Measurement of surface effects on the rotational diffusion of a colloidal particle

A growing number of nanotechnologies involve rotating particles. Because the particles are normally close to a solid surface, hydrodynamic interaction may affect particle rotation. Here, we track probes composed of two particles tethered to a solid surface by a DNA molecule to measure for the first time the effect of a surface on the rotational viscous drag. We use a model that superimposes solutions of the Stokes equation in the presence of a wall to confirm and interpret our measurements. We show that the hydrodynamic interaction between the surface and the probe increases the rotational viscous drag and that the effect strongly depends on the geometry of the probe.