Astrid Kronenberger

• The Atomic Force Microscope (AFM) is an instrument which offers the opportunity to enter the nanometer-scale world of biophysics and nanotechnology. Within this thesis, the AFM is used to investigate and characterise polymer supported liposomes and engineered channel proteins for their applicability in nanocompartment systems as well as beta-sheet forming polypeptides with respect to their possible application in nanoelectronics. The molecular systems of interest are polymer supported liposomes, which we characterise, as well as the transmembrane protein FhuA. Therefore, a protein purification process is established and protein crystallisation experiments are performed. Additionally, high resolution measurements on the test system bacteriorhodopsin are carried out in order to optimise imaging conditions. Furthermore, we investigate different types of artificial polypeptides which self-assemble into beta-sheets. The resulting beta-sheets are characterised and tested for their suitability as building blocks for nanoelectronic purposes. For these different research foci, suitable sample preparation methods are developed and the measurement settings are optimised. The quality of the results is directly influenced by the choice of substrate, the immobilisation method, the measurement conditions (air, solution, buffer composition) and the measurement modus (tapping mode, contact mode) as well as by the nature of the investigated object itself.