Institut des Sciences Moléculaires d'Orsay



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Accueil > Équipes scientifiques > Biophysique, biophotonique > Microscopies à Sondes Locales (AFM, SECM, modes électriques,…) > Stages, thèses, Post-docs > Surface density of charge of bio-membranes : new investigation at nanometric scale and in liquid environment.

Stage M2 / Thèse

Surface density of charge of bio-membranes : new investigation at nanometric scale and in liquid environment.

par Marliere Christian - 11 octobre 2015 (modifié le 14 décembre 2015)

The scientific aim of this research is to improve the fundamental understanding of the first steps of bacterial adhesion on solid surfaces by studying, in-situ and at sub-micrometric scale, electrical phenomena –as variation of local charges, ionic fluxes- at the membranes of bacteria of interest.
For this purpose, a unique combination of experimental approaches based on microscopy techniques is proposed : (1) Scanning probe microscopy, AFM (Atomic Force Microscopy) and its derived electrical modes as Scanning Electro-Chemical mode (SECM) or the new Electro-Mechanical Scanning Microscopy mode (EMSM, see below) recently discovered. They will be used to quantify biomolecules adhesion forces and discriminate electrostatic interactions ; (2) up-to-date fluorescence imaging techniques with ultrahigh spatial resolution as TIRF (Total Internal Reflection Fluorescence) set-up for optimal imaging of the bacteria/surface interface and quantification of bio-adhesion to surfaces. The stress will be put on the improvement of the new method of measurement of local electric charges and ionic transfers by an electro-mechanical AFM mode –EMSM- (Nanoscale, 2015, 7, 8843, an in vivo study of electrical charge distribution on the bacterial cell wall by AFM in vibrating force mode). The main aims will be : (i) the characterization of the local heterogeneities of membrane’s surface charges and their temporal changes during the modification of the contact interface between bacteria and the solid surface as studied by TIRF ; (ii) the study of cross-linked coupling between physicochemical properties of membranes and cellular metabolism during colonization of the solid surface by bacteria and formation of bacterial network : aggregates, biofilms.
This multidisciplinary research (molecular physics, optics, chemistry, photobiology, microbiology) will be done through strong interactions with several research groups specialized in microbiology and chemical functionalization of surfaces (INRA-AgroParisTech, université de Rouen, etc).

Keywords : Scanning Force Microscopy ; Fluorescence microscopy ; AFM ; SECM ; TIRF ; biomolecule adhesion ;

Contact :
Christian Marlière / 01 69 15 75 11 / 06 70 53 21 90 /

Voir en ligne : Scanning Probe Microscopy (AFM, SECM, electric modes, …)