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We elucidate the crucial role of the cetyl trimethylammonium bromide (CTAB) surfactant in the anisotropic growth mechanism of gold nano-bipyramids, nano-objects with remarkable optical properties and high tunability. Atomistic molecular dynamics simulations predict different surface coverages of the CTAB (positively charged) heads and their (bromide) counterions as function of the gold exposed surfaces. High concentration of CTAB surfactant promotes formation of gold nanograins in solution that work as precursors for the smooth anisotropic growth of more elongated nano-bipyramidal objects. Nanobipyramids feature higher index facets with respect to nanorods, allowing higher CTAB coverages that stabilize their formation and leading to narrower inter-micelles channels that smooth down their anisotropic growth. Absorption spectroscopy and scanning electron microscopy confirmed the formation of nanograins and demonstrated the importance of surfactant concentration on driving the growth towards nano-bipyramids rather than nanorods. The outcome explains the formation of the monodisperse bipyramidal nano-objects, the origin of their controlled shapes and sizes along with their remarkable stability.

Injectable therapies for intervertebral disc (IVD) repair are gaining much interest. Recently, a chitosan (CH)-based injectable scaffold has been developed that has similar mechanical properties to human nucleus pulposus (NP) and provides a suitable environment for encapsulated NP cell survival and proteoglycan production. The hypothesis of the study was that the biological response of the encapsulated cells can be further increased by adding gelatine and Link N (LN, a naturally occurring peptide present in cartilage and IVD extracellular matrix), known to increase cell adhesion and proteoglycan production, respectively. The effect of gelatine on the mechanical properties of a CH hydrogel was evaluated through rheological and compressive mechanical tests. Production of proteoglycan [assessed as glycosaminoglycan (GAG)] by encapsulated NP cells was determined in the presence or absence of gelatine in normal or degenerative medium supplemented with LN. Normal and degenerative media replicate the healthy and degenerative disc environment, respectively. Gelatine slightly reduced the gelation rate of CH hydrogel but improved its final mechanical properties in compression. LN had a minimal effect in normal medium but induced significantly more GAG production in degenerative medium (p < 0.001, 4.7-fold superior to the control), reaching similar results to transforming growth factor (TGF)-β (used as a positive control). GAG production was further increased in CH-gelatine hydrogels, confirming an additive effect of LN and gelatine in a degenerative environment. The results supported the concept that CH-gelatine hydrogels supplemented with LN can help restore the function of the NP during the early stages of IVD degeneration.

Injectable hydrogels designed for cell therapy need to be adhesive to the surrounding tissues to maximize their retention and the communication between the host and the encapsulated cells. Catechol grafting is an efficient and well-known strategy to improve the adhesive properties of various polymers, including chitosan. However, catechol groups are also known to be cytotoxic as they oxidize into quinones in alkaline environments. Usually, hydrogels made from catechol-grafted chitosan (cat-CH) oxidize quickly, which tends to limit adhesion and prevent cell encapsulation. In this work, we limited oxidation and improved the cytocompatibility of cat-CH hydrogels by grafting chitosan with dihydroxybenzoic acid (DHBA), a small cat-bearing molecule known to have a high resistance to oxidation. We show that DHBA-grafted CH (dhba-CH) oxidized significantly slower and to a lesser extent that cat-CH made with hydrocaffeic acid (hca-CH). By combining dhba-CH with sodium bicarbonate and phosphate buffer, we fabricated thermosensitive injectable hydrogels with higher mechanical properties, quicker gelation and significantly lower oxidation than previously designed cat-CH systems. The resulting gels are highly adhesive on inorganic substrates and support L929 fibroblast encapsulation with high viability (≥90% after 24 hours), something that was not possible in any previously designed cat-CH gel system. These properties make the dhba-CH hydrogels excellent candidates for minimally invasive and targeted cell therapy in applications that require high adhesive strength.

International audience; Nowadays, little information is available regarding the N‐glycosylation pathway in the green microalga Chlamydomonas reinhardtii. Recent investigation demonstrated that C. reinhardtii synthesizes linear oligomannosides. Maturation of these oligomannosides results in N‐glycans that are partially methylated and carry one or two xylose residues. One xylose residue was demonstrated to be a core β(1,2)‐xylose. Recently, N‐glycoproteomic analysis performed on glycoproteins secreted by C. reinhardtii demonstrated that the xylosyltransferase A (XTA) was responsible for the addition of the core β(1,2)‐xylose. Furthermore, another xylosyltransferase candidate named XTB was suggested to be involved in the xylosylation in C. reinhardtii. In the present study, we focus especially on the characterization of the structures of the xylosylated N‐glycans from C. reinhardtii taking advantage of insertional mutants of XTA and XTB, and of the XTA/XTB double‐mutant. The combination of mass spectrometry approaches allowed us to identify the major N‐glycan structures bearing one or two xylose residues. They confirm that XTA is responsible for the addition of the core β(1,2)‐xylose, whereas XTB is involved in the addition of the xylose residue onto the linear branch of the N‐glycan as well as in the partial addition of the core β(1,2)‐xylose suggesting that this transferase exhibits a low substrate specificity. Analysis of the double‐mutant suggests that an additional xylosyltransferase is involved in the xylosylation process in C. reinhardtii. Additional putative candidates have been identified in the C. reinhardtii genome. Altogether, these results pave the way for a better understanding of the C. reinhardtii N‐glycosylation pathway.

International audience; The plasmonic features of gold nanomaterials provide intriguing optical effects which can find potential applications in various fields. These effects depend strongly on the size and shape of the metal nanostructures. For instance, Au bipyramids (AuBPs) exhibit intense and well-defined plasmon resonance, easily tunable by controlling their aspect ratio, which can act synergistically with chromophores for enhancing their photophysical properties. In Rose Bengal-nanoparticle systems it is now well established that the control of the dye-to-nanoparticle distance ranging from 10 to 20 nm as well as spectral overlaps is crucial to achieve appropriate coupling between the plasmon resonance and the dye, thus affecting its ability to generate singlet oxygen (1 O 2). We have developed AuBPs@mSiO 2 core-shell nanostructures that provide control over the distance between the metal surface and the photosensitizers for improving the production of 1 O 2 (metal-enhanced 1 O 2 production-ME 1 O 2). A drastic enhancement of 1 O 2 generation is evidenced for the resulting AuBPs and AuBPs@mSiO 2 in the presence of Rose Bengal, using a combination of three indirect methods of 1 O 2 detection, namely in operando Electron Paramagnetic Resonance (EPR) with 2,2,6,6-tetramethylpiperidine (TEMP) as a chemical trap, photooxygenation of the fluorescence probe anthracene-9,10-dipropionic acid (ADPA), and photooxygenation of methionine to methionine sulfoxide in a segmented flow microreactor.

Cell microencapsulation is a promising approach to improve cell therapy outcomes by protecting injected cells from rapid dispersion and allowing bidirectional diffusion of nutrients, oxygen, and waste that promote cell survival in the target tissues. Here, we describe a simple and scalable emulsification method to encapsulate animal cells in chitosan microbeads using thermosensitive gel formulations without any chemical modification and cross-linker. The process consists of a water-in-oil emulsion where the aqueous phase droplets contain cells (L929 fibroblasts or human mesenchymal stromal cells), chitosan acidic solution and gelling agents (sodium hydrogen carbonate and phosphate buffer or beta-glycerophosphate). The oil temperature is maintained at 37 °C, allowing rapid physical gelation of the microbeads. Alginate beads prepared with the same method were used as a control. Microbeads with a diameter of 300-450 μm were successfully produced. Chitosan and alginate (2% w/v) microbeads presented similar rigidity in compression, but chitosan microbeads endured80% strain without rupture, while alginate microbeads presented fragile breakage at50% strain. High cell viability and metabolic activity were observed after up to 7 days in culture for encapsulated cells. Mesenchymal stromal cells encapsulated in chitosan microbeads released higher amounts of the vascular endothelial growth factor after 24 h compared to the cells encapsulated in manually cast macrogels. Moreover, microbeads were injectable through 23G needles without significant deformation or rupture. The emulsion-generated chitosan microbeads are a promising delivery vehicle for therapeutic cells because of their cytocompatibility, biodegradation, mechanical strength, and injectability. Clinical-scale encapsulation of therapeutic cells such as mesenchymal stromal cells in chitosan microbeads can readily be achieved using this simple and scalable emulsion-based process.

International audience; Drought-induced dehydration of vegetative tissues in lycopods affects growth and survival. Different species of Selaginella have evolved a series of specialized mechanisms to tolerate desiccation in vegetative tissues in response to water stress. In the present study, we report on the structural characterization of the leaf cell wall of the desiccation-tolerant species S. involvens and two desiccation-sensitive species, namely S. kraussiana and S. moellendorffii. Isolated cell walls from hydrated and desiccated leaves of each species were fractionated and the resulting oligosaccharide fragments were analyzed to determine their structural features. Our results demonstrate that desiccation induces substantial modifications in the cell wall composition and structure. Altogether, these data highlight the fact that structural remodeling of cell wall hemicellulosic polysaccharides including XXXG-rich xyloglucan, arabinoxylan and acetylated galactomannan is an important process in order to mitigate desiccation stress in Selaginella.

A thermosensitive chitosan-based hydrogel was developed, which mimics the mechanical properties of the human nucleus pulposus (NP) tissue and provides a suitable environment for seeded NP cells to live and produce glycosaminoglycans. This scaffold is injectable through 25G needle and rapidly gels

The efficacy of cell therapy is limited by low retention and survival of transplanted cells in the target tissues. In this work, we hypothesize that pharmacological preconditioning with celastrol, a natural potent antioxidant, could improve the viability and functions of mesenchymal stromal cells (MSC) encapsulated within an injectable scaffold. Bone marrow MSCs from rat (rMSC) and human (hMSC) origin were preconditioned for 1 hour with celastrol 1 μM or vehicle (DMSO 0.1% v / v), then encapsulated within a chitosan-based thermosensitive hydrogel. Cell viability was compared by alamarBlue and live/dead assay. Paracrine function was studied first by quantifying the proangiogenic growth factors released, followed by assessing scratched HUVEC culture wound closure velocity and proliferation of HUVEC when cocultured with encapsulated hMSC. In vivo, the proangiogenic activity was studied by evaluating the neovessel density around the subcutaneously injected hydrogel after one week in rats. Preconditioning strongly enhanced the viability of rMSC and hMSC compared to vehicle-treated cells, with 90% and 75% survival versus 36% and 58% survival, respectively, after 7 days in complete media and 80% versus 64% survival for hMSC after 4 days in low serum media ( p < 0.05 ). Celastrol-treated cells increased quantities of proangiogenic cytokines compared to vehicle-pretreated cells, with a significant 3.0-fold and 1.8-fold increase of VEGFa and SDF-1α, respectively ( p < 0.05 ). The enhanced paracrine function of preconditioned MSC was demonstrated by accelerated growth and wound closure velocity of injured HUVEC monolayer ( p < 0.05 ) in vitro. Moreover, celastrol-treated cells, but not vehicle-treated cells, led to a significant increase of neovessel density in the peri-implant region after one week in vivo compared to the control (blank hydrogel). These results suggest that combining cell pretreatment with celastrol and encapsulation in hydrogel could potentiate MSC therapy for many diseases, benefiting particularly ischemic diseases.

Polysaccharides were extracted from seven plants endemic to Gabon to study their potential immunological activities. Peripheral blood mononuclear cell (PBMC) (5 × 105 cells/mL) proliferation, cytokine and immunoglobulin G (IgG) assays were performed after stimulation with different concentrations of polysaccharide fractions compared with lipopolysaccharides (LPS) and concanavalin A (ConA) from healthy volunteers. The culture supernatants were used for cytokine and IgG detection by enzyme-linked immunosorbent assay (ELISA). The results show that pectin and hemicellulose extracts from Uvaria klainei, Petersianthus macrocarpus, Trichoscypha addonii, Aphanocalyx microphyllus, Librevillea klaineana, Neochevalierodendron stephanii and Scorodophloeus zenkeri induced production levels that were variable from one individual to another for IL-12 (3–40 pg/mL), IL-10 (6–443 pg/mL), IL-6 (7–370 pg/mL), GM-CSF (3–170 pg/mL) and IFN-γ (5–80 pg/mL). Only hemicelluloses from Aphanocalyx microphyllus produce a small amount of IgG (OD = 0.034), while the proliferation of cells stimulated with these polysaccharides increased up to 318% above the proliferation of unstimulated cells. However, this proliferation of PBMCs was abolished when the pectin of some of these plants was treated with endopolygalacturonase (p < 0.05), but the trend of cytokine synthesis remained the same, both before and after enzymatic treatment or saponification. This study suggests that these polysaccharides stimulate cells in a structure-dependent manner. The rhamnogalacturonan-I (RGI) fragment alone was not able to induce the proliferation of PBMC. This study confirms the immunostimulatory properties of polysaccharides.

The current models developed to determine the pore water chemistry of clayrocks consider that Ca, Mg and Fe are controlled by equilibrium reactions with pure carbonates. However, the Ca/Mg ratios measured in pore water are not always in agreement with calculations. Here we investigated the interaction between calcite and dolomite at ambient temperature and at 80 °C. During batch experiments, despite the fast equilibration of the solution composition (within weeks), the gaseous CO2 concentration increased during several months at ambient temperature while it reached a steady state at 80 °C. The observations made at ambient temperature are apparently in conflict (metastable system). However, nanoscale characterizations proved to be useful to evidence a mineralogical evolution during the experiments. Indeed, local equilibria in solution enabled the precipitation of secondary phases despite their undersaturation with respect to the bulk solution and the dissolution of pristine phases. These results suggest that the dissolution/precipitation kinetics are slow and ongoing despite the apparent stability of the system, something usually not considered in the prediction of sedimentary facies over a geological timescale.

International audience; Neuroinflammation is a process common to several brain pathologies. Despites its medical relevance, it still remains poorly understood; there is therefore a need to develop new in vivo imaging strategies to monitor inflammatory processes longitudinally. We here present the development of a hybrid imaging nanoprobe named NP3, that was specifically designed to get internalized by phagocytic cells and imaged in vivo with MRI and bi-photon microscopy. NP3 is composed of a 16 nm core of gadolinium fluoride (GdF3), coated with bisphosphonate polyethylene glycol (PEG) and functionalized with a Lemke-type fluorophore (LEM-A). It has a hydrodynamic diameter of 28±8 nm and a zeta potential of-42±6 mV. The MR relaxivity ratio at 7T is r1/r2 = 20; therefore, NP3 is well suited as a T2/T2* contrast agent. In vitro cytotoxicity assessments performed on four human cell lines revealed no toxic effects of NP3. In addition, NP3 is internalized by macrophages in vitro without inducing inflammation or cytotoxicity. In vivo, uptake of NP3 has been observed in the spleen and the liver. NP3 has a prolonged vascular remanence, which is an advantage for macrophage uptake in vivo. The proof-of-concept that NP3 may be used as a contrast agent targeting phagocytic cells is provided in an animal model of ischemic stroke in transgenic CX3CR1-GFP/+ mice using three complementary imaging modalities: MRI, intravital two-photon microscopy and phase contrast imaging with synchrotron X-rays. In summary, 2 NP3 is a promising preclinical tool for the multiscale and multimodal investigation of neuroinflammation.

International audience; Microalgae are emerging production systems for recombinant proteins like monoclonal antibodies. In this context, the characterization of the host cell N-glycosylation machinery and of the microalgae-made biopharmaceuticals, which are mainly glycoprotein-based products, requires efficient analytical methodologies dedicated to the profiling of the N-glycans. Herein, in order to gain knowledge regarding its N-glycosylation pathway, we profile the protein N-linked oligosaccharides isolated from the diatom Phaeodactylum tricornutum that has been used successfully to produce functional monoclonal antibodies. The combination of ion mobility spectrometry–mass Spectrometry and electrospray ionization-multistage tandem mass spectrometry allows us to decipher the detailed structure of the oligomannoside isomers and to demonstrate that the processing of the oligomannosides N-linked to proteins occurs in this diatom as reported in mammals. Therefore, P. tricornutum synthesizes human-like oligomannosides in contrast to other microalgae species. This represent an advantage as an alternative ecofriendly expression system to produce biopharmaceuticals used for human therapy

International audience; In a waste management context, predicting the mobility of contaminants is essential. A key issue entails assessing the applicability of current knowledge on adsorption processes to natural systems. Such is the focus herein for nickel in interaction with Callovo-Oxfordian (COx) clay rock, a formation selected in France for possible radioactive waste disposal. The challenge is to link predictive modeling results with the experimental data characterizing the behavior of the labile and naturally occurring Ni fraction by implementing a new simple method. Retention studies on compact systems serve to complete this work. Combined electron microprobe and laser ablation high-resolution inductively coupled plasma mass spectrometry data show that natural Ni (∼39 mg kg–1) is homogeneously distributed within the clay matrix, which corresponds to the main reservoir (∼70%). Data interpretation of desorption tests yields an in situ Kd value of ∼80 L kg–1 and a labile Ni amount of ∼5 mg kg–1, that is, ∼13% of the Ni inventory. Predictive modeling explains the sorption data in considering that only weak clay fraction sites take part in the adsorption. The role of the clay matrix in Ni retention is confirmed by analyzing the Ni-spiked compact COx samples, whereby an increase of the Ni content in the clay fraction is observed following the retention experiment.

In this work, we propose a novel approach to design robust microfluidic devices with integrated plasmonic transducers allowing portability, reduced analysis time through dynamic measurements and high sensitivity. Specifically, the strategy we apply involves two steps: (i) the controlled deposition of gold bipyramidal nanoparticles (AuBPs) onto a functionalized solid glass substrate and (ii) the integration of the as-fabricated plasmonic substrate into a polydimethylsiloxane (PDMS) microfluidic circuit. The localized surface plasmon resonance (LSPR) sensitivity of the plasmonic-microfluidic device was evaluated by monitoring the optical responses at refractive index changes, proving a bulk sensitivity of 243 nm RIU-1 for the longitudinal LSPR band of isolated AuBPs and 150 nm RIU-1 for the band assigned to end-to-end linked nanoparticles. A strong electric field generated in the gaps between AuBPs-due to the generation of the so-called extrinsic 'hot-spots'-was subsequently proved by the volumetric surface enhanced Raman scattering (SERS) detection of molecules in continuous flow conditions by loading the analyte into the microfluidic channel via a syringe pump. In conclusion, our miniaturized portable microfluidic system aims to detect and identify, in real-time with high accuracy, analyte molecules in laminal flow, thus providing a groundwork for further complex biosensing applications.

A glycoluril-based molecular clip incorporating two tetrathiafulvalene (TTF) sidewalls has been synthesized using a straightforward Diels–Alder synthetic route and its ability to self-assemble with fullerene C60 in a 2 : 1 stoichiometry has been demonstrated in solution.

We investigated the mechanisms of interactions between divalent aqueous Hg and rock samples originating from an outcropping rock formation, the Albian Tegulines Clay (France, Aube). Two solid samples collected at two different depths (7.7 and 21.2 m depth) in the rock formation were selected since, in situ, they had and were still experiencing contrasting redox conditions, and thus had different mineralogy with regards to the minerals containing redox-sensitive elements, in particular iron. The sample that was the closer to the surface was under oxidizing conditions and contained goethite and siderite, while the deeper one was under reducing conditions and had more siderite, together with pyrite and magnetite. The redox state of the samples was preserved throughout the present study by careful conditioning, preparation, and use them under O2-free conditions. The two samples had similar affinity for Hg, with a retention coefficient (RD) ranging between 102 and 106 mol·kg−1 when the aqueous Hg concentration ranged between 4.4 and 107 ng·L−1 with the lowest concentration for the highest RD. However, the mechanisms of interaction differed. In the oxidized sample, no change in Hg redox state was observed, and the retention was due to reversible adsorption on the mineral phases (including organic matter). In contrast, upon interaction with the deeper and reduced sample, Hg was not only adsorbed on the mineral phases, but part of it was also reduced to dissolve elemental Hg. This reduction was attributed to magnetite and siderite and highlights the influence of mineralogy on the geochemical cycle of Hg.

Surface enhanced spectroscopies are proven to be highly efficient in biosensing applications. Their implementation as analytical tools in the detection of medically relevant target analytes demonstrated their ability to considerably decrease the minimum detected analyte concentration, thus showing improved sensitivity compared to commercially available detection kits. In this work, we propose the employment of Surface Enhanced Infrared Absorption (SEIRA), a less exploited analysis tool, for the efficient, specific, and ultrasensitive detection of the biotin-streptavidin recognition interaction using a gold nano-bipyramid-based (AuBPs) immunosensor. The unique optical properties of the AuBPs, such as tunability of the LSPR band ranging from the visible to NIR regions of the spectrum, great absorption capabilities and locally enhanced electromagnetic field at their tips and edges, enable an improved efficiency of the IR absorption of the target analytes. To the as-synthesized AuBPs, a chemically formed p-ATP@biotin recognition element was grafted due to the strong Au-S interaction, followed by the exposure of the obtained biotinylated nanosystem to the streptavidin target analyte. FT-IR experimental measurements as well as theoretical simulations confirm both the successful grafting of the p-ATP@biotin onto the Au surface and successful capture of the target streptavidin protein. A limit of detection of 10−12 M streptavidin concentration was determined, thus standing as a “proof-of-concept” for the development of efficient ultrasensitive SEIRA biosensing devices for more complex biologically relevant applications.

International audience; Samples of Albian Tégulines Clay outcropping near Brienne-le-Château in the eastern part of the Paris Basin were subjected to a geochemical characterization of organic matter (OM), combining OM bulk Rock-Eval analysis (RE), organic petrography and molecular analysis. In this study, the objective was to investigate the oxidation of natural organic matter in critical zone developed in early reduced marine clay formation. For that purpose, core samples from three boreholes crosscutting the Tégulines Clay formation down to the Greensands were selected. Several meters of Brienne marls preserved Tégulines Clay from atmosphere and therefore from high weathering and high oxidation in AUB240 borehole, whereas Tégulines Clay were weathered in their upper part in AUB1010 and in AUB230 boreholes as a result to their vicinity to the surface. The results showed that the Total Organic Carbon (TOC) contents in all clays are very low, ranging between 0.3 and 0.7 wt.%. The RE bulk data and Tmax parameter of OM in preserved Tégulines Clay indicate that the OM is immature. The organic petrography shows a predominance of gel-like amorphous OM preserved by natural sulphurisation in anoxic environments. Organic matter in Tégulines Clay from the AUB230 and AUB1010 boreholes show similar characteristics. The OM at the top of Tégulines Clay contains large amounts of oxidized lignocellulosic debris and has high RE Oxygen-Index values. In the first upper 10 m of the clays, the RE bulk, organic petrography and molecular data revealed oxidative events (high OI and high oxidized debris contents). Below 10 m, the OM is almost preserved. The OM in the reduced marine Tégulines Clay formation is very little functionalized and seems to be slightly reactive but not negligibly with the inorganic fractions in presence of oxygen.

In cassiterite, tin is associated with metals (titanium, niobium, tantalum, indium, tungsten, iron, manganese, mercury). Knowledge of mineral chemistry and trace-element distribution is essential for: the understanding of ore formation, the exploration phase, the feasibility of ore treatment, and disposal/treatment of tailings after the exploitation phase. However, the availability of analytical methods make these characterisations difficult. We present a multitechnical approach to chemical and structural data that includes scanning electron microscopy (SEM)-based imaging and microanalysis techniques such as: secondary and backscattered electrons, cathodoluminescence (CL), electron probe microanalyser (EPMA), electron backscattered diffraction (EBSD) and confocal Raman-imaging integrated in a SEM (RISE). The presented results show the complementarity of the used analytical techniques. SEM, CL, EBSD, EPMA provide information from the interaction of an electron beam with minerals, leading to atomistic information about their composition, whereas RISE, Raman spectroscopy and imaging completes the studies with information about molecular vibrations, which are sensitive to structural modifications of the minerals. The correlation of Raman bands with the presence/absence of Nb, Ta, Fe (heterovalent substitution) and Ti (homovalent substitution) is established at a submicrometric scale. Combination of the different techniques makes it possible to establish a direct link between chemical and crystallographic data of cassiterite.

International audience; Monolithic silica sol-gel glasses doped with platinum(II) acetylide complexes possessing respectively four or six phenylacetylene units (PE2-CH2OH and PE3-CH2OH) in combination with various concentrations of spherical and bipyramidal gold nanoparticles (AuNPs) known to enhance non-linear optical absorption, were prepared and polished to high optical quality. The non-linear absorption of the glasses was measured and compared to glasses doped solely with AuNPs, a platinum(II) acetylide with shorter delocalized structure, or combinations of both. At 532 nm excitation wavelength the chromophore inhibited the non-linear scattering previously found for glasses only doped with AuNPs. The measured non-linear absorption was attributed to reverse saturable absorption from the chromophore, as previously reported for PE2-CH2OH/AuNP glasses. At 600 nm strong nonlinear absorption was observed for the PE3-CH2OH/AuNPs glasses, also attributed to reverse saturable absorption. But contrary to previous findings for PE2-CH2OH/AuNPs, no distinct enhancement of the non-linear absorption for PE3-CH2OH/AuNPs was observed. A numerical population model for PE3-CH2OH was used to give a qualitative explanation of this difference. A stronger linear absorption in PE3-CH2OH would cause the highly absorbing triplet state to populate quicker during the leading edge of the laser pulse and this would in turn reduce the influence from two-photon absorption enhancement from AuNPs.

International audience; A five-year-old interface between a Low Alkali Concrete (LAC) formulation (CEM III/ B containing 66% slag and 10% nano-silica) and Opalinus Clay (OPA) from a field experiment at Mont Terri Underground Rock Laboratory in Switzerland (Jenni et al., 2014) has been studied to decipher the textural, mineralogical and chemical changes that occurred between the two reacting materials.Reactivity between LAC concrete and OPA is found to be limited to a similar to 1 mm thick highly porous (ca. 75% porosity) white crust developed on the concrete side. Quantitative mineralogical mapping of the white crust using an electron microprobe and infrared spectroscopy on the cement matrix provides evidence of a Mg-rich phase accounting for approximatively 25 wt % of the matrix associated with 11 wt % of calcite, calcium silicate hydrate (C-S-H) and other cement phases. EDX analyses and electron diffraction combined with transmission electron microscopy of the Mg-rich phase provide evidence for a tri-octahedral 2: 1 phyllosilicate with mean composition:(Ca-0.5 +/- 0.2) (Mg-2.0 +/- 0.4, Fe-0.2 +/- 0.1, Al-0.5 +/- 0.3,square(0.3 +/- 0.3)) (Al-0.9 +/- 0.2, Si-3.1 +/- 0.2) O-10 (OH)(2), where square represents vacancies in the octahedral site.Apart from this reactive contact, textural, mineralogical and chemical modifications at the contact with the LAC concrete are limited. OPA mineralogy remains largely unmodified. X-ray micro-fluorescence and EPMA mapping of major elements on the OPA side also provides evidence for a Mg-enriched 300-400 mu m thick layer. The cation exchange capacity (CEC) values measured in the OPA in contact with the LAC concrete range between 153 and 175 meq kg(-1) of dry OPA, close to the reference value of 170 +/- 10 meq kg(-1) of dry OPA (Pearson et al., 2003). Changing cation occupancies at the interface with LAC concrete are mainly marked by increased Ca, Mg and K, and decreased Na. Leaching tests performed on OPA with deionized water and at different solid to water ratios strongly suggest that Cl and SO4 have either conservative behaviour or are constrained by the solubility of a precipitated sulfate phase. The Cl and SO4 concentrations measured at 2 cm from the interface are close to concentrations of undisturbed OPA pore waters (SO4: 4.5 +/- 1.5 mmol kg(-1) of dry OPA; Cl: 7.5 +/- 2.1 mmol kg(-1)of dry OPA), and increase towards the interface with the concrete. The SO4 to Cl ratio also increases towards the interface, suggesting that the increasing anion concentrations are not related to porosity variations but rather to a concentration gradient and sulfate phase precipitation near the interface.

We experimentally investigate the extensional flow of a sheet – or curtain – of viscoelastic liquid falling freely from a slot at constant flow rate under gravity. Extruded liquids are aqueous solutions of flexible polyethylene oxide (PEO) and of semi-rigid partially hydrolysed polyacrylamide (HPAM) with low shear viscosities. Velocimetry measurements reveal that the mean velocity field $U(z)$ (where $z$ is the distance from the slot exit) does not reduce to a free fall. More precisely, we show that the liquid falls initially with sub-gravitational accelerations up to a distance from the slot which scales as $g\unicode[STIX]{x1D70F}_{fil}^{2}$ (where $g$ is gravity and $\unicode[STIX]{x1D70F}_{fil}$ is the extensional relaxation time of the liquid) due to the stretching of polymer molecules. Beyond this elastic length, inertia dominates and the local acceleration reaches the asymptotic free-fall value $g$. The length of the sub-gravitational part of the curtain is shown to be much larger than the equivalent viscous length $((4\unicode[STIX]{x1D702}/\unicode[STIX]{x1D70C})^{2}/g)^{1/3}$ for Newtonian liquids of density $\unicode[STIX]{x1D70C}$ and dynamic viscosity $\unicode[STIX]{x1D702}$ which is usually small compared to the curtain length. By analogy with Newtonian curtains, we show that the velocity field $U(z)$ rescales on a master curve. Besides, the flow is shown to be only weakly affected by the history of polymer deformations in the die upstream of the curtain. Furthermore, investigations on the curtain stability reveal that polymer addition reduces the minimum flow rate required to maintain a continuous sheet of liquid.

Background Protein N-glycosylation is initiated within the endoplasmic reticulum through the synthesis of a lipid-linked oligosaccharides (LLO) precursor. This precursor is then transferred en bloc on neo-synthesized proteins through the action of the oligosaccharyltransferase giving birth to glycoproteins. The N-linked glycans bore by the glycoproteins are then processed into oligomannosides prior to the exit of the glycoproteins from the endoplasmic reticulum and its entrance into the Golgi apparatus. In this compartment, the N-linked glycans are further maturated in complex type N-glycans. This process has been well studied in a lot of eukaryotes including higher plants. In contrast, little information regarding the LLO precursor and synthesis of N-linked glycans is available in microalgae. Methods In this report, a user-friendly extraction method combining microsomal enrichment and solvent extractions followed by purification steps is described. This strategy is aiming to extract LLO precursor from microalgae. Then, the oligosaccharide moiety released from the extracted LLO were analyzed by multistage tandem mass spectrometry in two models of microalgae namely the green microalgae, Chlamydomonas reinhardtii and the diatom, Phaeodactylum tricornutum. Results The validity of the developed method was confirmed by the analysis of the oligosaccharide structures released from the LLO of two xylosyltransferase mutants of C. reinhardtii confirming that this green microalga synthesizes a linear Glc3Man5GlcNAc2 identical to the one of the wild-type cells. In contrast, the analysis of the oligosaccharide released from the LLO of the diatom P. tricornutum demonstrated for the first time a Glc2Man9GlcNAc2 structure. Conclusion The method described in this article allows the fast, non-radioactive and reliable multistage tandem mass spectrometry characterization of oligosaccharides released from LLO of microalgae including the ones belonging to the Phaeodactylaceae and Chlorophyceae classes, respectively. The method is fully adaptable for extracting and characterizing the LLO oligosaccharide moiety from microalgae belonging to other phyla. Electronic supplementary material The online version of this article (10.1186/s13007-018-0374-8) contains supplementary material, which is available to authorized users.

International audience; Although Phaeodactylum tricornutum is gaining importance in plant molecular farming for the production of high-value molecules such as monoclonal antibodies, little is currently known about key cell metabolism occurring in this diatom such as protein glycosylation. For example, incorporation of fucose residues in the glycans N-linked to protein in P. tricornutum is questionable. Indeed, such epitope has previously been found on N-glycans of endogenous glycoproteins in P. tricornutum. Meanwhile, the potential immunogenicity of the α(1,3)-fucose epitope present on plant-derived biopharmaceuticals is still a matter of debate. In this paper, we have studied molecular actors potentially involved in the fucosylation of the glycoproteins in P. tricornutum. Based on sequence similarities, we have identified a putative P. tricornutum GDP-L-fucose transporter and three fucosyltransferase (FuT) candidates. The putative P. tricornutum GDP-L-fucose transporter coding sequence was expressed in the Chinese Hamster Ovary (CHO)-gmt5 mutant lacking its endogenous GDP-L-fucose transporter activity. We show that the P. tricornutum transporter is able to rescue the fucosylation of proteins in this CHO-gmt5 mutant cell line, thus demonstrating the functional activity of the diatom transporter and its appropriate Golgi localization. In addition, we overexpressed one of the three FuT candidates, namely the FuT54599, in P. tricornutum and investigated its localization within Golgi stacks of the diatom. Our findings show that overexpression of the FuT54599 leads to a significant increase of the α(1,3)-fucosylation of the diatom endogenous glycoproteins.

International audience; Monocytes/macrophages and vascular smooth muscle cells (vSMCs) are the main cell types implicated in atherosclerosis development, and unlike other mature cell types, both retain a remarkable plasticity. In mature vessels, differentiated vSMCs control the vascular tone and the blood pressure. In response to vascular injury and modifications of the local environment (inflammation, oxidative stress), vSMCs switch from a contractile to a secretory phenotype and also display macrophagic markers expression and a macrophagic behaviour. Endothelial dysfunction promotes adhesion to the endothelium of monocytes, which infiltrate the sub-endothelium and differentiate into macrophages. The latter become polarised into M1 (pro-inflammatory), M2 (anti-inflammatory) or Mox macrophages (oxidative stress phenotype). Both monocyte-derived macrophages and macrophage-like vSMCs are able to internalise and accumulate oxLDL, leading to formation of “foam cells” within atherosclerotic plaques. Variations in the levels of nitric oxide (NO) can affect several of the molecular pathways implicated in the described phenomena. Elucidation of the underlying mechanisms could help to identify novel specific therapeutic targets, but to date much remains to be explored. The present article is an overview of the different factors and signalling pathways implicated in plaque formation and of the effects of NO on the molecular steps of the phenotypic switch of macrophages and vSMCs.

We report dielectric barrier discharge (DBD)-based atmospheric pressure (AP) plasma enhanced chemical vapor deposition (PECVD) experiments using argon carrier gas and ethyl lactate (EL) as the precursor molecule (“monomer”). As in our preceding research with other monomers, unprecedented precision and reproducibility is again demonstrated, here to create plasma polymerized (PP-EL) deposits. PP-EL is thought to be an excellent candidate for bio-medical applications on account of the non-toxic nature of resulting PP-EL deposits. We have shown that a narrow range of energy values absorbed from the plasma, Em, between roughly 21 and 42 eV/molecule, lead to PP-EL coatings of widely varying structural and physical properties, ones with controlled retention of chemical features of the EL monomer, and a predictable rate of degradation in aqueous media.

Fast-gelling chitosan thermosensitive hydrogels have proven to be excellent matrices for targeted drug-delivery and cell therapy. In this work, we demonstrate the possibility of designing injectable bioadhesive hydrogels with a high gelation rate by modifying chitosan with catechol (cat-CH) and using sodium bicarbonate (SHC) as a gelling agent. Cat-CH/SHC hydrogels gel under 5 min at 37 °C and reach a high secant modulus after 24 h (E = 90 kPa at 50% strain). Besides, they show significantly higher adhesion to tissues than chitosan hydrogels thanks to the combination of catechol grafting and physical crosslinking. Their pH and osmolality stayed inside the physiological range. While biocompability tests will be mandatory to conclude regarding their potential for drug or cell encapsulation, these hydrogels uniquely combine physiological compatibility, injectability, fast gelation, good cohesion, and bioadhesion.

For extrusion-based bioprinting, the inks must be printable and rapidly present sufficient mechanical properties to support additional layers and provide a cohesive, manipulable structure. Thermosensitive hydrogels may be interesting candidates. However, the use of these materials is particularly challenging, since their rheological properties evolve with time and temperature. In this work, a rheological approach to characterize the printability of chitosan-based thermosensitive inks was developed. The method consists of evaluating: (1) the gelation kinetic at room temperature and at 37 °C; (2) shear-thinning behavior to estimate the shear rate applied during printing as a function of printing parameters; and (3) the viscosity after shear removal (recovery test) to simulate behaviour after biomaterial deposition. Hydrogels containing 2 and 3% w v−1 chitosan, combined with different gelling agents (sodium hydrogen carbonate (SHC), phosphate buffer, beta-glycerophosphate (BGP)) were tested, and compared with alginate/gelatin bioink as controls. To correlate the rheological studies with real printing conditions, a 3D-Discovery bioprinter was used to print hydrogels and the visual aspect of the printed structure was observed. Unconfined compressive tests were carried out to study the impact of applied shear rate during printing on the mechanical properties of printed structures. All pre-hydrogel solutions presented shear-thinning properties. The recovery of viscosity was found to depend on the hydrogel formulation, as well as the level of shear rate and the state of gelation at the time of printing. Formulations made with SHC and phosphate buffer presented too rapid gelation and phase separation, leading to poor printing results. One particularly promising formulation composed of SHC and BGP, when printed at a shear rate of 140 s−1, before its gelation time (t g ⩽ 15 min), resulted in good printability and 3D structures with rigidity comparable with the alginate/gelatin bioink. The methodology introduced in this paper could be used to evaluate the printability of other time- and temperature-dependent biomaterial inks in the future.

A great amount of effort is directed towards the progress of cancer treatment approaches aspiring to develop non-invasive, targeted and highly efficient therapies. In this context, Photothermal (PTT) and Photodynamic (PDT) Therapies were proven as promising. This work aims to integrate the therapeutic activities of two near-infrared (NIR) photoactive biomaterials - gold nano-bipyramids (AuBPs) and Indocyanine Green (ICG) - into one single targeted hybrid nanosystem able to operate as dual PTT-PDT agent with higher efficiency compared with each one alone. Firstly, different aspect ratio' AuBPs were systematically investigated in water solution for their intrinsic ability to efficiently generate toxic reactive oxygen species, namely oxygen singlet (1O2), under NIR laser irradiation, as this effect is less investigated in literature. Interestingly, the photodynamic activity of AuBPs measured by monitoring the photooxidation of 9,10-Anthracenediyl-bis(methylene)dimalonic acid (ABDA) - a well-known 1O2 sensor, is important, counting for 30 % decrease in ABDA optical absorbance for the most active AuBPs, well-correlating with the previously determined photothermal conversion efficiency. Furthermore, ICG was successfully grafted onto the Poly-lactic acid (PLA) coating of plasmonic nanoparticles and, consequently, the as-designed fully integrated hybrid nanosystem shows improved PTT-PDT performance in solution. Specifically, by triggering simultaneous PTT-PDT activities, the 1O2 amount is doubled, while the heating monitoring shows higher and faster increase in temperature compared to AuBPs alone. Finally, the efficiency of the combined PTT-PDT therapeutic activity was validated in vitro against B16-F10 cell line by covalent conjugation of the nanosystem with Folic Acid, which ensures the cellular recognition by overexpression of folate receptor.

International audience; The Brassica rapa hairy root based expression platform, a turnip hairy root based expression system, is able to produce human complex glycoproteins such as the alpha—L—iduronidase (IDUA) with an activity similar to the one produced by Chinese Hamster Ovary (CHO) cells. In this article, a particular attention has been paid to the N‐ and O‐glycosylation that characterize the alpha‐L‐iduronidase produced using this hairy root based system. This analysis showed that the recombinant protein is characterized by highly homogeneous post translational profiles enabling a strong batch to batch reproducibility. Indeed, on each of the 6 N‐glycosylation sites of the IDUA, a single N‐glycan composed of a core Man3GlcNAc2 carrying one beta(1,2)‐xylose and one alpha(1,3)‐fucose epitope (M3XFGN2) was identified, highlighting the high homogeneity of the production system. Hydroxylation of proline residues and arabinosylation were identified during O‐glycosylation analysis, still with a remarkable reproducibility. This platform is thus positioned as an effective and consistent expression system for the production of human complex therapeutic proteins.

The construction of a repository for high-level radioactive waste (HLW) in a deep clay formation will produce large volumes of excavated rock that must be stored of at the surface. This material will be weathered for decades to century, and its evolution with time must be assessed in order to decide on its future technological use (i.e. backfill materials of HLW repository) and to evaluate its impact on the surrounding environment (e.g. acid drainage). Predictive modelling that required a consistent set of kinetic data must be used for such evaluation. To this end, the kinetics of mineralogical transformations were investigated on an argillaceous rock from the tailings stored at the surface of an underground research laboratory (Callovian-Oxfordian – COx – argillaceous rock, Bure, France). Mineralogical analysis and flow-through experiments were combined in order to quantify the oxidation kinetics of this material. Deionized water was brought into equilibrium with the atmosphere and was percolated through a suspension of powdered COx rock. Examination of the samples prior to and after the experiments showed that the main transformations were pyrite oxidation associated with calcite and dolomite dissolution. The acidity produced by pyrite oxidation was totally buffered by the dissolution of carbonate minerals that in turn affected the composition of the clay exchanger. Geochemical modelling was used to confirm the relevance of a selected mineralogical assemblage with associated kinetic parameters in order to evaluate the extent of COx rock weathering with time.

The search for novel, more compliant vascular grafts for the replacement of blood vessels is ongoing, and predictive tools are needed to identify the most promising biomaterials. A simple analytical model was designed that enables the calculation of the ratio between the ultimate stress (σult) and the elastic modulus (E). To reach both the compliance of small-diameter coronary arteries (0.0725%/mmHg) and a burst pressure of 2031 mmHg, a material with a minimum σult/E ratio of 1.78 is required. Based on this result and on data from the literature, random electrospun Polyurethane/Polycaprolactone (PU/PCL) tubular scaffolds were fabricated and compared to commercial ePTFE prostheses. PU/PCL grafts showed mechanical properties close to those of native arteries, with a circumferential elastic modulus of 4.8 MPa and a compliance of 0.036%/mmHg at physiological pressure range (80–120 mmHg) for a 145 μm-thick prosthesis. In contrast, commercial expanded polytetrafluoroethylene (ePTFE) grafts presented a high Young's modulus (17.4 MPa) and poor compliance of 0.0034%/mmHg. The electrospun PU/PCL did not however reach the target values as its σult/E ratio was lower than expected, at 1.54, well below the calculated threshold (1.78). The model tended to overestimate both the compliance and burst pressure, with the differences between the analytical and experimental results ranging between 13 and 34%, depending on the pressure range tested. This can be explained by the anisotropy of random electrospun PU/PCL and its slightly non-linear elastic behavior, in contrast to the hypotheses of our model. Impermeability tests showed that the electrospun scaffolds were impermeable to blood for all thicknesses above 50 μm. In conclusion, this analytical model allows to select materials with suitable mechanical properties for the design of small-diameter vascular grafts. The novel electrospun PU/PCL tubular scaffolds showed strongly improved compliance as compared to commercial ePTFE prostheses.

International audience; Real time in vivo detection of Amyloid β (Aβ) deposits at an early stage may lead to faster and more conclusive diagnosis of Alzheimer’s disease (AD) and can facilitate the follow up of the effect of therapeutic interventions. In this work, the capability of new hybrid nanomaterials to target and detect Aβ aggregates using magnetic resonance (MRI) and fluorescence imaging is demonstrated. These smart contrast agents contain paramagnetic nanoparticles surrounded by luminescent conjugated oligothiophenes (LCOs) known to selectively bind to Aβ aggregates, with emission spectra strongly dependent on their conformations, opening the possibilities for several fluorescence imaging modes for AD diagnostics. Relaxivity is evaluated in vitro and ex vivo. The capability of these contrast media to link to Aβ fibrils in stained sections is revealed using transmission electron microscopy and fluorescence microscopy. Preliminary in vivo experiments show the ability of the contrast agent to diffuse through the blood–brain barrier of model animals and specifically stain amyloid deposits.

International audience; In this work, we demonstrate the feasibility of gold bipyramidal-shaped nanoparticles (AuBPs) to be used as active plasmonic nanoplatforms for the detection of the biotin–streptavidin interaction in aqueous solution via both Localized Surface Plasmon Resonance and Surface Enhanced Raman Scattering (LSPR/SERS). Our proof of concept exploits the precise attachment of the recognition element at the tips of AuBPs, where the electromagnetic field is stronger, which is beneficial to the surface sensitivity of longitudinal LSPR on the local refractive index and to the electromagnetic enhancement of SERS activity, too. Indeed, successive red shifts of the longitudinal LSPR associated with increased local refractive index reveal the attachment of para-aminothiophenol (p-ATP) chemically labeled Biotin to the Au surface and the specific capture of the target protein by biotin-functionalized AuBPs. Finite-Difference Time-Domain simulations based on the reconstructed index of refraction confirm LSPR measurements. However, the molecular identification of the biotin–streptavidin interaction remains elusive by LSPR investigation alone. Remarkably, we succeeded to complement the LSPR detection with reliable SERS measurements which permitted to (a) certify the molecular identification of biotin–streptavidin interaction and (b) extend the limit of detection of streptavidin in solution toward 10–12 M. Finally, to further probe the possibility to implement the AuBPs as dual LSPR-SERS based immunoassays in solution for real clinical diagnostics, we additionally investigated the AuBP’s performance to transduce the specific antihuman IgG- human IgG binding event, providing thus a reference design for building unique plasmonic immunoassays for dual-optical detection of target proteins in aqueous solution.

We determine both experimentally and numerically the onset of elastic flow instabilities in viscoelastic polymer solutions with different levels of shear thinning., We determine both experimentally and numerically the onset of elastic flow instabilities in viscoelastic polymer solutions with different levels of shear thinning. Previous experiments realized in microfluidic serpentine channels using dilute polymeric solutions showed that the onset of elastic instabilities strongly depends on the channel curvature. The scaling dependence is well captured by the general instability scaling criterion proposed by Pakdel and McKinley [Phys. Rev. Lett., 1996, 76, 2459:1–4]. We determine here the influence of fluid shear thinning on the onset of such purely-elastic flow instabilities. By testing a set of polyethylene oxide solutions of high molecular weight at different polymer concentrations in microfluidic serpentine channels we observe that shear thinning has a stabilizing effect on the microfluidic flow. Three-dimensional numerical simulations performed using the White–Metzner model predict similar trends, which are not captured by a simple scaling analysis using the Pakdel–McKinley criterion.

The success of promising anti-cancer adoptive cell therapies relies on the abilities of the perfused CD8(+) T lymphocytes to gain access to and persist within the tumor microenvironment to carry out their cytotoxic functions. We propose a new method for their local delivery as a living concentrate, which may not only reduce the numbers of cells required for treatment but also enhance their site-specific mobilization. Using combinations of sodium hydrogen carbonate and phosphate buffer as gelling agents, novel injectable chitosan-based biocompatible thermogels (CTGels) having excellent mechanical properties and cytocompatibility have been developed. Three thermogel formulations with acceptable physicochemical properties, such as physiological pH and osmolality, macroporosity, and gelation rates were compared. The CTGel2 formulation outperformed the others by providing an environment suitable for the encapsulation of viable CD8(+) T lymphocytes, supporting their proliferation and gradual release. In addition, the encapsulated T cell phenotypes were influenced by surrounding conditions and by tumor cells, while maintaining their capacity to kill tumor cells. This strongly suggests that cells encapsulated in this formulation retain their anti-cancer functions, and that this locally injectable hydrogel may be further developed to complement a wide variety of existing immunotherapies.

International audience; Fluorescent gold nanoparticles (GNPs) were prepared by chain-end grafting of RAFT copolymers bearing multiple fluorophores distributed along the chain. Two different synthetic approaches in water were first studied with well-defined and biocompatible homopolymers. Both led to very stable samples and the corona thickness at the gold surface increased with the polymer molecular weight. The two-step ligand exchange approach was then selected to synthesize GNPs grafted with polymer–chromophore conjugates exhibiting different molecular weights, backbone architectures and chromophores. Again, the thickness of the organic corona increased with the polymer molecular weight but was also dependent on the conformation of the conjugate chains which depends on the nature of the chromophores. By adjusting these parameters, it was possible to control the average chromophore–gold distance which is of paramount importance for the fluorescence properties of the nanoparticles. We indeed showed that the fluorescence of the hybrid nano-objects increased with the corona thickness.

A large research reactor for performingdielectric barrier discharge (DBD) experiments at atmospheric pressure (AP) has been used with argon (Ar) carrier gas under constant plasma conditions (f = 20 kHz, Va(f) = 8 kVp-p = 2.8 kVrms). Various permanent gases (H2, O2, N2, light hydrocarbons) and some heavier organic molecules were introduced as reactive “dopant” flows, Fd, at ‰ concentrations in the F = 10 standard liters per minute (slm) flow of argon. We have earlier perfected and reported a method for measuring Eg, the energy dissipated per cycle of the applied a.c. voltage, and ΔEg, the energy difference with and without reactive dopant in the Ar flow. The latter and Fd permit calculation of Em, the energy absorbed from the plasma by each dopant molecule. Plots of Em versus Fd and 1/Fd yield much valuable information about excitation, fragmentation, and polymerization in the DBD plasma environment. Optical emission (OES) and Fourier-transform infrared (FTIR) spectroscopies help to further enhance and complement interpretation of measured data.

The use of injectable hydrogels is presently limited by the difficulty to achieve rapid gelation, high mechanical resistance and excellent cytocompatibility. In our study, high-strength injectable thermosensitive hydrogels of unmodified chitosan (CH) were obtained by combining sodium hydrogen carbonate (SHC) with phosphate buffer (PB) or beta-glycerophosphate (BGP) as gelling agents. A synergic effect led to the acceleration of gelation and a remarkable improvement of the storage modulus (G′) of the hydrogels. Furthermore, the new hydrogels exhibited drastically enhanced Young moduli and resistance in compression as compared to conventional hydrogels prepared with BGP, PB or their combination. This was achieved while reducing the total salt concentration in the hydrogels. The gelation was rapid and the hydrogels presented porous structures and physiological pH, and did not show any cytotoxicity to L929 fibroblast cells in vitro. Overall, these new hydrogels provide interesting alternatives for use as blood vessel embolizing agents or as injectable scaffolds for drug delivery and/or cell seeding in tissue engineering strategies.

We report experiments at atmospheric pressure (AP) using a dielectric barrier discharge (DBD) reactor designed for plasma polymerization (PP) with "monomers" at ‰ concentrations in ca.10 standard liters per minute of argon (Ar) carrier gas. We have perfected a method for measuring Eg, the energy dissipated per cycle of the applied a.c. high voltage, Va(f), but the focus here is on ΔEg, the energy difference with and without a flow, Fd, of monomer in the Ar flow, with the plasma being sustained at Va(f) = 2.8 kVrms, f = 20 kHz. From ΔEg and Fd, we derive a characteristic energy per molecule, Em (in eV), and investigate plots of Em versus Fd and 1/Fd for three model "monomers": formic, acetic, and acrylic acid. These data, along with those for lighter or heavier organic compounds, reveal novel information about energy absorption from the plasma and ensuing polymerization reactions.

Pectin methylesterases (PMEs) catalyze the demethylesterification of homogalacturonan domains of pectin in plant cell walls and are regulated by endogenous pectin methylesterase inhibitors (PMEIs). In Arabidopsis dark-grown hypocotyls, one PME (AtPME3) and one PMEI (AtPMEI7) were identified as potential interacting proteins. Using RT-quantitative PCR analysis and gene promoter::GUS fusions, we first showed that AtPME3 and AtPMEI7 genes had overlapping patterns of expression in etiolated hypocotyls. The two proteins were identified in hypocotyl cell wall extracts by proteomics. To investigate the potential interaction between AtPME3 and AtPMEI7, both proteins were expressed in a heterologous system and purified by affinity chromatography. The activity of recombinant AtPME3 was characterized on homogalacturonans (HGs) with distinct degrees/patterns of methylesterification. AtPME3 showed the highest activity at pH 7.5 on HG substrates with a degree of methylesterification between 60 and 80% and a random distribution of methyl esters. On the best HG substrate, AtPME3 generates long non-methylesterified stretches and leaves short highly methylesterified zones, indicating that it acts as a processive enzyme. The recombinant AtPMEI7 and AtPME3 interaction reduces the level of demethylesterification of the HG substrate but does not inhibit the processivity of the enzyme. These data suggest that the AtPME3·AtPMEI7 complex is not covalently linked and could, depending on the pH, be alternately formed and dissociated. Docking analysis indicated that the inhibition of AtPME3 could occur via the interaction of AtPMEI7 with a PME ligand-binding cleft structure. All of these data indicate that AtPME3 and AtPMEI7 could be partners involved in the fine tuning of HG methylesterification during plant development.

Chitosan-thermosensitive hydrogels present interesting features for the embolization of blood vessels, but need to be better characterized and optimized. Chitosan polymer (degree of deacetylation (DDA) of 94%) was purified and combined with Visipaque (VIS), a nonionic isotonic contrast agent composed of iodixanol. A beta-glycerolphosphate (βGP) solution was then added to induce gelation at body temperature. The gelation process was monitored by rheometry, measuring the evolution of the sample storage (G') and loss (G″) moduli as a function of VIS and βGP concentration. Adding VIS significantly slowed down gelation kinetics, but a 12% and higher βGP concentration provided a radiopaque solution, which at 37°C, gels immediately. A custom-made in vitro embolization bench test was developed to assess the gel's occlusive properties, and its injectability through a small diameter catheter was verified. Results show that the short-term occlusive properties of the gel were insufficient when using a βGP concentration of 12% w/v (about 0.4M), but that increasing the βGP to 20% (0.6M) allowed an acceleration of the gelation and the immediate blocking of flow above physiological pressure. The contrast agent was rapidly released in solution, such that it would not interfere with future follow-up imaging. In accordance with the literature data, the cytotoxicity of gel extracts increased with βGP concentration and to a lesser extent with VIS concentration. Preliminary in vivo testing showed easy injection by catheter and good visibility under fluoroscopy. These results suggest that radiopaque CH/βGP20%/VIS hydrogels present significant potential as embolizing agents for blood vessels and aneurysms. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1551-1562, 2016.

A large reactor for performing dielectric barrier discharges (DBD) experiments at atmospheric pressure (AP) has been built and tested. The area of electrodes is more than 40 times greater than that of a small DBD cell, in which we have perfected a method formeasuring Eg, the energy dissipated per cycle of the applied a.c. high voltage, Va(f). This methodology has been successfully applied to plasma polymerization experiments on the larger system, using volatile organic precursors (dopants) at ‰ concentrations in 10 standard liters per minute of argon (Ar). We measured ΔEg, the energy difference with and without dopant, for Va(f) ∼ 3 kVrms (20 ≤ f ≤ 40 kHz). From ΔEg we then derived Etot/N, the energy per molecule, and observed surprisingly good agreement with data published in the literature relating to low-pressure (LP) plasmas.

International audience; The Callovian-Oxfordian (COx) clay formation in the Paris Basin (France) has been the target of many studies investigating the feasibility of deep nuclear waste disposal in a reduced clay formation. To determine the mobility of radionuclides in the host rock formation, modeling of the porewater chemistry, particularly iron solute concentrations, is necessary. Notably, this study aims to understand the supersaturation of Fe(III) oxyhydroxides given by models. Fe(III) oxyhydroxides have been identified magnetically in unpreserved Callovian-Oxfordian samples. In this study, a set of magnetic measurements are used to detect the Fe-bearing magnetic minerals present in the COx clay formation. A core sample from the borehole FOR 1118, preserved from air since its collection, is the target of this study. The magnetic measurements performed show that magnetite and goethite are the main magnetic minerals (

Plasma polymerized coatings (PP) are increasingly used for biomedical applications in contact with body fluids. We optimized and studied the stability, mechanical properties, and adhesion in air and aqueous media of amine (NH2)-rich PP in low-pressure r.f. plasma from [NH3/C2H4] mixtures (L-PPE:N). Quartz crystal microbalance with dissipation monitoring (QCM-D) revealed partial dissolution or water-uptake (swelling) in real-time in various solutions, which helped identify the best gas mixture ratio for compromise between stability and high concentration of (NH2) groups. Nanoindention revealed strong decrease of Young's modulus and hardness in water. Finally, a Cross-Hatch peel test was used to optimize L-PPE:N adhesion on poly(tetrafluoroethylene) (PTFE): plasma pre-treatment prevented both dry and wet delamination.

International audience; In many countries, environmental impact of toxic chemicals has to be considered for the implementation of industrial facilities. The assessment of the toxic chemical environmental impact for a given facility requires evaluating the mobility of the various toxic chemicals potentially involved in the industrial activity in its surrounding environment. Numerical evaluations of the migration of the identified toxic elements from the industrial facilities toward the biosphere necessitate a good parametrization of their retention behavior. Outcropping clay-rich formations are considered as a potential host for a radioactive waste repository in many countries. Radioactive waste can contain toxic chemicals such as As, Cr and B leading to evaluate their migration in such clay systems. Sub-surface clay-rich rocks are notably characterized by redox transitions, which can influence the migration of many contaminants 1. The retention behavior of arsenic (As), chromium (Cr) and boron (B), was investigated for an outcropping clay-rock formation, the Albian Tégulines Clay (France, Aube) currently studied as potential a host-rock for long-live low activity level (LL-LL) radioactive waste At the vicinity of the surface, Tégulines Clay is affected by weathering processes leading to contrasted geochemical conditions with depth. One of the main features of the weathering is the occurrence of a redox transition zone near the surface. Batch sorption experiments of As(V), As(III), Cr(VI) and B were performed on samples collected at two depths representative either of oxidized or reduced mineral assemblages. Batch sorption experiments highlighted a distinct behavior of As, Cr and B oxyanions. The in-situ redox state of the Tégulines Clay samples has a significant effect on Cr retention (Cr(VI) heterogeneous reduction reactions followed by Cr(III) precipitation). On the contrary, As(V) reduction into As(III) is moderate and its retention slightly affected by the in-situ redox state of the Tégulines Clay. As(V) retention is higher than As(III) retention. Boron retention is strongly influenced by its natural abundance in the Tégulines clay samples and the distribution coefficient of B (Kd) is expected to be very low for in-situ conditions due to the significant amount of natural B in the pore water 2. The comparison of the retention properties of two Tégulines Clay samples towards three oxyanions with contrasted chemical properties highlighted the roles of clay mineralogy, natural abundance, and reducing capacity of the investigated materials.References:1Lerouge, C. et al., 2018. Geofluids, 20.2Debure, M. et al., 2018. Science of The Total Environment, 642, 216-229.

N - glycosylation is a major post - translational modifi cation step in the biosynthesis of proteins in eukaryotes. This process consists of two main steps, the early N - glycan processing occurring in the endoplasmic reticulum and its maturation in the Golgi apparatus. The early N - glycan processing steps are con- served among eukaryotes and are involved in the quality control of proteins. In contrast, the maturation steps in the Golgi apparatus give rise to a large variety of organism - specifi c complex structures. This divergence in the resulting N - glycan structures is a key issue when the plant is used as a cell factory for the production of human therapeutic proteins. In this chapter, we describe the main aspects of the N - glycan biosynthesis in plants as well as strategies that have been developed to engineer this N - glycosylation pathway in order to allow the produc- tion in transgenic plants of pharmaceutical proteins that carry human - like glycans.