Expanding the Properties and Utility of DNA-Engineered Nanoparticle Superlattices through Monodispersity, Metallization, and Interfacing with Electronic Circuitry

Oh, Taegon

doi:https://doi.org/10.21985/n2-fpwv-ty67

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Expanding the Properties and Utility of DNA-Engineered Nanoparticle Superlattices through Monodispersity, Metallization, and Interfacing with Electronic Circuitry

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Colloidal crystal engineering with DNA offers new opportunities for materials scientists to build and program the structures of superlattices beyond what can be accomplished in Nature with atomic crystal lattices. Thus far, such materials primarily have been studied for their optical properties due to the insulating nature of the DNA bonds and the large distances between the particles, a consequence of DNA length. In addition, the size heterogeneity of the colloidal crystals generated by all known techniques, limits the use of such structures for device applications. My thesis introduces strategies for controlling the growth and monodispersity of colloidal crystals engineered with DNA, introduces a novel way to metallize and strengthen the DNA bond interconnects, so that such structures can be moved from aqueous media into a wide variety of other media, and explores the functional consequences of metallization in the context of conductivity. Chapter 1 reviews the field of colloidal crystal engineering with DNA, setting the stage for the experiments carried out in this thesis. In Chapter 2, On Wire Lithography (OWL) is used to create nanowire devices that allow for the selective functionalization of electrodes with DNA and the controlled growth of nanoparticle devices in a pre-designed nanogap. Chapter 3 takes inspiration from biology where density gradients are used to separate proteins based upon size. In Chapter 3, a powerful density gradient method for controlling the growth of superlattices in such a way that they can be driven to one size is described. In this method, growth quenching is effected by the superlattices falling into sublayers that do not permit growth. Chapter 4 describes a post-synthetic stabilization procedure for DNA-assembled colloidal crystals that relies on Ag+ ions to form coordinate covalent bonds between the nucleobases in the “DNA bonds”. This substantially increases the stability of such structures and avoids the need to move them into solid-state matrices to study or use them. Using the methods introduced in Chapter 2 and the synthetic procedures described in Chapters 3 and 4, the work in Chapter 5 explores the conductivity of the metallized superlattices, showing that Ag+ not only stabilizes the DNA bonds but transforms them into conducting entities. Chapter 6 provides a forward looking perspective and examines the consequences of these advances with respect to generating programmable device architectures based upon nanoparticle superlattices engineered with DNA.

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