Personal web page : http://iramis.cea.fr/nimbe/Phocea/Membres/Annuaire/index.php?uid=carrot
Laboratory link : http://iramis.cea.fr/nimbe/licsen/
Bacteria are always present in our environment whether natural, industrial, medical-hospital ... Their presence is generally not harmful and can even be beneficial. Nevertheless, some of them being pathogenic, they can represent a real danger and be at the origin of public health problems. Controlling this microbial flora and its development still remain a challenge in different areas of applications.
Very recent studies have shown that after only a few hours of adhesion to surfaces, bacteria were able to "feel" contact with the surface and to modify their proteome. Among the under or over expressed proteins, some are involved in the reactivity of bacteria to antimicrobials. These original data could explain some of the resistance phenomena observed today. What are the surfaces characteristics involved in these physiological evolutions? This is a crucial question to which it is now essential to provide elements of knowledge and answers, in order to help to the choice of surfaces and/or to the modifications of surfaces to be made (implants, medical environment, etc.).
The proposed thesis will therefore focus on the design of surfaces modified by polymers already studied previously (BRICAPAC project),1 showing a strong interaction with bacteria and a modular bacteriostatic effect. Here, we will try to better understand the impact of these interactions while changing the physicochemical parameters of the polymer layer. We will also graft other types of polymers with, for example, different charges, or to form amphiphilic or ampholytic copolymers. 3D surfaces will also be grafted (from nanoparticles) to study the impact of interactions in solution. Finally, nanostructured surfaces with defined patterns can be obtained from grafted polymers or nanoparticles, thanks to inkjet printing techniques. These new surfaces should make it possible to identify the factors behind the previously discussed adaptations (chemical composition, bacterial/surface adhesion interactions, mechanical stress, etc.). The proposed thesis will therefore concern the study of the reactivity of bacteria to antimicrobial agents, after adhesion to these surfaces. It will be carried out in close collaboration with a partner team specialized in bioadhesion and reactivity of immobilized bacteria (AgroParisTech INRA, UMR GMPA, Massy).