Hollow fiber-supported hydrogels with mesh-size asymmetry

Hollow fiber-supported hydrogel membranes were developed and then modified to create mesh-size asymmetry in the gel phase within the wall of the fiber . A gradient cross-linking technique was used fur modification. A shell-and -tube hollow fiber module was constructed consisting of a single hollow fib er inside a housing with the ends sealed with epoxy. Fluid phase resistance calculations for the hollow fiber with different solution flow patterns we re reviewed and applied to this particular experimental arrangement. Result s showed that the fluid phase resistance for creatinine diffusion is signif icant and accounts for over 30% of the total resistance; while for protein diffusion, the boundary resistance is minimal with membrane resistance acco unting for more than 90% of the total resistance. Diffusion experiments wit h continuous flow on both sides of the fiber with creatinine, Fab or IgG we re performed with homogeneous and asymmetric membranes. Solute permeability decreased upon gradient cross-linking, while the selectivity for creatinin e over IgG and Fab over IgG increased relative to the homogeneous membrane. The transport properties of the hollow fiber-supported hydrogels are consi stent with those measured with unsupported hydrogels and flat-sheet-support ed hydrogel membranes. (C) 2000 Elsevier Science B.V. All rights reserved.