Date of Award

Fall 2021

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

First Advisor

Andrew B. Greytak

Abstract

Colloidal semiconductor quantum dots (QDs) have garnered significant interest as promising materials for biological applications due to their improved photostability and narrow, tunable photoluminescence properties compared to organic fluorophores. To facilitate their utility as fluorescent bioimaging probes, QDs must undergo post-synthetic modifications to exchange their native hydrophobic ligands from synthesis with hydrophilic ones that enable colloidal dispersions in aqueous environments. Many examples exist that demonstrate surface modifications for water-soluble QDs and their efficacy in biological systems, however, there is a need to develop a more thorough understanding of how hydrophilic ligands coordinate to QD surfaces in order to develop more robust QD systems. The central themes of this dissertation are to describe how hydrophilic ligands bind to QD surfaces, what types of ligands lead to the formation of robust surface coatings, and how to identify properties of ligands that lead to stronger binding. I will begin by introducing the general applications of QDs and the necessary considerations regarding their synthesis, purification, and ligand exchange chemistry. Then, I will describe the first direct comparison of the influence of block and random copolymer ligands on QD stability in the presence of an endogenous competitor ligand. Finally, I will demonstrate the relative binding strength of molecular ligands in water as a function of ligand chain length and binding denticity. Through these systematic investigations, I aim to improve upon our understanding of ligand-QD interactions towards the development of stable and robust fluorescent QD bioimaging probes.

Rights

© 2021, John Hardin Dunlap

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