Engineering phases and kinetics for processing DNA-linked particle materials

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1133386CrockerIntellectual Merits: DNA has been suggested as an effective way to program collections of microscopic particles to self-assemble into desired structures. The idea is appealingly simple: particle species bearing complementary DNA strands will stick together, and the ordered structure that maximizes such contacts between complementary species will self-assemble spontaneously from the mixture. Unfortunately, the notion of pre-programmed structure is not appropriate for realizing a broad array of useful DNA-linked particle materials, or DLPMs. It is not, for instance, how real atomic materials work: there are typically several different crystal structures that are local minima of a systems free energy, and what structure actually forms under prescribed conditions depends on relative nucleation and growth rates, and possible solid-solid transformations between different phases. Moreover, the quality of any resulting ordered structure, as defined by the density of morphological and compositional defects, is strongly influenced by a variety of processing variables such as the thermal history during nucleation and growth. Here, the PIs propose that the correct pathway to establish DLPMs as a practical material class is to consider simultaneously both materials and processes in the context of an expanded design paradigm. The overarching intellectual goals of this proposal are therefore (1) to establish a quantitative understanding of the nucleation and growth thermodynamics and kinetics of binary DLPMs using experiments and predictive computer simulations (2) to demonstrate the ability to process DLPMs much in the same way as any other material, i.e. by developing approaches for controlling nucleation, growth, and any potential solid-solid transformations using thermal or chemical stimuli to achieve these goals, we aim to develop an experimental system to enable real time real space optical microscopy for dynamical analysis of binary DLPMs with tunable interparticle interactions. The experimental work will be coupled closely to a comprehensive computer simulation effort that will elucidate fundamental mechanisms and provide high-throughput analysis of material-process combinations.Broader Impacts:In principle, new materials called metamaterials, formed of organized arrays and circuits of optically active nanoparticles instead of atoms, promise to allow the manipulation of photons with the same density and versatility that microelectronics brings to computation. This would alleviate the current optoelectronic technology bottleneck between microelectronics and fiber optic telecommunications as well as enable new information technologies. The primary challenge is building these revolutionary new materials. This project will develop and validate a general self-assembly design and material processing platform for producing complex, ordered particle composite materials. It is anticipated that the design rules that emerge from this project will be directly applicable to the making useful metamaterialsif optically active particles are assembled with DNA, the resulting material can be used as is for prototyping and proof of concept studies, or alternatively, as a template for conversion into a solid composite material more appropriate for applications.This interdisciplinary project will provide ample opportunities for student training at both the graduate and undergraduate levels. The two graduate students principally involved in this project will be expected to be actively involved in both the computational and experimental facets. Students will be exposed to a state-of-the-art toolkit which includes nanoparticle and colloidal functionalization, advanced microscopy and various numerical modeling and simulation techniques. Moreover, the rich, visual nature of the simulation and experimental data, and their potential application in remarkable technology. directed self-assembly will facilitate outreach efforts to high-school students in the Philadelphia public schools and convey the excitement of scientific research. Both Sinno and Crocker are increasingly active in various outreach activities at Penn and neighboring institutions and this project will provide additional materials for continuing these efforts.