Delpouve N.,CNRS Laboratory for the Characterization of Amorphous Polymers |
Stoclet G.,University of Lille Nord de France |
Saiter A.,CNRS Laboratory for the Characterization of Amorphous Polymers |
Dargent E.,CNRS Laboratory for the Characterization of Amorphous Polymers |
Marais S.,CNRS Polymers, Biopolymer and Surfaces Laboratory
Journal of Physical Chemistry B | Year: 2012
Crystallization is among the easiest ways to improve polymer barrier properties because of the tortuosity increase within the material and the strong coupling between amorphous and crystalline phases. In this work, poly(lactic acid) (PLA) films have undergone α∼ thermal crystallization or different drawing processes. Although no effect of α∼ thermal crystallization on water permeability is observed, the drawing processes lead to an enhancement of the PLA barrier properties. This work clearly shows that, in the case of PLA, the crystallinity degree is not the main parameter governing the barrier properties contrary to the crystalline and amorphous phase organizations which play a key role. X-ray analyses confirm that the macromolecular chain orientation in the amorphous phase is the main cause of the improvement of the drawn PLA water barrier property. This improvement is due to the orthotropic structure formation for sufficient draw ratios, particularly when using the Simultaneous Biaxial drawing mode. Moreover, independently of the draw conditions, the drawing process tends to reduce the plasticization coefficient. Consequently, the drawn material barrier properties are not much affected by the water passage. © 2012 American Chemical Society.
Demay-Drouhard P.,University of Paris 13 |
Nehlig E.,University of Paris 13 |
Hardouin J.,CNRS Polymers, Biopolymer and Surfaces Laboratory |
Motte L.,University of Paris 13 |
Guenin E.,University of Paris 13
Chemistry - A European Journal | Year: 2013
A light click away: The first application of the thiol-yne reaction to nanoparticle functionalization is described (see figure). This metal-free click chemistry approach is compatible with the addition of various molecules at the surface and can be combined with CuAAC methodology to perform chemoselective double functionalization. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Glinel K.,Catholic University of Louvain |
Thebault P.,CNRS Polymers, Biopolymer and Surfaces Laboratory |
Humblot V.,University Pierre and Marie Curie |
Pradier C.M.,University Pierre and Marie Curie |
Jouenne T.,CNRS Polymers, Biopolymer and Surfaces Laboratory
Acta Biomaterialia | Year: 2012
Prevention of bacterial adhesion and biofilm formation on the surfaces of materials is a topic of major medical and societal importance. Various synthetic approaches based on immobilization or release of bactericidal substances such as metal derivatives, polyammonium salts and antibiotics were extensively explored to produce antibacterial coatings. Although providing encouraging results, these approaches suffer from the use of active agents which may be associated with side-effects such as cytotoxicity, hypersensibility, inflammatory responses or the progressive alarming phenomenon of antibiotic resistance. In addition to these synthetic approaches, living organisms, e.g. animals and plants, have developed fascinating strategies over millions of years to prevent efficiently the colonization of their surfaces by pathogens. These strategies have been recently mimicked to create a new generation of bio-inspired biofilm-resistant surfaces. In this review, we discuss some of these bio-inspired methods devoted to the development of antibiofilm surfaces. We describe the elaboration of antibacterial coatings based on natural bactericidal substances produced by living organisms such as antimicrobial peptides, bacteriolytic enzymes and essential oils. We discuss also the development of layers mimicking algae surfaces and based on anti-quorum-sensing molecules which affect cell-to-cell communication. Finally, we report on very recent strategies directly inspired from marine animal life and based on surface microstructuring. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Lenormand H.,CNRS Polymers, Biopolymer and Surfaces Laboratory |
Vincent J.-C.,CNRS Polymers, Biopolymer and Surfaces Laboratory
Carbohydrate Polymers | Year: 2011
Hyaluronan (HA) hydrolysis catalysed by hyaluronidase (HAase) is enhanced when bovine serum albumin (BSA) is present and competes with HAase to form electrostatic complexes with HA. At 1 g L -1 HA and BSA concentrations, BSA is able to form three types of complexes with HA depending on pH ranging from 2.5 to 6: insoluble neutral complexes at low pH values, sedimentable slightly charged complexes at pH near 4 and soluble highly charged complexes at pH near 5. The BSA content, charge and solubility of the HA-BSA complexes increase when pH is increased up to the pI of BSA. The normalised charge excess does not exceed 20% for the sedimentable complexes and 40% for the soluble complexes. It has been shown that the sedimentable slightly charged HA-BSA complexes are the most efficient to compete with HAase and release it. All the HA-BSA complexes are hydrolysable by HAase. The HA-BSA binding site shows that one BSA molecule is associated with 85-170 HA carboxyl groups, depending on pH. Similar results have been obtained for lysozyme over an extended pH domain, including the neutrality. © 2011 Elsevier Ltd. All rights reserved.
Wu A.-M.,University of Southampton |
Hornblad E.,Swedish University of Agricultural Sciences |
Voxeur A.,Laboratoire Of Glycobiologie Et Matrice Extracellulaire Vegetale |
Gerber L.,Swedish University of Agricultural Sciences |
And 4 more authors.
Plant Physiology | Year: 2010
The hemicellulose glucuronoxylan (GX) is a major component of plant secondary cell walls. However, our understanding of GX synthesis remains limited. Here, we identify and analyze two new genes from Arabidopsis (Arabidopsis thaliana), IRREGULAR XYLEM9-LIKE (IRX9-L) and IRX14-LIKE (IRX14-L) that encode glycosyltransferase family 43 members proposed to function during xylan backbone elongation. We place IRX9-L and IRX14-L in a genetic framework with six previously described glycosyltransferase genes (IRX9, IRX10, IRX10-L, IRX14, FRAGILE FIBER8 [FRA8], and FRA8 HOMOLOG [F8H]) and investigate their function in GX synthesis. Double-mutant analysis identifies IRX9-L and IRX14-L as functional homologs of IRX9 and IRX14, respectively. Characterization of irx9 irx10 irx14 fra8 and irx9-L irx10-L irx14-L f8h quadruple mutants allows definition of a set of genes comprising IRX9, IRX10, IRX14, and FRA8 that perform the main role in GX synthesis during vegetative development. The IRX9-L, IRX10-L, IRX14-L, and F8H genes are able to partially substitute for their respective homologs and normally perform a minor function. The irx14 irx14-L double mutant virtually lacks xylan, whereas irx9 irx9-L and fra8 f8h double mutants form lowered amounts of GX displaying a greatly reduced degree of backbone polymerization. Our findings reveal two distinct sets of four genes each differentially contributing to GX biosynthesis. © 2010 American Society of Plant Biologists.