Supramolecular, or non-covalent, interactions remain a hallmark of biological systems, dictating biologic activity from the structure of DNA to protein folding and cell-substrate interactions. Harnessing the power of supramolecular interactions commonly experienced in biological systems provides numerous functionalities for modifying synthetic materials. Hydrogen bonding, ionic interactions, and metal-ligand interactions highlight the supramolecular interactions examined in this work. Their broad utility in the fields of nanoparticle formulations, polymer chemistry, and additive manufacturing facilitated the generation of numerous biological materials.
Metal-ligand interactions facilitated carbon nanohorn functionalization with quantum dots through the zinc-sulfur interaction. The incorporation of platinum-based chemotherapeutic cisplatin generated a theranostic nanohorn capable of real-time imaging and drug delivery concurrent with photothermal therapies. These nanoparticles remain non-toxic without chemotherapy, providing patient-specific. Furthermore, metal-ligand interactions proved vital to retaining quantum dots on nanoparticle surfaces for up to three days, both limiting their toxicity and enhancing their imaging potential.
Controlled release of biologics remain highly sought-after, as they remain widely regarded as next-generation therapeutics for a number of diseases. Geometry-controlled release afforded by additive manufacturing advances next-generation drug delivery solutions. Poly(ether ester) ionomers composed of sulfonated isophthalate and poly(ethylene glycol) provided polymers well suited for low-temperature material extrusion additive manufacturing. Ionic interactions featured in the development of these ionomers and proved vital to their ultimate success to print from filament. Contrary to ionic interactions, hydrogen bonding ureas coupled poly(ethylene glycol) segments and provided superior mechanical properties compared to ionic interactions. Furthermore, the urea bond linking together poly(ethylene glycol) chains proved fully degradable over the course of one month in solution with urease. The strength of these supramolecular interactions demanded further examination in the photopolymerization of monofunctional monomers to create free-standing films. Furthermore, the incorporation of both hydrogen bonding acrylamides and ionic groups provided faster polymerization times and higher moduli films upon light irradiation. Vat photopolymerization additive manufacturing generated 3-dimensional parts from monofunctional monomers. These soluble parts created from additive manufacturing provide future scaffolds for controlled release applications. Controlled release, whether a biologic or chemotherapeutic, remains a vital portion of the biomedical sciences and supramolecular interactions provides the future of materials for these applications. / Ph. D. / Biology remains the unprecedented expert in the manipulation of non-covalent (or supramolecular) interactions to maintain structure and function. As an example, the structure of DNA maintains many hydrogen bonding units which allow for dynamic reading of genetic material but retain its characteristic structure. Proteins, made from linear chains of amino acids, utilize these interactions to fold into conformations necessary for their function. Harnessing these interactions in the creation of next-generation materials lies at the center of this work.
Metal-sulfur bonds highlight initial work to encapsulate both drug and imaging agent onto a carbon nanoparticle. This complex revealed favorable biocompatibility and the ability to deliver drug in the elimination of bladder cancer cells in vitro. Furthermore, the complex revealed the maintenance of imaging capabilities over many days and continued to release low levels of chemotherapeutic during this time, potentially eradicating cancer cells long after initial treatment. Utilizing this nanoparticle, clinicians can monitor the location of nanoparticles in real-time and tailor doses specific to each patient.
Ionic interactions provided enhanced mechanical properties of both water-soluble and water-insoluble polymers. The water-soluble polymers experienced significantly increased melt viscosity upon the addition of divalent cations, potentially creating non-covalent crosslinks in the molten state. Water-insoluble polymers acted as effective biological adhesives, likely arising from the interaction of ionic groups with its surrounding environment. Hydrogen bonding functioned to increase the mechanical integrity of water-soluble polymers for enhanced processing. The incorporation of urea groups into water-soluble polymers provided a readily available nitrogen source for plant growth while eliminating potential downstream environmental toxicity. Urethane functionality, generated with biologically-friendly byproducts, also provided hydrogen bonding to improve mechanical integrity of water-soluble polymers.
Traditionally, stereolithography 3D printing demanded the use of covalent (or permanent) crosslinking to generate 3D shapes. Hydrogen bonding and ionic interactions coupled together to provide rapidly-formed free-standing films held together only through non-covalent interactions. Comparison of hydrogen bonding, ionic bonding, and both together provided insights onto the kinetics and strength of these films. These interactions proved strong enough to generate well-defined 3D structures through 3D printing. Furthermore, these parts proved water-soluble after fully forming, proving the reversibility of these bonds.
Biologically-inspired interactions drive the future of materials research, and harnessing these interactions provides a better-performing material. Probing new materials for controlled release applications utilizing reversible interactions provided new families of ionic and hydrogen-bonding polymers. Whether soluble or insoluble, biological or not, these interactions pave the way to increase mechanical integrity of commonplace materials with the added reversibility hallmark of supramolecular interactions.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/86521 |
| Date | 30 June 2017 |
| Creators | Pekkanen, Allison Marie |
| Contributors | Biomedical Engineering, Long, Timothy E., Whittington, Abby R., Tong, Rong, Rylander, M. Nichole, Williams, Christopher B. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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