Selective Separation of Similarly Sized Proteins with Tunable Nanoporous Block Copolymer Membranes
Nunes, Suzana Pereira
KAUST DepartmentAdvanced Membranes and Porous Materials Research Center
Biological and Environmental Sciences and Engineering (BESE) Division
Chemical Engineering Program
Environmental Science and Engineering Program
Nanostructured Polymeric Membrane Lab
Physical Science and Engineering (PSE) Division
Water Desalination and Reuse Research Center (WDRC)
Online Publication Date2012-12-26
Print Publication Date2013-01-22
Permanent link to this recordhttp://hdl.handle.net/10754/629998
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AbstractAn integral asymmetric membrane was fabricated in a fast and one-step process by combining the self-assembly of an amphiphilic block copolymer (PS-b-P4VP) with nonsolvent-induced phase separation. The structure was found to be composed of a thin layer of densely packed highly ordered cylindrical channels with uniform pore sizes perpendicular to the surface on top of a nonordered sponge-like layer. The as-assembled membrane obtained a water flux of more than 3200 L m h bar, which was at least an order of magnitude higher than the water fluxes of commercially available membranes with comparable pore sizes, making this membrane particularly well suited to size-selective and charge-based separation of biomolecules. To test the performance of the membrane, we conducted diffusion experiments at the physiological pH of 7.4 using bovine serum albumin (BSA) and globulin-γ, two proteins with different diameters but too close in size (2-fold difference in molecular mass) to be efficiently separated via conventional dialysis membrane processes. The diffusion rate differed by a factor of 87, the highest value reported to date. We also analyzed charge-based diffusive transport and separation of two proteins of similar molecular weight (BSA and bovine hemoglobin (BHb)) through the membrane as a function of external pH. The membrane achieved a selectivity of about 10 at pH 4.7, the isoelectric point (pI) of BSA. We then positively charged the membrane to improve the separation selectivity. With the modified membrane BSA was completely blocked when the pH was 7.0, the pI of BHb, while BHb was completely blocked at pH 4.7. Our results demonstrate the potential of our asymmetric membrane to efficiently separate biological substances/pharmaceuticals in bioscience, biotechnology, and biomedicine applications. © 2012 American Chemical Society.
CitationQiu X, Yu H, Karunakaran M, Pradeep N, Nunes SP, et al. (2012) Selective Separation of Similarly Sized Proteins with Tunable Nanoporous Block Copolymer Membranes. ACS Nano 7: 768–776. Available: http://dx.doi.org/10.1021/nn305073e.
SponsorsThe work was supported by the KAUST Seed-Fund Project "Isoporous Membranes". We thank Lan Zhao from Advanced Nanofabrication, Imaging and Characterization Lab at KAUST for her help with the morphological characterization.
PublisherAmerican Chemical Society (ACS)