Sequence-Dependent Stability of DNA-Modified Gold Nanoparticles

The binding affinity of deoxynucleosides (dA, dG, dC, and dT) to gold nanoparticles was studied using a colorimetric assay to determine if nucleobase sequence may play a role in binding alkanethiol-capped oligonucleotides to gold nanoparticles. These data indicate that the deoxynucleoside dT has a much lower binding affinity to the gold nanoparticle surface than the deoxynucleosides dG, dC, and dA. These data can be correlated with a previous study in our lab which indicated that alkanethiol-capped oligonucleotides containing (dT)20 spacers have a significantly higher surface coverage than oligonucleotides containing (dA)20 spacers. To probe the physical consequences of this phenomenon, gold nanoparticles were loaded with alkanethiol-capped poly dT, dA, and dC oligonucleotide sequences of 5−20 bases in length, and the stabilities of the particles in electrolytic media were measured by monitoring a colorimetric change associated with particle agglomeration. The gold nanoparticles loaded with alkanethiol-ca...