Dresden 2009 – scientific programme

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BP: Fachverband Biologische Physik

BP 17: Poster II

BP 17.10: Poster

Wednesday, March 25, 2009, 17:15–19:45, P3

AFM as a chance for studying in situ protein adsorption and bacterial adhesion — •Peter Loskill, Yvonne Schmitt, and Karin Jacobs — Saarland University, Experimental Physics, D-66041 Saarbruecken, Germany

The interaction of proteins and of microorganisms with biological or artificial surfaces is a key factor in disease pathogenesis. To reveal the interactions, we follow two pathways: One ansatz is to characterize protein adsorption on a fundamental level via AFM in non-contact mode imaging, another is to directly probe bacterial adhesion by AFM - force spectroscopy. For proteins like amylase we have probed the adsorption kinetics by ellipsometry. Surprisingly, the kinetics is not only depending on surface chemistry, but also on the sub-surface composition [1,2]. In situ AFM scans of protein adsorption reveal the spatial statistics of adsorption sites and allow for a characterization of the mobility of proteins on the surface and the role of protein-protein interactions. Characterizing bacteria/substrate interaction, we use staphylococcus aureus as a model system. S. aureus is known to build complex cell consortia consisting of multilayered organisms, forming a biofilm. Wall-bound and secreted proteins mediate attachment. Since the bacterial cell wall cannot be treated as a homogeneous surface, it is necessary to differentiate between local and global adhesion measurements. To investigate the global adhesion properties of a bacterium in a planktonic state we directly use them as AFM probes.

[1] A. Quinn et al., Europhysics Lett. 81 (2008) 56003

[2] M. Bellion et al., J. Phys.: Condens. Matter 20 (2008) 404226