PUB - Publikationen an der Universität Bielefeld

A membrane is a barrier that can be passable to some things but impassable to others. Such things may be molecules, ions, or other small particles. Biological membranes come with a great variety, ranging from cell membranes, nuclear membranes to tissue membranes that cover the surface of internal organs. In contrast, synthetic membranes have been fabricated and utilized by humans for use in laboratories and industry for filtration and separation. The scope of this work is to establish and characterize free-standing as well as substrate supported membranes of the thickness of only a few molecules. The fabrication of these 2D-nanomambranes was achieved by the Langmuir-Blodgett (LB) technique, by a horizontal Montal-Mueller method, as well as by crosslinking of selfassembled layers. Isotherms of monolayer material were investigated at the LB trough. Transferred to substrates, they were studied with atomic force microscopy (AFM), helium ion microscopy (HIM), and infrared spectroscopy. Self assembling phenomena of hotopolymerizable lipids on HOPG were revealed by AFM in dependence of their degree of polymerization. Infrared spectroscopy clarified the polymerization process from a chemical perspective. Free-standing membranes of polymerized lipids could be investigated by AFM and HIM due to their enhanced mechanical properties. Free-standing lipid membranes were also fabricated in a fluid chamber. In this aqueous environment, electrophysiological recordings of lipid bilayer membranes were performed with the final measurement of free translocation of short DNA fragments through embedded α-Hemolysin pores. Specific membrane capacitance as well as conductance of α-Hemolysin were analyzed. Furthermore, solid-state membranes from selfassembled monolayers were fabricated and studied electrophysiologically. Ion permeation through these carbon nanomembranes (CNM) of various ion species was investigated with respect to their potential application for filtration purposes.