Nanolithography and Bio-Programmable Assembly for the Rational Design and Synthesis of Colloidal Crystals

Colloidal materials packed into various 3-dimensional architectures have been the basis for many new and exciting developments that lie at the intersection of chemistry, biology, physics and materials science. Much work has been done to understand the fundamental forces that govern assembly processes at these relatively large length scales. Nonetheless, much work is still needed before this new class of materials is as well understood as their atomic and molecular counterparts. These materials have diverse technological applications for the development of electronic, optoelectronic and magnetic materials. However, full realization of this potential will require fine control over all aspects of the crystal growth process.;Chapters two and three examine "universal" chemical lithographic techniques to pattern biomolecules including DNA and proteins using dip-pen nanolithography (DPN) that could in principle be used for subsequent bio-programmable colloidal assembly. An agarose matrix was found to facilitate the direct-write deposition of high molecular weight species, with tunable transport rates. Chapter three introduces the concept of electrochemically activated DPN by reversibly toggling a quinone-functionalized substrate between active and passivating forms. These methods overcome challenges of transporting high-molecular weight species such as biomolecules by DPN, and provide universal methodology for patterning biomolecules.;Chapter four explores how specific bonding interactions between a substrate and colloids affects colloidal crystal growth using DNA-mediated crystallization. A stepwise growth process is developed to systematically study, observe and control these interactions for the development of colloidal crystal thin-films. Even in the absence of epitaxial processes, the judicious choice of DNA interconnects allows one to tune the interfacial energy between various crystal facets and the substrate, and results in the ability to control orientation, which is not possible in atomic systems.;Chapter five examines the temperature-dependent annealing process in DNA-mediated colloidal crystallization. The crystal quality is assessed according to size and strain, and these crystal metrics are related to the dehybridization transition of the DNA-nanoparticle superlattice. Flexible spacers included in the DNA sequence allow the "annealing window" to be expanded relative to the melting temperature, expanding synthetic capabilities for the development of metamaterials and photonic crystals.