A Fly-Through Mission Strategy Targeting Peptide as a Signature of Chemical Evolution and Possible Life in Enceladus Plumes

In situ detection of organic molecules in the extraterrestrial environment provides a key step towards better understanding the variety and the distribution of building blocks of life and it may ultimately lead to finding extraterrestrial life within the Solar System. Here we present combined results of two separate experiments that enable us to realize such in situ life signature detection from the deep habitats of the "Ocean World": a hydrothermal reactor experiment simulating complex organic synthesis and a simulated fly-through capture experiment of organic-bearing microparticles using silica aerogels, followed by subsequent analysis. Both experiments employ peptide as a plausible organics existing in Encleadus plume particles produced in its subsurface ocean. Recent laboratory hydrothermal experiments and a theoretical model on silica saturation indicated an on going hydrothermal reactions in subsurface Enceladus ocean. Given the porous chondritic origin of the core, it is likely that organic compounds originated by radiation chemistry such as amino acid precursors could have been provided, leached, and altered through widespread water-rock interactions. By using the same laboratory experimental setup from the latest water-rock interaction study, we performed amino acid polymerization experiments for 144 days and monitored the organic complexity changing over time. So far over 3,000 peaks up to the size of greater than 600 MW were observed through the analysis of capillary electrophoresis time-of-flight mass spectrometry (CE-TOF-MS) with an indication of amino acid derivatives and short peptides. Generally abiotic polymerization of enantiomeric amino acids results in forming stereoisomeric peptides with identical molecular weight and formula as opposed to homochiral biopolymers. Assuming Enceladus plume particles may contain a mixture of stereoisomeric peptides, we were able to distinguish 16 of the 17 stereoisomeric tripeptides as a test sample using capillary electrophoresis (CE) under optimized conditions. We further conducted Enceladus plume fly-through capture experiment by accelerating peptides soaked in rock particles up to a speed of 5.7 km/s and capturing with originally developed hydrophobic silica aerogels. Direct peptide extraction with acetonitrile-water followed by CE analysis led to detection of only but two stereoisomeric acidic peptide peaks, presenting the first run-through hypervelocuty impact sample analysis targeting peptides as key molecule to to understand the ongoing astrobiology on Enceladus

Tubular ultrafiltration ceramic membrane based on titania nanoparticles immobilized on macroporous clay-alumina support: Elaboration, characterization and application to dye removal

The development of new membranes with improved separation properties, high mechanical and thermal stability using inexpensive and naturally abundant materials is of utmost importance for sustainable development and environmental applications. Ceramic materials due to their high chemical, mechanical and thermal stability in combination to their facile surface functionalization have inspired material scientists to design innovative low-cost ceramic-based membrane supports. This study focuses on the preparation and characterization of novel asymmetric ultrafiltration ceramic membrane coated with single separation layer made of TiO2 nanoparticles, and its application to removal of alizarin dye from aqueous solutions. The membrane was prepared by a simple and one-step deposition of micrometer-thick titania layer on the internal surface of the tubular-shape porous clay-alumina membrane support from an aqueous colloidal suspension of titanium oxide (TiO2) nanoparticles with size of 10 nm. The colloidal suspension was prepared in the presence of 0.2 wt.% of Dolapix, and 30 g of an aqueous solution of polyvinyl alcohol at 12 wt.% and 66 mL of H2O. Microfiltration tubular supports of 10 mm/7 mm (outer/inner diameter) were prepared through an extrusion method followed by a sintering process using China Clay Rajmahal grade and alumina, as mineral precursors. The composition of 25% of clay and 75% of alumina was selected in this work as it showed a lower sintering temperature (T-f = 1350 degrees C) which could ensure low cost elaboration process, an average water flux of 850 L h(-1) m(-2) bar(-1) as well as enhanced mechanical performance (approximate to 37 MPa) and large porosity (48%) with an average pore diameter of 0.75 mu m. SEM characterization showed that at the sintering temperature of 800 degrees C, the TiO2 nanoparticles coated densely and homogeneously the ceramic support forming a thin layer of about 4.2 mu m in thickness and leading to a clear reduction of the mean pore size (50 nm approximatively) while providing a water permeability of 117 L h(-1) m(-2) bar(-1). The so-designed ultrafiltration (UF) tubular ceramic membrane has proved efficient for alizarin red dye removal with a retention rate of 99% and a permeate flux of 70 L h(-1) m(-2) at pH 9 and a transmembrane pressure of 5 bar. (C) 2017 Elsevier B.V. All rights reserved

Propriétés énantiosélectives de copolymères à base de bêta-cyclodextrines modifiées (application à l'électrophorèse capillaire et à la chromatographie liquide haute performance)

LILLE1-BU (590092102) / SudocSudocFranceF

Porous polymers and metallic nanoparticles: A hybrid wedding as a robust method toward efficient supported catalytic systems

International audienc

Synthèse de nouvelles phases monolithes versatiles à base de N-acryloxysuccinimide pour l'électrochromatographie

L intérêt grandissant porté au cours de ces dix dernières années aux monolithes organiques pour des applications électroséparatives se justifie en partie par leur préparation aisée au sein de systèmes miniaturisés, le large choix des monomères précurseurs disponibles, ainsi que la possibilité d ajuster les paramètres structuraux du matériau final par un contrôle judicieux des conditions opératoires. Au cours de ce travail, la synthèse de nouvelles phases monolithiques a été mise au point selon une stratégie en deux étapes. Dans une première étape, la copolymérisation radicalaire photo-initiée du Nacryloxysuccinimide avec le diméthacrylate d éthylène glycol réalisée en présence de toluène, a permis l élaboration de monolithes macroporeux réactifs et hautement perméables. La présence d esters de succinimide dans la structure chimique du monolithe polymère a été mise à profit pour fonctionnaliser la surface du monolithe par des greffons de nature variée par réaction de substitution nucléophile faisant intervenir des dérivés aminés. Le choix judicieux des greffons a permis la mise au point rapide de phases stationnaires présentant des propriétés électrochromatographiques ciblées. Ainsi, le contrôle du caractère hydrophobe des supports obtenus par greffage d alkylamines de taille variable a été mis en évidence par la séparation de dérivés benzéniques selon un mécanisme à polarité de phase inversée avec de très bonnes efficacités (200000 plateaux par mètre). L utilisation de phases stationnaires monolithiques greffées par des sélecteurs aromatiques a été proposée comme alternative aux monolithes aliphatiques hydrophobes. La synthèse de monolithes organiques hydrophiles a été possible par la fonctionnalisation du support réactif par des alkyldiamines. La préparation d une phase stationnaire chirale a été réalisée selon une approche originale de chimie click consistant à immobiliser un dérivé de cyclodextrine. Dans le but d étendre l application des monolithes à base de NAS au greffage de biomacromolécules, une nouvelle matrice monolithique incorporant dans sa structure chimique un co-monomère hydrophile a été élaborée. Les résultats préliminaires ont montré que l augmentation du caractère hydrophile du squelette monolithique permet d accroître sensiblement la réactivité des esters de Nhydroxysuccinimide en milieu aqueuxThe continuously growing interest observed over the past ten years in the field of organic monoliths dedicated to electroseparation applications is mainly due to their easy preparation methods which are also well-suited to the development of miniaturized systems, the wide range of available monomers and the possibility of tuning the structural parameters of the final material by a judicious control of the synthesis conditions. In the present work, the synthesis of new monolithic stationary phases has been developed using a two-stage strategy. In a first step, the photo-initiated free radical copolymerization of Nacryloxysuccinimide with ethylene glycol dimethacrylate was performed in the presence of toluene allowing the preparation of reactive and macroporous monoliths with high permeability properties. The presence of succinimide esters in the chemical structure of the polymer monolith was used to functionalize the surface of the monolith by various grafts through nucleophilic substitution reaction involving amino derivatives. The judicious choice of the grafts permits the fast development of stationary phases with target electrochromatographic properties. Indeed, the tuning of the hydrophobic nature of the monolithic materials was obtained by the grafting of varied alkylamines and was demonstrated by the separation of benzene derivatives by reversed phase mechanism with very good efficiencies (200 000 plates per meter). The use of monolithic stationary phases grafted with aromatic selectors has been proposed as an alternative to the aliphatic-grafted hydrophobic monoliths. The synthesis of organic hydrophilic monoliths was possible by functionalization of the reactive support by alkyldiamines. The preparation of a chiral stationary phase was performed using an original click chemistry approach involving the immobilization of a cyclodextrin derivative. With the aim to extend the application range of NAS-based monoliths to the grafting of biomacromolecules for selective capture and enzymatic digestion applications, a new monolithic matrix incorporating in its chemical structure a hydrophilic comonomer was prepared. Preliminary results showed that the increase in the hydrophilic character of the polymeric skeleton allows increasing significantly the reactivity of N-hydroxysuccinimide esters in aqueous mediumPARIS-EST-Université (770839901) / SudocSudocFranceF

Preparation, characterisation and enantioselective separation properties of a chiral stationary phase based on silica beads coated with a 2-hydroxypropyl-β-cyclodextrin polymer

International audienc

From beta-cyclodextrin polyelectrolyte to layer-by-layer self-assembly microcapsules: From inhibition of bacterial growth to bactericidal effect

International audiencePathogenic bacteria resistance to antimicrobial agents has emerged as a major health issue. Developing new systems enabling inhibitory and bactericidal effects is crucial. Herein, layer-by-layer technique (LbL) was used to fabricate microcapsules composed of biopolymers, cationic polycyclodextrin (P(CD+)) and anionic alginate (alg−). This was achieved through successive adsorption of these polyelectrolytes onto calcium carbonate microparticles (CaCO3) used as template. Then, a chelating agent was added for removing the CaCO3 core, leading to microcapsules. Quartz crystal microbalance and zeta potential measurements evidenced the successful alternate adsorption of polyelectrolytes and related charge reversal, respectively, upon the LbL deposition. The shape of the capsules was characterized by Scanning Electron Microscopy (SEM) and fluorescence microscopy. The antibacterial activity of P(CD+) was first evidenced on two well-known bacteria: Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) using well diffusion method on Plate Count Agar (PCA) medium. Then, an inhibitory effect on the bacteria growth has been observed for the P(CD+)-based microcapsules during bacterial culture in Luria-Bertani (LB) broth medium. Our results pointed out towards a strong dependence of the extent of inhibition on the number of self-assembled polyelectrolytes' layers and capsules’ concentration. The effect increased with both concentration and number of layers. Acridine orange staining evidenced the bactericidal effect of P(CD+)-based microcapsules. This contribution demonstrates unambiguously that: i) aqueous solutions of P(CD+) exhibit antibacterial activity at physiological pH suggesting that P(CD+) can act as a versatile alternative to the widely studied chitosan whose antimicrobial activity is limited to acidic pH and ii) (P(CD+)/alg−)n hollow capsules can be exploited as an antibacterial agents with additional host properties

Gold nanoparticles supported onto amine-functionalized in-capillary monoliths meant for flow-through catalysis: A comparative study

International audienc

Metallic Nanoparticles Adsorbed at the Pore Surface of Polymers with Various Porous Morphologies: Toward Hybrid Materials Meant for Heterogeneous Supported Catalysis

International audienceHybrid materials consisting of metallic nanoparticles (NPs) adsorbed on porous polymericsupports have been the subject of intense research for many years. Such materials indeed gain fromintrinsic properties, e.g., high specific surface area, catalytic properties, porous features, etc., of bothcomponents. Rational design of such materials is fundamental regarding the functionalization of thesupport surface and thus the interactions required for the metallic NPs to be strongly immobilizedat the pore surface. Herein are presented some significant scientific contributions to this rapidlyexpanding research field. This contribution will notably focus on various examples of such hybridsystems prepared from porous polymers, whatever the morphology and size of the pores. Suchporous polymeric supports can display pores with sizes ranging from a few nanometers to hundredsof microns while pore morphologies, such as spherical, tubular, etc., and/or open or closed, canbe obtained. These systems have allowed some catalytic molecular reactions to be successfullyundertaken, such as the reduction of nitroaromatic compounds or dyes, e.g., methylene blue andEosin Y, boronic acid-based C–C homocoupling reactions, but also cascade reactions consisting oftwo catalytic reactions achieved in a row