicrobial materials have been developed to struggle against bacteria and other micro- and macro-organism attachment to different surfaces. However the “miracle solution” has still to be found. The research presented here concerns the synthesis of bio-based polymeric materials and the biological tests that showed their antifouling and, at the same time, antibacterial activity. The raw material used for the coating synthesis was natural rubber. The polyisoprene chains were fragmented to obtain oligomers, which had reactive chemical groups at their chain ends, therefore they could be modified to insert polymerizable and biocidal groups. Films were obtained by radical photopolymerization of the natural rubber derived oligomers and their structure was altered, in order to understand the mechanism of attachment inhibition and to increase the efficiency of the anti-biofouling action. The adhesion of three species of pathogenic bacteria and six strains of marine bacteria was studied. The coatings were able to inhibit bacterial attachment by contact, as it was verified that no detectable leaching of toxic molecules occurred.

Grafting commercial surfactants appears to be a simple way to modify electrodes and conducting interfaces, avoiding the synthesis of complex organic molecules. A new surface functionalization route is presented to build surfactant coatings with monolayer thickness grafting molecules considered as nonreactive. A monolayer of -SO2Cl functions (from a p-benzenesulfonyl chloride) was first electrografted. It showed a high reactivity toward weak nucleophiles commonly found on surfactant end-moieties such as hydroxyl groups (-OH), and it was used to covalently graft the following: (1) nonionic diblock oligomers (Brij or CiEj, CxH2x + (OCH2CH2)nOH with x = 16 and n = 23 for Brij58, x = 16 and n = 10 for Brij C10, and x = 16 and n = 2 for Brij52); (2) poly(ethylene glycol) (PEG) short chains (PEO9 for (OCH2CH2)nOH with n = 9) and mixed formula. The surface modification due to these molecular coatings was investigated in terms of wetting properties and interfacial electrochemistry characteristics (charge transfer ...

The MegaJoule Laser (LMJ) for inertial confinement fusion experiments is currently in operation at CEA-CESTA in France. All the lenses are coated by an antireflective (AR) layer to optimize the light power transmission. This AR layer is manufactured by sol-gel process, a soft chemical process, associated with a liquid phase coating technique to realize thin film of metal oxide. These optical components are hardened into ammoniac vapors in order to mechanically reinforce the AR coating and to make them more handling. This hardening induces a thickness reduction of the layer so an increase of the stiffness and sometimes a crazing of the layer. As these optical components undergo a high-power laser beam, so, it is important to verify if the AR properties (optical and mechanical) influence the value of the threshold laser damage. A series of coated samples have been manufactured having variable elastic moduli to discuss this point. In that purpose, a homemade Laser Induced Damage Threshold (LIDT) setup has been developed to test the layers under laser flux. We describe the used methods and different results are given. Preliminary results obtained on several coated samples with variable elastic moduli are presented. We show that whatever are the elastic stiffness of the AR coating, an overall decrease of the threshold appears with no noticeable effect of the mechanical properties of the AR coatings. Some possible explanations are given.

International audience; Elaborating advanced nanomaterials based on the assembly of nanoparticles (NPs) is a versatile route for targeting and tuning a wide variety of properties like optical, magnetic, and electrical properties or sensing. This route usually employs a so-called soft chemistry which has the advantage of being quite cheap and transferable to an industrial level. However, getting quantitative information on the quality of the mechanical consolidation of the nanoparticle assembly (ordered or disordered) in a nondestructive manner is not often achieved, although it is crucial for applications and integration of materials in devices. Therefore, we present in this Article a complete method where we evaluate the elasticity of weakly (van der Waals nanocontacts) to strongly (covalent-hydrogen nanocontacts) interacting nanoparticle assemblies. This complete work is realized on a disordered silica nanoparticle network obtained by the sol–gel method. A precise control of the chemical and physical properties of the nanoparticle surface molecular landscape is achieved thanks to infrared, visible, and ultraviolet spectroscopies as well as surface tension measurements and atomic force microscopy, while the nanoparticle assembly elastic stiffness is evaluated by ultrafast nanoacoustics based on an optical pump–probe method.

International audience; This paper describes how to quantify the scattering that appears in thin films deposited on a flat substrate. The defects appear during the deposition process and are hard to identify from classical optical microscopy pictures due to their small surface and contrast. A new way to probe the microroughness of optical components is described for heterogeneous or large samples (cm2) that requires a statistical analysis of each image over a full mapping of the sample. Due to possible optical misalignment or surface waviness, an automatic adjustment of the optical focus plane was implemented for each image during the surface mapping. In this way, we could measure the scattering using a microscope set-up. The results are linked to diffuse reflection and transmission losses (extinction coefficient k) and several different contributions from the total scattering are identified.

This article describes the synthesis and the evaluation of the biological activity of antibacterial bio-based elastomeric materials. The synthesis strategy relies on the photo-copolymerization of macromonomers containing an isoprenic repeating unit (obtained from Natural Rubber) and original monomers designed from Zosteric Acid scaffold (known for its antifouling activity) and covalently bound to the polymer network. The materials were obtained as cross-linked thick films and were characterized by InfraRed Spectroscopy, contact angle, and thermal analyses. No significant release of any bioactive substance was observed after immersions in water, confirming the non-leaching property. Biological assays were carried out with five strains of pathogenic bacteria and three strains of marine bacteria and the results highlighted the antibacterial and fouling release properties of these novel promising materials.

International audience; Asymmetric poly(ethylene oxide)-b-poly(ethyl acrylate) block copolymers bearing polymerizable (meth)acrylate groups at the end of the hydrophobic block were synthesized and self-assembled in water. The micellar structures were studied by static light scattering (SLS), dynamic light scattering (DLS) and small angle neutrons scattering (SANS). The micelles were checked to be dynamical and in a thermodynamic equilibrium. In order to stabilize the micelles, a photoinitiator was added and UV light was applied to initiate the cross-linking of micelles cores. Light scattering and SANS showed a very weak influence of the addition of the photoinitiator on the size and aggregation number of micelles. The photopolymerization takes place within a few seconds and the cross-linking process barely modifies the structural properties of the micelles. The efficiency of the core cross-linking was estimated in terms of (meth)acrylate double bonds conversion and rate of incorporation of unimers into the cross-linked structures. (1)H NMR showed a complete conversion of double bonds. Transmission electron microscopy (TEM), light and neutron scattering studies showed almost no modification of the structures, indicating that the exchange dynamics of unimers barely affects the structure during the cross-linking process. Size exclusion chromatography (SEC) analyses in DMF revealed a non-negligible amount of nonstabilized unimers. The crosslinked stars can be easily isolated from the remaining unimers by flash chromatography using hydrophobically modified silica gel.

Transparent gels prepared from an acid solution of TiOCl(2) in N,N-dimethylformamide (DMF) and water have been studied by small-angle X-ray scattering (SAXS). The sol-gel transformation of the titanium inorganic polymer was studied as a function of chemical composition of the sol and of the annealing time. Quantitative information was obtained by modeling the SAXS data with the Burford and Beaucage models. From the fits to the data, the radius of gyration of the primary particles, the so-called building blocks, the size xi of the homogeneous objects forming a fractal network in the gel, and the fractal dimension of the gel were obtained. We found fractal dimensions varying between D(f) = 1.75 and 2.2 and a radius of gyration of the building blocks equal to R(g) = 0.46 nm, which remained almost constant for all studied samples. The analysis of the homogeneous domain size xi as a function of the annealing time shows the existence of an incubation time preceding the rapid growth of the aggregates at high titanium concentration.

Using X-ray photon correlation spectroscopy, we studied the layer fluctuations in the lamellar phase of an ionic lyotropic system. We measured the relaxation rate of in-plane (undulation) fluctuations as a function of the wave vector. Static and dynamic results obtained during the same experiment were combined to yield the values of both elastic constants of the lamellar phase (compression and bending moduli) as well as that of the sliding viscosity. The results are in very good agreement with dynamic light scattering data, validating the use of the technique in ordered phases.

International audience; Charged surfactant bilayers deposited in thick multilayer films and swollen in vapor or in solution have been studied by coherent X-ray scattering. We report a pronounced static speckle pattern which persists under conditions of full hydration, despite the fact that the bilayers are fluid, relatively soft, and consisting of soluble amphiphiles (DDABr). Characteristic of the macroscopic domains size, the speckle pattern is observed in the plane of incidence (rocking curves). Contrarily, out-of-plane scans, which probe smaller lateral distances along the multilayer, exhibit a smooth diffuse scattering curve characteristic of thermal fluctuations of membranes. r Many phospholipids and synthetic surfactant bilayers spontaneously form lamellar phases in water. These stacks with a microstructure characteristic of smectic-A lyotropic liquid crystals are model systems for studying structure, interactions, and elasticity of membranes, which are of intense interest in soft matter and biophysical research. One central issue here is the role of thermal fluctuations, and more generally of collective motions in fluid membrane assemblies. In the past, X-ray scattering has been used extensively to study the collective motions such as bilayer undulations, assuming that the diffuse scattering around the lamellar Bragg peaks (on the diffuse sheets) reflects thermal diffuse scattering. Here, we use coherent reflectivity [1] as a sensitive test to see whether the diffuse scattering measured in a given range of wave vectors can fully be understood in terms of fluctuating membranes. For the scattering experiments on membrane multilayers, we have recently presented a new approach [2] illustrated in Fig. 1, which combines ARTICLE IN PRESS www.elsevier.com/locate/physb 0921-4526/$-see front matter r

Spherical polymeric micelles were formed in water by poly(ethylene oxide) end-capped with small hydrophobic chains. These star-like polymers showed dynamic arm exchange, but could be transformed into frozen star polymers by in situ UV irradiation. The effect of adding dynamic star polymers on the liquid–solid transition and crystallization of frozen star polymers was studied using small-angle X-ray scattering and rheology. Frozen star polymers produced with 112 arms showed a liquid–solid transition in dense suspensions that was only weakly modified when half of the polymers was replaced by dynamic star polymers. Frozen star polymers with 55 arms did not show a liquid–solid transition in dense suspensions, but the transition could be induced by replacement of a fraction of frozen star polymers with dynamic star polymers. The same effect could be obtained if a fraction of frozen star polymers with 55 arms was replaced with frozen star polymers with 112 arms. Dense binary suspensions of frozen star polymers ...

Self-assembled monolayers (SAMs) that contain fluorophore units are nowadays widely used to tune surface properties and design new chemical sensor chips. It is well-known that the nature of the substrate may strongly interfere with the emission properties of the grafted molecules, but the organization of the monolayer may also have an important role. To study the influence of the SAM organization on the luminescence properties, we prepared different coumarin-based derivatives endowed with tethered chains of different lengths and elaborated the corresponding SAMs on glass slides. Besides SAM structural characterizations by atomic force microscopy and X-ray reflectivity, we carried out contact angle measurements and applied the Van Oss-Chaudhury-Good theory, which was rarely used previously for self-assembled monolayers. As expected, by increasing the tethered chain length, a higher surface coverage, a higher degree of organization, and a stronger molecular packing were observed. However, it appears to facilitate the self-quenching process, and thus, this strongly affects the fluorescent properties of the SAMs.

The effect of dynamic arm exchange on the crystallization and the jamming of multiarm starlike polymers was studied using small angle x-ray scattering and rheology. Poly(ethylene oxide) end capped with a small hydrophobic chain formed spherical micelles in water. Dynamic arm exchange allowed rapid crystallization and caused a discontinuous liquid-solid transition in dense suspensions after cooling. It is shown here that this is caused by spontaneous fine-tuning of the number of arms per micelle (f). Elimination of arm exchange by in situ photo-cross-linking of the core did not influence the behavior when f was at the optimum value. However, suboptimal values of f inhibited crystallization and the liquid-solid transition.

By using digital video microscopy, we study the three-dimensional displacement of fluorescent colloidal particles that are located close to a water-air interface. Our technique takes advantage of the diffraction pattern generated by fluorescent spheres that are found below the focal plane of the microscope objective. By means of image analysis software, we are able to determine the spatial location of a few beads in a sequence of digital images, which allows us to reconstruct their trajectories. From their corresponding mean square displacements, we get the diffusion coefficients in the directions parallel and perpendicular to the interface. We find a qualitatively different kind of diffusion between the two directions, in agreement with theoretical predictions that are obtained from established models as well as our own proposals. Quite interesting, we observe the enhanced Brownian motion in the parallel direction.

Using the surface enhanced ellipsometric contrast microscopy, we follow the last stage of the spreading of egg phosphatidylcholine nanodroplets on a hydrophilic substrate in a humid atmosphere, focusing on the vanishing trilayer in terraced droplets reduced to coexisting monolayer and trilayer. We find that the line interface between them exhibits two coexisting states, one mobile and one fixed. From there, it is possible to elucidate the internal structure and the spreading mechanism of the stratified liquid in a case of asymmetric wetting, i.e., where the lipid film is made of an odd number of leaflets.

Model polymer nanocomposites based on geometrically well defined and protected Laponite particles dispersed in Poly(ethylene oxide) were investigated in order to improve the understanding of the filler dispersion effects on rheology by varying two experimental factors, namely preparation method and PEO matrix molecular weight. Preparation methods are divided into a solution dispersion and a melt dispersion by twin screw extrusion. The linear viscoelastic properties of the samples prepared by solution method revealed an elastic solid like behaviour at Laponite weight fractions as low as 0.1%, dramatically lower than the percolation threshold so far reported for such kind of systems. The sample preparation by melt dispersion, although leading to dispersed particles, does not achieve the same levels of modulus as compared to solution prepared mixtures. We propose a qualitative interpretation of this phenomenon, based on the mixture between a liquid and a dispersed phase of rather solid character. Further experiments using small angle X-ray scattering techniques (SAXS) show that the modulus level is not necessarily related to the height of the correlation peak characteristic of the Laponite stacks. However, for samples prepared with varying PEO matrix molecular weight the fraction of Laponite stacks decreases with increasing PEO molecular weight. The rheology master curve analyses show that confinements of polymer chains arising from high concentrations of particles and high molecular weight matrix chains do not impact the level of the low frequency modulus. However, a slower polymer dynamics, as observed for higher molecular weights, leads to an increase of the modulus at low particle loadings.

Aqueous solutions of globular proteins gel after heat-induced denaturation. The structure of β-lactoglobulin gels was studied as a function of the pH (2–8) and the NaCl concentration (0–1 M) over a wide range of length scales (1 nm-100 µm) using a combination of scattering techniques and microscopy. The gel structure depended on the strength of the electrostatic interaction that was varied by changing the charge density of the proteins (pH) or the screening length (ionic strength). Homogeneous so-called finely stranded gels were formed at strong interaction, while more heterogeneous so-called particulate gels were formed at weak interaction. It is shown that phase separation of growing irreversibly bound protein aggregates explains the abrupt transition between the two structures for small changes of the ionic strength or the pH. Phase separation was limited to the formation of protein rich domains with a radius of several microns that associated into the particulate gels. The structure of homogeneous gels is shown to be determined by the amplitude of the (critical) concentration fluctuations of protein aggregates that were frozen-in by gelation. The characteristic length scales of the homogeneous gels varied between about 20 nm and 1 µm.

The paper gives an overview on interactions between two opposing interfaces in liquids. The interfaces are either solid (two silica surfaces) or fluid (in foam films or in membrane stacks). The liquids are either simple ones (water or salty water) or contain polyelectrolytes. In the latter case, the confinement leads to a structuring of the polyelectrolytes which leads to oscillatory forces in addition to DLVO forces. The effect of interface properties on the interactions is studied by modification of interfaces. In case of solid interfaces, they are modified by the adsorption of polyelectrolyte multilayers, while fluid interfaces are varied by changing the amphiphile/polymer combination. With regard to the studied problem, different methods are used to study the interactions.

We have investigated the x-ray scattering signal of highly aligned multilayers of the zwitterionic lipid 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine containing pores formed by the antimicrobial peptide alamethicin as a function of the peptide/lipid ratio. We are able to obtain information on the structure factor of the pore fluid, which then yields the interaction potential between pores in the plane of the bilayers. Aside from a hard core with a radius corresponding to the geometric radius of the pore, we find a repulsive lipid-mediated interaction with a range of $\simeq 30$ {\AA} and a contact value of 2.4 $k_BT$. This result is in qualitative agreement with recent theoretical models.

International audience; We have investigated the structure, fluctuations and elasticity parameters of charged fluid membranes composed of didodecyldimethylammonium halide bilayers (DDAX) with different counterions (X = Cl− or Br−) by non-specular (diffuse) X-ray scattering. The samples have been prepared as highly aligned thick stacks on silicon support and have been swollen at controlled osmotic pressures. From line-shape analysis of the diffuse scattering, we can determine the fluctuation amplitudes of the membranes in the Łα phase and the characteristic correlation lengths. According to the Caillé model, the measured structural parameters have been expressed in terms of the exponent η and smectic penetration length λ, from which the smectic compression modulus B (J/m3) and the bending modulus K (J/m) have been determined, as a function of the swelling state. We show that the results are in quantitative agreement with the mean-field electrostatic Poisson-Boltzmann calculations, controlled by the bilayers surface charge density (surfactant head groups with free or condensed counterions).

The structure and fluctuations of the swollen L(alpha) lamellar phase of highly charged surfactant didodecyldimethylammonium halide fluid bilayers (DDA+X-) are studied using high-resolution small-angle x-ray scattering and medium-resolution, high-contrast small-angle neutron-scattering. The Caille parameter eta, as a function of the swelling (L(alpha) periodicity d), was determined from the full q-range fits of the measured scattering profiles for three different counterions (X- = Cl-, Br-, and NO3-). This parameter quantifies the amplitude of the membrane fluctuations within the Landau-de Gennes smectic-A linear elasticity theory. The different anions used gave strong specific effects at the maximum swelling of the L(alpha) phase, while at lower swellings a two-phase coexistence of swollen and collapsed lamellae (d approximately 30 and approximately 80 angstroms) was observed for bromide and nitrate ions. Over the intermediate dilution range for all three counterions, a single L(alpha) phase can be continuously swollen with pure water which is governed by an equation of state (i.e., osmotic pressure versus period) and thermally excited fluctuation amplitudes that can be well described by the same Poisson-Boltzmann calculation. The membranes were found to be slightly stiffer than predicted by purely electrostatic repulsions, and this is tentatively attributed to an extra bending rigidity contribution from the surfactant chains.

The agent responsible for the recent severe acute respiratory syndrome (SARS) outbreak is a previously unidentified coronavirus. While there is a wealth of epidemiological studies, little if any molecular characterization of SARS coronavirus (SCoV) proteins has been carried out. Here we describe the molecular characterization of SCoV E protein, a critical component of the virus responsible for virion envelope morphogenesis. We conclusively show that SCoV E protein contains an unusually short, palindromic transmembrane helical hairpin around a previously unidentified pseudo-center of symmetry, a structural feature which seems to be unique to SCoV. The hairpin deforms lipid bilayers by way of increasing their curvature, providing for the first time a molecular explanation of E protein's pivotal role in viral budding. The molecular understanding of this critical component of SCoV may represent the beginning of a concerted effort aimed at inhibiting its function, and consequently, viral infectivity.

International audience; In this review article we discuss the thin film analytical techniques of interface sensitive X-ray and neutron scattering applied to aligned stacks of amphiphilic bilayers, in particular phospholipid membranes in the fluid L α phase. We briefly discuss how the structure, composition, fluctuations and interactions in lipid or synthetic membranes can be studied by modern surface sensitive scattering techniques, using X-rays or neutrons as a probe. These techniques offer an in-situ approach to study lipid bilayer systems in different environments over length scales extending from micrometer to nanometer, both with and without additional membrane-active molecules such as amphiphilic peptides or membrane proteins.

We investigated the structure of the hydrophobic domain of the severe acute respiratory syndrome E protein in model lipid membranes by x-ray reflectivity and x-ray scattering. In particular, we used x-ray reflectivity to study the location of an iodine-labeled residue within the lipid bilayer. The label imposes spatial constraints on the protein topology. Experimental data taken as a function of protein/lipid ratio P/L and different swelling states support the hairpin conformation of severe acute respiratory syndrome E protein reported previously. Changes in the bilayer thickness and acyl-chain ordering are presented as a function of P/L, and discussed in view of different structural models.

Introduction: Continuous production of drug delivery systems (DDS) assisted by microfluidics has drawn a growing interest because of the high reproducibility, low batch-to-batch variation of formulations, narrow and controlled particle size distribution and scale-up facilities induced by this process. Besides, microfluidics offers opportunities for high throughput screening of process parameters and the implementation of Process Analytical Technologies (PAT) as close to the product as possible. In this context, we propose to spotlight the GALECHIP concept through the development of an instrumented microfluidic pilot considered as a Galenic Lab-on-Chip to formulate nanomedicines, such as lipid nanocapsules (LNC), under controlled process conditions which are essential to obtain DDS with controlled properties. Therefore, we propose (i) a parametric study of LNC formulation by microfluidics with 3D printed PEEK chips in order to rationally develop the formulation process of LNC and (ii) the in-operando Small Angle X-ray Scattering (SAXS) investigations with Silicon/Glass (Si/Glass) chips in order to understand the physicochemical mechanisms involved in the formation of LNC. Methods: LNC were produced by a phase inversion composition (PIC) process with own-developed microfluidic pilot and chips. LNC were characterized in terms of structure, size and polydispersity index (PDI). In operando SAXS characterizations of LNC were performed at the SOLEIL Synchrotron to study the PIC phenomenology. Results: A formulation chart with 28 compositions (different ratios of oil, surfactant and co-surfactant) allowing the formulation of LNC from 25 to 100 nm has been selected. A mixing plan has been conducted with the PEEK chip to assess the impact of flowrate (x5) and lipid fraction (x3) in a scale up perspective. Results show that above 60 nm a small size decrease is observed with the high flowrate. However, the high lipid fractions lead to similar results than initial formulation, but "unachieved" formulation obtained for a few compositions proves that a special attention must be given to the mixing zone design when increasing the lipid content. An in-operando study of the PIC process has been conducted for two formulations (25 and 50 nm) by SAXS measurements performed in different regions of interest of the Si/Glass chip (mixing point and after intermediates and last elbows). Results show the structure evolution of formed nano-objects, from reverse micelles to LNC. Conclusion: GALECHIP is a microfluidic tool contributing to (i) the pharmaceutical development and (ii) the implementation of PAT for process understanding. The whole project is done with the ultimate goal of "better understanding" and "better producing" in order to "better administer" future nano-DDS candidates.

This manuscript presents the synthesis of new elastomeric materials based on natural rubber derived building blocks and organic monomers having antifouling and/or antibacterial properties, covalently bound to the polymer network. Original acrylate monomers bearing an organic bioactive moiety (a Guanidinium group or Zosteric acid derivates) were synthesized and co-polymerized with telechelic acrylate oligomers from polyisoprene. No significant leaching of the bioactive monomers occurred and the material resisted to long water immersions. Freestanding films prepared from acrylate oligoisoprenes also showed a weak antibiofouling activity which was drastically increased by integrating the guanidinium and the Zosteric acid monomers. The coatings were active against several strains of pathogenic bacteria among which Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis and Staphylococcus epidermidis. In order to covalently graft oligoisoprenes to surfaces, new bifunctional oligoisoprenes bearing an alkoxy-silane end moiety were designed and coupled with silicon-containing materials. An alternative approach was followed by prefunctionalizing the surface with amino groups and by covalently grafting oligomers with carbonyl chain-ends. Post-polymerization from the surface free chain-ends resulted in a thick oligoisoprene coating with strong resistance to solvent immersion (water, THF). In this way, we were able to build dense and tethered molecular layers, thin films and thick coatings.; Ce manuscrit présente la synthèse de nouveaux matériaux élastomères dérivés du caoutchouc naturel et de monomères organiques possédant des propriétés antifouling et/ou antibactériennes, liés de manière covalente au réseau polymère. Des monomères acrylates originaux comportant un groupement bioactif (un groupe guanidinium ou des dérivés de l'acide Zostérique) ont été synthétisés et co-polymérisés avec des oligomères acrylates téléchéliques. Aucun relargage significatif des monomères bioactifs n’'a eu lieu après immersion dans l'eau. Les films auto-portés synthétisés uniquement à partir des oligoisoprènes de type acrylate ont montré une faible activité antibactérienne qui a pu être drastiquement améliorée en intégrant aux films des monomères bioactifs. Les revêtements se sont montrés actifs contre plusieurs souches de bactéries pathogènes, parmi lesquelles P.aeruginosa, S.aureus, Bacillus subtilis et S.epidermidis. Afin de greffer de manière covalente des brosses d'oligoisoprène sur des surfaces, de nouveaux oligoisoprènes bifonctionnels comportant un groupe terminal alkoxy-silane ont été préparés puis couplés avec des matériaux à base de silicium. Une autre approche a également été étudiée, consistant à pré-fonctionnaliser la surface avec des groupements amino puis à partir de ces fonctions à greffer des oligomères ayant des extrémités carbonylés. La post-polymérisation à partir des extrémités de chaîne libres à la surface a donné un revêtement épais d’'oligoisoprène offrant une forte résistance à l'immersion dans des solvants (eau, THF). De cette manière, nous avons pu accéder à des couches moléculaires denses et liées, à des films minces et à des revêtements épais.

This manuscript presents the synthesis of new elastomeric materials based on natural rubber derived building blocks and organic monomers having antifouling and/or antibacterial properties, covalently bound to the polymer network. Original acrylate monomers bearing an organic bioactive moiety (a Guanidinium group or Zosteric acid derivates) were synthesized and co-polymerized with telechelic acrylate oligomers from polyisoprene. No significant leaching of the bioactive monomers occurred and the material resisted to long water immersions. Freestanding films prepared from acrylate oligoisoprenes also showed a weak antibiofouling activity which was drastically increased by integrating the guanidinium and the Zosteric acid monomers. The coatings were active against several strains of pathogenic bacteria among which Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis and Staphylococcus epidermidis. In order to covalently graft oligoisoprenes to surfaces, new bifunctional oligoisoprenes bearing an alkoxy-silane end moiety were designed and coupled with silicon-containing materials. An alternative approach was followed by prefunctionalizing the surface with amino groups and by covalently grafting oligomers with carbonyl chain-ends. Post-polymerization from the surface free chain-ends resulted in a thick oligoisoprene coating with strong resistance to solvent immersion (water, THF). In this way, we were able to build dense and tethered molecular layers, thin films and thick coatings., Ce manuscrit présente la synthèse de nouveaux matériaux élastomères dérivés du caoutchouc naturel et de monomères organiques possédant des propriétés antifouling et/ou antibactériennes, liés de manière covalente au réseau polymère. Des monomères acrylates originaux comportant un groupement bioactif (un groupe guanidinium ou des dérivés de l'acide Zostérique) ont été synthétisés et co-polymérisés avec des oligomères acrylates téléchéliques. Aucun relargage significatif des monomères bioactifs n’'a eu lieu après immersion dans l'eau. Les films auto-portés synthétisés uniquement à partir des oligoisoprènes de type acrylate ont montré une faible activité antibactérienne qui a pu être drastiquement améliorée en intégrant aux films des monomères bioactifs. Les revêtements se sont montrés actifs contre plusieurs souches de bactéries pathogènes, parmi lesquelles P.aeruginosa, S.aureus, Bacillus subtilis et S.epidermidis. Afin de greffer de manière covalente des brosses d'oligoisoprène sur des surfaces, de nouveaux oligoisoprènes bifonctionnels comportant un groupe terminal alkoxy-silane ont été préparés puis couplés avec des matériaux à base de silicium. Une autre approche a également été étudiée, consistant à pré-fonctionnaliser la surface avec des groupements amino puis à partir de ces fonctions à greffer des oligomères ayant des extrémités carbonylés. La post-polymérisation à partir des extrémités de chaîne libres à la surface a donné un revêtement épais d’'oligoisoprène offrant une forte résistance à l'immersion dans des solvants (eau, THF). De cette manière, nous avons pu accéder à des couches moléculaires denses et liées, à des films minces et à des revêtements épais.

We explore the Brownian motion of colloids near different interfaces (water-air, water solid,…) using three dimensional digital video microscopy and reconstruction of singles colloids trajectories in 3D over time. Satisfying agreements between data and published theoretical models were found for simplest cases. In addition we propose a theoretical approach able to transit from the free interface configuration (water-air) to the bound condition (liquid-solid). We also considered within this frame the situation where a solid interface was functionalized with a grafted short alkyl chain (flat and hydrophobic fixed wall) to compare with same solid interface made hydrophilic from a UV-ozone plasma treatment that creates hydroxyl groups (Si-OH). From the stabilization of a phospholipid bilayer, we also studied colloidal and hydrodynamic interaction with a soft (DOPC in Lα) or freezed (DMPC at Lβ) biomimetic membrane covering the solid interface (SiO2 glass).; Le mouvement Brownien dans l’eau de colloïdes proches d’interfaces de différente nature (eau/air, eau/verre, …) est étudié en utilisant une technique de microscopie numérique permettant de reconstruire les trajectoires individuelles en trois dimensions. Des accords satisfaisants entre les trajectoires et les modèles théoriques publiés ont été trouvés pour les cas les plus simples. En outre, nous proposons une approche théorique capable de passer de la configuration d'interface libre (type eau-air) à l'état lié (type liquide-solide). Nous avons également considéré dans ce cadre la situation dans laquelle une interface solide a été fonctionnalisée et rendue hydrophobe pour comparer le mouvement Brownien près de l’interface avec la même interface solide rendue très hydrophile par un traitement au plasma UV-ozone qui crée des groupes hydroxyle (Si-OH ). Nous avons également étudié l'interaction colloïdale et hydrodynamique avec des interfaces recouvertes d’une membrane biomimétique phospholipidique molle (DOPC en phase fluide) ou gelée (DMPC en phase gel), toutes deux recouvrant le verre (SiO2).

We explore the Brownian motion of colloids near different interfaces (water-air, water solid,…) using three dimensional digital video microscopy and reconstruction of singles colloids trajectories in 3D over time. Satisfying agreements between data and published theoretical models were found for simplest cases. In addition we propose a theoretical approach able to transit from the free interface configuration (water-air) to the bound condition (liquid-solid). We also considered within this frame the situation where a solid interface was functionalized with a grafted short alkyl chain (flat and hydrophobic fixed wall) to compare with same solid interface made hydrophilic from a UV-ozone plasma treatment that creates hydroxyl groups (Si-OH). From the stabilization of a phospholipid bilayer, we also studied colloidal and hydrodynamic interaction with a soft (DOPC in Lα) or freezed (DMPC at Lβ) biomimetic membrane covering the solid interface (SiO2 glass)., Le mouvement Brownien dans l’eau de colloïdes proches d’interfaces de différente nature (eau/air, eau/verre, …) est étudié en utilisant une technique de microscopie numérique permettant de reconstruire les trajectoires individuelles en trois dimensions. Des accords satisfaisants entre les trajectoires et les modèles théoriques publiés ont été trouvés pour les cas les plus simples. En outre, nous proposons une approche théorique capable de passer de la configuration d'interface libre (type eau-air) à l'état lié (type liquide-solide). Nous avons également considéré dans ce cadre la situation dans laquelle une interface solide a été fonctionnalisée et rendue hydrophobe pour comparer le mouvement Brownien près de l’interface avec la même interface solide rendue très hydrophile par un traitement au plasma UV-ozone qui crée des groupes hydroxyle (Si-OH ). Nous avons également étudié l'interaction colloïdale et hydrodynamique avec des interfaces recouvertes d’une membrane biomimétique phospholipidique molle (DOPC en phase fluide) ou gelée (DMPC en phase gel), toutes deux recouvrant le verre (SiO2).

Lipid bilayers are the structural backbone of biological membranes and provide a two-dimensional environment for proteins. Tethered on a hydrophilic substrate, these biomimetic models are fluid, long-term stable and localized. In this regard, we propose a direct, cheap and versatile strategy of surface functionalization to tether membranes on a substrate adapted to their structural and dynamics study. The process is based on the functionalization of any flat metal thin film by the covalent binding of commercial surfactant molecules (Brij, …) as “anchor-harpoons”-like systems. Most of these molecules possess unresponsive –OH terminated groups on their hydrophilic moiety (anchor) that can bind a first organic layer by nucleophilic substitution. The opposite hydrophobic tail (harpoon) of the molecule can insert into the membrane and make it stable. An ideal mixing ratio of anchor-harpoons molecules with purely hydrophilic ones (PEG, …), provides the required hydration and density of anchors to the interface for tethering fluid membranes away from the substrate. A few nanometers distance enable ionic flows through the membrane and protein inclusion. The substrate conductivity enables studying ion dynamics facing the membrane by means of electrochemical impedance spectroscopy. Flatness and semi-transparency of the conductor opens the route to many other techniques’ including exalted light microscopy or fluorescence. Localized on electrodes, tethered bilayers further provide a biomimetic model and a support for biotechnology applications., Les bicouches lipidiques constituent l’architecture socle des membranes biologiques et l’environnement bidimensionnel de leurs protéines. Ancrées sur une interface hydrophile hydratée, ces systèmes conservent leur fluidité et sont localisés durablement près d’un substrat. Dans ce domaine, nous avons développé une stratégie de fonctionnalisation rapide, peu coûteuse et versatile, permettant la formation d’une membrane biomimétique fluide, ancrée sur des substrats conducteurs spécifiquement conçus pour son étude structurale et dynamique. La chimie de surface proposée forme une liaison covalente forte entre le substrat et des molécules commerciales amphiphiles (Brij, etc), utilisées comme système ancre-harpon. L’extrémité hydrophile (coté ancre) possédant un alcool primaire peu réactif est engagée sur une première couche organique par substitution nucléophile. L’autre extrémité hydrophobe (l’harpon) peut s’insérer dans la membrane et la stabiliser. Un mélange adapté, de ces molécules ancre-harpon avec d’autres purement hydrophiles (PEG, etc), apporte l’hydratation et la densité d’ancres nécessaire à l’interface pour maintenir la membrane éloignée du substrat, permettant ainsi l’intégration de protéines et le transport ionique à travers la membrane. Grâce au support conducteur, la dynamique des ions face aux membranes peut être étudiée par spectroscopie d’impédance électrochimique. Sa faible rugosité et semi-transparence permettent aussi l’utilisation de nombreuses autres techniques dont les microscopies optiques, exaltées ou de fluorescence. Localisées sur une électrode, ces bicouches ancrées s’ouvrent également aux applications biotechnologiques.