Postdoctoral scholarships in Polymer Material Science funded by the Initiative of Excellence of the University of Strasbourg in collaboration with the University of Haute-Alsace

• The postdoctoral position is open in the Material Science Institute of Mulhouse  (IS2M- CNRS-UMR7361) and the work will be done in strong collaboration with  the 1121 Unit of INSERM
• The post is available immediately and is full-time, fixed-term for 18 months.
• Net salary: approx. 2000€/month.

Context

Today, an increasing attention is placed on the development of a new-generation precision material with predictable and changeable properties in response to environmental stimuli. Very recently, our teams have introduced a new strategy to achieve for the first time fully reversible mechanoresponsive surfaces. The ligands are embedded into PEG brushes grafted onto a reactive plasma polymer matrix deposited onto a stretchable polydimethylsiloxane substrate. By stretching the substrate, the ligands become accessible to proteinic receptors. Returning to the non-stretched state, the receptors are expelled from the PEG brush assuring a full reversibility of the process (see figure 1).

Figure 1: Illustration of the fully reversible mechanoresponsive surfaces

Our explanation of such a mechanism was based on the existence of lateral forces exerted by PEG chains on streptavidin when the substrate is returning to the non-­stretched state. Indeed, the streptavidin changes its conformation which strongly affects the biotin-streptavidin interaction, streptavidin being ultimately released from the surface. Also such a mechanism is probable; its validity needs to be clearly demonstrated.

Objectives of the Postdoctoral works (18 months)

The first goal of the work will be to investigate the influence of parameters such as PEG chain length, density of grafted ligands on cell adhesion in the stretched state and on cell and organization of epithelial cells on mechanically responsive substrates will be investigated by varying the aforementioned parameters (PEG chain lengths, density of RGD…). The efforts will be particularly made on the understanding of the kinetics of formation of the extracellular matrix according to the density of RGD exhibited. The detachment of cell sheets by bringing back the substrate to unstretched position will be examined according to the physico-chemical parameters of the substrate (RGD density, PEG length) and as a function of culture time. Cell viability will be also studied after detachment. This part of the work will be performed at INSERM.

1. Bacharouche, F. Badique, A. Fahs, M.V. Spanedda, A. Geissler, J.P. Malval, M.F. Vallat, K. Anselme, G. Francius, B. Frisch, J. Hemmerlé, P. Schaaf, V. Roucoules ACS Nano 2013, 7, 3457-3465
2. Bacharouche, H.Haidara, P.Kunemann, M.F. Vallat, V.Roucoules Sensors and Actuators A 2013, 197, 25
3. Bacharouche, P.Kunemann, P.Fioux, M.F. Vallat, J.Lalevée, J.Hemmerlé, V. Roucoules Applied Surface Science 2013, 270, 64-76.
4. Geissler, M. F. Vallat, P. Fioux,, J.S. Thomann, B. Frisch, J.C. Voegel, J. Hemmerle , P. Schaaf, V. Roucoules Plasma Processes and Polymers 2010, 7, 64-77
5. Geissler, M-F. Vallat, Loic Vidal, JC. Voegel, J. Hemmerlé, P. Schaaf, V. Roucoules Langmuir 2008, 24, 4874-4880.
6. Roucoules, A. Ponche, A. Geissler, F. Siffer, L. Vidal, S. Ollivier, M.F. Vallat, P. Marie, J.C. Voegel, P. Schaaf, J. Hemmerlé Langmuir 2007, 23, 13136-13145

Requirements:

The successful candidate will have a PhD in Material Science and have a strong background in Polymer Science and Physical-Chemical Chemistry. Experience in basic surface characterization techniques such as FT-IR, XPS, AFM and detachment by bringing the substrate back to the unstretched state. This will first require characterization of the substrate through different techniques such a fluorescence microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. This part of work will be performed at IS2M.

Then, epithelial cell cultures will be investigated on these surfaces (epithelial cells are good candidates because one of the potential applications of these mechanically responsive surfaces is the formation of an epithelial sheet). Adhesion, proliferation fluorescence microscopy is essential. A background in cell culture and cell adhesion should be an advantage but is not mandatory.

Applications:

Applications should include a CV, a publication list, contact details for two academic referees and should be sent to Pr. V.Roucoules (email: Vincent.Roucoules@uha.fr) and Pr. P.Schaaf (email:schaaf@unistra.fr).