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2 results on '"Sophie Klemm"'

1. Bracket fungi, natural lightweight construction materials: hierarchical microstructure and compressive behavior of Fomes fomentarius fruit bodies

Author

Cecilia Müller, Claudia Fleck, and Sophie Klemm

Subjects
0106 biological sciences, hierarchical microstructure, Materials science, failure mechanism, Bracket fungus, 02 engineering and technology, natural foam, mechanical properties, 01 natural sciences, Viscoelasticity, 010608 biotechnology, Honeycomb, General Materials Science, ddc:530, Composite material, Porosity, bracket fungus, biology, General Chemistry, 021001 nanoscience & nanotechnology, biology.organism_classification, Microstructure, 530 Physik, Compressive strength, mycelium, Deformation bands, 0210 nano-technology, Fomes fomentarius
Abstract

Bracket fungisuch as Fomes fomentarius(“tinder fungus”), have strong, light and tough fruit bodies that make them interesting role-models for bio-inspired, biodegradable applications. So far, little is known about the relation between their microstructure and mechanical properties, information needed for designing novel composites. The fruit bodies (mycelia) of tinder fungus are hierarchically structured honeycomb foams. The mycelium has a transversely isotropic microstructure with open porosity on the nano- and micro-length scales. The lowest resolution porosity appears as elongated tubes that extend from beneath the woody upper surface down towards the lower side that faces the ground. The tube walls are made of a network of hollow, fibrous cells (hyphae), mainly consisting of chitin. When tested mechanically, the material shows the typical compressive stress/strain curve of foams, where an initially linear course is followed by an extended plateau region. The as-harvested material exhibits pronounced viscoelastic recovery, but the tube walls are visibly damaged. Compared with the transverse direction, the load-bearing capability and energy absorption parallel to the tube long axis are ~ 5 and ~ 10 times higher, respectively. Unexpectedly however, the energy absorption efficiency is similar for both loading directions. Buckling of the tubes and cracking of their walls are the main damage mechanisms, and the damage zones coalesce into deformation bands as it is typical for foams. Drying leads to ~ 7 times higher plateau stresses, damage becomes extensive, and the mycelium loses its viscoelastic recovery capability. Interestingly, rehydration restores the properties of the wet state. It is compelling to imagine an adaptive role to natural dry/wet conditions.

Published
2021

2. Development of Polythiourethane/ZnO-Based Anti-Fouling Materials and Evaluation of the Adhesion of Staphylococcus aureus and Candida glabrata Using Single-Cell Force Spectroscopy

Author

Mickaël Castelain, Sophie Klemm, Claire Tendero, Miguel C. Teixeira, Mafalda Cavalheiro, Rainer Adelung, Etienne Dague, Martina Baum, Cécile Formosa-Dague, Zibin Nan, Anna Gapeeva, Haoyi Qiu, Christian-Albrechts-Universität zu Kiel (CAU), Équipe Ingénierie pour les sciences du vivant (LAAS-ELIA), Laboratoire d'analyse et d'architecture des systèmes (LAAS), Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse - Jean Jaurès (UT2J)-Université Toulouse 1 Capitole (UT1), Université Fédérale Toulouse Midi-Pyrénées, Toulouse Biotechnology Institute (TBI), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Universidade de Lisboa (ULISBOA), Centre interuniversitaire de recherche et d'ingenierie des matériaux (CIRIMAT), Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC), Fédération de Recherche Fluides, Energie, Réacteurs, Matériaux et Transferts (FERMAT), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-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), ANR-18-CE42-000, Centre National de la Recherche Scientifique - CNRS (FRANCE), Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE), Institut national de recherche pour l'agriculture, l'alimentation et l'environnement - INRAE (FRANCE), Institut National des Sciences Appliquées de Toulouse - INSA (FRANCE), Office National d'Etudes et Recherches Aérospatiales - ONERA (FRANCE), Université Toulouse III - Paul Sabatier - UT3 (FRANCE), Christian-Albrechts-Universität zu Kiel - CAU (GERMANY), Universidade de Lisboa - ULisboa (PORTUGAL), Laboratoire d'Analyse et d'Architecture des Systèmes - LAAS (Toulouse, France), Centre Interuniversitaire de Recherche et d'Ingénierie des Matériaux - CIRIMAT (Toulouse, France), Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT)-Université de Toulouse (UT)-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 Toulouse - Jean Jaurès (UT2J), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse Capitole (UT Capitole), Université de Toulouse (UT), 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)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Universidade de Lisboa = University of Lisbon (ULISBOA), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3)

Subjects
C. glabrata, General Chemical Engineering, Matériaux, Initial attachment, microbial adhesion, 02 engineering and technology, Tetrapodal shaped ZnO, tetrapodal shaped ZnO, 010402 general chemistry, medicine.disease_cause, 01 natural sciences, Article, Nanomaterials, [SPI.MAT]Engineering Sciences [physics]/Materials, PTU/ZnO composite, lcsh:Chemistry, chemistry.chemical_compound, Polythiourethane, medicine, General Materials Science, chemistry.chemical_classification, initial attachment, Candida glabrata, biology, Polydimethylsiloxane, Chemistry, Force spectroscopy, Biofilm, Anti-fouling, Adhesion, Polymer, 021001 nanoscience & nanotechnology, biology.organism_classification, S. aureus, Microbial adhesion, 0104 chemical sciences, polythiourethane, Chemical engineering, lcsh:QD1-999, Staphylococcus aureus, 0210 nano-technology, Single cell force spectroscopy
Abstract

The attachment of bacteria and other microbes to natural and artificial surfaces leads to the development of biofilms, which can further cause nosocomial infections. Thus, an important field of research is the development of new materials capable of preventing the initial adhesion of pathogenic microorganisms. In this work, novel polymer/particle composite materials, based on a polythiourethane (PTU) matrix and either spherical (s-ZnO) or tetrapodal (t-ZnO) shaped ZnO fillers, were developed and characterized with respect to their mechanical, chemical and surface properties. To then evaluate their potential as anti-fouling surfaces, the adhesion of two different pathogenic microorganism species, Staphylococcus aureus and Candida glabrata, was studied using atomic force microscopy (AFM). Our results show that the adhesion of both S. aureus and C. glabrata to PTU and PTU/ZnO is decreased compared to a model surface polydimethylsiloxane (PDMS). It was furthermore found that the amount of both s-ZnO and t-ZnO filler had a direct influence on the adhesion of S. aureus, as increasing amounts of ZnO particles resulted in reduced adhesion of the cells. For both microorganisms, material composites with 5 wt.% of t-ZnO particles showed the greatest potential for anti-fouling with significantly decreased adhesion of cells. Altogether, both pathogens exhibit a reduced capacity to adhere to the newly developed nanomaterials used in this study, thus showing their potential for bio-medical applications.

Published
2021
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