Bulletin of the American Physical Society
2007 APS March Meeting
Volume 52, Number 1
Monday–Friday, March 5–9, 2007; Denver, Colorado
Session D38: Nanoinstrumentation for Biological and Other Applications |
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Sponsoring Units: GIMS Chair: Karen Waldrip, Sandia National Laboratories Room: Colorado Convention Center 501 |
Monday, March 5, 2007 2:30PM - 2:42PM |
D38.00001: Assembly of a minimal protocell Steen Rasmussen What is minimal life, how can we make it, and how can it be useful? We present experimental and computational results towards bridging nonliving and living matter, which results in life that is different and much simpler than contemporary life. A simple yet tightly coupled catalytic cooperation between genes, metabolism, and container forms the design underpinnings of our protocell, which is a minimal self-replicating molecular machine. Experimentally, we have recently demonstrated this coupling by having an informational molecule (8-oxoguanine) catalytically control the light driven metabolic (Ru-bpy based) production of container materials (fatty acids). This is a significant milestone towards assembling a minimal self-replicating molecular machine. Recent theoretical investigations indicate that coordinated exponential component growth should naturally emerge as a result from such a catalytic coupling between the main protocellular components. A 3-D dissipative particle simulation (DPD) study of the full protocell life-cycle exposes a number of anticipated systemic issues associated with the remaining experimental challenges for the implementation of the minimal protocell. Finally we outline how more general self-replicating materials could be useful. [Preview Abstract] |
Monday, March 5, 2007 2:42PM - 2:54PM |
D38.00002: High throughput electronic cell identification techniques for microfluidic systems David Wood, Gary Braun, Jean-Luc Fraikin, Loren Swenson, Norbert Reich, Andrew Cleland We address the problem of whole-cell identification using an all-electronic microfluidic approach, with potential applications to cell sorting. We present the development of a radiofrequency microsensor, capable of detecting cells or cell labels in a microfluidic system. This device has demonstrated detection of individual cellular labels at throughputs of 30,000 labels/s in a single microfluidic channel. We also present the development of digital barcodes, which can be used to label cells for identifying individual strains in a diverse population. These barcodes were developed using fully-scalable lithographic techniques, providing a means for low-cost, large volume production. We have demonstrated biological functionalization of these barcodes as well as readout, using our radiofrequency microsensor, at throughputs greater than 1,000 labels/s. [Preview Abstract] |
Monday, March 5, 2007 2:54PM - 3:06PM |
D38.00003: Dynamic Detection of a Single Bacterium: Nonlinear Rotation Rate Shifts of Driven Magnetic Microspheres Brandon H. McNaughton, Rodney R. Agayan, Raoul Kopelman We report on a new technique which was used to detect single Escherichia coli that is based on the changes in the nonlinear rotation of a magnetic microsphere driven by a magnetic field. The presence of one Escherichia Coli bacterium on the surface of a 2.0 micron magnetic microsphere (with an aluminum ``nanocap'' that indicates the microsphere's orientation) caused an easily measurable change in the drag of the system and, therefore, in the nonlinear rotation rate. The straight-forward measurement uses standard microscopy techniques and the observed average shift in the nonlinear rotation frequency changed by a factor of $\sim$3.8 (Arxiv preprint cond-mat/0610144). Further miniaturization will allow for dynamic detection of viruses and potentially even biomolecules in fluidic environments. [Preview Abstract] |
Monday, March 5, 2007 3:06PM - 3:18PM |
D38.00004: Nanolaser spectroscopy of Normal and Genetically Defective Mitochondria: New Biostatistical Tool for Studying Disease Paul Gourley, Judy Hendricks, Robert Naviaux, Michael Yaffe We report an analysis of wild and mutant strains of mitochondria from yeast cells using nanolaser spectroscopy to measure cytochrome density and its statistical variation in the population. The first strain 110 was derived from wild-type strain 104 (Saccharomyces cerevisiae) by removal of its mitochondrial DNA (mtDNA), resulting in loss of all mtDNA-encoded proteins and RNAs, and loss of the pigmented, heme-containing cytochromes a and b that can be detected in the laser spectra. Histograms of laser wavelengths produced by wild-type mitochondria produced peaked distributions, while mutant mitochondria exhibit asymmetric, highly skewed distributions. Surprisingly, all of these distributions exhibit extended tails and can be self-consistently fit with log-normal distribution functions. In striking contrast, the mitochondrial diameters (measured separately by microscopy) exhibit normal Gaussian distributions. These results indicate that the nanolaser spectra are useful for quantifying cytochrome content in mitochondria and may have important implications for quantifying defects in mitochondria that manifest human disease. [Preview Abstract] |
Monday, March 5, 2007 3:18PM - 3:30PM |
D38.00005: Gas sensing behavior of individual carbon nanotube field effect transistors Michael Stadermann, Alexander Artyukhin, Olgica Bakajin, Aleksandr Noy Carbon nanotube field effect transistors (FETs) have been found to be gas sensors with amazing sensitivity. Thus far, however, the exact sensing mechanism of the devices remains unknown. Recent results indicate that the analytes may bind to defects in the nanotubes and change their conductance through charge transfer, but all of these measurements have been performed in networks of carbon nanotubes, in which the properties of the network rather than those of the individual tube are measured. In this work, we study the behavior of individual nanotube devices. We measure the response times of both pristine as well as damaged nanotubes to determine the effect of defects on the sensor response, and we measure devices with coated and uncoated electrodes to determine the contribution of the contacts. [Preview Abstract] |
Monday, March 5, 2007 3:30PM - 3:42PM |
D38.00006: Large-scale assembly of CNT based DNA sensor array on SiO2 substrate Joohyung Lee, Byung Yang Lee, Dong Joon Lee, Kyungeun Byun, Seunghun Hong DNA sensors based on CNTs have been attracting attention due to their possible applications such as genotyping, disease diagnosis, etc. Previous works were mostly based on CNTs functionalized with DNA molecules. However, a major bottleneck holding back their practical applications has been a lack of mass production method of such sensors. Furthermore, immobilization of DNA on CNTs using linker molecules can severely degrade their electrical properties. Herein, we report a new method to fabricate a large-scale array of CNT-based DNA sensors on SiO2 and glass substrates. In this method, non-polar molecular patterns guide the assembly of CNTs onto uncoated bare surface regions (Nature Nanotechnology 1, 66 (2006)). After fabrication of electrodes on the CNT patterns, we further functionalized the bare surface regions with single-stranded (ss) PNAand successfully demonstrated detection of target ss-DNA with high sensitivity. Since we functionalize the bare surface between CNTs, this process can be applied to virtually general nanotubes circuits on SiO2 or glass substrates to fabricate DNA sensors. [Preview Abstract] |
Monday, March 5, 2007 3:42PM - 3:54PM |
D38.00007: Calcium Induced Voltage Gating and Negative Incremental Resistance in Single Conical Nanopores. Zuzanna Siwy, Matthew Powell, Michael Sullivan, Christina Trautmann, Robert Eisenberg We will present a nanopore device working in an ionic solution that has transport characteristics similar to unijunction transistors working in electronic circuits, namely negative incremental resistance and voltage dependent ion current fluctuations. Our device consists of a single conical nanopore in solutions containing potassium chloride and sub-millimolar concentrations of calcium and cobalt ions. I will talk about importance of electrostatic and chemical interactions of translocating ions with pore walls. We explain the transport effects on the basis of transient binding of calcium ions to chemical groups on the pore walls that cause transient changes in electric potential inside a conical nanopore. Possibilities of constructing a chemical oscillator with tens of Hz operating frequency will be presented as well. We will also discuss application of this oscillating system to building a synthetic stochastic sensor. Since the system operates far from equilibrium, we expect it to be very sensitive to any changes/perturbations, e.g. presence of molecules that we want to detect. The mechanism of detection strongly suggests that the sensor will respond to a whole variety of organic molecules with little modification. [Preview Abstract] |
Monday, March 5, 2007 3:54PM - 4:06PM |
D38.00008: Protein denaturing on Nanospheres James Forrest, Jonathan Teichroeb We have used localized surface plasmon resonance (LSPR) to monitor the structural changes that accompany thermal denaturing of Bovine Serum Albumin(BSA) adsorbed onto gold nanospheres of size 5nm-60nm. The effect of the protein on the LSPR was monitored by visible extinction spectroscopy. The position of the resonance is affected by the conformation of the adsorbed protein layer, and as such can be used as a very sensitive probe of thermal denaturing that is specific to the adsorbed protein. The results are compared to detailed calculations and show that full calculations can lead to significant increases in knowledge where gold nanospheres are used as biosensors. Thermal denaturing on spheres with diameter $>$ 20 nm show strong similarity to bulk calorimetric studies of BSA in solution. BSA adsorbed on nanospheres with d$\leq$ 15 nm shows a qualitative difference in behavior, suggesting a sensitivity of denaturing characteristics on local surface curvature. Studies of isothermal denaturing kinetics were used to obtain an activatiuon barrier for thermal denaturing. This activation barrier also exhibited a strong dependence on nanoparticle size. These results may have important implications for other protein-nanoparticle interactions. [Preview Abstract] |
Monday, March 5, 2007 4:06PM - 4:18PM |
D38.00009: Nanoscale Radiofrequency Molecular Biosensing Jean-Luc Fraikin, David Wood, Mike Stanton, Andrew Cleland We are developing an all-electronic, radiofrequency, nanoscale-biosensor. We use RF reflectometry to measure impedance changes in the sensor electrodes, which should occur upon binding of the target analyte, enhanced through the subsequent attachment of gold nanospheres, using a sandwich-type assay. The sensor is embedded in a microfluidic, lab-on-a-chip configuration, allowing for in-situ sensor functionalization. We are pursuing various routes to sensor functionalization, including both oligonucleotide and peptide linking chemistries. The electrical functionality of our sensor prototype has been demonstrated, yielding sensitivity to impedance changes of order 1 part in $10^{5}$, with an active sensing volume of order a few hundred attoliters. Using this technique we expect sensitivity to single-nanosphere binding events to be attainable. [Preview Abstract] |
Monday, March 5, 2007 4:18PM - 4:30PM |
D38.00010: Nano-scale resolution full-field microscopy using tabletop extreme ultraviolet lasers Fernando Brizuela, Courtney Brewer, Georgiy Vaschenko, Yong Wang, Miguel Larotonda, Bradley Luther, Mario Marconi, Jorge Rocca, Carmen Menoni, Weilun Chao, Yanwei Liu, Erik Anderson, David Attwood, Alexander Vinogradov, Igor Artioukov, Yuri Pershyn, Viktor Kondratenko We have developed two compact full-field extreme ultraviolet (EUV) microscopes that combine short-wavelength light from high-brightness tabletop lasers with zone plate and multilayer-coated reflective optics. One of these systems uses 47 nm wavelength light from a desktop-sized capillary discharge laser with resolution down to 70nm. This microscope can image in both transmission and reflection mode, allowing for imaging of surfaces. The other microscope uses 13 nm wavelength light from a table-top optically pumped EUV laser to acquire images with spatial resolution better than 38 nm. Both of these systems have the ability to render images with typical acquisition times of 10- 30 seconds These results open a path to the development of compact and widely available extreme-ultraviolet imaging tools capable of inspecting samples in a variety of environments with a 15-20 nm spatial resolution and a picosecond time resolution. [Preview Abstract] |
Monday, March 5, 2007 4:30PM - 4:42PM |
D38.00011: Nano-Optics for Chemical and Materials Characterization Michael Beversluis, Stephan Stranick Light microscopy can provide non-destructive, real-time, three-dimensional imaging with chemically-specific contrast, but diffraction frequently limits the resolution to roughly 200 nm. Recently, structured illumination techniques have allowed fluorescence imaging to reach 50 nm resolution [1]. Since these fluorescence techniques were developed for use in microbiology, a key challenge is to take the resolution-enhancing features and apply them to contrast mechanisms like vibrational spectroscopy (e.g., Raman and CARS microscopy) that provide morphological and chemically specific imaging.. We are developing a new hybrid technique that combines the resolution enhancement of structured illumination microscopy with scanning techniques that can record hyperspectral images with 100 nm spatial resolution. We will show such superresolving images of semiconductor nanostructures and discuss the advantages and requirements for this technique. Referenence: 1. M. G. L. Gustafsson, P. Natl. Acad. Sci. USA 102, 13081-13086 (2005). [Preview Abstract] |
Monday, March 5, 2007 4:42PM - 4:54PM |
D38.00012: Simultaneous Surface-Enhanced Raman Scattering Imaging and Spectroscopy in Confocal Mode. Denis Pristinski$^1$, Melek Erol$^2$, Henry Du$^1$, Svetlana Sukhishvili$^2$ Noble colloidal metal nanoparticles deposited on a planar substrate facilitate ultrasensitive measurements via surface-enhanced Raman scattering (SERS) spectroscopy. Due to the random nature of nanoparticle immobilization, the variation of interparticle distance and possible aggregate formation cause significant fluctuation in SERS signal intensity across the substrate. To study the nature of these intensity fluctuations we have built a microscope capable of simultaneous imaging in epi-fluorescent mode and spectroscopy of a point of interest in confocal mode. Two excitation beams from the same laser (DPSS 532 nm) are mixed to expose the imaged area and to focus on the point of interest through high N.A. objective. The scattered light collected by the same objective is filtered and split between a cooled CCD camera for imaging and a fiber-connected spectrometer for confocal mode spectroscopy. Positively charged Ag nanoparticles prepared by polyethyleneimine-assisted reduction were deposited on glass substrate and used for the assessment of uniformity of SERS signal from subsequently adsorbed anionic molecules and for the identification of proteins. \newline \newline $^1$ Department of Chemical, BioMedical, and Materials Engineering \newline $^2$ Department of Chemistry and Chemical Biology [Preview Abstract] |
Monday, March 5, 2007 4:54PM - 5:06PM |
D38.00013: Initial Development of a sub-micron Angle Resolved Photoemission Microscope Aaron Bostwick, Jessica McChesney, Eli Rotenberg -abstract- We have begun initial development of a sub-micron angle resolved photoemmision microscope. The current test system consists of an SES-200 detector and a zone plate based focusing system operating at 180eV photon energy. We have measured angle resolved spectra using the SES-200 angle-dispersive collection mode at resolution of $\sim $500nm. We have used this to show orientational contrast on highly oriented pyrolytic graphite (HOPG). The domains on HOPG are on the order of 1-20 microns and are well orientated along the c-axis but show random azimuthal order. We are able to clearly image these domains even though they show no chemical contrast, and can measure the single crystal band structure on disordered polycrystalline sample. We believe this demonstrates the promise of such a system for the measurement of materials which cannot be found in bulk single crystals. [Preview Abstract] |
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