Diffusion of DNA-coated colloids on DNA coated surface

In order for DNA-coated colloids to anneal and form crystals, they must roll and diffuse while attached to each other. Here we report on the diffusion of DNA-coated colloidal spheres on a flat DNA-coated substrate. Near the DNA-melting temperature, the mean square displacement is linear in time as expected for normal diffusion, but the diffusion coefficient is much smaller than for free diffusion. As the temperature is lowered, the motion becomes subdiffusive, which suggests the presence of random free energy barriers in the DNA-mediated interactions.