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Manfred Lindau – One of the best experts on this subject based on the ideXlab platform.

  • Surface-modified CMOS IC electrochemical sensor array targeting single chromaffin cells for highly parallel Amperometry measurements
    Pflugers Archiv : European journal of physiology, 2017
    Co-Authors: Meng Huang, Joannalyn Delacruz, John C. Ruelas, Shailendra S. Rathore, Manfred Lindau

    Abstract:

    Amperometry is a powerful method to record quantal release events from chromaffin cells and is widely used to assess how specific drugs modify quantal size, kinetics of release, and early fusion pore properties. Surface-modified CMOS-based electrochemical sensor arrays allow simultaneous recordings from multiple cells. A reliable, low-cost technique is presented here for efficient targeting of single cells specifically to the electrode sites. An SU-8 microwell structure is patterned on the chip surface to provide insulation for the circuitry as well as cell trapping at the electrode sites. A shifted electrode design is also incorporated to increase the flexibility of the dimension and shape of the microwells. The sensitivity of the electrodes is validated by a dopamine injection experiment. Microwells with dimensions slightly larger than the cells to be trapped ensure excellent single-cell targeting efficiency, increasing the reliability and efficiency for on-chip single-cell Amperometry measurements. The surface-modified device was validated with parallel recordings of live chromaffin cells trapped in the microwells. Rapid amperometric spikes with no diffusional broadening were observed, indicating that the trapped and recorded cells were in very close contact with the electrodes. The live cell recording confirms in a single experiment that spike parameters vary significantly from cell to cell but the large number of cells recorded simultaneously provides the statistical significance.

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  • Exocytotic catecholamine release is not associated with cation flux through channels in the vesicle membrane but Na^+ influx through the fusion pore
    Nature Cell Biology, 2007
    Co-Authors: Liang Wei Gong, Guillermo Alvarez De Toledo, Manfred Lindau

    Abstract:

    Release of charged neurotransmitter molecules through a narrow fusion pore requires charge compensation by other ions. It has been proposed that this may occur by ion flow from the cytosol through channels in the vesicle membrane, which would generate a net outward current. This hypothesis was tested in chromaffin cells using cell-attached patch Amperometry that simultaneously measured catecholamine release from single vesicles and ionic current across the patch membrane. No detectable current was associated with catecholamine release indicating that

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  • Patch Amperometry: High-resolution measurements of single-vesicle fusion and release.
    Nature methods, 2005
    Co-Authors: Gregor Dernick, Liang Wei Gong, Lucia Tabares, Guillermo Alvarez De Toledo, Manfred Lindau

    Abstract:

    Protocol Published in association with Cold Spring Harbor Laboratory Press Nature Methods – 2, 699 – 708 (2005) doi:10.1038/nmeth0905-699 Patch Amperometry: high-resolution measurements of single-vesicle fusion and release Gregor Dernick1, 3, Liang-Wei Gong1, 3, Lucia Tabares2, Guillermo Alvarez de Toledo2 & Manfred Lindau1 1 School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14850, USA. 2 Department of Physiology and Biophysics, School of Medicine, University of Seville, E-41009 Seville, Spain. 3 Present addresses: F. Hoffmann-La Roche Ltd., CH-4070 Basel, Switzerland (G.D.), and Department of Cell Biology and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06510, USA (L.-W.G.). Correspondence should be addressed to Manfred Lindau ml95@cornell.edu Patch Amperometry is a new technique for the observation of single-vesicle exocytosis. Exocytosis of single vesicles as small as 50 nm in diameter can be detected by cell-attached patch-clamp admittance measurements1, 2, 3, 4 indicating fusion of vesicles with the plasma membrane or by Amperometry with a carbon fiber electrode (CFE)5, 6, 7, 8, 9 indicating release of oxidizable molecules such as catecholamines. The admittance measurement provides the membrane capacitance that increases in proportion to the membrane area because of the incorporation of the vesicle into the patch membrane. It also reveals the fusion pore conductance during an exocytotic event, giving an estimate of fusion pore dimensions. Amperometry provides the amount and time course of release of molecules that are readily oxidizable such as dopamine, norepinephrine or serotonin. This technique is capable of detecting as little as a few thousand molecules8, 9. It also resolves the flux of catecholamines through a narrow fusion pore in a so-called foot signal that precedes rapid release indicated by an amperometric spike6. Patch Amperometry combines high-resolution patch capacitance measurements with Amperometry by placing the amperometric detector inside the patch pipet10. The method provides precise information on single-vesicle size and quantal content, fusion pore conductance and permeability of the pore for catecholamines10, 11, 12, 13, 14. Thus, it is a unique tool to investigate the mechanisms that modulate quantal size and the effect of molecular manipulations affecting the properties of the fusion pore. Here we provide step-by-step instructions for the application of this method

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Andrea Versari – One of the best experts on this subject based on the ideXlab platform.

  • Fast Analysis of Total Polyphenol Content and Antioxidant Activity in Wines and Oenological Tannins Using a Flow Injection System with Tandem Diode Array and Electrochemical Detections
    Food Analytical Methods, 2019
    Co-Authors: Arianna Ricci, Nemanja Teslic, Violeta-ivanova Petropolus, Giuseppina Paola Parpinello, Andrea Versari

    Abstract:

    An analytical method for simultaneous determination of total polyphenol content (TPC) and antioxidant activity (AA) of wines (white and red wines) and oenological tannins, using a flow injection system with sequential diode array and electrochemical Amperometry detectors (DAD-ECD), was proposed. The signal at 280 nm provided aggregate data for TPC. The anodic peak related to wine phenolic oxidation was scanned using pulsed integrated Amperometry over the potential of 800 mV vs. Ag/AgCl, to obtain AA. Serial dilutions avoided the poisoning at the glassy carbon (GC) electrode and the linear response obtained with both detectors was compared with spectrophotometric assays commonly used in oenology laboratory. Intraday and interday analytical repetitions showed a good repeatability and reproducibility (relative standard deviation RSD

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Paul W. Bohn – One of the best experts on this subject based on the ideXlab platform.

  • Capture of Single Silver Nanoparticles in Nanopore Arrays Detected by Simultaneous Amperometry and Surface-Enhanced Raman Scattering.
    Analytical chemistry, 2019
    Co-Authors: Ju-young Kim, Donghoon Han, Garrison M. Crouch, Seung-ryong Kwon, Paul W. Bohn

    Abstract:

    The attoliter volumes and confinement abilities of zero-dimensional nanopore-electrode arrays (NEAs) hold considerable promise for examining the behavior of single nanoparticles. In this work, we use surface-enhanced Raman scattering (SERS) in tandem with Amperometry in order to monitor single Ag Raman-sentinel nanoparticles transported to and captured in single nanopores. To that end, highly ordered solid-state NEAs were fabricated to contain periodic arrays of nanopores, each housing a single recessed Au-ring electrode. These were used to electrostatically capture and trap single silver nanoparticles (AgNPs) functionalized with the electrochemically stable Raman reporter, 1,4-bis(2-methylstyryl)benzene (bis-MSB). Transport and capture of the bis-MSB-tagged AgNPs in the nanopores was followed by simultaneous Amperometry and SERS signals characteristic of AgNP oxidation and enhanced Raman scattering by bis-MSB at silver–gold hot spots, respectively. The frequency and magnitude of oxidation-current spikes …

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  • Capture of Single Silver Nanoparticles in Nanopore
    Arrays Detected by Simultaneous Amperometry and Surface-Enhanced Raman
    Scattering
    , 2019
    Co-Authors: Ju-young Kim, Donghoon Han, Garrison M. Crouch, Seung-ryong Kwon, Paul W. Bohn

    Abstract:

    The attoliter volumes
    and confinement abilities of zero-dimensional nanopore-electrode arrays
    (NEAs) hold considerable promise for examining the behavior of single
    nanoparticles. In this work, we use surface-enhanced Raman scattering
    (SERS) in tandem with Amperometry in order to monitor single Ag Raman-sentinel
    nanoparticles transported to and captured in single nanopores. To
    that end, highly ordered solid-state NEAs were fabricated to contain
    periodic arrays of nanopores, each housing a single recessed Au-ring
    electrode. These were used to electrostatically capture and trap single
    silver nanoparticles (AgNPs) functionalized with the electrochemically
    stable Raman reporter, 1,4-bis­(2-methylstyryl)­benzene (bis-MSB). Transport
    and capture of the bis-MSB-tagged AgNPs in the nanopores was followed
    by simultaneous Amperometry and SERS signals characteristic of AgNP
    oxidation and enhanced Raman scattering by bis-MSB at silver–gold
    hot spots, respectively. The frequency and magnitude of oxidation-current
    spikes increased with stepwise increases in DC voltage, and characteristic
    bis-MSB SERS spectra were observed. Under AC excitation, on the other
    hand, two distinctly different types of SERS signals were observed,
    independent of frequency and amplitude: (1) strong, transient (100 s) monotonically diminishing spectra.
    We hypothesize that the former behavior results from AgNP aggregates,
    whereas the latter occurs as a result of multiple incomplete AgNP-oxidation
    events in succession. These results show that attoliter-volume NEAs
    are competent for acquiring concurrent SERS spectra and for Amperometry
    of single nanoparticles and that together these measurements can illuminate
    the collision dynamics of nanoparticles in confined environments

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