Synthesis and characterization of responsive nanoporous materials

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Title Synthesis and characterization of responsive nanoporous materials
Publication Type dissertation
School or College College of Science
Department Chemistry
Author Abelow, Alexis Elizabeth
Date 2011-12
Description This thesis describes the synthesis and properties of polymer or oligonucleotide-modified nanoporous membranes and nanopores which exhibit a response to external stimuli, synthesized with the intention of mimicking biological protein channels. The responsiveness of these systems arises as a function of the polymer or oligonucleotide modifier, which exhibit a change in conformation with exposure to temperature, pH, introduction of a small molecule, or electric potential. First, the transport of ions through supported silica colloidal films modified with poly(L-alanine) on platinum electrodes was studied using cyclic voltammetry. By monitoring the flux of a redox species through the polymer-modified colloidal film it is demonstrated that the polymer expands and contracts when the temperature was increased and decreased, respectively. We also observed an expansion and contraction as the pH was increased and decreased, respectively. Transport of a neutral dye molecule through free-standing silica colloidal films modified with poly(L-alanine) was also studied. As noted previously, the polymer expands and contracts as the pH is increased and decreased, respectively. Next, the transport was monitored through both silica colloidal film-modified Pt microelectrodes and Pt single nanopore electrodes as an oligonucleotide-based binder, or aptamer, was attached. The aptamer is responsive to a small molecule, cocaine where, in the absence of cocaine, only one "arm" of the aptamer is folded in on itself, leaving the rest of the chain partially unfolded, blocking the nanopores. However, when the cocaine molecule is introduced into solution, the aptamer folds completely in on itself, forming a three-armed structure with the small molecule encapsulated in the middle. This change in conformation is monitored by observing the change in transport of a redox species through the pores as cocaine is introduced into the system. We observed an increase rate of transport as the aptamer bound to cocaine in both systems, consistent with previous reports of aptamer behavior. Next, two types of electro-active polymers, polypyrrole (PPy) or poly(3,4-ethylene-dioxythiophene) (PEDOT), were vapor-phase polymerized onto the surface of a commercially available aluminum oxide nanoporous membrane, or Anodisc. These polymers expand in the reduced state and contract in the oxidized state to produce a responsive membrane.
Type Text
Publisher University of Utah
Subject Nanomaterials; Nanoporous; Polymer; Responsive nanoporous materials; Nanoporous membranes; Nanopores
Dissertation Institution University of Utah
Dissertation Name Doctor of Philosophy
Language eng
Rights Management Copyright © Alexis Elizabeth Abelow 2011
Format application/pdf
Format Medium application/pdf
Format Extent 13,897,624 bytes
Identifier us-etd3,75799
Source Original housed in Marriott Library Special Collections, TA7.5 2011 .A23
ARK ark:/87278/s66d67rj
Setname ir_etd
ID 194666
Reference URL https://collections.lib.utah.edu/ark:/87278/s66d67rj
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