Henry Hess University of Florida
Amar Flood Indiana University
Heiner Linke University of Oregon
Andrew J. Turberfield University of Oxford
FF1: Synthetic Motors and Active Molecules
Tuesday PM, March 25, 2008
Room 3018 (Moscone West)
9:30 AM - **FF1.1
In Control of Motion with Synthetic Molecular Motors.
Ben Feringa 1 Show Abstract
1 Chemistry, University of Groningen, Groningen Netherlands
Molecular motors are among the most challenging goals of nanoscience and will proof crucial to power future nanomachines.The design of synthetic molecular motors to achieve controlled translational and rotary motion is discussed. Progress in our program toward controlled motion on surfaces, the acceleration of rotary motors and molecular motors at work will be described.
10:00 AM - FF1.2
Fast and Stable Photochromic Oxazines.
Francisco Raymo 1 Show Abstract
1 Chemistry, University of Miami, Coral Gables, Florida, United States
In search of strategies to improve the switching speeds and fatigue resistances of spiropyrans, we have designed and synthesized a new family of photochromic compounds based on the photoinduced opening and thermal closing of [1,3]oxazine rings. Specifically, the laser excitation of these molecules at 355 nm cleaves a [C–O] bond with the concomitant opening of a [1,3]oxazine ring in less than 6 ns and with quantum yields ranging form 0.03 to 0.28 in acetonitrile at ambient temperature. This process generates a 4-nitrophenolate chromophore with the concomitant appearance of a ground-state absorption at 440 nm. The photogenerated isomers revert to the original species with first-order kinetics and lifetimes ranging from 25 to 140 ns. Thus, a full switching cycle can be completed on a nanosecond timescales with these photochromic switches. Furthermore, these compounds tolerate thousands of switching cycles with no sign of decomposition even in the presence of molecular oxygen. In addition, these molecules can be trapped within rigid polymer matrices and operated under these conditions with microsecond switching speeds.
10:15 AM - FF1.3
Shape-Adaptive Chemical Architectures: Cooperative Mechanical Coupling Schemes for Assembly, Transport, and Sensing.
Dongwhan Lee 1 Show Abstract
1 Chemistry, Indiana University , Bloomington, Indiana, United States
With an increasing demand to reduce the size and dimensions of electronic and mechanical devices, significant research efforts have recently been made in synthetic chemistry front to construct higher-order assemblies from molecular building blocks. Critical to the success of this bottom-up approach is the availability of functional components that can relay signals over a long distance with high fidelity. Many naturally occurring machinery can amplify local structural distortions and transduce them to chemical signals at remotely located sites. Unlike electronic coupling, such mechanical coupling in general is less restricted by the distance requirements between the two communicating parts. Drawing inspirations from naturally occurring constructs, we have designed and synthesized a new class of C3-symmetric aromatic-rich compounds displaying correlated molecular motions. These structurally pre-organized but conformationally flexible molecules have proven to be versatile functional components in molecular devices and materials for transport, switching, and sensing. Extreme modularity in our synthetic design, along with novel structural and electronic properties associated with the tris(N-salicylideneamine) functionality, has allowed us to demonstrate the feasibility of (a) uptake and release of small molecule guests by shape-adaptive organic crystalline materials, (b) self-assembly of discotic molecules displaying enhanced emission properties upon aggregation, (c) fluorescence sensing and switching by mechanical control of excited-state geometry, (d) FRET as a viable mechanism for sensory signal amplification and allosteric switching, and (e) cooperative structural folding for predetermined helicity and its translation to supramolecular chirality of nanofibril structures. In this presentation will be discussed the advent, current progress, proposed evolution, and potential applications of the shape-adaptive molecules developed in my laboratory.
10:30 AM - **FF1.4
Amphidynamic Materials and Molecular Machines: Approaching Barrierless Motion in Crystalline Solids.
Miguel Garcia-Garibay 1 Show Abstract
1 Chemistry and Biochemistry, UCLA, Los Angeles, California, United States
Growing interest in artificial molecular machinery has recently led to the exploration and development of amphidynamic crystals, a new class of functional materials with physical properties that may be modified by controlling their internal motion in the solid state. Our contributions in this area have covered molecules with shapes and function analogous to those of macroscopic gyroscopes. They consist of an intrinsically barrierless dialkynyl rotator that acts as the dynamic component, such as axially substituted 1,4-dialkynyl phenylenes, and two triarylmethyl (trityl) or triptycyl groups that act as the stator. In our quest to design crystals with internal dynamics that approach gas phase frequencies and barriers, we have prepared and analyzed several molecular gyroscopes with novel high-symmetry rotators, including structures with bicyclo[2.2.2]octanes, carboranes, cubanes and diamantanes, as well as structures with triply bridged and “exploded” stators.
11:30 AM - FF1.5
Autonomous Motion: Tracking the Behavior of Catalytically Powered Janus Particles.
Shengrong Ye 1 , Hua Ke 1 , Mikala Shremshock 1 , Kenneth Showalter 1 , R. Carroll 1 Show Abstract
1 , West Virginia University, Morgantown, West Virginia, United States
11:45 AM - FF1.6
James Tour 1 Show Abstract
1 Chemistry Department, Rice University, Houston, Texas, United States
12:00 PM - FF1.7
Gated Molecular Baskets.
Jovica Badjic 1 Show Abstract
1 , Ohio State University, Columbus, Ohio, United States
It is a challenge to fundamentally address the relationship between structure and function in complex chemical environments. Our approach consists of investigating the mechanism of operation of folded molecules that are designed to perform useful functions. First, we have studied the working mechanisms of basket-like hosts capable to fold and thus incarcerate a guest. The folding process is mediated by intramolecular hydrogen bonding or metal-to-ligand coordination of the heterocyclic “flaps” appended to the basket rim. The incarceration of a guest is dictated by (a) its coordination to the metal cation, or (b) rapid opening and closing of the hydrogen bonding ‘flaps”. In this way, the guest exchange is restricted by the baskets’ conformational behavior, which allows exploring the relationship between the molecular exchange kinetics and chemical reactions occurring in the confined space. Second, we have been developing molecular machines, “allosteric molecular resonators”, to investigate the controlled and synchronized motions of distant molecular parts in artificial systems. The constrictive binding, allostery and cooperativity have been altogether put at work for obtaining assemblies capable to perform complex operations.
12:15 PM - FF1.8
Using Anions to Operate the Translational Isomerism of a Rotaxane.
Sheng-Hsien Chiu 1 Show Abstract
1 Chemistry, National Taiwan University , Taipei Taiwan
12:30 PM - **FF1.9
Nanoparticles and Molecular Machines for Drug Delivery and On-Command Release.
Jeffrey Zink 1 Show Abstract
1 Chemistry and Biochemistry, UCLA, Los Angeles, California, United States
Transferred FF1.10 @ 11:45 AM to *FF1.9 @ 11:15 AMNanoparticles and Molecular Machines for Drug Delivery and On-Command Release. Jeffrey I. Zink
FF2: Biological Approaches in Nanoscale Motion
Tuesday PM, March 25, 2008
Room 3018 (Moscone West)
2:30 PM - **FF2.1
Molecular Motors in Nanoscale Surface Characterization and Organization of Biomolecules on a Chip.
Alf Mansson 1 , Petr Vikhorev 1 , Nuria Albet-Torres 1 , Martina Balaz 1 , Natalia Vikhoreva 1 , Mark Sundberg 1 , Richard Bunk 2 , Kenneth Liljesson 1 , Leif Nilsson 4 , Babak Heidari 3 , Sven Tagerud 1 , Ian Nicholls 1 , Par Omling 2 , Lars Montelius 2 Show Abstract
1 , University of Kalmar, Kalmar Sweden, 2 , Lund University, Lund Sweden, 4 , LHV Mätfakta, Kalmar Sweden, 3 , Obducat AB, Malmö Sweden
In several recent studies nano- and microstructured surfaces have been used to achieve guidance of molecular motor based transport with the objective to develop lab-on-a-chip devices. From these studies it is clear that 1. the motor function is strongly dependent on the underlying surface chemistry, 2. the motor driven transport of e.g. actin filaments is apparently random in the absence of chemical and topographic guiding and 3. the motor propelled filaments act as less than 10 nm wide scaffolds with regularly spaced, specific binding sites (e.g. lysine residues), for other biomolecules. Here, these properties are analyzed in greater detail in relation to their possible exploitation in characterization and organization of surfaces. Recently, we observed good correlation between water contact angles (from 10 to 80 degrees) of pure and silanized glass and SiO2-surfaces and the capability of adsorbed heavy meromyosin (HMM) motor fragments to propel actin filaments. Studies using total internal reflection fluorescence spectroscopy, quartz crystal microbalance and ATPase assays, with a fluorescent ATP analogue, attribute the correlation to different HMM configurations on surfaces with differing contact angles and charge. A detailed model for the HMM adsorption will be presented together with arguments that HMM adsorption, HMM catalytic activity and HMM propelled actin filament sliding may be exploited for highly parallel, far-field light-microscopy based characterization of surface chemistry on the nanoscale. The other main facet of this work is motor-driven organization of surfaces with particular emphasis on time-varying 2-dimensional gradients of biomolecules, with potential usefulness in sensing applications and cell biological studies. In this process, a large ensemble of HMM propelled actin filaments, are spreading on a surface according to a diffusion equation with an apparent diffusion coefficient (D) proportional to the sliding velocity and the persistence length (P) of the filament path. The possible relationship to the persistence length of the actin filament itself will be considered. Interestingly, the parameter D can be directly related to an energy term and drag forces in analogy with the Einstein equation. Thus, D = ΔG/γ where ΔG is the free energy of ATP hydrolysis required to propel the actin filament a distance determined by P. The effective drag coefficient,γ, on the other hand, is proportional to the average on-time of an actomyosin interaction. Gradients of approximately Gaussian shape of HMM-propelled actin filaments and actin-attached biomolecules will be described for non-patterned surfaces. Moreover, as will be exemplified, micrometer scale gradients of arbitrary shapes may be produced by motor driven “diffusion” of actin filaments on suitably micropatterned surfaces. The characteristic features of these types of gradients will be discussed.
3:00 PM - FF2.2
Molecular Motor-Based Assays for Altered Nanomechanical Function of Ca2+-Regulatory Proteins in Cardiomyopathies.
P. Chase 1 2 5 , Nicolas Brunet 2 1 6 , Goran Mihajlovic 4 3 7 , Peng Xiong 4 3 , Stephan von Molnar 4 3 Show Abstract
1 Biological Science, Florida State University, Tallahassee, Florida, United States, 2 Molecular Biophysics, Florida State University, Tallahassee, Florida, United States, 5 Chemical and Biomedical Engineering, Florida State University, Tallahassee, Florida, United States, 6 Physiology & Biophysics, University of Washington, Seattle, Washington, United States, 4 Materials Research and Technology (MARTECH), Florida State University, Tallahassee, Florida, United States, 3 Physics, Florida State University, Tallahassee, Florida, United States, 7 Materials Science Division, Argonne National Laboratory, Argonne, Illinois, United States
3:15 PM - FF2.3
Culture of Insect Heart Muscle Tissues and its Applicability to Bio-Actuators.
Yoshitake Akiyama 1 , Yuji Furukawa 1 , Keisuke Morishima 1 , Kikuo Iwabuchi 2 Show Abstract
1 Department of Mechanical Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo Japan, 2 Department of Applied Biological Science, Tokyo University of Agriculture and Technology, Tokyo Japan
Fundamentals of bioactuators using mammalian heart muscle cells were reported so far, such as pillar actuator, micro pump, self-assembled micro device, muscular thin film, etc. However, they are not yet realized in practice because the required culture conditions of pH and temperature for mammal cells are difficult to keep, furthermore, they can only work under 5% CO2-atmosphere and culture medium has to be replaced every few days. Regarding insect cells, on the other hand, they seem to be robust over a wide range of culture conditions as they are poikilothermic, and are expected as a new candidate for a bioactuator element which can overtake defects of mammal cells. Unfortunately, there is no report to have cultured insect heart muscle cells and apply them to a bioactuator element. In the present paper, a moth is chosen among many insects as it is known very robust, and its heart muscle tissues are excised and cultured as a bulk of cells because the culture of cell itself is quite difficult. A moth larva has a long and thin tubal heart called “dorsal vessel DV.” Lepidoptera larvae, Ctenoplusia agnata were used in this study. Resulting from culture examinations, the suitable culture conditions for keeping DVs contracting were determined as TC-100 medium with 20% FBS and 5% hemolymph, Cell-Tak Coating, 25 degrees C.The micropillars, 1000μm in height and 100μm in diameter were fabricated by forming poly(dimethylsiloxane) PDMS in a PTFE mold with drilled holes. The micro pillars were coated with Cell-Tak after oxygen plasma treatment. The excised DVs were plated on the pretreated micropillars after mechanically mincing, which were cultured under the conditions described above but without medium replacement. On the 2nd day, the micropillar began to move autonomously by cyclic shrinking of muscle tissues and could continue for more than 60 days. The frequencies of motion seem to depend on the inherent characteristic of tissue and were about 0.2 or 0.25 Hz in the present study. As a result of image analysis on the 37th day, the maximum displacement of gravity center of the micropillar’s top was 19 μm. The driving force estimated by that is about 4.6 μN which is larger than 3.4 μN by cardiomyocytes reported by Y. Tanaka et al. Furthermore, the pillars could be actuated when electric stimulus is given to the cultivated tissue, that suggests a possibility to control pillar’s motion from outside too.As above mentioned, the moth heart tissue was cultured rather easier than that of a mouse, and was connected to micropillars. This fundamental bio-mechanical system could work either autonomously or heteronomously, and its durability was more than 60 days even without medium replacement. Taking these merit into account, the cultured insect cell tissue seems to possess a high potential as a bioactuator element, hence much possibility to be applied to bio-MEMS in near future.
3:30 PM - **FF2.4
Molecular Motors-driven Fabrication of Natural Microfluidics Networks: The Case for Fungal Intelligence.
Dan Nicolau 1 Show Abstract
1 Electrical Engineering & Electronics, University of Liverpool, Liverpool United Kingdom
4:30 PM - **FF2.5
How the World’s Smallest Rotary Motor Works.
George Oster 1 Show Abstract
1 George Oster, University of California, Berkeley, California, United States
ATP synthase (also called FoF1 ATPase) is the universal enzyme that manufactures ATP from ADP and phosphate using the energy derived from a transmembrane protonmotive gradient. It can also reverse itself and hydrolyze ATP to pump protons against an electrochemical gradient. This protein consists of two rotary motors connected to a common shaft, and rotating in the opposite direction. The F1 motor generates a mechanical torque using the hydrolysis energy of ATP. The Fo motor generates a rotary torque in the opposite direction using the energy stored in a transmembrane electrochemical gradient. Thus ATP synthase comprises what must be the world's smallest rotary engine. Each motor can be reversed: The Fo motor can drive the F1 motor in reverse to synthesize ATP, and the F1 motor can drive the Fo motor in reverse to pump protons. Thus ATP synthase exhibits two of the major energy transduction pathways employed by the cell to convert chemical energy into mechanical force. I will present a model for this molecular machine that accounts for all of the experimentally measured mechanochemical behavior.
5:00 PM - FF2.6
Measurement of Forces Generated by Chemomechanical Protein Aggregates using Polymer BioMEMS.
Stefan Schwan 1 , Nicholas Ferrell 2 , Andreas Cismak 1 , Uwe Spohn 1 , Andreas Heilmann 1 , Derek Hansford 2 Show Abstract
1 Biological Materials and Interfaces, Fraunhofer Institut Werkstoffmechanik, Halle (Saale) Germany, 2 Department of Biomedical Engineering, Ohio State University , Columbus, Ohio, United States
5:15 PM - **FF2.7
Quantifying the Transport of Cargoes Pulled by Several Molecular Motors.
Stefan Klumpp 1 , Janina Beeg 2 , Melanie Mueller 2 , Rumiana Dimova 2 , Ruben Serral Gracia 2 , Eberhard Unger 3 , Reinhard Lipowsky 2 Show Abstract
1 Center for Theoretical Biological Physics, UC San Diego, La Jolla, California, United States, 2 , Max Planck Institute of Colloids and Interfaces, Potsdam Germany, 3 , Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena Germany
Tuesday, March 2Extended Presentation time to 30 Minutes*FF2.7 @ 4:15 PMQuantifying the Transport of Cargoes Pulled by Several Molecular Motors. Stefan Klumpp
5:45 PM - FF2.8
Unexpected Velocity-dependent Cargo Loading onto Molecular Shuttles.
Ashutosh Agarwal 1 , Henry Hess 1 Show Abstract
1 Materials Science and Engineering, University of Florida, Gainesville, Florida, United States
Tuesday, March 25Transferred Poster FF3.4 to FF2.8 @ 4:45 PMUnexpected Velocity-dependent Cargo Loading onto Molecular Shuttles. Ashutosh Agarwal
FF3: Poster Session: Molecular Motors, Nanomachines, and Active Nanostructures
Wednesday AM, March 26, 2008
Salon Level (Marriott)
9:00 PM - FF3.1
Functionalized Hybrid Structures for Active Molecular Electronics: Experimental Investigation and Theoretical Study.
Kabeer Jasuja 1 , Arthur Thompson 2 , Mark Battig 1 , Vikas Berry 1 Show Abstract
1 Department of Chemical Engineering, Kansas State University, Manhattan, Kansas, United States, 2 Department of Electrical Engineering, Kansas State University, Manhattan, Kansas, United States
Molecular electro-mechanical-systems (MoEMS) are recently gaining a lot of interest due to their controllable functionality and potential applications in sensors and biomedicine. MoEMS evolves from molecular electronics and molecular mechanics. A number of techniques have been used to sandwich molecules between electrodes, for example STM, AFM and break junctions and have helped develop understanding of molecular electronics. There has also been a keen interest in the study of ‘active’ molecular systems like azo-polymers, rotaxane, molecular motors etc, which have been studied using AFM, liquid crystals etc. Here we present a study of a novel MoEMS system where ‘active’ molecules are sandwiched between metal nanoparticles which act as flexible electrodes. A novel fabrication process enables such an integration of flexible-nanoelectrodes and active-molecules. The mechanically-active molecular-links are excited to produce electromechanical response. We will demonstrate the response of these molecular opto-electromechanical structures and will also show a chemical sensor based on these MoEMS.
9:00 PM - FF3.10
Experimental Realization of a Feedback Controlled Brownian Ratchet.
Benjamin Lopez 1 , Erin Craig 1 , Nathan Kuwada 1 , Heiner Linke 1 Show Abstract
1 Physics, University of Oregon, Eugene, Oregon, United States
A flashing ratchet is a Brownian motor that rectifies thermal fluctuations of diffusive particles through the use of a time-dependent periodic and asymmetric potential. It has been shown theoretically that a feedback-controlled flashing ratchet has a center of mass speed as much as one order of magnitude larger than the optimal periodically flashing ratchet . For dimeric molecular motors, feedback control mechanisms are likely to be crucial to achieve processivity and can help explain experimental data . Our immediate goals for this project are to implement the first feedback ratchet, and to test theory that predicts the efficiency of different feedback algorithms as a function of feedback delay. In particular, there is a maximum displacement feedback scheme  that predicts for small N to provide an even larger center of mass velocity than the threshold average force scheme described in reference 1. In our experiment a scanning line optical trap setup is used to transport micron-sized particles using a feedback controlled Brownian ratchet. This system can create potential energy landscapes that realize the steps of a Brownian ratchet process. At the time of writing, we have a scan line of 20 microns in length that stably traps 0.9 micron silica spheres. A flat potential with variations on the order of kT, and a ratchet potential with two-micron periods and an asymmetry of 1/3 have been realized. A ratchet depth of 40 kT per watt of output laser power has been measured. Real time particle tracking at 100 Hz is achieved through software based video analysis. To see a significant effect for small N the feedback delay time must be less than 0.05 L2/D , where L is the ratchet period length and D is the diffusion constant. With current experimental parameters this value is 21 ms. In this setup feedback has a minimum implementation delay of 4 ms, and feedback effects should be experimentally observable. We will present speed of ratchet velocity for different feedback algorithms and particle numbers, and compare these results to modeling results. Another application of this setup will be to experimentally model the motion of linear, two headed, processive molecular motors. It is difficult to systematically vary parameters in studies of biological molecular motors and using a model system can help understand the performance of different operational principles for molecular motors. F.J. Cao, L. Dinis, and J.M.R. Parrondo, Phys. Rev. Lett. 93, (2004). M. Bier, BioSystems 88, 301 (2007). E.M. Craig, N. Kuwada, B. Lopez, H. Linke, to be published (2007). E.M. Craig, B. Long, J.M. Parrondo, H. Linke, to appear in Europhys. Lett.(2007).
9:00 PM - FF3.11
Giant ‘Dry’ Actuation of PEDOT:PSS Thin Films.
Dimitri Charrier 1 , Lukas Brinek 1 , Martijn Kemerink 1 , Rene Janssen 1 Show Abstract
1 , Eindhoven University of Technology, Eindhoven, Noord Brabant, Netherlands
9:00 PM - FF3.12
Fatigue and Wear of Microtubules Induced by Kinesin Motor Activity.
Yoli Jeune 1 , Krishna Nittala 1 , Henry Hess 1 Show Abstract
1 Materials Science Engineering, University of Florida, Gainesville, Florida, United States
9:00 PM - FF3.13
Enzyme Assisted Formation of Peptide Nanotubes.
Richard Williams 1 2 , Rein Ulijn 1 2 Show Abstract
1 Materials Science, Manchester University, Manchester United Kingdom, 2 Manchester Interdisciplinary Biocentre, Manchester University, Manchester United Kingdom
9:00 PM - FF3.14
Photoresponsive Liquid Crystal Elastomers.
Timothy White 1 2 , Vincent Tondiglia 1 3 , Hilmar Koerner 4 5 , Richard Vaia 4 , Svetlana Serak 6 , Vladimir Grozhik 6 , Nelson Tabiriyan 6 , Timothy Bunning 1 Show Abstract
1 , AFRL/RXPJ, WPAFB, Ohio, United States, 2 , General Dynamics, WPAFB, Ohio, United States, 3 , SAIC, WPAFB, Ohio, United States, 4 , AFRL/RXBP, WPAFB, Ohio, United States, 5 , Univ. of Dayton Research Institute, WPAFB, Ohio, United States, 6 , BEAM Co., Winter Park, Florida, United States
A liquid crystalline elastomer (LCE) containing both main chain and side chain azobenzene mesogens exhibits bidirectional actuation upon illumination of low power polarized laser light. Large angle deformation (+/-70 deg), the direction of which is controlled by the laser polarization, is achieved in less than 300 ms. We recently have shown that at high laser intensity, a shape-restoring monodomain azobenzene LCE can controllably and reversibly oscillate over a large range (120 deg) at a frequency of 23 Hz. Finally, recent work on the development of a high modulus (> 1 GPa) LCE photoactuator formed from the copolymerization of an LC crosslinker and a monofunctional azobenzene LC monomer will also be presented. The resulting copolymer is a side-chain LCE that can bend up to 85 deg in nearly 200 ms.
9:00 PM - FF3.17
Efficiency Considerations of Synthetic Molecular Machines under Redox Control.
Amar Flood 1 , Kumar Parimal 1 , Kristy McNitt 1 , Albert Fahrenbach 1 Show Abstract
1 Chemistry, Indiana University , Bloomington, Indiana, United States
9:00 PM - FF3.19
Fabrication of Thermoresponsive Copolymer-grafted Surface for Insect Cell Driven Actuator.
Yui Sakuma 1 , Yoshitake Akiyama 1 , Kikuo Iwabuchi 1 , Yoshikatsu Akiyama 2 , Masayuki Yamato 2 , Teruo Okano 2 , Keisuke Morishima 1 Show Abstract
1 , Tokyo University of Agriculture and Technology, Tokyo Japan, 2 , Tokyo Women's Medical University, Tokyo Japan
9:00 PM - FF3.2
Photoreorientation of Light-Addressable, Azobenzene-Based, Photomechanical Monolayers.
Joseph Dahdah 1 , T. Furtak 1 , D. Walba 2 , G. Fang 2 , Y. Yi 2 , J. Maclennan 2 , N. Clark 2 Show Abstract
1 Physics, Colorado School of Mines, Golden, Colorado, United States, 2 Physics, University of Colorado, Boulder, Colorado, United States
Azobenzene-based photomechanical monolayers have received a great deal of attention for potential as platforms for light-addressable nano-engineered structures in bioscience, photonics, and display technologies. We have developed an aminoazobenzene material, derived from methyl red, which forms high quality, covalently anchored monolayers on glass. These monolayers demonstrate unusually high sensitivity to polarized light, which controls the molecular orientation distribution through optical anisotropy of the trans-cis isomerization. In an effort to understand and optimize this phenomenon we are studying the influence of the two-dimensional molecular field on the structure and light-driven reorganization of the monolayer. To determine the orientational order parameters of this surface and their modification upon illumination we have employed a combination of optical techniques: second harmonic generation, spectroscopic ellipsometry, and dichroism spectroscopy. These optical studies are analyzed in terms of a photochemical model incorporating all known mechanisms for photoorientation. The model addresses optical local field and mean molecular field effects in a self-consistent manner. --Supported by NSF through the Liquid Crystal Materials Research Center: DMR-0213918
9:00 PM - FF3.20
Photomodulation of Reactivity using Molecular Switches: Towards the Development of Novel Functional Materials.
Vincent Lemieux 1 , Neil Branda 1 Show Abstract
1 4D LABS, Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada
We recently described a versatile approach, based on molecular photoswitching strategies, for photoreleasing active compounds from inert “masked” forms.(1) Low-energy visible light converts thermally stable “locked” compounds into thermally unstable forms that undergo spontaneous fragmentation. The rationally designed photoresponsive architecture permits selective stimulation of various compounds using different light sources and thus allows selective and sequential release of payloads. This technology offers an elevated level of control compared to existing systems that undergo spatial and temporal photorelease and has the potential to deliver pharmaceuticals and other biologically relevant molecules as well as designer reagents for synthesis and photolithography. Our progress towards the development of practical applications will be presented.(1) V. Lemieux, S. Gauthier, N.R. Branda, Angew. Chem. Int. Ed. 2006, 45(41), 6820.
9:00 PM - FF3.21
Direct Imaging of Electrostatic and Electromechanical Interactions in a Conductive Liquid Environment.
Sergei Kalinin 1 , Brian Rodriguez 1 , Philip Rack 1 2 , Katya Seal 1 , Stephen Jesse 1 Show Abstract
1 , Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States, 2 , University of Tennesse, Knoxville, Tennessee, United States
9:00 PM - FF3.22
Nanoscale Self-Assembly Of Bimetallic “Janus” Particles into Dimers and Higher Structures.
Shengrong Ye 1 , R. Carroll 1 Show Abstract
1 , West Virginia University, Morgantown, West Virginia, United States
9:00 PM - FF3.23
Computer Simulation of Molecular Shuttles Propelled by Motor Proteins.
Takahiro Nitta 1 , Akihito Tanahashi 1 , Yu Obara 1 , Motohisa Hirano 1 , Maria Razumova 2 , Michael Regnier 2 , Henry Hess 3 Show Abstract
1 Dept. Math. and Design Eng., Gifu University, Gifu, Gifu, Japan, 2 Dept. Bioengineering, University of Washington, Seattle, Washington, United States, 3 Dept. Materials Sci. and Eng., University of Florida, Gainesville, Florida, United States
9:00 PM - FF3.24
Nanoscale Assembly and Measurement of Molecular Machines.
Tao Ye 1 Show Abstract
1 School of Natural Sciences, University of California, Merced, Merced, California, United States
Significant progress has been made in creating synthetic molecules capable of internal conformational changes in response to external stimuli in the solution phase. However, their single molecule properties in technologically relevant environments, such as at interfaces and in nanoscale assemblies remain to be investigated. Working with synthetic chemists, we have probed and controlled molecular machines down to the single molecule level. I will describe two types of molecular motions, linear motion by rotaxanes driven by electrochemistry, and light-driven switching motion by azobenzene derivatives. Critical to single molecule observations and control are purposeful molecular design and nanoscale assembly that determine the orientation, spacing and steric interactions of these single molecule machines. Molecules and assemblies can perform desired motion only when they are properly interfaced to their nanoscale environments.
9:00 PM - FF3.25
Towards Electromechanical Imaging of Cellular Systems in a Liquid Environment.
Brian Rodriguez 1 , Gary Thompson 3 , Sophia Hohlbauch 2 , Irene Revenko 2 , Nick Geisse 2 , Alexey Vertegel 3 , Roger Proksch 2 , Sergei Kalinin 1 Show Abstract
1 Materials Sciences and Technology Division and the Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States, 3 Department of Bioengineering, Clemson University, Clemson, South Carolina, United States, 2 , Asylum Research, Santa Barbara, California, United States
Coupling between electrical and mechanical phenomena is ubiquitous in biological systems, underpinning phenomena ranging from cardiac activity to outer hair cell stereocilia to energy storage in mitochondria. Investigating the electromechanical response of biological systems at the nanoscale will also improve our understanding of their functionality at the macroscale. The electromechanical probing of cellular systems thus can be used both as an imaging and characterization tool, as well as a first step in the development of artificial cell-based electromotors. However, probing electromechanics of cellular systems is traditionally impeded by the requirement of conductive liquid media necessary to support biological activity and cell viability. In this presentation, we will summarize recent progress on scanning probe microscopy imaging of electromechanical phenomena in biological samples under physiological conditions with advanced imaging and spectroscopic modes, including Piezoresponse Force Microscopy (PFM). These improvements include a better understanding of the conditions for electromechanical contrast in conductive solutions through the study of model ferroelectric systems. We will also present results on the local electromechanical probing of several model cellular and biomolecular systems in a liquid environment, including insulin and lysozyme amyloid fibrils, breast adenocarcinoma cells, and bacteriorhodopsin. The specific features of PFM operation in liquid are delineated and bottlenecks on the route towards single molecular resolution electromechanical imaging of biological systems will be discussed. This research is supported (SVK, BJR) by the Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, managed and operated by UT-Battelle, LLC for the Office of Basic Energy Sciences, US Department of Energy.
9:00 PM - FF3.26
Fabrication of Micro Bio-fabricated Actuator Powered by Cardiomyocyte.
Hiroshi Horiguchi 1 , Yoshitake Akiyama 1 , Keisuke Morishima 1 Show Abstract
1 , Tokyo university of Agriculture and Technology, Tokyo Japan
Here, we propose a novel concept of fabrication process for micro bio-actuator powered by cardiomyocytes. We have already developed and reported a micro bio-actuator powered by cardiomyocytes such as a pump. The cardiomyocytes, which can contract spontaneously and convert chemical energy into mechanical energy efficiently without changing it into thermal energy, are considered as a high performance actuator. But, contractile force of single cardiomyocyte is inadequate to actuate micro robot and mechanical system. So the integration of the cardiomyocytes to generate high contractile force has been researched. In this study, we integrate cardiomyocytes such as muscle tissue to generate high contractile force of cardiomyocytes and apply bio-fabricated actuator to mechanical system.We suggest a micro cardiomyocyte gel structures as the integration of cardiomyocyte. The cardiomyocyte gel structure is cardiomyocyte culture in three dimensional gel structures utilized such as scaffold. The micro cardiomyocyte gel structure is deformed by the contractile force of cardiomyocytes in the three dimensional gel structures. Fabrication process of micro cardiomyocyte gel structure has four steps. First, a PDMS membrane with circular micro grooves is fabricated using photolithography. Second, the PDMS chamber is fabricated by attaching the PDMS membrane to a PDMS frame. Third, the liquid mixture consisting of isolated cardiomyocytes from neonatal rats, collagen type I prepared from rat tails, a basement membrane protein mixture and culture medium is poured into the circular casting molds and incubated for 45 to 60 minutes at 37 degree Celsius under 5% CO2 atmosphere to allow hardening of the liquid mixture. After the incubation, 1.0 ml culture medium is poured into the PDMS chamber. After 7 days of culture, the PDMS chamber is attached to stretching device and stretched to generate high contractile force of cardiomyocytes for an additional 7 days. After stretching, we think that three dimensional gel structure contracts spontaneously. The prototype of micro cardiomyocyte gel structure on the surface of the PDMS membrane was observed using inverted microscope. First contraction of single cardiomyocyte in the gel structure was observed at 2 days. At 6 days, the cardiomyocyte gel structure condensed around the central cylinder within the PDMS membrane and contracted synchronously. The thickness of the gel structure was 200μm and its frequency was about 0.35Hz. In future, these devices will be one of the key components of self-powered medical and ubiquitous equipments.
9:00 PM - FF3.3
Kinetics of a DNA-mediated Docking Reaction Between Tethered Vesicles.
Yee-Hung Chan 1 , Peter Lenz 2 , Steven Boxer 1 Show Abstract
1 Chemistry, Stanford University, Stanford, California, United States, 2 Physics, Philipps-University, Marburg Germany
9:00 PM - FF3.5
DNA-mediated Fusion of Lipid Vesicles.
Yee-Hung Chan 1 , Bettina van Lengerich 1 , Steven Boxer 1 Show Abstract
1 Chemistry, Stanford University, Stanford, California, United States
Hybridization of DNA-oligonucleotides coupled to lipids at the 5' end can be used tether liposomes to supported lipid bilayers* and to mediate docking**, but fusion has not been observed because the duplex DNA acts as a spacer between the two membranes. A modified synthesis allows coupling of the lipid to the 3' end of the DNA strand. Now, hybridization between 5' and 3' DNA-lipids on different vesicles may bring the membrane surfaces closer together. This approximates the geometry believed to be relevant in SNARE protein-mediated neuronal fusion. Reaction of vesicles displaying complementary DNA linked at the 5' and 3' ends leads to both lipid and content mixing, indicating DNA-mediated vesicle fusion is occurring. The rate of mixing shows a dependence on the copy number and sequence of the complimentary DNA. Progress towards visualizing individual fusion events using mobile vesicles tethered to supported bilayers by fluorescence microscopy is described.* Yoshina-Ishii et al., JACS, 125, 3696 (2003); 127, 1356 (2005);Langmuir, 22, 2384 & 5682 (2006). ** Chan et al. submitted
9:00 PM - FF3.6
Lattice Simulations of Microtubule “Nanospool” Formation Dynamics.
Jasmine Davenport 1 , Henry Hess 1 , Simon Phillpot 1 Show Abstract
1 Materials Science & Engineering, University of Florida, Gainesville, Florida, United States
Biotinylated microtubule filaments partially coated with streptavidin and gliding on surface-adhered kinesin motor proteins converge to form linear “nanowire” and circular “nanospool” structures. We present a computer simulation method that models the dynamics of microtubule gliding and interaction. In this method, each microtubule is composed of a head, a number of body segments, and a tail. The microtubules move across a hexagonal lattice with the direction of motion of the head segment being determined probabilistically; the body and tail segments follow the path of the head. The surface density of microtubules, their lengths, their rigidities and their modes of interaction can all be varied. The analysis of the motion and interaction of the microtubules over large distances allows statistically meaningful data to be obtained which can be compared to experimental results, and will aid in predictions of the formation of nanowires and nanospools. This work is supported by NSF-DMR 0645023.
9:00 PM - FF3.7
Electrically Switchable Liquid Crystal Polymer Rod Actuators.
Matthew Shafran 1 , Kostas Sierros 1 , Darran Cairns 1 Show Abstract
1 , West Virginia University, Morgantown, West Virginia, United States
9:00 PM - FF3.8
Engineering a Kinesin Biomolecular Motor for Controlling Cargo-specific Transport and Materials Assembly.
Adrienne Greene 1 2 , Amanda Carroll-Portillo 1 , George Bachand 1 Show Abstract
1 Biomolecular Interfaces and Systems, Sandia National Laboratories, Albuquerque, New Mexico, United States, 2 Department of Biology, The University of New Mexico, Albuquerque, New Mexico, United States
9:00 PM - FF3.9
Adsorption and Function of Heavy Meromyosin Motors Related to Surface Charge and Contact Angle.
Nuria Albet Torres 1 , John O'Mahony 1 , Christy Charlton 1 , Martina Balaz 1 , Patricia Lisboa 2 , Teodor Aastrup 3 , Alf Månsson 1 , Ian Nicholls 1 Show Abstract
1 School of Pure and Applied Natural Sciences, University of Kalmar, Kalmar Sweden, 2 Institute for Health and Consumer Protection, European Commission - Joint Research Centre, Ispra Italy, 3 , Attana AB, Stockholm Sweden