Mechanisms of DNA-Coupling of Gold Nanoparticles

Ulrike Rehn, Ralf B. Wehrspohn, and Ulrich Gösele

Max-Planck-Institute of Microstructure Physics, Weinberg 2, D-06120 Halle/Saale, Germany




During the few last years a wide range of applications using DNA has been developed in materials science. Complementary DNA strands allow for the directed assembly of nanoparticles and thus for the creation of new hybrid materials. Since gold nanoparticles have strongly size-dependent optical properties, they are ideal probes to investigate mechanisms and conditions of DNA-mediated particle coupling. We coupled gold nanoparticles mainly via double-stranded (ds) DNA and investigated the thus obtained particle networks by UV/VIS spectroscopy and TEM. The particle diameter determines the aggregate size: the bigger the particles, the smaller the aggregates. Besides some morphological aspects we will present results on the mechanism of the aggregate formation. One important parameter for efficient particle coupling is the persistence length of the DNA. The increased stiffness and the resulting high persistence length of dsDNA decreases the extend of non-specific DNA/particle interactions. Moreover, dsDNA allows for the investigation of the melting properties of DNA bonded onto gold nanoparticles as well as the influence of cations on the particle network generation. The detailed understanding of the mechanisms of DNA/nanoparticle coupling is crucial for the development of advanced technologies using DNA-hybrid materials as building blocks.