Rapid Size-Based Protein Discrimination inside Hybrid Isoporous Membranes

Abstract

Owing to their unique morphology, isoporous membranes derived from block copolymers (BCPs) have rapidly advanced the process of macromolecular separation. In such separations, fouling is the most daunting challenge, affecting both the permeability and selectivity of high-performance isoporous membranes. To overcome this, we increase the hydrophilicity of nanostructured BCP isoporous membranes by incorporating hydrophilic polymer-grafted graphene oxide nanosheets into them. Due to the synergy of these two highly functional components, the hybrid isoporous membranes show pH-responsive and alcohol-gating behaviors, along with improved bactericidal capabilities. Leveraging the high permeability and selectivity behavior of BCP isoporous membranes together with the antifouling capabilities imparted by the polymer-grafted graphene oxide nanosheets, we achieved the highest separation factor (33) ever obtained during the ultrafiltration of the common blood proteins bovine serum albumin and immunoglobulin. This was accompanied by a 60% enhanced flux compared to that of the pristine BCP membranes during this challenging size-based separation of a protein mixture. We surmise that such fouling-resistant hybrid isoporous membranes with rationally functionalized filler materials can be used to replace existing membranes for specific energy-efficient bioseparation applications with improved performance.

Next-Generation Ultrafiltration Membranes Enabled by Block Polymers

“…One intriguing feature of using P4VP-containing block polymers is that the pore walls are lined with pyridine moieties. These pyridine groups can serve as a reactive handle for pore wall functionalization, facilitating the introduction of cysteine, dopamine, ,, and graphene oxide to improve fouling resistance and bactericidal properties. Additionally, reaction of the pyridine groups with either methyl iodide or propane-1,3-sultone results in cationic or zwitterionic pores, respectively, which can be used to selectively bind charged organic dyes with sizes of ∼1 nm, which would otherwise be too small to remove by UF …”

“…Based on the Hagen–Poiseuille model (eq ), the water permeability for a free-standing block polymer membrane can be increased by decreasing the film thickness, increasing the pore size, and increasing the total porosity . Generally, the pore size can be increased by increasing the block polymer molar mass. ,, However, large adjustments in the average pore size significantly alter the MWCO. Therefore, increasing the porosity could be a more robust approach that does not alter solute rejection.…”

“…26 Generally, the pore size can be increased by increasing the block polymer molar mass. 21,120,153 However, large adjustments in the average pore size significantly alter the MWCO. Therefore, increasing the porosity could be a more robust approach that does not alter solute rejection.…”

Selective Swelling and Functionalization of Integral Asymmetric Isoporous Block Copolymer Membranes

“…Although the membrane based technology to separate proteins having large difference in molecular weight is well developed at present, fractionation of proteins having identical molecular weight is still confronted with low selectivity of the current commercially available ultrafiltration membranes. In the quest of membranes having higher selectivity compared to the current commercially available membranes, the permeation and retention behavior of the SNIPS membranes have been investigated using several model proteins, such as bovine serum albumin, [ 41,65,79,80,82–85 ] hemoglobin, [ 41,79,80,85 ] catalase, [ 41,79,86 ] γ ‐globulin, [ 82,83 ] lysosome, [ 86 ] myoglobin, [ 86 ] and ferritin, [ 86 ] etc. Fractionation of proteins is not only influenced by the pore size and pore size distribution of the membranes.…”

Preprogrammed Dynamic Microstructured Polymer Interfaces

“…Due to the combination of these properties, the membrane demonstrated high performance for protein separation. [41]…”