Effects of Substrate Hydrophobicity/Hydrophilicity on Height Measurement of Individual DNA Molecules

Effects of substrate hydrophobicity/hydrophilicity on height measurement
of individual ds-DNA molecules are investigated with tapping mode atomic
force microscopy (TMAFM) and vibrating mode scanning polarization force
microscopy (VSPFM). The measured heights of ds-DNA on hydrophobic highly
oriented pyrolytic graphite (HOPG) are remarkably less than those on
hydrophilic bare mica and Ni ²⁺ treated mica in both TMAFM and VSPFM. By analysing the results, we propose that the hydrophobicity/hydrophilicity of substrate can greatly influence the height measurement of DNA molecules.