Using DNA to Design Plasmonic Metamaterials with Tunable Optical Properties

Abstract : Due to their potential for creating designer materials, the 3D assembly of nanoparticle building blocks into macroscopic structures with well-defined order and symmetry remains one of the most important challenges in materials science. [ 1 5 ] Furthermore, superlattices consisting of noble-metal nanoparticles have emerged as a new platform for the bottom-up design of plasmonic metamaterials. [ 6 8 ] The allure of optical metamaterials is that they provide a means for altering the temporal and spatial propagation of electromagnetic fields, resulting in materials that exhibit many properties that do not exist in nature. [ 9 13 ] With the vast array of nanostructures now synthetically realizable, computational methods play a crucial role in identifying the assemblies that exhibit the most exciting properties. [ 14 ] Once target assemblies are identified, the synthesis of nanometer-scale structures for use at optical and IR wavelengths must be taken into account. Many of the current methods to fabricate metamaterials in the optical range use serial lithographic-based approaches. [ 6 ] The challenge of controlled assembly into well-defined architectures has kept bottom-up methods that rely on the self-organization of colloidal metal nanoparticles from being fully explored for metamaterial applications. [ 8 ] DNA-mediated assembly of nanoparticles has the potential to help overcome this challenge. The predictability and programmability of DNA makes it a powerful tool for the rational assembly of plasmonic nanoparticles with tunable nearest-neighbor distances and symmetries. [ 1,15 18 ] Herein, we combine theory and experiment to study a new class of plasmonic superlattices first using electrodynamics simulations to identify that superlattices of spherical silver nanoparticles (Ag NPs) have the potential to exhibit emergent metamaterial properties, including epsilon-near-zero (ENZ) behavior, [ 13 ] and a region with an optically metallic response.