Poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide-block-ethylene glycol methacrylate) were grafted from commercial polyamide thin-film composite nanofiltration membranes using surface-initiated atom transfer radical polymerization. The results from Fourier-transform infrared spectroscopy confirmed the successful grafting of both polymers from the membrane surfaces. Contact angle measurements were done to illustrate the temperature responsive wettability of the modified membrane surfaces. Modified membranes were used in flux measurements of wastewater produced during coal bed methane gas exploration. The degree of fouling of the original and the modified membranes was examined by pure water flux recovery measurements after produced water filtration and a temperature-controlled water rinse.

Protein A chromatography is ubiquitous to antibody purification. The high specificity of Protein A for binding the Fc-region of antibodies and related products enables unmatched clearance of process impurities like host cell proteins, DNA, and virus particles. A recent development is the commercialization of research-scale Protein A membrane chromatography products that can perform capture step purification with short residence times (RT) on the order of seconds. This study investigates process-relevant performance and physical properties of four Protein A membranes: Purilogics Purexa™ PrA, Gore^® Protein Capture Device, Cytiva HiTrap™ Fibro PrismA, and Sartorius Sartobind^® Protein A. Performance metrics include dynamic binding capacity, equilibrium binding capacity, regeneration-reuse, impurity clearance, and elution volumes. Physical properties include permeability, pore diameter, specific surface area, and dead volume. Key results indicate that all membranes except the Gore^® Protein Capture Device operate with flow rate-independent binding capacities; the Purilogics Purexa™ PrA and Cytiva HiTrap Fibro™ PrismA have binding capacities on par with resins, with orders of magnitude faster throughput; and dead volume and hydrodynamics play major roles in elution behavior. Results from this study will enable bioprocess scientists to understand the ways that Protein A membranes can fit into their antibody process development strategies.