Assembly of DNA-functionalized gold nanoparticles studied by UV/Vis-spectroscopy and dynamic light scattering

Abstract

The DNA mediated assembly of complementary DNA-functionalized gold nanoparticles (DNA–AuNP) was investigated by means of UV/Vis-spectroscopy and Dynamic Light Scattering (DLS). The melting temperature of the aggregates was determined to be T_m = 31 °C. Characterization of the assembly at 20 °C, 25 °C and 30 °C showed a decrease of the initial assembly growth rate with increasing temperature. The correlation of the wavelengths at the absorbance maxima λ_max and the hydrodynamic radii R_h of the AuNP assemblies proved the dependence of the optical properties on the assembly size while at higher assembly temperature (30 °C) a larger redshift of λ_max with increasing R_h was observed than at lower temperatures. This tendency might give information about the dependence of the internal structure of the DNA–AuNP assemblies on assembly temperature. It is assumed that at higher temperatures more compact assemblies are built than at lower temperatures of 20 °C and 25 °C. To the best of our knowledge, this is the first systematic time-resolved in situ investigation of DNA-mediated AuNP assembly by UV/Vis-spectroscopy and DLS.