Directed motion of proteins along tethered polyelectrolytes

We present the first time-resolved investigation of motions of proteins in densely grafted layers of spherical polyelectrolyte brushes. Using small-angle x-ray scattering combined with rapid stopped-flow mixing, we followed the uptake of bovine serum albumin by poly(acrylic acid) layer with high spatial and temporal resolution. We find that the total amount of adsorbed protein scales with time as t(1/4). This subdiffusive behavior is explained on the basis of directed motion of the protein along the polyelectrolyte chains.