Date of Award

2018-01-01

Degree Name

Master of Science

Department

Chemistry

Advisor(s)

Lela Vuković

Abstract

Non-covalent interactions between single-stranded DNA (ssDNA) oligonucleotides and carbon nanotubes have provided a unique class of tunable chemistries for applications in nanotube chirality purification, gene delivery, electrochemistry, and nanosensor development. However, mechanistic insight into both the photophysical and intermolecular phenomena underlying their utility in such applications is lacking, resulting in non-systematic approaches to producing DNAnanotube based technologies. In this work, we explore the molecular interactions between ssDNA polymers, in particular (GT)6, and single-walled carbon nanotubes (SWNT) in an ultrasensitive nanosensor for a modulatory neurotransmitters dopamine. Classical molecular dynamics simulations show that (GT)6 oligonucleotides adopt ordered, ring-like conformations around SWNT in contrast to the helical adsorption pattern observed for most previously used longer SWNT-adsorbed ssDNA sequences. We also performed replica exchange molecular dynamics simulations to produce a free energy landscape of (GT)6 conformations at SWNT, and determined that the ring-like structure of (GT)6 at SWNT is one of the most stable conformations, i.e. a free energy minimum structure. Our results show that the ring-like and helical conformations of ssDNA also leave two distinct electrostatic potential footprints at the SWNT surface. We show that adsorbed dopamine has a synergistic effect on ssDNA-SWNT hybrid materials. It leads to disruption of ssDNA conformation and their electrostatic footprint at SWNT surface, explaining more intense optical response of SWNT upon adsorption of dopamine.

Language

en

Provenance

Received from ProQuest

File Size

53 pages

File Format

application/pdf

Rights Holder

Aliasghar Alizadehmojarad

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Included in

Biophysics Commons

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