Nucleation and Growth of Two-dimensional Gold Plates on DNA Film

Abstract

Nano- and micro-sized metal plates have recently been interested in promising functional building blocks due to their high surface-to-volume ratio, unique optical & electrical properties. However, synthesis of anisotropic 2D metal particles require elaborate multi steps such as shape transformation by etching process or seeded growth process. Therefore, we developed a method to synthesize 2D inorganic particles by using DNA film as a template. It is well known that DNA shows liquid crystal phase depending on the concentration. Oriented DNA film can be formed by simple coating process inducing competitive interaction between shearing force and elastic energy minimization during water evaporation. Since this film has a dense negative charge on the surface, it can be used as a template for synthesizing various inorganic particles by forming charge complex with metal ions. Here, we synthesized anisotropic two-dimensional gold particles by simply dipping preformed DNA film into chloroauric acid solution and reducing agent sequentially. Nano- and micro-sized particles have been successfully synthesized, and order & orientation of DNA chains in the film are maintained even after all procedures. This will offer possibility of other biomaterials, including DNA, as a versatile platform for nucleation and growth of inorganic compounds.