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Author
Title Particle transport and ion current rectification in conical-shaped nanopores
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Publication Date
Degree PhD
Discipline/Department Chemistry
Degree Level doctoral
University/Publisher University of Utah
Abstract This dissertation presents experimental and computational investigations of nanoparticle transport and ion current rectification in conical-shaped glass nanopore membranes (GNMs). Chapter 1 provides an overview of the Coulter counter or “resistive pulse” method, ion current rectification, and finite-element simulations used in solving mass transfer problems in conical-shaped nanopores. Chapter 2 describes a fundamental study of the electrophoretic translocation of charged polystyrene nanoparticles in conical-shaped pores contained within glass membranes using the Coulter counter principle, in which the time-dependent current is recorded as the nanoparticle is driven across the membrane. Particle translocation through the conical-shaped nanopore results in a direction-dependent and asymmetric triangularshaped resistive pulse. The simulation and xperimental results indicate that nanoparticle size can be differentiated based on pulse height. Chapter 3 presents experimental, theoretical, and finite-element simulation investigations of the pressure-driven translocation of nanoparticles across a conicalshaped GNM. Analytical theory and finite-element simulation for pressure-driven flow through a conical-shaped pore were developed to compute the volumetric flow rate, the position-dependent particle velocity, and the particle translocation frequency. The translocation frequencies computed from theory and simulation were found to be in agreement with experimental observations. Chapter 4 reports the pressure-dependent ion current rectification that occurs in conical-shaped glass nanopores in low ionic strength solutions. Because the pressureinduced flow rate is proportional to the third power of the nanopore orifice radius, the pressure-driven flow can eliminate rectification in nanopores with radii of ?200 nm but has a negligible influence on rectification in a nanopore with a radius of ?30 nm. The dependence of the i-V response on pressure is due to the dependence of cation and anion distributions on convective flow within the nanopore. Chapter 5 describes pressure-reversal methods to capture and release individual nanoparticles. One (or more) particle is driven through the orifice of a conical-shaped nanopore by pressure-induced flow. A reverse of flow, following the initial translocation, drives the particle back through the nanopore orifice in the opposite direction. The sequence of particle translocations in the capture step is preserved and can be read out in the release step. The observed instantaneous transfer rate and return probability are in good agreement with finite-element simulations of particle convection and diffusion in the confined geometry of the nanopore.
Subjects/Keywords Capture and release; Coulter counter; Ion current rectification; Nanopores; Particle transport; Resistive pulse analysis
Rights Copyright © Wenjie Lan 2011
Country of Publication us
Record ID oai:utah:us-etd3,77269
Other Identifiers us-etd3,77269
Repository utah
Date Retrieved
Date Indexed 2016-09-14
Grantor University of Utah

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…5.3 Results and discussion ........................................................................................ 130 5.3.1 Capture and release of 120 and 160 nm radius particles in a mixed particle solution…

…130 5.3.2 Capture and release of multiple 120 nm radius particles.......................... 134 5.3.3 Finite-element simulations ....................................................................... 136 5.3.4 Capturing and releasing single…

…two-dimensional 3D – three-dimensional Å– angstrom -COOH – carboxylic acid DLS – dynamic light scattering ECR – electrophoretic capture and release EOF – electroosmotic flow Eq – equation ESZ – electrical sensing zone FEM – finite-element method GNM…

…120 5.1. (a) Schematic illustration of glass nanopore membrane (GNM), and particle capture and release method using a three-part pressure waveform. (b) Schematic of the particle translocation and resulting i-t recording…

…127 5.3. i-t recordings corresponding to the capture and release of 120 and 160 nm radius nanoparticles using a 210 nm radius GNM in a 0.1 M KCl solution (pH 7.4) at P = -5 mmHg (capture) and P = +5 mmHg (release). Pulses…

…a), (a’), (b), and (b’). ..................... 131 xiv 5.4. (a) i-t recording for the capture and release of 120 nm radius particles (GNM size: 210 nm radius, 1.3 × 1010 particles/mL, Vapp: 200 mV…

…solution. (b) Instantaneous translocation rates for the particle capture and release experiments ( 10 mmHg pressures for the data in part a). Each red point represents the rate at which particles enter the pore within a 1 s time…

…particle concentration distribution within a 210 nm radius pore during a capture and release experiment. The particle concentration at the pore orifice was set as constant (2.2 10-8 mol/m3). The particles were treated as points in this continuum…

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