Nanoelectrochemical sensors for kinetic measurements and electroanalytical chemistry
Item
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Title
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Nanoelectrochemical sensors for kinetic measurements and electroanalytical chemistry
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Identifier
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d_2009_2013:a97453ed23cb:11892
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identifier
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12557
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Creator
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Wang, Yixian,
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Contributor
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Michael Mirkin
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Date
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2013
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry | Analytical chemistry | Physical chemistry
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Abstract
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My PhD research is in the field of nanoelectrochemistry. It includes both fundamental kinetics studies of charge transfer processes and chemical reactions at nanoscopic liquid/liquid and solid/liquid interfaces and applications of the nanometer-sized probes and scanning electrochemical microscopy (SECM) as analytical tools.;Nanopipettes can be used to study kinetics of heterogeneous ion transfer (IT) reactions. Common ion voltammetry was developed for determining the kinetic parameters of the rapid tetraethylammonium transfer at the dichloroethane/water interface. This new type of voltammetry provides two limiting currents corresponding to the ingress of the common ion into the pipette and its egress to the external solution, from which one can evaluate the related geometric and transport parameters. Then, the kinetics of IT processes of tetrabutylammonium and similarly sized but asymmetric 1-methyl-3-octylimidazolium at the water/ionic liquid nanointerface was determined for the first time by employing this new approach.;Nanopipettes were also used as SECM tips to carry out feedback-mode imaging of various substrates with the nanoscale resolution. Quantitative SECM measurements performed with the polished pipettes as small as 8 nm radius at extremely short tip/substrate distances (~1 nm). A new mode of the SECM operation---electron transfer/ion transfer mode---was developed for simultaneous mapping of surface reactivity and topography.;We developed the methodology for resistive-pulse sensing with nanopipettes and used it to detect Au nanoparticles, nanoparticles coated with an allergen epitope peptide layer, and gold particles with bound antipeanut antibodies on the peptide layer. The current pulses produced by antibody-conjugated particles and either bare gold or Au-peptide nanoparticles occurred at different translocation voltages and exhibited opposite signs of the current change, which is essential for selective resistive-pulse sensing of antibodies with nanopipettes.;I modified Pt nanoelectrodes with platinum black and then used them to detect reactive oxygen and nitrogen species (ROS and RNS) inside macrophages. Our results supported the hypothesis of the ROS/RNS leakage from phagolysosomes. The data also showed that a macrophage can avoid oxidative damage by rapidly reducing ROS/RNS concentration levels in its cytoplasm.
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Type
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dissertation
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Source
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2009_2013.csv
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degree
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Ph.D.
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Program
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Chemistry
