DOI
https://doi.org/10.25772/HD5W-4A39
Author ORCID Identifier
https://orcid.org/0000-0002-7167-530X
Defense Date
2021
Document Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Nanoscience and Nanotechnology
First Advisor
Joseph Reiner
Abstract
Single molecule nanopore spectroscopy serves as an emerging tool for studying small molecules in aqueous environments without the need for additional chemical labels. Recently it has been seeing increased use as a tool for investigating small metallic nanoparticles and clusters. These clusters consist of a handful of metallic atoms (e.g. Au18) and are regularly ‘passivated’ with organic ligands to provide functionality and protect against aggregation. There has been a widening gap in research studying the surface kinetics of these passivating ligands at the single molecule level as well as during the exchange process. In this work we investigated these surface kinetics using nanopore spectroscopy, which revealed a number of unique properties and kinetics. By trapping small metallic clusters (approx. 2 nm in diameter) in the sensing region of a biological nanopore and studying the resulting current blockade we were able to elucidate quantized discrete state transitions occurring on relatively long time scales (10 ms < t < 10s) dependent on capping ligand mass. We attributed this behavior to reorganization of the ligand surface. We then showcase how this technique can monitor single ligand exchange reactions within the nanopore and use the previously discovered quantized state transitions to identify number and type of ligand exchange occurring. Finally, we reveal that the nanopore can detect different isomers of Mercaptobenzoic Acid (MBA) ligands capping a gold metallic cluster, and we show that differences in their previously mentioned quantized state structures are due to weak interactions.
Rights
© Bobby Cox
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
5-5-2021
Included in
Biological and Chemical Physics Commons, Materials Chemistry Commons, Organic Chemistry Commons, Physical Chemistry Commons