CHARACTERIZATION OF LARGE-PORE POLYMERIC SUPPORTS FOR USE IN PERFUSION BIOCHROMATOGRAPHY

Perfusion chromatography is uniquely characterized by the flow of a po rtion of the column eluent directly through the resin in the packed be d. The benefits of this phenomenon and some of the properties of perfu sive resins have been described before, and can be summarized as enhan ced mass transport to interior binding sites. Here we extend the under standing of this phenomenon by comparing resins with different pore si ze distributions. Resins are chosen to give approximately the same spe cific pore volumes (as shown in the characterization section) but the varying contribution of large pores is used to control the amount of l iquid flowing through the beads. POROS R1 has the largest contribution of throughpores, and therefore the greatest intraparticle flow. POROS R2 has a lower contribution of throughpores, and a higher surface are a coming from a greater population of diffusive pores, but still shows significant mass transport enhancements relative to a purely diffusiv e control. Oligo R3 is dominated by a high population of diffusive por es, and is used comparatively as a non-perfusive resin. Although the p ore size distribution can be engineered to control mass transport rate s, the resulting surface area is not the only means by which binding c apacity can be controlled. Surface coatings are employed to increase b inding capacity without fundamentally altering the mass transport prop erties. Models are used to describe the amount of flow transecting the beads, and comparisons of coated resins to uncoated (polystyrene) res ins leads to the conclusion that these coatings do not obstruct the th roughpore structures. This is an important conclusion since the bindin g capacity of the coated product, in some cases, is shown to be over 1 0-fold higher than the precursor polystyrene scaffold (i.e., POROS R1 or POROS R2). (C) 1998 Elsevier Science B.V. All rights reserved.