Concentration scaling of protein deposition kinetics

Abstract

Measurement of the phase velocities of guided modes in optical waveguides yields information about the optical parameters of the waveguide and the medium surrounding it. Application of this technique to a planar waveguide upon which proteins are allowed to adsorb from solution has yielded the first experimental data accurate enough to be able to test analytical expressions for the kinetics of random sequential deposition in two dimensions. The equation of Schaaf and Talbot for intermediate coverages is found to describe the measured kinetics with good accuracy. The rate of deposition should scale linearly with bulk protein concentration, but this was found to be the case only at very low values (≳/20 μg/${\mathrm{cm}}^3$); at higher concentrations a very marked deviation occurs. A concomitant deviation occurs at the jamming limit coverage, which attains about 76% at a concentration of 400 μg/${\mathrm{cm}}^3$.