Solute diffusion in hydrogels. An examination of the retardation effect

A new expression which describes the retardation of salutes within stiff-chained, swollen hydrogels was developed based on the idea that solute transport is determined by the probability of the solute finding an opening between the polymer chains greater than the radius of the solute molecule. The retardation factor expression derived was tested against experimentally determined diffusivities of globular proteins released from protein-loaded calcium alginate hydrogels, as well as from experimental and simulation data from the literature. The expression provided close agreement with the observed effects of polymer volume fraction, solute hydrodynamic radius, and polymer chain radius on solute diffusivity. (C) 1998 Elsevier Science Ltd. All rights reserved.