2017 |
Al Salloum, H., Saunier, J., Dazzi, A., Vigneron, J., Etcheberry, A., Marliere, C., Aymes-Chodur, C., Herry, J. M., Bernard, M., Jubeli, E., & Yagoubi, N. (2017). Characterization of the surface physico-chemistry of plasticized PVC used in blood bag and infusion tubing. Materials Science & Engineering C-Materials For Biological Applications, 75, 317–334.
Résumé: Commercial infusion tubing and blood storage devices (tubing, blood and platelets bags) made of plasticized PVC were analyzed by spectroscopic, chromatographic and microscopic techniques in order to identify and quantify the additives added to the polymer (lubricants, thermal stabilizers, plasticizers) and to put into evidence their blooming onto the surface of the devices. For all the samples, deposits were observed on the surface but with different kinds of morphologies. Ethylene bis amide lubricant and metallic stearate stabilizers were implicated in the formation of these layers. In contact with aqueous media, these insoluble deposits were damaged, suggesting a possible particulate contamination of the infused solutions. (C) 2017 Elsevier B.V. All rights reserved.
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Chan, A. J., Sarkar, P., Gaboriaud, F., Fontaine-Aupart, M. P., & Marliere, C. (2017). Control of interface interactions between natural rubber and solid surfaces through charge effects: an AFM study in force spectroscopic mode. Rsc Advances, 7(69), 43574–43589.
Résumé: This work presents a detailed investigation of interface interactions between natural rubber (NR) particles and solid surfaces in aqueous mediumat high ionic strength (0.1 M) using AFM in fast force spectroscopy mode. In this study, an original method for fixing the NR on the substrate was developed. This avoided the usual perturbations common in standard immobilization techniques. We proved that the adhesion process of the NR is monitored by slight changes in the surface charge state of the contacting solid surfaces made of silicon oxide or silicon nitride. The results were interpreted using Dynamic Force Spectroscopy theory, with the introduction of a supplementary term describing the electrostatic energy. Furthermore, these experiments revealed that adhesion between NR and tip was time dependent in a cumulative process. In addition, an increase of the adhesion between NR and AFM tip with the size of the rubber particles was measured. This was related to the higher concentration in lipids versus proteins for larger NR particles. These results are of great importance both for practical applications in solution-based industrial processes and to the fundamental knowledge of adhesion process involved for biopolymers or living cells.
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Dajkovic, A., Tesson, B., Chauhan, S., Courtin, P., Keary, R., Flores, P., Marliere, C., Filipe, S. R., Chapot-Chartier, M. P., & Carballido-Lopez, R. (2017). Hydrolysis of peptidoglycan is modulated by amidation of meso-diaminopimelic acid and Mg2+ in Bacillus subtilis. Molecular Microbiology, 104(6), 972–988.
Résumé: The ability of excess Mg2+ to compensate the absence of cell wall related genes in Bacillus subtilis has been known for a long time, but the mechanism has remained obscure. Here, we show that the rigidity of wild-type cells remains unaffected with excess Mg2+, but the proportion of amidated meso-diaminopimelic (mDAP) acid in their peptidoglycan (PG) is significantly reduced. We identify the amidotransferase AsnB as responsible for mDAP amidation and show that the gene encoding it is essential without added Mg2+. Growth without excess Mg2+ causes asnB mutant cells to deform and ultimately lyse. In cell regions with deformations, PG insertion is orderly and indistinguishable from the wild-type. However, PG degradation is unevenly distributed along the sidewalls. Furthermore, asnB mutant cells exhibit increased sensitivity to antibiotics targeting the cell wall. These results suggest that absence of amidated mDAP causes a lethal deregulation of PG hydrolysis that can be inhibited by increased levels of Mg2+. Consistently, we find that Mg2+ inhibits autolysis of wild-type cells. We suggest that Mg2+ helps to maintain the balance between PG synthesis and hydrolysis in cell wall mutants where this balance is perturbed in favor of increased degradation.
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Nouman, M., Saunier, J., Jubeli, E., Marliere, C., & Yagoubi, N. (2017). Impact of of sterilization and oxidation processes on the additive blooming observed on the surface of polyurethane. European Polymer Journal, 90, 37–53.
Résumé: The surface state is a major parameter for the biocompatibility of medical devices. During storage, the blooming of additives may occur on the surface of polymers and modify their properties. In this study, the impact of sterilizing and oxidation treatments on blooming was studied. The study was realized on polyurethane used in the fabrication of catheters on which the blooming of antioxidant crystals has been previously observed. Sterilization by ionizing radiations (beta, gamma) was performed on this material and samples were submitted to different kinds of oxidation process (UV, H2O2 and macrophages action). Surface evolution was investigated using AFM microscopy, FTIR-ATR and SEM.
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Saunier, J., Herry, J. M., Yagoubi, N., & Marliere, C. (2017). Exploring complex transitions between polymorphs on a small scale by coupling AFM, FTIR and DSC: the case of Irganox 1076 (R) antioxidant. Rsc Advances, 7(7), 3804–3818.
Résumé: This study illustrates the significant interest of using atomic force microscopy (AFM) in force curve imaging mode for discovering and studying not easily detectable solid/solid transitions between polymorphs: we show that AFM in this imaging mode is a powerful means for studying in situ these transitions as they can be (i) detected in a very early step because of the high spatial resolution (at nanometer scale) of AFM and (ii) be distinguished from melting/recrystallization processes that can occur in the same temperature range. This was illustrated with the case of Irganox 1076 (R). This compound is a phenolic antioxidant currently used in standard polymers; it can bloom on the surface of polymer-based medical devices and its polymorphism might affect the device surface state and thus the biocompatibility. In a previous paper, the polymorphism of this compound was studied: four forms were characterized at a macroscopic level and one of them (form III) was identified on the surface of a polyurethane catheter. However, it was difficult to characterize the transitions between the different forms with only classical tools (DSC, FTIR and SAXS). In the present study, to evidence these transitions, we use AFM measurements coupled with a heating stage and we correlate them to ATR-FTIR measurements and to DSC analysis. This new study put into evidence a solid-solid transition between form III and II.
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2016 |
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Marliere, C. (2016). A direct and at nanometer scale study of electrical charge distribution on membranes of alive cells. In Electro-Activity Of Biological Systems (Vol. 6).
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2015 |
De Wit, R., Gautret, P., Bettarel, Y., Roques, C., Marliere, C., Ramonda, M., Thanh, T. N., Quang, H. T., & Bouvier, T. (2015). Viruses Occur Incorporated in Biogenic High-Mg Calcite from Hypersaline Microbial Mats. Plos One, 10(6), e0130552.
Résumé: Using three different microscopy techniques (epifluorescence, electronic and atomic force microscopy), we showed that high-Mg calcite grains in calcifying microbial mats from the hypersaline lake “La Salada de Chiprana”, Spain, contain viruses with a diameter of 50-80 nm. Energy-dispersive X-ray spectrometer analysis revealed that they contain nitrogen and phosphorus in a molar ratio of similar to 9, which is typical for viruses. Nucleic acid staining revealed that they contain DNA or RNA. As characteristic for hypersaline environments, the concentrations of free and attached viruses were high (>10(10) viruses per g of mat). In addition, we showed that acid treatment (dissolution of calcite) resulted in release of viruses into suspension and estimated that there were similar to 15 x 109 viruses per g of calcite. We suggest that virus-mineral interactions are one of the possible ways for the formation of nano-sized structures often described as “nanobacteria” and that viruses may play a role in initiating calcification.
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Marliere, C., & Dhahri, S. (2015). An in vivo study of electrical charge distribution on the bacterial cell wall by atomic force microscopy in vibrating force mode. Nanoscale, 7(19), 8843–8857.
Résumé: We report an in vivo electromechanical atomic force microscopy (AFM) study of charge distribution on the cell wall of Gram+ Rhodococcus wratislaviensis bacteria, naturally adherent to a glass substrate, under physiological conditions. The method presented in this paper relies on a detailed study of AFM approach/retract curves giving the variation of the interaction force versus distance between the tip and the sample. In addition to classical height and mechanical (as stiffness) data, mapping of local electrical properties, such as bacterial surface charge, was proved to be feasible at a spatial resolution better than a few tens of nanometers. This innovative method relies on the measurement of the cantilever's surface stress through its deflection far from (>10 nm) the repulsive contact zone: the variations of surface stress come from the modification of electrical surface charge of the cantilever (as in classical electrocapillary measurements) likely stemming from its charging during contact of both the tip and the sample electrical double layers. This method offers an important improvement in local electrical and electrochemical measurements at the solid/liquid interface, particularly in high-molarity electrolytes when compared to techniques focused on the direct use of electrostatic force. It thus opens a new way to directly investigate in situ biological electrical surface processes involved in numerous practical applications and fundamental problems such as bacterial adhesion, biofilm formation, microbial fuel cells, etc.
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Saunier, J., Herry, J. M., Marliere, C., Renault, M., Bellon-Fontaine, M. N., & Yagoubi, N. (2015). Modification of the bacterial adhesion of Staphylococcus aureus by antioxidant blooming on polyurethane films. Materials Science & Engineering C-Materials For Biological Applications, 56, 522–531.
Résumé: Medical device-related infections are a major problem in hospital. The risk of developing an infection is linked to the bacterial adhesion ability of pathogen strains on the device and their ability to form a biofilm. Here we focused on polymer surfaces exhibiting a blooming of antioxidant (Irganox 3114 (R)) and Irganox 1076 (R)) on their surface. We tried to put into evidence the effect of such a phenomenon on the bacterial adhesion in terms of number of viable cultivable bacteria and bacteria localization on the surface. We showed that the blooming has a tendency to increase the Staphylococcus aureus adhesion phenomenon in part for topographic reasons. (C) 2015 Elsevier B.V. All rights reserved.
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2013 |
Dhahri, S., Ramonda, M., & Marliere, C. (2013). In-Situ Determination of the Mechanical Properties of Gliding or Non-Motile Bacteria by Atomic Force Microscopy under Physiological Conditions without Immobilization. Plos One, 8(4), e61663.
Résumé: We present a study about AFM imaging of living, moving or self-immobilized bacteria in their genuine physiological liquid medium. No external immobilization protocol, neither chemical nor mechanical, was needed. For the first time, the native gliding movements of Gram-negative Nostoc cyanobacteria upon the surface, at speeds up to 900 μm/h, were studied by AFM. This was possible thanks to an improved combination of a gentle sample preparation process and an AFM procedure based on fast and complete force-distance curves made at every pixel, drastically reducing lateral forces. No limitation in spatial resolution or imaging rate was detected. Gram-positive and non-motile Rhodococcus wratislaviensis bacteria were studied as well. From the approach curves, Young modulus and turgor pressure were measured for both strains at different gliding speeds and are ranging from 20 +/- 3 to 105 +/- 5 MPa and 40 +/- 5 to 310 +/- 30 kPa depending on the bacterium and the gliding speed. For Nostoc, spatially limited zones with higher values of stiffness were observed. The related spatial period is much higher than the mean length of Nostoc nodules. This was explained by an inhomogeneous mechanical activation of nodules in the cyanobacterium. We also observed the presence of a soft extra cellular matrix (ECM) around the Nostoc bacterium. Both strains left a track of polymeric slime with variable thicknesses. For Rhodococcus, it is equal to few hundreds of nanometers, likely to promote its adhesion to the sample. While gliding, the Nostoc secretes a slime layer the thickness of which is in the nanometer range and increases with the gliding speed. This result reinforces the hypothesis of a propulsion mechanism based, for Nostoc cyanobacteria, on ejection of slime. These results open a large window on new studies of both dynamical phenomena of practical and fundamental interests such as the formation of biofilms and dynamic properties of bacteria in real physiological conditions.
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2011 |
Wang, T., Boer-Duchemin, E., Tranvouez, E., Cartwright, R., Comtet, G., Dujardin, G., & Mayne, A. J. (2011). Low voltage fabrication of sub-nanometer insulating layers on hydrogenated diamond. JOURNAL OF APPLIED PHYSICS, 110(3), 034311.
Résumé: A new regime of electrochemical anodic oxidation with an atomic force microscope (AFM) is introduced for producing insulating layers on a hydrogenated diamond surface. In this new regime, when a low surface voltage (V(S) < +2 V) is applied to the sample, an insulating layer is created without any measurable change in the topography. Insulating layers created in this fashion are shown to preserve the high sub-surface conductance of hydrogenated diamond surfaces, contrary to the oxide layers accompanied by a topographic change, which destroy sub-surface conductance. (C) 2011 American Institute of Physics. [doi:10.1063/1.3615956]
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2010 |
Boer-Duchemin, E., Tranvouez, E., & Dujardin, G. (2010). The interaction of an atomic force microscope tip with a nano-object: a model for determining the lateral force. Nanotechnology, 21(45), 455704.
Résumé: A calculation of the lateral force interaction between an atomic force microscope (AFM) tip and a nano-object on a substrate is presented. In particular, the case where the AFM tip is used to manipulate the nano-object is considered; i.e., the tip is displaced across the nano-object with the feedback off. The Hamaker equations are used to calculate the force when the tip and sample are not in contact and the Johnson, Kendall and Roberts (JKR) or Derjaguin, Muller and Toporov (DMT) formalisms are used for the contact force. The effect of the material parameters, the choice of contact theory and the shape of the nano-object on the resulting lateral forces are explored. The calculation is applied to an experimental system consisting of a cadmium selenide nanorod on graphite.
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2009 |
Tranvouez, E., Boer-Duchemin, E., Mayne, A. J., Vanderbruggen, T., Scheele, M., Cartwright, R., Comtet, G., Dujardin, G., Schneegans, O., Chretien, P., & Houze, F. (2009). Influence of morphology on the conductance of single-crystal diamond surfaces measured by atomic force microscopy. J. Appl. Phys., 106(5), 054301.
Résumé: A detailed atomic force microscopy (AFM) study of the conductance of hydrogenated single-crystal diamond (100) surfaces over submicron length scales is presented. The hydrogenation process was found to influence the surface morphology by reducing surface roughness, with the subsequent appearance of small triangular structures (with side lengths of 200 nm). Conducting AFM measurements revealed variations in the current and resistance that were related to the topography. Possible explanations include surface inhomogeneity of the electronic structure or variations in the contact resistance due to the surface roughness.
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Tranvouez, E., Orieux, A., Boer-Duchemin, E., Devillers, C. H., Huc, V., Comtet, G., & Dujardin, G. (2009). Manipulation of cadmium selenide nanorods with an atomic force microscope. Nanotechnology, 20(16), 165304.
Résumé: We have used an atomic force microscope (AFM) to manipulate and study ligand-capped cadmium selenide nanorods deposited on highly oriented pyrolitic graphite (HOPG). The AFM tip was used to manipulate (i.e., translate and rotate) the nanorods by applying a force perpendicular to the nanorod axis. The manipulation result was shown to depend on the point of impact of the AFM tip with the nanorod and whether the nanorod had been manipulated previously. Forces applied parallel to the nanorod axis, however, did not give rise to manipulation. These results are interpreted by considering the atomic-scale interactions of the HOPG substrate with the organic ligands surrounding the nanorods. The vertical deflection of the cantilever was recorded during manipulation and was combined with a model in order to estimate the value of the horizontal force between the tip and nanorod during manipulation. This horizontal force is estimated to be on the order of a few tens of nN.
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