What Controls the Melting Properties of DNA-Linked Gold Nanoparticle Assemblies?*

Abstract

Understanding the fundamental origins of the melting properties of DNA-linked nanoparticle aggregates is of paramount importance because these properties directly impact one’s ability to formulate high sensitivity and selectivity DNA detection systems and construct materials from these novel nanoparticle materials. Nanoparticles heavily functionalized with oligonucleotides have been used as probes in a variety of DNA detection methods and as elemental building blocks in materials synthesis schemes based upon the sequence-specific hybridization properties of DNA. The size of the nanoparticle often dictates the types of formats that can be used to detect DNA hybridization events. The base sequences of the probe and target DNA are adapted from the 141-bp anthrax protective antigen gene. Transmission electron microscopy images of DNA-functionalized gold nanoparticles were obtained on a Hitachi 8100 transmission electron microscope. A high DNA surface density on the nanoparticle is advantageous in terms of particle stabilization, especially at elevated salt concentrations, which are necessary to effect DNA hybridization.