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Bioinspired Complex Nanoarchitectures by DNA Supramolecular Polymerization

Bioinspired nanoarchitectures are of great interest for applications in fields such as nanomedicine, tissue engineering, and biosensing. With this interest, understanding how the physical properties of these complex nanostructures relate to their function is increasingly important. This dissertation describes the creation of complex nanoarchitectures with controlled structure and the investigation of the effect of nanocarrier physical properties on cell uptake for applications in nanomedicine. DNA self-assembly by supramolecular polymerization was chosen to create complex nanostructures of controlled architectures. We demonstrated that the supramolecular polymerization of DNA known as hybridization chain reaction (HCR) is in fact a living polymerization. The living nature of HCR was established by a demonstration of continued polymerization upon further monomer addition. Living character presents opportunities to synthesize structures of complex nanoarchitectures of viii controlled size. Modifying the strands of HCR produces non-linear supramolecular polymer architectures, including bottlebrushes, star polymers, and brush-arm star polymers. The controlled synthesis of these noncovalent supramolecular polymer architectures presents opportunities for studying the relationship between architecture and physical properties from the perspective of polymer physics. Additionally, this method for creating non-linear architectures could find applications in fields such as synthetic biology, biosensing, and nanomedicine. The effect of nanoparticle stiffness on cell uptake was investigated using a model nanocarrier created by tile-based DNA self-assembly. A new ensemble method of nanomechanical analysis was developed by using Forster resonance energy transfer to measure the deflections caused by increasing osmotic pressure on the nanoparticles. Nanoparticle stiffness was modulated by incorporating an intercalating molecule to bind between the bases of DNA, which was demonstrated to stiffen the structure. Uptake of soft and hard nanoparticles was studied, however it was not shown to vary significantly over the experimental range of stiffness. Despite this negative result, comparison of the nanoparticle stiffness with those of biological materials, such as cells and viruses, suggests that further investigation is still warranted to understand the effect of mechanical properties of nanoparticles on cell uptake. Our results can be used to inform the design of these further investigations.
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