Understanding metal cation interactions with oligonucleotides at liquid/solid interfaces is essential for a variety of applications ranging from the development of accurate and reliable biosensors to material directed synthetic strategies. Here, we combined nonlinear optical spectroscopy and atomic force microscopy (AFM) for a uniquely sensitive, label-free approach to detect and quantify single-stranded DNA structural changes and binding interactions in the presence and absence of Mg2+ at an aqueous/silica interface. Sum frequency generation (SFG) directly probed vibrational resonances and reordering of surface-bound DNA on silica surfaces with the addition of Mg2+, while second harmonic generation (SHG) quantified binding constants and metal ion coverage per DNA strand over a range of oligonucleotides lengths. Through statistical analysis, AFM was used to quantify shifts in the DNA height and tilt angle distributions before and after the addition of Mg2+. The implications of structural changes due to surface-bound DNA-metal ion binding are discussed.

Surface-bound DNA interactions with metal cations studied by nonlinear optics and atomic force microscopy

243rd National Meeting (2012)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.