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

Abstract

A study aimed at understanding the factors that control the optical properties of DNA-linked gold nanoparticle aggregates containing oligonucleotide linkers of varying length is described. A "melting analysis" was performed on each of the DNA-linked aggregates to verify DNA hybridization and the reversibility of aggregate formation. The melting analyses of each of the annealed DNA-linked aggregates show that complete aggregate dissociation occurs as evidenced by a return to the original extinction values associated with the dispersed particles. Dynamic light scattering was performed on the DNA-modified Au nanoparticles upon addition of the different-length DNA linkers to measure the initial growth rate of the aggregates. Interestingly, this suggests that with regard to the optical properties for these composite materials, DNA linkers might be more useful as kinetic controllers of aggregate growth than as spacer units.