Controlled structural evolution of large silver nanoparticles and their DNA-Mediated bimetallic reversible assemblies

We have synthesized the monodisperse large silver nanoparticles with a variety of controlled shapes and sizes using poly (sodium 4-styrene sulfonate) as a structure-directing reagent. We have demonstrated that the molecular weight (70K, 200K and 1000K) and concentration of the polymer can effectively and systematically control the silver nanoparticle structures that are strongly associated with the unique optical properties based upon their surface nanostructures. The crystalline structures of the particles have been further analyzed by diffraction methods. Importantly, the silver nanoparticles can be functionalized with DNA for reversible assembly formation with complementary DNA-gold nanoparticle conjugates, demonstrating that these novel structures can be utilized as smart probes and functional platforms for diagnostic and therapeutic applications. The reversibility of the bimetallic assembly is confirmed by the thermal denaturation.