(581g) Pattern Formation by Adsorbed Proteins on a Solid Surface

When a protein is absorbed from a solution on to a solid-liquid interface, some have reported that the adsorbed proteins show some form of spatial pattern, even when the solution is dilute, surface coverage is low and there is no surface diffusion. Others have shown using a two-dimensional pair correlation function, that no structure exists. The thesis here is that the mass transfer process can be unstable because of the electrostatic effects. This can either be due to an extremum in the electrostatic potential in the non-equilibrium double layer or due to the changing surface charge density since the adsorption of protein is expected to cancel the surface charge density. A linear stability analysis indicates that indeed the system becomes unstable due to the electrostatic effects. The results are analyzed and yield a characteristic length scale over which spatial structures can be observed and in turn under what conditions they cannot be observed.