Date of Award

8-2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Materials Science and Engineering

Advisor

Mefford, Olin T

Committee Member

Kitchens , Christopher L

Committee Member

Foulger , Stephen H

Abstract

This study was conducted to track ligand exchange on the surface of metallic nanoparticles in order obtain a better understanding of binding strength of various functional groups. This study develops groundwork for further understanding ligand exchange as nanoparticles transition from engineered to natural systems. A problem exists in knowing the fate of these particles if they are released into natural systems, by accident or with intent. To gain a better understanding of what may occur we look at the binding strength of different ligands. This is done to gain knowledge of the possibility of displacement of ligands occurring in the environment. In order to monitor the binding strength of different ligands a new characterization technique utilizing the phenomena of Fluorescent Resonance Energy Transfer (FRET) is employed. This technique utilizes the quenching properties of gold nanoparticles and fluorescent-labeled ligands to monitor competitive binding between two ligands. The use of fluorescence allows for a sensitive measurement (on the nanomole scale) of ligand exchange on the surface of gold nanoparticles.
This study was conducted in three different parts. The first one was conducted to monitor the competitive binding between bound ligands and incoming mono-functional ligands. This was accomplished by tagging five different functional ligands with a fluorescein-dye. As the fluorescein-terminated ligands exchange on the surface of gold nanoparticles a change in fluorescence intensity is observed. The second study was conducted in the same manner as the first, however this study monitored the effect of bi-functional ligands verse mono-functional ligands as well to monitor concentration effects. The third study conducted was done using a two-dye system. In these studies both the incoming and bound ligand were tagged with a fluorescent-dye. This was done to monitor direct exchange of ligands.

Share

COinS