Dissertation/Thesis Abstract

Self-Assembly and Hydrogelation of Fmoc-Phenylalanine Derivatives
by Ryan, Derek M., Ph.D., University of Rochester, 2011, 364; 3478357
Abstract (Summary)

The ability of peptides and small molecules to spontaneously self-assemble into amyloid-like fibrils has been exploited in the development of noncovalent hydrogels. Noncovalent hydrogels have been utilized for numerous biomedical applications such as cell culture, drug delivery, and tissue scaffolding. To date a large number of the reported small molecule based hydrogels have been discovered serendipitously, making customization of the bulk material properties a largely trial and error process. Fluorenylmethoxycarbonyl (Fmoc) protected amino acids have been shown to be a potent low molecular weight hydrogelators. There is a growing need for further understanding of the molecular recognition events that drive the self-assembly and hydrogelation processes. Insights into the molecular origins of the self-assembly will facilitate the de novo development of amino acid based noncovalent hydrogelators.

This thesis investigates the influence of side chain π-π interactions on the self-assembly and hydrogelation of Fmoc-Phenylalanine derivatives. Halogenation of the phenyl side chain was shown to promote the assembly of a previously unassembled amino acid derivative. It was also demonstrated that the rate of self-assembly could be effectively tuned through substitution of the phenyl side chain of Fmoc-Phenylalanine, which influenced the rates of hydrogel formation. It was hypothesized that the formation of complementary π-π interactions between the phenyl side chains was responsible for the onset of self-assembly. In addition, it was demonstrated that efficient hydrogen bonding between the C-terminus and solvent was critical for self-assembly. By increasing the water solubility of the compounds through C-terminal substitutions the bulk rheological properties of the hydrogels could be perturbed. Lastly, the ability of complementary π-π interactions to drive the selective co-assembly of two distinct monomeric units was investigated. The findings presented in this thesis facilitated the development of sophisticated self-assembled materials with ability to tune mechanical properties through synthetic customization of the molecular structure.

Indexing (document details)
Advisor: Nilsson, Bradley, Dumont, Marc
Commitee: Boeckman, Robert, Miller, Benjamin, Turner, Douglas
School: University of Rochester
Department: School of Arts and Sciences
School Location: United States -- New York
Source: DAI-B 73/01, Dissertation Abstracts International
Subjects: Organic chemistry, Materials science
Keywords: Fmoc-phenylalanine derivatives, Hydrogelation, Self-assembly
Publication Number: 3478357
ISBN: 978-1-124-95803-3
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