HAL Portal ESPCI (Ecole Supérieure de Physique et de Chimie Industrielles)
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Couplage C(sp<sup>2</sup>)–H/C(sp<sup>2</sup>)–H du limonène pallado-catalysé
No full textInternational audienceLimonene undergoes a regioselective Pd(II)-catalyzed C-(sp 2 )-H/C(sp 2 )-H coupling with acrylic acid esters and amides, α,βunsaturated ketones, styrenes, and allyl acetate, affording novel 1,3-dienes. DFT computations gave results in accord with the experimental results and allowed for the formulation of a plausible mechanism. The postfunctionalization of one of the coupled products was achieved via a large-scale Sonogashira reaction conducted under micellar catalysis.Le limonène est engagé dans un couplage C-(sp2 )-H/C(sp2 )-H régiolélectif pallado-catalysé avec des acrylates, des acrylamides, des cétones α,β-insaturées, des styrènes et l'acétate d'allyle. Ce couplage génère des nouveaux diènes-1,3. Des calculs DFT ont donné des résultats en accord avec les résultats expérimentaux et ont permis la proposition d'un mécanisme plausible. La post-fonctionnalisation d'un des produits de couplage a été possible par une réaction de Sonogashira sur grande échelle par catalyse en milieu micellaire
Shear-induced phase behavior of bidisperse jammed suspensions of soft particles
No full textInternational audienceParticle dynamics simulations are used to determine the shear-induced microstructure and rheology of jammed suspensions of soft particles. These suspensions, known as soft particle glasses (SPGs), have an amorphous structure at rest but transform into ordered phases in strong shear flow when the particle size distribution is relatively monodisperse. Here, a series of bidisperse SPGs with different particle radii and number density ratios are considered, and their shear-induced phase diagrams are correlated with the macroscopic rheology at different shear rates and volume fractions. These shear-induced phase diagrams reveal that a combination of these parameters can lead to the emergence of various microstructures such as amorphous, layered, crystals, and in some cases, coexistence of amorphous and ordered phases. The evolution of the shear stress is correlated with the change in the microstructure and is a shear-activated process. Stress shows pseudo-steady behavior during an induction period before the final microstructural change leading to the formation of ordered structures. The outcomes provide a promising method to control the phase behavior of soft suspensions and build new self-assembled microstructures
Acoustic levitation as a tool for cell‐driven self‐organization of human cell spheroids during long‐term 3D culture
No full textInternational audienceAcoustic levitation, which allows contactless manipulation of micro‐objects with ultrasounds, is a promising technique for spheroids formation and culture. This acoustofluidic technique favors cell–cell interactions, away from the walls of the chip, which leads to the spontaneous self‐organization of cells. Using this approach, we generated spheroids of mesenchymal stromal cells, hepatic and endothelial cells, and showed that long‐term culture of cells in acoustic levitation is feasible. We also demonstrated that this self‐organization and its dynamics depended weakly on the acoustic parameters but were strongly dependent on the levitated cell type. Moreover, spheroid organization was modified by actin cytoskeleton inhibitors orcalcium‐mediated interaction inhibitors. Our results confirmed that acoustic levitation is a rising technique for fundamental research and biotechnological industrial application in the rapidly growing field of microphysiological systems. It allowed easily obtaining spheroids of specific and predictable shape and size, which could be cultivated over several days, without requiring hydrogels or extracellular matrix
Targeting of 3D oral cancer spheroids by αVβ6 integrin using near-infrared peptide-conjugated IRDye 680
No full textInternational audienceBackground: In the treatment of oral cavity cancer, margin status is one of the most critical prognostic factors. Positive margins are associated with higher local recurrence and lower survival rates. Therefore, the universal goal of oral surgical oncology is to achieve microscopically clear margins. Near-infrared fluorescence guided surgery (FGS) could improve surgical resection using fluorescent probes. αVβ6 integrin has shown great potential for cancer targeting due to its overexpression in oral cancers. Red fluorescent contrast agent IRDye 680 coupled with anti-αVβ6 peptide (IRDye-A20) represents an asset to improve FGS of oral cancer. This study investigates the potential of IRDye-A20 as a selective imaging agent in 3D three-dimensional tongue cancer cells. Methods αVβ6 integrin expression was evaluated by RT-qPCR and Western Blotting in 2D HSC-3 human tongue cancer cells and MRC-5 human fibroblasts. Targeting ability of IRDye-A20 was studied in both cell lines by flow cytometry technique. 3D tumor spheroid models, homotypic (HSC-3) and stroma-enriched heterotypic (HSC-3/MRC-5) spheroids were produced by liquid overlay procedure and further characterized using (immuno)histological and fluorescence-based techniques. IRDye-A20 selectivity was evaluated in each type of spheroids and each cell population.Results: αVβ6 integrin was overexpressed in 2D HSC-3 cancer cells but not in MRC-5 fibroblasts and consistently, only HSC-3 were labelled with IRDye-A20. Round shaped spheroids with an average diameter of 400 μm were produced with a final ratio of 55%/45% between HSC-3 and MRC-5 cells, respectively. Immunofluorescence experiments demonstrated an uniform expression of αVβ6 integrin in homotypic spheroid, while its expression was restricted to cancer cells only in heterotypic spheroid. In stroma-enriched 3D model, Cytokeratin 19 and E-cadherin were expressed only by cancer cells while vimentin and fibronectin were expressed by fibroblasts. Using flow cytometry, we demonstrated that IRDye-A20 labeled the whole homotypic spheroid, while in the heterotypic model all cancer cells were highly fluorescent, with a negligible fluorescence in fibroblasts.Conclusions: The present study demonstrated an efficient selective targeting of A20FMDV2-conjugated IRDye 680 in 3D tongue cancer cells stroma-enriched spheroids. Thus, IRDye-A20 could be a promising candidate for the future development of the fluorescence-guided surgery of oral cancers
Direct Numerical Analysis of Dynamic Facilitation in Glass-Forming Liquids
No full textInternational audienceWe propose a computational strategy to quantify the temperature evolution of the timescales and length scales over which dynamic facilitation affects the relaxation dynamics of glass-forming liquids at low temperatures, which requires no assumption about the nature of the dynamics. In two glass models, we find that dynamic facilitation depends strongly on temperature, leading to a subdiffusive spreading of relaxation events which we characterize using a temperature-dependent dynamic exponent. We also establish that this temperature evolution represents a major contribution to the increase of the structural relaxation time
Optimizing multi-user indoor sound communications with acoustic reconfigurable metasurfaces
No full textInternational audienceSound in indoor spaces forms a complex wavefield due to multiple scattering encountered by the sound. Indoor acoustic communication involving multiple sources and receivers thus inevitably suffers from cross-talks. Here, we demonstrate the isolation of acoustic communication channels in a room by wavefield shaping using acoustic reconfigurable metasurfaces (ARMs) controlled by optimization protocols based on communication theories. The ARMs have 200 electrically switchable units, each selectively offering 0 or π phase shifts in the reflected waves. The sound field is reshaped for maximal Shannon capacity and minimal cross-talk simultaneously. We demonstrate diverse acoustic functionalities over a spectrum much larger than the coherence bandwidth of the room, including multi-channel, multi-spectral channel isolations, and frequency-multiplexed acoustic communication. Our work shows that wavefield shaping in complex media can offer new strategies for future acoustic engineering
Cyclometalated luminescent platinum(II) complexes of dissymmetrical 2,2':4',2"terpyridine and its self-assembled dimer presenting Pt-Ag dative bonds
No full textInternational audienceA series of cyclometalated (N^C^N) Pt(II)-platinum complexes featuring a terpyridine ligand with a non-coordinating nitrogen atom and a Pt-C bond was synthesized. In the presence of Ag + , the bis(isonitrile)Pt(II) complex formed a remarkable self-assembled helicoidal dimer stabilized by coordination of Ag(I) and metallophilic Pt-Ag interactions. Its assembly was observed in the solid state and maintained in solution. All complexes show strong luminescence and multiple emitting states, which could be rationalized based on solid state X-ray structures and coordinating environment
Advanced Characterization Methodology to Unravel the Biodegradability of Metal–Organic Framework Nanoparticles in Extremely Diluted Conditions
No full textInternational audiencePorous iron(III) carboxylate metal-organic frameworks (MIL-100; MIL stands for Material of Institute Lavoisier) of submicronic size (nanoMOFs) have attracted a growing interest in the field of drug delivery due to their high drug payloads, excellent entrapment efficiencies, biodegradable character, and poor toxicity. However, only a few studies have dealt with the nanoMOF degradation mechanism, which is key to their biological applications. Complementary methods have been used here to investigate the degradation mechanism of Fe-based nanoMOFs under neutral or acidic conditions and in the presence of albumin. High-resolution STEM-HAADF coupled with energy-dispersive X-ray spectroscopy enabled the monitoring of the crystalline organization and elemental distribution during degradation. NanoMOFs were also deposited onto silicon substrates by dip-coating, forming stable thin films of high optical quality. The mean film thickness and structural changes were further monitored by IR ellipsometry, approaching the "sink conditions" occurring in vivo. This approach is essential for the successful design of biocompatible nano-vectors under extreme diluted conditions. It was revealed that while the presence of a protein coating layer did not impede the degradation process, the pH of the medium in contact with the nanoMOFs played a major role. The degradation of nanoMOFs occurred to a larger extent under neutral conditions, rapidly and homogeneously within the crystalline matrices, and was associated with the departure of their constitutive organic ligand. Remarkably, the nanoMOFs' particles maintained their global morphology during degradation.</div
Compensation des aberrations de l'holographie Doppler du fond d'œil humain par corrélation du signal de sous-ouverture
No full textInternational audienceThe process of obtaining images of capillary vessels in the human eye’s fundus using Doppler holography encounters difficulties due to ocular aberrations. To enhance the accuracy of these images, it is advantageous to apply an adaptive aberration correction technique. This study focuses on numerical Shack-Hartmann, which employs sub-pupil correlation as the wavefront sensing method. Application of this technique to Doppler holography encounters unique challenges due to the holographic detection properties. A detailed comparative analysis of the regularization technique against direct gradient integration in the estimation of aberrations is made. Two different reference images for the measurement of image shifts across subapertures are considered. The comparison reveals that direct gradient integration exhibits greater effectiveness in correcting asymmetrical aberrations.Le processus d'obtention d'images des vaisseaux capillaires dans le fond d'œil humain à l'aide de l'holographie Doppler rencontre des difficultés dues aux aberrations oculaires. Pour améliorer la précision de ces images, il est avantageux d'appliquer une technique de correction adaptative des aberrations. Cette étude se concentre sur l'approche numérique Shack-Hartmann, qui utilise la corrélation des sous-pupilles comme méthode de détection du front d'onde. L'application de cette technique à l'holographie Doppler présente des défis uniques en raison des propriétés de détection holographique. Une analyse comparative détaillée de la technique de régularisation par rapport à l'intégration directe des gradients pour l'estimation des aberrations est réalisée. Deux images de référence différentes pour la mesure des décalages d'image entre les sous-ouvertures sont prises en compte. La comparaison révèle que l'intégration directe des gradients s'avère plus efficace pour corriger les aberrations asymétriques
Direct numerical simulation of bubble rising in turbulence
No full textInternational audienceWe describe the rising trajectory of bubbles in isotropic turbulence and quantify the slowdown of the mean rise velocity of bubbles with sizes within the inertial subrange. We perform direct numerical simulations of bubbles, for a wide range of turbulence intensity, bubble inertia and deformability, with systematic comparison with the corresponding quiescent case, with Reynolds number at the Taylor microscale from 38 to 77. Turbulent fluctuations randomise the rising trajectory and cause a reduction of the mean rise velocity compared with the rise velocity in quiescent flow . The decrease in mean rise velocity of bubbles is shown to be primarily a function of the ratio of the turbulence intensity and the buoyancy forces, described by the Froude number , where is the root-mean-square velocity fluctuations, is gravity and is the bubble diameter. The bubble inertia, characterised by the ratio of inertial to viscous forces (Galileo number), and the bubble deformability, characterised by the ratio of buoyancy forces to surface tension (Bond number), modulate the rise trajectory and velocity in quiescent fluid. The slowdown of these bubbles in the inertial subrange is not due to preferential sampling, as is the case with sub-Kolmogorov bubbles. Instead, it is caused by the nonlinear drag–velocity relationship, where velocity fluctuations lead to an increased average drag. For Fr > 0.5 , we confirm the scaling , as proposed previously by Ruth et al. ( J. Fluid Mech. , vol. 924, 2021, p. A2), over a wide range of bubble inertia and deformability