Synthetic and Analytical Techniques to Break Symmetry and Control Structure in Crystals Engineered with DNA


When attached to another species (e.g. a nanoparticle), the sequence specificity of DNA can be repurposed to program interactions between such entities and to direct their formation into ordered structures. The research presented in this thesis aims to push the boundaries of structures that can be made via this approach. Specifically, it focuses on the development of syntheses for exotic low-symmetry nanoparticles that can be used as building blocks, the development of new analytical tools that enable high-throughput structural analysis of such building blocks, and the introduction of post-synthetic modifications to tune structure. Chapter 1 describes the state-of-the field and presents several Lessons learned over the past two decades that guide the use of DNA for crystal engineering. Chapter 2 presents a strategy to algorithmically characterize the structure of a nanoparticle population with individual particle resolution. In particular, image analysis software was developed for measuring quantitative structural values for >7 anisotropic particle shapes from electron microscopy images. This tool is extremely useful for nanomaterials characterization and provides important structural insight, and thus it was made freely available online. Chapters 3 and 4 explore the origins of symmetry breaking in nanoparticle syntheses. Specifically, these chapters identify a previously unexplained nanoparticle-catalyzed nucleation mechanism and detail a platform-type approach for synthesizing a number of low symmetry nanoparticles. Chapter 5 explores the DNA-mediated crystallization of particles from Chapter 4 and identifies a unique series of phase transitions. This chapter identifies a novel symmetry breaking event in the DNA shell that enables the formation of an unexpected low symmetry lattice. Chapter 6 describes how the intrinsic properties of DNA can induce significant structural changes in response to specific stimuli which enable one to tune crystal properties (e.g. optoelectronic). These advances dramatically progress the ability to rationally design complex colloidal crystals for diverse applications ranging from metamaterials to catalysis to therapeutics.

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