Rational Self-Assembly of Ordered Nanoparticle Composites using DNA Interactions

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CBET-0829045SinnoIntellectual Merit: This combined computational and experimental project is focused on the engineering of ordered nano-particle composites whose self-assembly is driven by reversible DNA bridges between particles. The creation of ordered arrays of metallic or semiconductor nanoparticles promises to enable new materials, called metamaterials, having truly unique and useful optical and electronic properties. Current approaches to such nano-particle assembly using screened coulomb and steric interactions depend sensitively on details of the particles? chemistry and size. In contrast, DNA-directed assembly allows the engineering of a matrix of specific attractive interactions among multiple nano-particle species, with the interaction strength and range controlled by DNA sequence alone. This project will specifically address the following two principal research aims. The first aim is to map out the expected equilibrium phase behavior of two component nano-particle suspensions as a function of the relative binding strengths and radii of the two components. The second aim is to elucidate the role that nucleation and growth kinetics play in limiting the accessible nano-composite structures and achievable defect densities. In both aims, detailed simulations will provide a broad survey of accessible phases; selected structures subsequently will be realized experimentally. Concurrent with these activities, new tools will be developed both for more accurate simulation (Monte Carlo with correlated moves) and experiment (super-resolution microscopy for nanostructural characterization). Using these components, this effort will lead to a DNA-based self-assembly scheme to enable the cook-book fabrication of ordered nanoparticle composites, where the crystal structures formed are determined by DNA sequence and geometry rather than particle chemistry. Broader Impacts: Metamaterials, especially those with properties such as a negative index of refraction are expected to find applications in future photonic and plasmonic circuitry, as well as super resolution microscopy. The aim of this project is to lay down fundamental principles for rationally designing such materials. The new tools developed as part of this project should have broad applicability well beyond the immediate scope of the specific investigations outlined here.This interdisciplinary project will provide ample opportunities for student training at both the graduate and undergraduate levels. Both of the graduate students involved in this project will expected to be actively involved in both the computational and experimental facets, which we believe is relatively easy to realize given the history of collaboration between the Crocker and Sinno research groups. Students will be exposed to a state-of-the-art toolkit which includes nano particle functionalization, advanced microscopy and numerical modeling techniques. Moreover, the rich, visual nature of the simulation and experimental data and their potential application in remarkable technology e.g. invisibility will facilitate outreach efforts to high-school students in the Philadelphia public schools and convey the excitement of scientific research.