Structure and Hybridization of Surface-Tethered DNA


Rastislav Levicky, Tonya Herne, Michael Tarlov Process Measurements Division
Chemical Science and Technology Laboratory
Sushil Satija
NIST Center for Neutron Research
Materials Science and Engineering Laboratory

The structure and hybridization of end-tethered, single-stranded DNA 'polymer brushes' were characterized using neutron reflectivity and surface-sensitive infrared spectroscopy. The DNA brushes were prepared by using mixed monolayers consisting of single-stranded, thiol-derivatized DNA and a mercaptohexanol passivating layer. The DNA bonds chemically to gold through a thiol group at the 5' end. The mercaptohexanol, which also bonds to gold through a thiol group, serves to block contacts between the single-stranded DNA and the gold substrate except at the thiol-functionalized 5' end. By preventing the adsorption of the DNA backbone to the substrate, the two-component monolayer approach aims to optimize the hybridization activity of the DNA. DNA concentration profiles obtained from neutron reflectivity experiments furnished direct evidence of changes in the configuration of the surface-tethered DNA. >From the infrared studies, a surface mode was identified which allows for monitoring the extent of contact between DNA backbone and gold.