High-capacity, protein-binding membranes based on polymer brushes grown in porous substrates

The use of atom transfer radical polymerization to grow poly(2-hydroxyethyl methacrylate) ( PHEMA) brushes in porous alumina followed by functionalization of the PHEMA with nitrilotriacetate-Cu2+ complexes yields membranes that adsorb proteins via coordination of Cu2+ to histidine residues. Adsorption isotherms show that these membranes have binding capacities as high as 0.9 mg of bovine serum albumin (BSA)/cm(2) of external membrane surface area ( 150 mg/cm(3) of membrane), and breakthrough curves indicate that saturation of the membranes with BSA or myoglobin occurs in less than 15 min. The efficiency of protein elution with ethylenediaminetetraacetic acid ( EDTA) solutions is essentially 100%, and the membranes show no detectable decrease in capacity over nine cycles of binding, elution, and regeneration with Cu2+. The unusually high capacity of these membranes for rapid protein binding makes them attractive for applications such as purification of His-tag proteins.