Proceedings of

the Beilstein Bozen Symposium

Functional Nanoscience

17 – 21 May 2010, Bolzano, Italy

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Preface

The Beilstein Symposia address contemporary issues in the chemical and related sciences by employing an interdisciplinary approach. Scientists from a wide range of areas – often outside chemistry – are invited to present aspects of their work for discussion with the aim of not only advancing science, but also, furthering interdisciplinary communication.

Feynman’s engaging title for his 1959 lecture, ‘‘There’s plenty of room at the bottom’’ is as valid now as it was when he gave it. He presented a vision of a scientific world beyond a few billionths of a meter that was at that time far away of any technological feasibilities and applications. However, it opened the minds towards the creation of new scientific disciplines that are now called nanoscience and nanotechnology. The ‘‘nano’’ prefix not only refers to the extremely small but also stands for the integration of traditional physics, chemistry, biology and engineering disciplines to form an interdisciplinary science which has far-reaching consequences for science, the environment and society.

Scientific research is about gaining knowledge of a system, which technology can then use for developing practical applications. In the nanoscale dimension, there are unrivalled possibilities for the development of functional objects and techniques in areas ranging from nanoelectronics, nanoscale sensors and novel data storage devices to novel materials and coatings, cosmetics, fuel cells, catalysts, to pharmaceuticals and medical implants. The properties and phenomena that these objects exhibit occur precisely because they are extremely small, existing in an environment where the laws of physics operate in unfamiliar ways. Today, the full ramifications of many experimental achievements are not always apparent and how many of these will result in applications in the future is unclear – the potential is perhaps only limited by our own imagination.

One of the main challenges of nanoscience and technology over the next decades is to achieve precise positional control of material at the nanoscale allowing, for example, the fabrication and manipulation of single molecules. Top-down approaches, such as lithography or bottom-up, as in biological systems, combined with imaging and manipulation techniques such as STM and optical tweezers are providing scientists with insights into the behavior and control of matter at the nanoscale.

In nature, we find complex, highly efficient and highly optimized systems such as biological cells which demonstrate how matter and energy can be controlled on the nanoscale. A higher degree of understanding of how biological systems are organized and function will not only increase our knowledge of living things but will find applications in other branches of nanoscience. This will not only enhance our ability to manufacture functional materials, but also holds promise to find solutions to more general problems in, for example, the areas of energy and health.

This symposium on Functional Nanoscience brought together experts in the field to present and discuss new results and approaches including the following aspects of nanoscience and nanotechnology, i. e. self-organization and self-assembly, molecular motors and transport, self-replicating biomimetic systems, quantum effects, molecular magnets, imaging and manipulation of molecules at the atomic scale / single molecule reactions.

We would like to thank particularly the authors who provided us with written versions of the papers that they presented. Special thanks go to all those involved with the preparation and organization of the symposium, to the chairmen who piloted us successfully through the sessions and to the speakers and participants for their contribution in making this symposium a success.

Frankfurt/Main, June 2011
Martin G. Hicks
Carsten Kettner

Functional Supramolecular Assemblies: First Glimpses and Upcoming Challenges

Yue Bing Zheng, Bala Krishna Pathem, J. Nathan Hohman and Paul S. Weiss

California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, University of California, Los Angeles

Functional supramolecular assemblies have emerged as candidates for nanosystems because of their potential for efficient, green, and cost-effective fabrication, as well as the capacity for tunability at molecular and atomic scales. Recent advances in the synthesis and characterization of supramolecular assemblies have already pointed to many opportunities ahead. While the practical integration of supramolecular assemblies into device manufacturing remains out of reach, learning to design the precise interactions between molecules and to control (and to predict) their structures will drive excitement, interest, and advances in bottom-up approaches to new materials and devices. This review discusses several key advances in the preparation of (and applications for) functional supramolecular assemblies, upcoming challenges, and our approaches toward the analysis of and precise control over functional supramolecular assemblies.

Catalytic Nanomotor Function and Locomotion Physics

Jonathan D. Posner1*, Jeffrey L. Moran1, Joseph Wang2 and Philip Wheat1

1Mechanical & Aerospace Engineering, Chemical Engineering, Arizona State University, Tempe

2Department of Nanoengineering, University of California San Diego, La Jolla

Abstract

Nobel Laureate Peter Mitchell originally proposed that an asymmetric ion flux across an organism's membrane could generate electric fields that drive locomotion. Although this locomotion mechanism was later rejected for some species of bacteria, modern nanofabrication tools have been harnessed to engineer bimetallic Janus particles that swim by ion fluxes generated by asymmetric electrochemical reactions. Here we have presented governing equations, scaling analyses, and numerical simulations that describe the motion of bimetallic rod-shaped motors in hydrogen peroxide solutions due to reaction-induced charge auto-electrophoresis. Our simulations show strong agreement with the scaling analysis and experiments. The analysis shows that electrokinetic locomotion results from electro-osmotic fluid slip around the nanomotor surface.

We have demonstrated the controlled motion of the nanomotors through micro-channel networks. We have shown that external magnetic field control of the motors can be used to pick-up, drag, and release micron scale colloidal cargo. Synthetic nanomachines may pave the way to integrated functional microdevices powered by autonomous transport.

Control of Rotary Motion at the Nanoscale: Motility, Actuation, Self-assembly

Petr Král*, Lela Vuković, Niladri Patra, Boyang Wang and Alexey Titov

Department of Chemistry, University of Illinois at Chicago

Abstract

Controlling motion of nanoscale systems is of fundamental importance for the development of many emerging nanotechnology areas. We review a variety of mechanisms that allow controlling rotary motion in nanoscale systems with numerous potential applications. The discussed mechanisms control molecular motors and propellers of liquids, nanoscale objects rolling on liquids, nanochannels with rotary switching motion and self-assembly of functional carbonaceous materials guided by water nanodroplets and carbon nanotubes.

A Single Molecule Nanoactuator: Toward a Device for Drug Discovery at the Limits of Sensitivity

James Youell1 and Keith Firman2*

1IBBS Biophysics Laboratories, School of Biological Sciences,
University of Portsmouth

2School of Biological Sciences, University of Portsmouth

Abstract

This work was initiated by single molecule studies of the molecular motor activity of the Type I Restriction – Modification enzyme EcoR124I at a time when the consensus viewpoint was that such motors could not manipulate microscale objects. Type I Restriction-Modification enzymes process DNA, prior to cleavage, by means of translocation and this work was described using such single molecule studies involving the use of a Magnetic Tweezer setup (which also demonstrated that a micron-sized magnetic bead could be pulled over several microns distance by the 20 nm motor).

Recently, this initial work has led to the development of an electronic version of the Magnetic Tweezer setup, which can also manipulate the DNA-attached bead, allowing its use as a biosensor and tool for drug discovery. The system can be used for a wide range of DNA-manipulating enzymes, many of which are potential drug targets.

Structurally Persistent Micelles: Theory and Experiment

Christof M. Jäger1, Andreas Hirsch2,3, Christoph Böttcher4 and Timothy Clark1,3*

1Computer-Chemie-Centrum and Interdisciplinary Center for Molecular Materials, Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg

2Interdisciplinary Center for Molecular Materials, Department of Chemistry and Pharmacy, University of Erlangen-Nürnberg

3Excellence Cluster “Engineering of Advanced Materials”, University of Erlangen-Nürnberg

4Research Center of Electron Microscopy, Institute of Chemistry and Biochemistry, Free University Berlin

Abstract

We describe the progress made in understanding the factors that determine the size, structure and stability of structurally persistent micelles using a combination of designed synthesis, cryo-TEM imaging and molecular-dynamics simulations. The importance of specific counterion effects is revealed in detail. An unexpected effect of sodium counterions leads to attraction between the polycarboxylate head groups of the tailored dendrimers that make up the micelles. This effect even leads to the formation of “superlattices” of highly negatively charged micelles.

Energy Transductions in ATP Synthase

Christoph von Ballmoos, Alexander Wiedenmann and Peter Dimroth*

Institute of Microbiology, Swiss Federal Institute of Technology (ETH) Zürich

Abstract

Life depends on chemical energy in the form of adenosinetriphosphate (ATP), most of which is produced by the F1Fo ATP synthase, a rotary nanomachine. Here, we report new insights into the torque-generating mechanism by the membrane-embedded Fo motor. High coupling ion concentrations on the ion entrance side are required to prepare the motor for rotation. In the absence of this condition, the motor is in a resting state, where the stator arginine is assumed to form a complex with the conserved carboxyl group of an empty rotor site. At high coupling ion concentrations, however, the motor switches into a mobile state, in which an incoming coupling ion has displaced the arginine and has formed a new complex with the rotor site. At appropriate driving forces, the ion dissociates from the next incoming rotor site and escapes into the cytoplasmic reservoir of the membrane. The resulting negatively charged site is attracted by the positively charged arginine, which elicits rotation and generates torque.

Reflections on Energy Conversion in Biological and Biomimetic Systems

Athel Cornish-Bowden*, María Luz Cárdenas and Élisabeth Lojou

Unité de Bioénergetique et Ingénierie des Protéines,
Centre National de la Recherche Scientifique, Marseilles

Abstract

In principle any form of energy (light, electrical, potential, chemical, kinetic energy, etc.) can be converted into any other, and a large part of biochemistry is concerned with the mechanisms of transduction. Despite this, misleading statements such as “glucose phosphorylation is coupled to ATP hydrolysis” appear even in modern books that appear in general to be based on a thorough understanding of thermodynamics. In reality, harnessing the chemical energy contained in an ATP molecule to drive metabolism involves no hydrolysis at all, and it is exactly because there is no hydrolysis that the process can work. At a grosser level, many authors still write as if production of mechanical work in organisms – from the packaging motor of bacteriophage to the muscles of large animals – operated in much the same way as industrial motors, i.e. that they release chemical energy as heat, which is then converted into work by the sort of pressure-volume effects discussed in elementary thermodynamics courses, but living motors – including not only muscles but also such examples as the DNA packaging motor of bacteriophage Φ29– are not heat engines. ATP hydrolysis is, of course, a net effect but the heat that is produced is lost: it cannot be converted into work because organisms have no known mechanisms for transforming heat into pressure-volume work, at least, not on a significant scale. Unfortunately, elementary courses tend to concentrate on the thermodynamics of gases to such an extent that the irrelevance of pressure-volume work to biochemistry is completely lost, and the Gibbs energy, for example, is seen as having something to do with heat, even though its main role in isothermal systems is as a device for expressing equilibrium constants on a logarithmic scale. Thorough understanding of these concepts will be essential for the successful development of new biotechnologies. The case of biohydrogen as a fuel is discussed.

Carbohydrate-based Nanoscience: Metallo-glycodendrimers and Quantum Dots as Multivalent Probes

Raghavendra Kikkeri1,2, Sung You Hong1,2, Dan Grünstein1,2, Paola Laurino1,2 and
Peter H. Seeberger1,2*

1Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany

2Institute of Chemistry and Biochemistry, Freie Universität Berlin

Abstract

Rapid progress in nanoscience and its potential applications have spurred observers to predict that nanotechnology will the foremost science of the 21st century. Nanomaterials are beginning to have a major impact on research across the material and life sciences. While wide varieties of nanomaterials have been prepared with proteins, DNA, lipids and polymers, serious limitations arise with the neo-glycoconjugates due to the ambiguous structures and lack of well-defined carbohydrates. This chapter highlights the contribution of glyconanomaterials to biological, biochemical and biophysical studies. Particular focus will be placed on metallo-glycodendrimers and glyconanoparticles.

Design of Hierarchically Sculptured Biological Surfaces with Anti-adhesive Properties

Kerstin Koch

Faculty of Life Sciences, Rhine-Waal University of Applied Science, Kleve, Germany

Abstract

In many plant species sophisticated functions such as water repellence, reduction of particle adhesion and reduction of insect attachment are correlated to a hierarchically sculptured surface design. One prominent example is given by the hierarchically sculptured, self-cleaning surface of the lotus leave (Nelumbo nucifera). In plants hierarchy of surfaces is often realized by combining microstructures with superimposed self-assembled nanostructures. Such functional biological surfaces are of great interest for the development of biomimetic self-cleaning materials. Examples of superhydrophobic plant surfaces are introduced here, and their hierarchical surface sculptures and existing and potential use of their properties in artificial materials are shown.

Towards Electron Beam Induced Deposition Improvements for Nanotechnology

Johannes J.L. Mulders1* and Aurelien Botman2

1FEI Electron Optics, Eindhoven, The Netherlands

2FEI Company, Hillsboro, USA

Abstract

Electron beam induced deposition can be applied as a direct write technique for the creation of 3 dimensional nano-scale structures. The technique does not require lift-off and mask based process steps and therefore has potential for application in rapid prototyping for nanotechnology, with a high degree of flexibility. The material quality and microstructure of the deposition however, is usually somewhat different to that of the pure material and hence the obtained properties of the nano-depositions do not reflect the bulk properties of the desired material. Current research is focused on improvements for the deposition processes with the aim to improve the purity of the deposition to such an extent that the local characteristic aimed for (such as conductivity) is good enough to attain the required local functionality. This paper reports on the current status and on some of the methods that have been applied to improve the deposition

Focused Electron Beam Induced Deposition – Principles and Applications

Michael Huth

Physikalisches Institut, Goethe-Universität Frankfurt, Germany

Abstract

Focused electron beam induced deposition (FEBID) is a direct beam writing technique for nano- and micro-structures. By proper selection of the precursor gas, which is dissociated in the focus of the electron beam, different functionalities of the resulting deposits can be obtained. This contribution discusses nano-granular FEBID materials. Quite generally, nano-granular metals can be considered as tunable model systems for studying the interplay of electronic correlation effects, quantum size effects and disorder. After the introduction into the FEBID process a brief overview of the different electronic transport regimes in nano-granular metals is given. Recent experimental results on electron irradiation effects on the transport properties are presented. These results indicate a new methodology for highly miniaturized strain sensor element fabrication based on the specific electronic properties of nano-granular FEBID structures.

Single-Atom Transistors: Atomic-scale Electronic Devices in Experiment and Simulation

Fang-Qing Xie1,4, Robert Maul2,3,4, Wolfgang Wenzel4,5, Gerd Schön3,4,5, Christian Obermair1,4 and Thomas Schimmel1,4,5*

1Institute of Applied Physics, Karlsruhe Institute of Technology, Germany

2Steinbuch Centre of Computing, Karlsruhe Institute of Technology

3Institut für Theoretische Festkörperphysik, Karlsruhe Institute of Technology

4Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology

5Institute of Nanotechnology, Forschungszentrum Karlsruhe, Karlsruhe Institute of Technology

Abstract

Controlling the electronic conductivity on the quantum level will impact the development of future nanoscale electronic circuits with ultralow energy consumption. Here we report about the invention of the single-atom transistor, a device which allows one to open and close an electronic circuit by the controlled and reproducible repositioning of one single atom. The atomic switching process is induced by a voltage applied to an independent, third “gate” electrode. In addition to the demonstration of single-atom switches, the controlled and reproducible operation of multi-atom quantum switches is demonstrated both in experiment and in atomistic calculation. Atomistic modelling of structural and conductance properties elucidates bistable electrode reconstruction as the underlying operation mechanism of the devices. Atomic transistors open intriguing perspectives for the emerging fields of quantum electronics and logics on the atomic scale.

Functional Nanoscience: Present and Future

David Winkler

CSIRO Materials Science and Engineering, Clayton South, Australia.

Fifty Years After Feynman

There have been many influences and drivers for the development of technologies that allow functional components to be constructed at smaller and smaller scale. The semiconductor revolution in the second half of the 20th century was driven by cost, speed, novel function, and power consumption. Semiconductor science and its child, large-scale integration of electronic circuitry, have been responsible for an unprecedented paradigm change in almost every aspect of human life. The change is arguably even more profound than that which resulted from the industrial revolution. As we shall see later in this paper, although the fundamental limits of Moore's Law have not yet been reached, this and the increasing energy consumption of these paradigm-breaking technologies will necessitate another paradigm shift in the near future...