RESEARCH ARTICLE Copyright © 2005 American Scientific Publishers All rights of reserved Printed in the United States of America Journal of Nanoscience and Nanotechnology Vol. 5, 1–9, 2005 Diatom Bionanotribology—Biological Surfaces in Relative Motion: Their Design, Friction, Adhesion, Lubrication and Wear Ille C. Gebeshuber, 1 Herbert Stachelberger 2 and Manfred Drack 3 1 Austrian Center of Competence for Tribology AC 2 T research GmbH, Viktor Kaplan-Strasse 2, A-2700 Wiener Neustadt, Austria and Institut für Allgemeine Physik, Technische Universität Wien, Wiedner Hauptstr. 8-10/E134, A-1040 Vienna, Austria 2 Institute of Chemical Engineering, Technische Universität Wien, Getreidemarkt 9/E1667, A-1060 Vienna, Austria 3 Center for Appropriate Technology, Technische Universität Wien, Wiedner Hauptstr. 8-10/E0965, A-1040 Vienna, Austria Tribology is the branch of engineering that deals with the interaction of surfaces in relative motion (as in bearings or gears): their design, friction, adhesion, lubrication and wear. Continuous minia- turization of technological devices like hard disc drives and biosensors increase the necessity for the fundamental understanding of tribological phenomena at the micro- and nanoscale. Biological systems show optimized performance also at this scale. Examples for biological fric- tion systems at different length scales include bacterial flagella, joints, articular cartilage and muscle connective tissues. 1 Scanning probe microscopy opened the nanocosmos to engineers: not only is microscopy now possible on the atomic scale, but even manipulation of single atoms and molecules can be per- formed with unprecedented precision. As opposed to this top-down approach, biological systems excel in bottom-up nanotechnology. Our model system for bionanotribological investigations are diatoms, for they are small, highly reproductive, and since they are transparent, they are accessible with different kinds of opti- cal microscopy methods. Furthermore, certain diatoms have proved to be rewarding samples for mechanical and topological in vivo investigations on the nanoscale. 2 There are several diatom species that actively move (e.g. Bacillaria paxillifer forms colonies in which the single cells slide against each other) or which can, as cell colonies, be elongated by as much as a major fraction of their original length (e.g. Ellerbeckia arenaria colonies can be reversibly elongated by one third of their original length). Therefore, we assume that some sort of lubrication of interactive surfaces is present in these species. Current studies in diatom bionanotribology comprise techniques like atomic force microscopy, histochemical analysis, infrared spectrometry, molecular spectroscopy and confocal infrared microscopy. Keywords: Tribology,Lubrication,Friction,Wear,Biomimetics,Diatoms,Nanotribology,Bionano- tribology, Natural Lubricants, Natural Adhesives, Environmentally Friendly Materials, Renewable Resources. * Author to whom correspondence should be addressed. J. Nanosci. Nanotech. 2005, Vol. 5, No. 1 © 2005 by American Scientific Publishers 1533-4880/2005/05/001/009/$17.00+.25 doi:10.1166/jnn.2005.t 1