Synthesis and DNA-Functionalization of Silver/Gold (Core/Shell) Nanoparticles
The goal of this project is to synthesize silver/gold (core/shell) nanoparticles and attach DNA strands. Silver nanoparticles show stronger scattering at higher energy compared to gold nanoparticles. However, DNA functionalization of silver surface is not trivial because of silver is easily oxidized. Synthesis of core/shell nanoparticle will enable DNA functionalization of nanoparticles with such unique optical properties. The silver particles are synthesized by reducing Ag+ ions (from aqueous silver nitrate) to metallic Ag with either sodium citrate, sodium borohydride, or a combination of both. These particles (10-12 nm) are then coated with gold by reducing Au3+ (from aqueous HAuCl4•3H2O) with sodium citrate in a solution of boiling silver nanoparticles. The DNA functionalization was accomplished by first cleaving disulfide bonds using DTT (1,4-dithiothreitol) in a phosphate buffer followed by incubation with nanoparticles in the same buffer. The core-shell structure has been directly imaged via TEM. The DNA-functionalized nanoparticles will be assembled into functional heterostructures using DNA origami-based templates.