@article{liu_gurgel_carbonell_2015, title={Preparation and characterization of anion exchange adsorptive nonwoven membranes with high protein binding capacity}, volume={493}, ISSN={["1873-3123"]}, DOI={10.1016/j.memsci.2015.06.002}, abstractNote={An anion exchange poly(butylene therephthalate) (PBT) nonwoven membrane with high protein binding capacity was developed by covalent coupling of diethylamine (DEA) to photo-induced poly(glycidyl methacrylate) (polyGMA) brushes grafted to the PBT fibers. The grafted layers were characterized using FTIR and SEM. The rates of adsorption of bovine serum albumin (BSA) to membranes with different grafted layer thicknesses (different average DEA concentrations) were determined. The static BSA binding capacities were found to be 820, 400 and 183 mg BSA/g-membrane at average DEA concentrations of 0.84, 0.35 and 0.20 mmol DEA/g-membrane respectively. These high capacities are indicative of multilayer binding of protein within the grafted layers. The larger binding capacities required longer adsorption times to reach equilibrium, indicating a diffusional resistance to mass transfer within the grafted layers. The average diffusion coefficient was determined. A column packed with anion exchange nonwoven membranes was used to separate human immunoglobulin G (hIgG) from human serum albumin (HSA). The obtained purity and yield of hIgG flowing through the column were 93.4±2% and 94.5±1.5% respectively. The purity and yield of HSA bound and eluted from the membrane were 98±1% and 94±4% respectively. The nonwoven packed column exhibited a high flow permeability (1.1×10−8 cm2) due to high bed porosity (78%).}, journal={JOURNAL OF MEMBRANE SCIENCE}, author={Liu, Haiyan and Gurgel, Patrick V. and Carbonell, Ruben G.}, year={2015}, month={Nov}, pages={349–359} }
 @article{liu_zheng_gurgel_carbonell_2013, title={Affinity membrane development from PBT nonwoven by photo-induced graft polymerization, hydrophilization and ligand attachment}, volume={428}, ISSN={["0376-7388"]}, DOI={10.1016/j.memsci.2012.09.047}, abstractNote={Nonwoven fabrics are of great interest as potential materials for bioseparations due to their interconnected porous structure, relatively high surface area and low cost. In this paper we focus on the development of a potentially disposable affinity membrane for pathogen removal from biological systems such as human plasma. Poly glycidyl methacrylate (polyGMA) was grafted on the fiber surface of a polybutylene terephthalate (PBT) nonwoven using photo-induced graft polymerization. SEM and FTIR were used to characterize the pore structure and surface chemistry of the resulting material. To minimize nonspecific protein binding and hydrophilize the material, diethylene glycol (DEG) and diol groups were attached covalently to the grafted layer of polyGMA. The amount of nonspecific binding was quantified by the adsorption of bovine serum albumin (BSA) and an E. coli extract. The results showed that the grafted matrix containing DEG or diol groups bound significantly less total protein, compared with unmodified material. The DEG modified membrane was further developed by attachment of a specific proprietary ligand that binds to the prion protein, the agent responsible for transmissible spongiform encephalopathies. The affinity membrane showed good selectivity for the capture of prion protein from hamster brain homogenate.}, journal={JOURNAL OF MEMBRANE SCIENCE}, author={Liu, Haiyan and Zheng, Yong and Gurgel, Patrick V. and Carbonell, Ruben G.}, year={2013}, month={Feb}, pages={562–575} }
 @article{zheng_liu_gurgel_carbonell_2010, title={Polypropylene nonwoven fabrics with conformal grafting of poly(glycidyl methacrylate) for bioseparations}, volume={364}, ISSN={["0376-7388"]}, DOI={10.1016/j.memsci.2010.08.037}, abstractNote={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.}, number={1-2}, journal={JOURNAL OF MEMBRANE SCIENCE}, author={Zheng, Yong and Liu, Haiyan and Gurgel, Patrick V. and Carbonell, Ruben G.}, year={2010}, month={Nov}, pages={362–371} }