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1. Natural Products as Angiogenesis Inhibitors

Author

D. H. Paper

Subjects
Adult, Angiogenesis, Pharmaceutical Science, Inflammation, Endogeny, Biology, Analytical Chemistry, Neovascularization, Pathogenesis, Drug Discovery, medicine, Animals, Humans, Pharmacology, Molecular Structure, Neovascularization, Pathologic, Plant Extracts, Organic Chemistry, Cancer, medicine.disease, Angiogenesis inhibitor, Complementary and alternative medicine, Immunology, Cancer research, Molecular Medicine, medicine.symptom, Wound healing
Abstract

Angiogenesis is a strictly controlled process in the healthy, adult human body. It is regulated by a variety of endogenous angiogenic and angiostatic factors. It is only switched on, e.g., during wound healing. Pathological angiogenesis occurs, for example, in cancer, chronic inflammation, or atherosclerosis. Angiogenesis inhibitors are able to interfere with various steps of angiogenesis, like basement destruction of blood vessels, proliferation and migration of endothelial cells, or the lumen formation. Among the known angiogenesis inhibitors compounds derived from natural sources, like flavonoids, sulphated carbohydrates, or triterpenoids are playing a prominent role.

Published
1998

2. Automatic Waypoint Generation to Improve Robot Navigation Through Narrow Spaces

Author

Javier Gonzalez-Jimenez, Jose-Raul Ruiz-Sarmiento, Cipriano Galindo, Javier Monroy, Francisco-Angel Moreno, Machine Perception and Intelligent Robotics Group (MAPIR), [Moreno,FA, Monroy,J, Ruiz-Sarmiento,JR, Galindo,C, Gonzalez-Jimenez,J] Machine Perception and Intelligent Robotics Group (MAPIR), Dept. of System Engineering and Automation Biomedical Research Institute of Malaga (IBIMA), University of Malaga, Málaga, Spain., and This work has been supported by the research projects WISER (DPI2017-84827-R), funded by the Spanish Government and the European Regional Development’s Funds (FEDER), MoveCare (ICT-26-2016b-GA-732158), funded by the European H2020 program, and by a postdoc contract from the I-PPIT program of the University of Malaga. The publication of this paper has been funded by the University of Malaga.

Subjects
0209 industrial biotechnology, Traverse, Phenomena and Processes::Mathematical Concepts::Algorithms [Medical Subject Headings], Computer science, Chemicals and Drugs::Inorganic Chemicals::Free Radicals::Reactive Oxygen Species [Medical Subject Headings], waypoint generation, Real-time computing, Information Science::Information Science::Computing Methodologies::Artificial Intelligence::Robotics [Medical Subject Headings], 02 engineering and technology, lcsh:Chemical technology, Biochemistry, Article, Analytical Chemistry, Task (project management), Waypoint generation, Organisms::Eukaryota::Animals::Chordata::Vertebrates::Mammals::Primates::Haplorhini::Catarrhini::Hominidae::Humans [Medical Subject Headings], Waypoint, robot deployment, 020901 industrial engineering & automation, Information Science::Information Science::Computing Methodologies::Artificial Intelligence [Medical Subject Headings], Navigation assistant, robot navigation, Artificial Intelligence, mobile robots, robot localization, 0202 electrical engineering, electronic engineering, information engineering, Mobile robots, Mapa, lcsh:TP1-1185, Electrical and Electronic Engineering, Instrumentation, business.industry, Robot localization, Robotics, Mobile robot, Atomic and Molecular Physics, and Optics, Inteligencia artificial, Trajectory, Robot navigation, Map, Robot, 020201 artificial intelligence & image processing, Noise (video), Artificial intelligence, business, Robótica, Robot deployment
Abstract

In domestic robotics, passing through narrow areas becomes critical for safe and effective robot navigation. Due to factors like sensor noise or miscalibration, even if the free space is sufficient for the robot to pass through, it may not see enough clearance to navigate, hence limiting its operational space. An approach to facing this is to insert waypoints strategically placed within the problematic areas in the map, which are considered by the robot planner when generating a trajectory and help to successfully traverse them. This is typically carried out by a human operator either by relying on their experience or by trial-and-error. In this paper, we present an automatic procedure to perform this task that: (i) detects problematic areas in the map and (ii) generates a set of auxiliary navigation waypoints from which more suitable trajectories can be generated by the robot planner. Our proposal, fully compatible with the robotic operating system (ROS), has been successfully applied to robots deployed in different houses within the H2020 MoveCare project. Moreover, we have performed extensive simulations with four state-of-the-art robots operating within real maps. The results reveal significant improvements in the number of successful navigations for the evaluated scenarios, demonstrating its efficacy in realistic situations.

Published
2019
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3. Preliminary investigation of the microwave pyrolysis mechanism of sludge based on high frequency structure simulator simulation of the electromagnetic field distribution

Author

Xuxin Zhao, Rui Ma, Na-Na Yuan, Shichang Sun, Xianghua Zhang, Lin Fang, Peixin Zhang, Shenzhen Univerisity [Shenzhen], Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), This paper was supported by the Shenzhen Science and Technology Planning Project (Grant Nos. JCYJ20150828113927076, JCYJ20130329113322731), the China National Natural Science Foundation (50906058) and the Natural Science Foundation of SZU (No. 827-000037)., Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Electromagnetic field, Hot Temperature, Environmental Engineering, Materials science, Carbon Compounds, Inorganic, 020209 energy, Microwave pyrolysis, Evaporation, Analytical chemistry, Bioengineering, 02 engineering and technology, 010501 environmental sciences, 01 natural sciences, 7. Clean energy, Electromagnetic Fields, [CHIM.GENI]Chemical Sciences/Chemical engineering, Waste Management, Electric field, HFSS simulation, 0202 electrical engineering, electronic engineering, information engineering, Desiccation, Microwaves, Waste Management and Disposal, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Sewage, Waste management, [SDE.IE]Environmental Sciences/Environmental Engineering, Renewable Energy, Sustainability and the Environment, Silicon Compounds, General Medicine, Thermal conduction, Raw sludge, 6. Clean water, Microwave irradiation, Electric field intensity, SiC sludge, Pyrolysis, Intensity (heat transfer)
Abstract

Under microwave irradiation, raw sludge was pyrolyzed mainly by evaporation of water, with a weight loss ratio of 84.8% and a maximum temperature not exceeding 200 °C. High-temperature pyrolysis of SiC sludge could be realized, with a weight loss ratio of 93.4% and a final pyrolysis temperature of 1131.7 °C. Variations between the electric field intensity distribution are the main reason for the differences of pyrolysis efficiencies. HFSS simulation showed that the electric field intensity of the raw sludge gradually decreased from 2.94 × 10 4 V/m to 0.88 × 10 4 V/m when pyrolysis ends, while that of SiC sludge decreased from 3.73 × 10 4 V/m at the beginning to 1.28 × 10 4 V/m, then increased to 4.03 × 10 4 V/m. The electromagnetic effect is the main factor (r ≥ 0.91) influencing the temperature increase and weight loss of raw sludge. Both the electromagnetic effect and heat conduction effect influenced temperature rise and weight loss of SiC sludge, but the former’s influence was comparatively larger.

Published
2017

4. Influence of the electrografting method on the performances of a flow electrochemical sensor using modified electrodes for trace analysis of copper (II)

Author

Cecilia Cristea, Robert Săndulescu, Cristelle Mériadec, Florence Geneste, Ionel Fizesan, Bogdan Feier, Soraya Ababou Girard, Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université Cluj-Napoca, facultatea, Institut de Physique de Rennes (IPR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), This paper was published under the frame of European Social Found, Human Resources Development Operational Programme 2007–2013, Project No. POSDRU/159/1.5/S/136893. The authors are also thankful for the financial support to 'Iuliu Hatieganu' University of Medicine and Pharmacy of Cluj-Napoca, for the research Grant 1491/8/28.01.2014 and for their help to Ioana Băjan, Ana Gui and Ioana Ionel, students of 'Iuliu Hatieganu' University of Medicine and Pharmacy, Faculty of Pharmacy., Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), and Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Copper detection, [CHIM.ORGA]Chemical Sciences/Organic chemistry, General Chemical Engineering, Electrografting, Inorganic chemistry, Open circuit preconcentration, chemistry.chemical_element, Electrochemistry, Copper, Analytical Chemistry, Electrochemical gas sensor, chemistry.chemical_compound, chemistry, Electrode, Cyclam, Graphite, Cyclic voltammetry, Voltammetry, Sensor
Abstract

The performances of carboxylate- and cyclam-modified graphite felt electrodes prepared by different electrografting methods for trace analysis of copper (II) were compared to determine the influence of the immobilization process of the linkers on the sensor properties. The derivatization performed by cathodic reduction of diazonium salts and by anodic oxidation of amines in organic and aqueous media was first evaluated by cyclic voltammetry and X-ray photoelectron spectroscopy analyses, showing a higher surface coverage for the reduction process. Cyclam was subsequently attached on the COOH-modified graphite felts by a coupling reaction. The modified electrodes were then employed in a flow analytical system for trace analysis of copper (II) ions. The influence of the surface coverage and the nature of the linker on the electrochemical signal obtained by linear sweep stripping voltammetry analysis after a preconcentration step performed at open circuit was highlighted. The selectivity estimated in the presence of lead used as a common ion interferent was higher when a selective receptor was used and depends on the nature of the linker.

Published
2015

5. Synchrotron FTIR microspectroscopy of Escherichia coli at single-cell scale under silver-induced stress conditions

Author

Claire Saulou, Muriel Mercier-Bonin, Isabelle Fourquaux, Paul Dumas, Claude Maranges, Frédéric Jamme, Muriel Cocaign-Bousquet, Laurence Girbal, Génie et Microbiologie des Procédés Alimentaires (GMPA), Institut National de la Recherche Agronomique (INRA)-AgroParisTech, Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés (LISBP), Institut National de la Recherche Agronomique (INRA)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT), Unité de recherche sur les Biopolymères, Interactions Assemblages (BIA), Institut National de la Recherche Agronomique (INRA), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT), Centre de Microscopie Électronique Appliquée à la Biologie (CMEAB), Toulouse Réseau Imagerie-Genotoul ( TRI-Genotoul), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), The authors gratefully acknowledge the 'BioPleasure' project of the Research National Agency (ANR-07-BLAN-0196-01) for funding., The research described in this paper was performed at the French national synchrotron facility SOLEIL (Gif-sur- Yvette, France), using the SMIS beamline (proposal no 20090556)., ANR-07-BLAN-0196,BIOPLEASURE,Plasma - surface engineering for biofilm prevention(2007), AgroParisTech-Institut National de la Recherche Agronomique (INRA), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées, Institut National des Sciences Appliquées (INSA), Hôpital de Rangueil, CHU Toulouse [Toulouse]-CHU Toulouse [Toulouse]-Toulouse Réseau Imagerie-Genotoul ( TRI-Genotoul), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de la Recherche Agronomique (INRA), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Hôpital de Rangueil, and CHU Toulouse [Toulouse]-CHU Toulouse [Toulouse]

Subjects
In situ, Analytical chemistry, medicine.disease_cause, Biochemistry, Analytical Chemistry, 03 medical and health sciences, Stress, Physiological, Spectroscopy, Fourier Transform Infrared, medicine, Escherichia coli, Fourier transform infrared spectroscopy, [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biochemistry [q-bio.BM], Protein secondary structure, 030304 developmental biology, 0303 health sciences, biology, Ionic silver, 030306 microbiology, Chemistry, Synchrotron FTIR-ATR microspectroscopy, Single-cell scale, [CHIM.MATE]Chemical Sciences/Material chemistry, biology.organism_classification, [SDV.MP.BAC]Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology, [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biomolecules [q-bio.BM], Antibacterial effect, Transmission electron microscopy, Attenuated total reflection, Ultrastructure, Biophysics, Silver Nitrate, Single-Cell Analysis, [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing, Synchrotrons, Bacteria
Abstract

International audience; The present work was focused on elucidating biochemical changes in the model bacterium Escherichia coli exposed to ionic silver mediated stress, at a single-cell scale. In order to achieve this, in situ synchrotron Fourier-transform infrared (sFTIR) microspectroscopy was performed, for the first time, on individual cells by attenuated total reflectance (ATR) combined with the use of zinc-selenide hemisphere for high spatial resolution. In a first part, the potential of the method was evaluated on bacteria subjected to a lethal 100 μM AgNO3 concentration for 2 h compared to untreated 100 % viable cells. Differences in cell composition were assessed for the C–H stretching and protein spectral regions, indicating that the inhibitory action was targeted against both fatty acids and proteins. Transmission electron microscopy (TEM) confirmed morphological damages of the cell ultrastructure. The relevance of ATR-sFTIR microspectroscopy for highlighting the heterogeneity in Ag+-mediated effects within a given bacterial population was also pointed out. In a second part, cells were exposed to sub-lethal Ag+ concentrations (

Published
2013

6. Synchrotron FTIR microspectroscopy of the yeast Saccharomyces cerevisiae after exposure to plasma-deposited nanosilver-containing coating

Author

Claire Saulou, Isabelle Fourquaux, Muriel Mercier-Bonin, P. Dumas, C. Maranges, Patrice Raynaud, Bernard Despax, Frédéric Jamme, Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés (LISBP), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National de la Recherche Agronomique (INRA), Université Fédérale Toulouse Midi-Pyrénées, LAboratoire PLasma et Conversion d'Energie (LAPLACE), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Unité de recherche sur les Biopolymères, Interactions Assemblages (BIA), Institut National de la Recherche Agronomique (INRA), Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA), Centre de Microscopie Électronique Appliquée à la Biologie (CMEAB), Hôpital de Rangueil, CHU Toulouse [Toulouse]-CHU Toulouse [Toulouse]-Toulouse Réseau Imagerie-Genotoul ( TRI-Genotoul), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Matériaux et Procédés Plasmas (LAPLACE-MPP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), The research described in this paper was performed at the French national synchrotron facility SOLEIL (Gif-sur-Yvette, France), using the SMIS beamline (proposal no 20060176)., ANR-07-BLAN-0196,BIOPLEASURE,Plasma - surface engineering for biofilm prevention(2007), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Hôpital de Rangueil, CHU Toulouse [Toulouse]-CHU Toulouse [Toulouse], Institut National de la Recherche Agronomique (INRA)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT), Toulouse Réseau Imagerie-Genotoul ( TRI-Genotoul), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), and Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3)

Subjects
Antifungal effect, Antifungal Agents, Silver, Cell Survival, Surface Properties, Scanning electron microscope, Thin films, Analytical chemistry, Metal Nanoparticles, Nanoparticle, Infrared spectroscopy, 02 engineering and technology, Saccharomyces cerevisiae, Biochemistry, Silver nanoparticle, Analytical Chemistry, Biomaterials, Plasma, 03 medical and health sciences, Nanosilvercontaining coating, Biological samples, Microscopy, Electron, Transmission, X-ray photoelectron spectroscopy, Synchrotron FTIR microspectroscopy, Spectroscopy, Fourier Transform Infrared, IR spectroscopy/Raman spectroscopy, Fourier transform infrared spectroscopy, [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biochemistry [q-bio.BM], [SPI.NANO]Engineering Sciences [physics]/Micro and nanotechnologies/Microelectronics, 030304 developmental biology, 0303 health sciences, Nanocomposite, Chemistry, 021001 nanoscience & nanotechnology, Nanoparticles/ Nanotechnology, [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biomolecules [q-bio.BM], [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology, Transmission electron microscopy, Cold plasma, Interface/Surface analysis, 0210 nano-technology, [SPI.SIGNAL]Engineering Sciences [physics]/Signal and Image processing, Synchrotrons, Nuclear chemistry
Abstract

International audience; The present work was focused on elucidating changes in the model yeast Saccharomyces cerevisiae (cell composition, ultrastructure) after exposure to antimicrobial plasma-mediated nanocomposite films. In order to achieve this, a nanosilver-containing coating was deposited onto stainless steel using radiofrequency HMDSO plasma deposition, combined with simultaneous silver sputtering. X-ray photoelectron spectroscopy (XPS) confirmed the presence of silver nanoparticles embedded in an organo-silicon matrix. In addition, scanning electron microscopy (SEM) demonstrated the nanoparticle-based morphology of the deposited layer. The antifungal properties towards S. cerevisiae were established, since a 1.4 log reduction in viable counts was observed after a 24-h adhesion compared to control conditions with the matrix alone. Differences in cell composition after exposure to the nanosilver was assessed for the protein region using, for the first time, synchrotron Fourier-transform infrared (FTIR) microspectroscopy of single S. cerevisiae cells, through in situ mapping with sub-cellular spatial resolution. IR spectrum of yeast cells recovered after a 24-h adhesion to the nanosilver-containing coating revealed a significant downshift (20 cm −1) of the amide I peak at 1655 cm −1 , compared to freshly harvested cells. This lower band position, corresponding to a loss in α-helix structures, is indicative of the disordered secondary structures of proteins, due to the transition between active and inactive conformations under nanosilver-induced stress conditions. No significant effect on the nucleic acid region was detected. The inhibitory action of silver was targeted against both cell wall and intracellular proteins such as enzymes. Transmission electron microscopy (TEM) observations of the yeastultrastructure confirmed serious morphological and structural damages. A homogeneous protein-binding distribution of nanosilver all over the cell was assumed, since the presence of electron-dense silver clusters was detected not only on the cell surface but also within the cell. For control experiments with the organosilicon matrix alone, no antimicrobial effect was observed, which was consistent with synchrotron FTIR results and TEM observations.

Published
2010