THE DYNAMICS OF DNA-CAPPED GOLD NANOPARTICLE SUPERLATTICE ASSEMBLY IN ELECTROLYTE SOLUTIONS

Abstract

Highly ordered nanoparticle arrays, or nanoparticle superlattices, are a sought after class of materials due to their novel physical properties, distinct from both the individual nanoparticle and the bulk material from which they are composed. Several successful methods have been established to produce these exotic materials. One method in particular, DNA-mediated assembly, has enabled a stunning variety of lattice structures to be constructed. By covalently conjugating DNA molecules to nanoparticle surfaces, this method uses the sequence binding specificity of DNA to mediate the large-scale assembly of nanoparticles. This method however, relies on complex sequence design, and is optimized to a very specific set of solution parameters, such as pH, ionic strength, and temperature. Here, we sought to expand the parameter base in which DNA capped gold nanoparticles can form superlattices in solution. This was achieved by treating DNA as a generic polymer, namely by eliminating the complex base-pairing interactions, greatly simplifying the assembly process. In particular we aimed to understand the solution phase parameters governing the assembly dynamics of DNA-capped gold nanoparticles. The adsorption dynamics of individual DNA-capped gold nanoparticles on a positively charged substrate was first characterized in various electrolyte solutions, establishing a kinetic model of adsorption. These same parameters were then used to facilitate the self-assembly of three-dimensional DNA-capped gold nanoparticles in solution. Finally, progress towards the application of solution phase two-dimensional nanoparticle superlattices was undertaken. We envision that this work characterizing and elucidating the solution phase dynamics of DNA-capped gold nanoparticles will serve to ultimately facilitate their application in functional materials.