Synthetically programmable DNA binding domains in aggregates of DNA-functionalized gold nanoparticles.

Abstract

Polyvalent DNA-functionalized gold nanoparticle conjugates (DNA–Au NPs) have proven useful in a variety of assembly,[1–3] biodiagnostic,[4–6] and nanotherapeutic[7–10] applications. Their widespread use is a consequence of: 1) their novel hybridization properties and 2) straightforward methods for synthesizing macroscopic quantities of them in relatively monodisperse form.[1,11,12] In some applications, the utility of DNA–Au NPs relies on their ability to assemble via DNA hybridization into polymeric aggregates (Scheme 1A).[1] This reaction is accompanied by a concomitant red-to-blue color change, a consequence of the dampening and red-shifting of the nanoparticle surface plasmon resonance (SPR) band at ~520 nm (for a 15-nm nanoparticle).[13] As the temperature is increased above the melting temperature of the duplex DNA linkages connecting the gold nanoparticles, the polymeric structure dehybridizes, the spectroscopic signature associated with the dispersed particles is restored, and a single, highly cooperative melting transition is observed. The melting transition occurs at a higher temperature and over a more narrow temperature range than free duplex DNA of the same sequence.[1,14,15]