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−Cu 2+ complexes yields membranes that adsorb proteins via coordination of Cu 2+ 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 Cu 2+ . The unusually high capacity of these membranes for rapid protein binding makes them attractive for applications such as purification of His-tag proteins.