Polypropylene nonwoven fabrics with conformal grafting of poly(glycidyl methacrylate) for bioseparations

Nonwovens fabrics are porous materials with great potential for use in the separation and purification of biotherapeutic proteins and other biomolecules after proper surface activation and modification. This work describes an activation process for polypropylene nonwoven membranes by conformal coating of poly(glycidyl methacrylate) (polyGMA) through a UV pretreatment–UV grafting process (UV–UV) in the presence of benzophenone as initiator. The grafting mechanism relies on the enhanced adsorption of benzophenone to the fiber surface after the UV pretreatment. It was found that this process results in highly conformal and uniform polyGMA grafts on the surface of the PP nonwoven fibers. After grafting, a hydrophilic spacer, diethylene glycol, an anion exchange ligand, diethyl amine, and a combination of diethylene glycol spacer-primary amine were attached to the PP nonwoven surface with the conformal polyGMA grafts. High equilibrium protein binding capacities for bovine serum albumin (BSA) under static and flow conditions were obtained (120 mg/g and 102 mg/g, respectively). A column packed with modified nonwovens exhibited higher permeability coefficient (1.08 × 10−7 cm2) than columns packed with chromatographic resins. The total porosity (to acetone) was found to be 0.80 and the interstitial porosity (to BSA) was 0.48, measured by pulse experiments using acetone and BSA respectively as tracers under nonbinding conditions.