HAL Portal ESPCI (Ecole Supérieure de Physique et de Chimie Industrielles)
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Evaluation of Jacalin lectin sorbents for the extraction of the human chorionic gonadotropin glycoforms prior to analysis by nano liquid chromatography-high resolution mass spectrometry
No full textInternational audienceHuman chorionic gonadotropin (hCG) is a dimeric, highly glycosylated hormone with a total of 4 N- and 4 O-glycosylation sites in its two subunits, hCGα and hCGβ. Recently, we developed a novel nano liquid chromatography coupled to high resolution mass spectrometry (nanoLC-HRMS) method for the analysis and thus the detection of the intact glycoforms of hCG. Here, a sorbent functionalized with the Jacalin lectin was evaluated in solid-phase extraction (SPE) for its potential to fractionate the hCG glycoforms prior to their nanoLC-HRMS analysis at the intact level, which may facilitate the detection of low-abundance glycoforms and may lead to a more detailed characterization of the hormone glycosylation. A commercial sorbent based on Jacalin immobilized on Sepharose and having a lectin density of 4.5 mg per ml of gel was selected to carry out SPE and its capacity was estimated to be of some tens of μg of hCG per ml of lectin sorbent. Next, the SPE protocol was modified to improve the extraction recoveries. Especially, it was noticed that an extensive pre-conditioning procedure prior to the first use of a cartridge was necessary to remove the residual non-grafted lectins. Indeed, if on-grafted lectins are not eliminated, they may bind a part of hCG glycoformes preventing they retention by the sorbent, leading to low extraction recoveries (around 10%). With the extensive pre-conditioning procedure, the average extraction recoveries for both hCGα and hCGβ glycoforms were about 50%, with either recombinant or urinary hCG. Qualitatively, the fractionation of hCG glycoforms between the washing and elution fractions was achieved with the urinary hCG sample by determining the number of glycoforms detected in each fraction. It appears that 12 hCGα glycoforms have a low affinity (detected only in the washing fraction), 1 a low-medium affinity (detected in washing and elution 1 fractions), 16 a medium affinity (detected in washing, elution 1 and 2 fractions), and 12 a high affinity (detected only in elution 1 and 2 fractions). For the hCGβ glycoforms, similarly, 3 have a low affinity and 12 a low-medium affinity. Additionally, the 3 hCGβ glycoforms were detected better. A different behavior was observed with the recombinant hCG sample, which indicates glycosylation differences between the two hCG samples. This shows the potential of lectin-based affinity fractionation before nanoLC-HRMS analysis to better characterize the glycosylation state of hCG at the intact level
Façonnage du front d'onde pour l’étude des milieux complexes
No full textInternational audienceLe façonnage du front d’onde permet de contrôler la propagation de la lumière dans les milieux complexes. Cette approche repose sur l’utilisation de modulateurs spatiaux de lumière, permettant de contrôler le champ optique sur un grand nombre de pixels, et sur des méthodes d’optimisation du champ ou de caractérisation du milieu par des matrices de transmission. Elle ouvre l’accès à de nouvelles applications en imagerie, en télécommunications ou encore en traitement optique de l’information
Pseudo-4-component photoredox-catalyzed alkylative amidination/carbamoylation of styrenes with isocyanides and redox-active esters
No full textInternational audienceWe report a photoredox-catalyzed pseudo-four-component process for the alkylative amidination of styrenes using isocyanides and redox-active esters (RAEs). This redox-neutral radical-polar crossover reaction shows broad functional group tolerance. The RAE serves as both a radical and nucleophile source, with the initially released phthalimide anion reintegrated into the final product. The resulting amidines can be readily derivatized into amides, tetrazoles, nitriles, or aldehydes, enhancing the synthetic utility of this approach
Extraction and chemical features of wood hemicelluloses: A review
No full textInternational audienceHemicelluloses have immense potential for applications in diverse fields, especially in polymeric materials. This review critically examines biomass treatment technologies, encompassing chemical, mechanical, and combined approaches to disrupt plant cell walls and enhance hemicellulose accessibility and solubility. The choice of a treatment method depends on factors like purpose, biomass composition, and economic and environmental considerations. Hemicelluloses extracted from wood are composed from up to 11 monomer units, most of them “neutral” monosaccharides (glucose, mannose etc.) but a couple “charged” (uronic acids). The average compositions of wood hemicelluloses change with the type of wood; the accuracy is not known. The content of “charged” monosaccharides may particularly suffer from underestimation due to strong hydrolysis. The chemical composition of intact wood hemicelluloses has never been determined: it is thus not known if hemicelluloses in wood are a mixture of several “simple” polysaccharides (such as glucomannans) or complex polysaccharides with up to 11 monomer units in the same macromolecule. Currently determined molecular weights (MW) of hemicelluloses range from 500 to 1,000,000 Da. The precision and accuracy of MWs are not known, primarily due to column inconsistency in analyzing anionic and neutral polymers. A combination of chromatography SEC methods and detectors is required for standardization
Operando observation of gate defects in quantum dot-based field effect transistors
No full textInternational audienceColloidal nanocrystals are now widely explored for their integration into more advanced electronic and optoelectronic devices. Among the key components enabling this progress is the field-effect transistor (FET). While widely used as a phototransistor, combining both light absorption and gate-induced current modulation, its primary role remains as a tool for extracting material parameters. The electrical output from FETs serves as the main measurement to probe carrier density and mobility in nanocrystal films. However, such an approach suffers from two main flaws: it relies on modeling to link the electrical output to material properties; and second, it can be affected by the presence of defects. Here, we use scanning photoemission microscopy to assess the energy profile in such nanocrystal-based FETs. This method is used to quantify the impact of a local gate defect, which appears to be quite significant, as its impact is stronger and has longer-range effects than the conventional gate operation. We also demonstrate that the method is effective in determining the process at the origin of electrical breakdown. Overall, the method appears well suited to bridge the gap between the material scale and the obtained electrical output and to quantify the impact of potential deviations from ideal behavior
PET Imaging of PD-L1 Occupancy for Preclinical Assessment of the Efficacy of Combined Anti–PD-L1 Immunotherapy and Targeted Therapy
No full textInternational audienceThe development of resistance significantly hampers the efficacy of immunotherapies in cancer treatment. The combination of JQ1, a BRD4 protein inhibitor, and anti–programmed death ligand 1 (PD-L1) immunotherapies has a synergic therapeutic potential to treat solid tumors. This study aimed to evaluate the potential of immuno-PET imaging for measuring pharmacodynamic biomarkers in response to this combination therapy targeting PD-L1. Methods: We synthesized different radioligands derived from the anti–PD-L1 C4 antibody and a minibody targeting murine CD8α for immuno-PET imaging. We conducted experiments on human non–small cell lung cancer and mouse colorectal carcinoma animal models to assess the efficacy of JQ1 and avelumab treatment on PD-L1 expression and immune cell infiltration by immuno-PET imaging. Taking advantage of the unique properties of the C4-derived minibody, we measured PD-L1 occupancy in tumors after treatment. Results: JQ1 efficiently reduced PD-L1 extracellular expression across all tested cell lines in vitro and in vivo. Avelumab and JQ1 treatments alone or in combination led to significant tumor growth reduction in the immunocompetent murine colorectal carcinoma model, reducing mean tumor growth from 725% in the control group to 125% in the combination group. Treatments also significantly increased the survival of mice by 4–12 d compared with the control group. Although imaging CD8-positive T-cell infiltration did not predict tumoral response, imaging the unoccupied fraction of PD-L1 after treatment was predictive of tumor growth reduction and survival. Conclusion: Immuno-PET imaging with noncompetitive radioligands throughout the treatment course could improve the efficiency and support rationalization of the dosing regimen of immunotherapies
Marangoni-driven patterns, ridges, and hills in surfactant-covered parametric surface waves
No full textInternational audienceParametric oscillations of an interface separating two fluid phases create nonlinear surface waves, called Faraday waves, which organise into simple patterns, such as squares and hexagons, as well as complex structures, such as double hexagonal and superlattice patterns. In this work, we study the influence of surfactant-induced Marangoni stresses on the formation and transition of Faraday-wave patterns. We use a control parameter, B, that assesses the relative importance of Marangoni stresses as compared with the surface-wave dynamics. Our results show that the threshold acceleration required to destabilise a surfactant-covered interface through vibration increases with increasing B. For a surfactant-free interface, a square-wave pattern is observed. As B is incremented, we report transitions from squares to asymmetric squares, weakly wavy stripes and ultimately to ridges and hills. These hills are a consequence of the bidirectional Marangoni stresses at the neck of the ridges. The mechanisms underlying the pattern transitions and the formation of exotic ridges and hills are discussed
Electronic Structure Dimensionality of the Quantum-Critical Ferromagnet YbNi 4 P 2
No full textInternational audienceYbNi4P2 is the first known ferromagnetic metal showing a second-order quantum phase transition. Current theoretical understanding rules out second order ferromagnetic quantum criticality in centrosymmetric 2D and 3D metals. Thus, studying the electronic structure of YbNi4P2 is of prime fundamental importance. Using angle-resolved photoemission spectroscopy, we experimentally prove the existence of 1D Fermi surface contours. In addition, our results demonstrate that part of the electronic structure of YbNi4P2 is made of states of higher dimensionality, thereby bringing into question the fact that ferromagnetic quantum criticality in centrosymmetric crystals, is exclusively found in 1D systems. Our experimental data show that the electronic structure of YbNi4P2 is a playground of mixed dimensionality, electron correlations, strong hybridization and spin-orbit coupling, all of them providing new insights in understanding the origin of ferromagnetic quantum criticality.</div
Rheology in Space - A review of past and present ESA experiments
No full textAccepted for publication in Journal of RheologyGravity affects the flow and the behavior at rest of complex fluids and flows by inducing sedimentation, drainage, and interfacial deformation, which can mask more fundamental physical processes. On Earth, standard countermeasures against gravity come with limitations in terms of possible formulations or the quality and homogeneity of the applied strain. Alternatively, one can run these experiments in free-fall or in orbit where the effects of gravity are canceled i.e., under microgravity conditions. In this short review, we present several European Space Agency-led projects of interest to rheologists that leverage microgravity environments: FAST/FASTER , which studies interfacial rheology using Capillary Pressure Tensiometers; SMD-FOAM, fundamental experiments on foam coarsening ; SMD-PASTA and SEEDS, aimed at understanding the dynamics of emulsion droplets, its evolution and microrheology using Diffusing Wave Spectroscopy; results associated with studies on granular materials in microgravity, including AstEx and CompGran; COLIS, which examines the thermally driven perturbation of soft colloidal glasses monitored by Dynamic Light Scattering; BIOMICS/KRABS, investigating the aggregation and migration of soft particles and red blood cells under flow. Microgravity experiments allowed for high-precision measurements of interfacial viscoelasticity, detailed studies of emulsion aging and drop coalescence, observed plastic rearrangements in colloidal glasses, characterized the dynamics under flow of red blood cell analogues, and rationalized the impact of gravity on convection and fluidization in agitated granular matter. Collectively, these experiments demonstrate the complementarity and the relevance of ESA's microgravity platforms in expanding the frontiers of soft matter rheology
A ruthenium terpyridine complex showing stable photocatalytic hydrogen evolution under red light
No full textInternational audienceWe report herein the synthesis of a novel terpyriridine ruthenium( ii ) complex, which shows stable hydrogen photoproduction under red light