Date of Award

8-2016

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

First Advisor

Jean A. Chmielewski

Committee Chair

Jean A. Chmielewski

Committee Member 1

Christine A. Hrycyna

Committee Member 2

David H. Thompson

Abstract

Collagen is a strong, sturdy, but malleable, protein found abundantly in the extracellular matrix. Consequently, it has become an invaluable biomaterial for use in regenerative medicine. However, natural collagen poses difficulties when it comes to customization and structural control, as well as the risk of infectious prions from animal sources. Our approach utilizes shorter, synthetic collagen mimetic peptide sequences. These peptides retain the incredible triple helical stability of natural collagen but can be modified with versatile metal-binding ligands. In the presence of an appropriate metal ion, the peptides self-assemble into diverse, three-dimensional morphologies. The peptide NCoH, functionalized with N-terminal NTA and C-terminal dihistidine, self-assembles into ruffled spheres called microflorettes that can be selectively functionalized internally and / or externally with biomolecules containing a His tag. A novel fluorophore, Rho-(Gly)3-(His)6, was synthesized to enable high-quality visualization of NCoH microflorette interactions with cells. Fluorescent confocal microscopy confirmed that NCoH microflorettes sequester HeLa and human mesenchymal stem cells. Moreover, these microflorettes were shown to bind to human epidermal growth factor.

The peptide NCoH alone holds great possibilities for use in biomedicine, but such possibilities could be expanded ever more by mixing NCoH with other collagen mimetic peptides. Self-assembly of mixtures of NCoH with the cross-linked peptide HBN in the presence of various divalent metal ions resulted in integrated mesh / florette systems. Joint metal-promoted self-assembly of NCoH mixed with its analogs HisCol and / or IdaCol results in an array of highly intricate morphologies, including and especially novel, spiraled “horned” bundles with well-ordered periodicity that form within minutes and under neutral conditions. Moreover, such assemblies can be carried out on a glass surface, producing structures with a high degree of order on both the micro- and nanoscales that could potentially be exploited for future biochemical applications. The vast array of structures that can be produced through metal-promoted self-assembly of collagen mimetic peptides holds great potential for the development of highly customizable tissue engineering therapies.

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