Date of Award

Fall 2024

Project Type

Dissertation

Program or Major

Chemistry

Degree Name

Doctor of Philosophy

First Advisor

Nathan J Oldenhuis

Second Advisor

Erik B Berda

Third Advisor

Roy Planalp

Abstract

This thesis explores innovative approaches to enhancing the functionality and applications of DNA-based materials through the development of DNA bottlebrush polymers (BBPs), DNA-intercalating supramolecular hydrogels (DISHs), and psoralen-based 3D printing techniques. The first chapter presents the synthesis and characterization of linear and cyclic DNA BBPs using a grafting-to approach. Plasmid DNA (pDNA) is used as the polymeric backbone, grafted with polyethylene glycol (PEG) side chains of varying molecular weights (750 Da, 2000 Da, and 5000 Da) to improve stability and functionality. Achieving high graft densities, up to 24% for mPEG750-CEA, and purifying the PEG-DNA conjugates were significant challenges addressed through spin filtration and AFM imaging. The study demonstrates that DNA BBPs can be synthesized on a large scale and applied to larger plasmids such as pEYFP (5045 bp) to generate highly concentrated samples up to 30 mg/mL with enhanced viscoelastic properties. The second chapter introduces DNA-intercalating supramolecular hydrogels, focusing on the use of intercalators such as acridine, thiazole orange, psoralen, and phenanthridine to form cross-links with DNA. Polymeric supramolecular hydrogels (PSHs) exhibit properties like tunable viscoelasticity, self-healing, and stimuli responsiveness, making them suitable for applications in drug delivery, tissue-mimicking materials, and 3D printing. This study develops DNA intercalating supramolecular hydrogels (DISHs) using bifunctional polymeric cross-linked DNA dyes: acridine, psoralen, thiazole orange, and phenanthridine. Mixing genomic salmon milt DNA with these cross-linkers led to significant changes in viscosity and fluorescence, confirmed by UV-Vis measurements. Temperature-dependent mechanical testing showed that Pso-PEG and Phen-PEG increased in viscosity with temperature, while Thi-PEG and Acr-PEG remained stable. Frequency sweeps revealed that Thi-PEG and Phen-PEG had increased elasticity at high frequencies, while Acr-PEG showed enhanced elasticity across all frequencies as temperature increased. These DISHs demonstrate tunable thermal and viscoelastic properties, offering new possibilities for robust, temperature-invariant materials in various applications. The third chapter explores the use of psoralen-based 3D printing to create highly controlled DNA hydrogels. Psoralen, a DNA intercalator activated by UV light at 365 nm, is used to form cross-links in DNA hydrogels. UV activation resulted in a purely elastic material for both 2Pso-PEG and 4Pso-PEG and a significant increase in mechanical strength, with storage moduli rising to 1,000 and 9,000 Pa respectively. 3D printing trials using the BioAssemblyBot demonstrated the hydrogels' capability to make simple structures with fidelity. The printed hydrogels maintained their structural integrity and mechanical properties, underscoring their potential for applications in tissue engineering and drug delivery systems. Overall, this thesis advances the field of DNA-based materials by developing new methodologies for creating and utilizing DNA BBPs, DNA-intercalating hydrogels, and psoralen-based 3D printing techniques. These innovations pave the way for future research and applications in biotechnology, materials science, and medicine.

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