Electrostatic retardation in macro-ion adsorption

In some cases the protein adsorption was found to be slower than expected from diffusion-controlled adsorption kinetics, which was attributed by van Dulm Norde (1983) to some barrier the adsorbing molecules have to break through before they adsorb at the interface. This barrier has been considered to be caused by electrostatic repulsion between protein molecules and the surface. This phenomenon can be associated with the objective of the present section and the observed barrier could be caused by long range forces. 

As discussed already in Section 7.6. the transfer of molecules or ions from the subsurface to the interface can be controlled by another, specific barrier which does not coincide with the electrostatic retardation arising from the transport of ions through the electric double layer. The maximum of electrostatic repulsion is located at a distance to the interface approximately equal to the radius of the adsorbing macro-ions. 

---