Endotoxin removal with poly(ethyleneimine)-immobilized adsorbers: Sepharose 4B versus flat sheet and hollow fibre membranes

Poly(ethyleneimine) was immobilized on poly(vinyl alcohol)-coated nylon flat sheet membranes, poly(vinyl alcohol) and poly(ethylenevinyl alcohol) hollow fibre membranes as well as Sepharose 4B. The resulting poly(ethyleneimine)-immobilized adsorbers were used for removal of E. coli derived endotoxin from buffers and bovine serum albumin solutions. The efficiency of poly(ethyleneimine) proved to be constant over a wide pH range, including phosphate buffered saline. The performance depended upon the matrix type employed: endotoxin clearance factors varied from 100 to 120 000 in protein-free solutions and 40 to 33 000 in solutions of bovine serum albumin using 6000 EU/ml as feed concentration. The best adsorber was the flat sheet membrane-immobilized poly(ethyleneimine), followed by the hollow fibre-immobilized poly(ethyleneimine) and poly(ethyleneimine)-Sepharose. The factors influencing endotoxin clearance were the mass transport (convective systems were superior to the diffusive system), the chemical composition and the surface structure of the underlying matrix.