Dresden 2011 – scientific programme

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BP: Fachverband Biologische Physik

BP 21: Biopolymers and Biomaterials II (with CPP)

BP 21.9: Talk

Wednesday, March 16, 2011, 12:45–13:00, ZEU 260

Characterizing bacterial adhesion: The role of van der Waals forces — •Nicolas Thewes, Peter Loskill, Sebastian Hümbert, and Karin Jacobs — Deparment of Experimental Physics, Saarland University, 66041 Saarbrücken, Germany

Bacterial adhesion to surfaces is a complicated process that not only depends on the type of bacterium and the type of surface, but also on subsurface composition, as we have shown in a recent study. To probe the adhesion of s. carnosus, various surfaces have been prepared, ranging from hydrophilic to hydrophobic, from smooth to rough surfaces. To probe the effect of subsurface composition on the adhesion strength, Si wafers with different Si oxide layer thicknesses have been used. Clearly, the adhesion is stronger on wafers with thin Si oxide layer, irrespective if the wafer was hydrophobized by a monolayer of silanes or not, which is a clear evidence that long-range van der Waals forces play a crucial role for bacterial adhesion. It moreover shows that subsurface composition must be taken as characteristics of a sample, much in the same way chemical composition, wetting properties or surface roughness are taken into account. An additional parameter to control is the proper immobilization of the bacteria on the AFM tip, with the help of which force/distance curves have been performed.