Defined DNA/nanoparticle conjugates

Glutathione monolayer-protected gold clusters were reacted by place exchange with 19 or 20-residue thiolated oligonucleoticles. The resulting DNA/nanoparticle conjugates could be separated on the basis of the number of bound oligonucleoticles by gel electrophoresis and assembled with one another by DNA-DNA hybridization. This approach overcomes previous limitations of DNA/nanoparticle synthesis and yields conjugates that are precisely defined with respect to both gold and nucleic acid content.