Relating Single-Molecule Measurements of Adsorption and Diffusion: A Path Towards Enhanced Surface Capture

Many processes, including heterogeneous catalysis and receptor-ligand binding, require adsorption of a molecule from bulk liquid to a specific site on a solid surface. Previous work in our group has demonstrated that many different types of molecules (including proteins and polymers) adsorb from bulk liquid to a solid surface and then diffuse via bulk-mediated transport.  Using total internal reflection fluorescence microscopy, we have tracked single molecules adsorbing and diffusing at a solid-liquid interface.  By modeling the surface diffusion as bulk-mediated transport, we can use our adsorption measurements to predict the nature of the surface diffusion and subsequently validate these predictions with independent measurements of surface diffusion.  Understanding the interplay between adsorption and diffusion provides a new framework for measuring the affinity of a molecule to a surface and will enable optimization of technologies based on surface capture.