Direct Observation of Wetting and Diffusion in the Hydrophobic Interior of Silica Nanotubes

Fluorescence microscopy techniques are used to investigate diffusion and wetting at the interior surface of template-synthesized silica nanotubes. Imaging of individual nanotubes reveals that complete modification of the nanotube interiors with hydrophobic ligands is attained during nanotube synthesis. Fluorescence recovery after photobleaching experiments show that (1) spontaneous dewetting of the nanotube interior occurs when the immersing solvent is displaced with pure water and (2) anomalously slow diffusion is observed at the nanotube interior surface.