Separation Of Bovine Serum Albumin Research Articles

Mechanism of shear-enhanced rotating-disk microfiltration for separation of microbe/protein bio-suspension

Shear-enhanced dynamic filtration is a promising approach for separating fermented biological products. In this study, we aimed to investigate the separation of bovine serum albumin (BSA) and polymethyl methacrylate (PMMA) particles in a binary suspension using rotating-disk microfiltration. Type-R and Type-RB rotating-disk configurations were designed and compared using experimental data and simulated results. The effects of operating conditions, including rotational speed and filtration pressure, on filtration flux, resistance, and protein rejection, were analyzed. Because the filter membrane rejected all the PMMA particles, the primary source of filtration resistance in the PMMA/BSA suspension was the fouling cake. Although BSA rejection increased with higher filtration pressure, it decreased as the rotational speed increased. Computational fluid dynamics simulations were used to model the flow velocity and shear stress distributions within the rotating-disk dynamic microfiltration system. The results showed that Type-RB achieved a 55 % increase in flux compared to Type-R, owing to a significant reduction in cake resistance by approximately 46 %. A proportional relationship between the mean cake mass and the ratio of qs/τw under varying operating conditions was established using a force balance model. These findings suggest that elevated shear stress significantly enhances filtration performance, with Type-RB demonstrating superior effectiveness for bio-suspension separation.

Modified PVDF ultrafiltration membrane with host–guest supramolecular trapping for efficient separation of multiple organic contaminants

In our modern lifestyle, the cocktail of organic pollutants from everyday items, such as hair dyes, cloth dyes, food colours, hair oils, cooking oils, and agricultural proteins, enters water streams through household pipelines. This unnoticed contamination, growing alarmingly, poses a serious challenge beyond the scope of conventional separation techniques, calling for a comprehensive solution. While membrane technology offers a promising solution, it grapples with persistent surface fouling issues. This study introduces a novel approach through the development of extraordinary Polyvinylidene fluoride-Montmorillonite-Cucurbit[6]uril (PVDF-M-CB[6]) mixed matrix membranes, presenting a potential breakthrough in overcoming surface fouling challenges and offering a versatile solution for the separation of an array of organic contaminants. Powered by the synergistic host–guest supramolecular complexation of CB[6] onto montmorillonite (M) clay support, these membranes demonstrate swift and selective encapsulation, leading to superior cationic dye rejection. Adding to the allure, CB[6]’s structure encourages favorable carbonyl interactions with bovine serum albumin (BSA), effectively repelling the protein away from the membrane, while also promoting seamless oil–water emulsion separation with an underwater oil contact angle of 150 ± 3°, displaying its superoleophobic nature and enhancing remarkable antifouling properties. The PV-M-CB[6] membranes showcased 2x removal of cationic dyes, 1.3x removal of anionic dyes, 1.4x oil–water emulsion separation, and 2x BSA separation compared to the pristine polyvinylidene fluoride (PVDF) membrane. These membranes displayed 98.3 % efficiency in oil–water emulsion separation and sustained a flux recovery ratio of over >75% after seven cycles. Overall, PV-M-CB[6] membranes represent an innovative solution with heightened hydrophilicity, remarkable antifouling performance, and exceptional proficiency in delivering one-stop organic foulant separation.

Bifunctionalized MOFs modified poly (aryl ether ketone sulfone) ultrafiltration membranes with high-efficient BSA separation and dye adsorption

In this study, by connecting the amino ligand in ZIF-8-NH2 with an alkyl side chain containing sulfonic acid groups in a one-step method, a novel nanofiller (ZIF-8-NS) with bifunctional amino and sulfonic acid groups was formed. Sulfonated poly (aryl ether ketone sulfone) containing fluorene group (F-SPAEKS) was chosen as the polymer matrix. The nanofiller not only had good hydrophilicity but also had electrostatic interaction with the polymer matrix, which effectively promoted the compatibility problem among the polymer matrix and the filler. The nanofillers were characterized by XRD, FT-IR, SEM and XPS. The composite membranes were prepared by the NIPs method. The antifouling and separation properties of the prepared mixed matrix membranes (MMMs) were investigated using positively charged dye (RHB) and negative charge bovine serum albumin (BSA) as model contaminants. The water flux of the pure membrane achieved 529.16 L/m2 h. When the addition amount of ZIF-8-NS was 0.1 %, the water flux of M4 (F-SPAEKS/ZIF-8-NS-0.1 %) could reach 838.84 L/m2 h. The retention rate of the BSA solution could reach 99.06 %, and the FRR value was kept at a high level (81.45 %). Meanwhile, the dynamic retention of M4 on the primary adsorption of the dye RHB could even reach 99.89 %. Therefore, the innovative design of the novel MMMs not only improved the flux, retention, and other separation properties but also enhanced their excellent adsorption capacity for RHB dyes. This result indicated that the nanofiller ZIF-8-NS provided an interesting reference for the study of ultrafiltration membranes.

Multilayer‐coated polyphenylsulfone membranes with superior antifouling properties of PEG‐NH2 hydrogel for ultrafiltration process

AbstractThis study explores application of poly (ethylene glycol) (PEG)‐based hydrogel to improve the antifouling properties and performance of polyphenylsulfone (PPSU) membrane. The modification of PPSU membrane was performed via coating different ratio of polydopamine (PDA) to 3‐(aminopropyl)triethoxysilane (APTES) as interlayer on surface of PPSU membrane followed by grafting of PEG‐NH2 hydrogel. The as‐prepared membranes were characterized and results confirmed the successful coating of interlayer and hydrogel. The performance of as‐prepared membranes was measured using pure water flux, humic acid (HA), and bovine serum albumin (BSA) separation. The PDA‐APTES (50:50) was selected as the optimal interlayer to graft hydrogel with respect to their superior effect on properties of resultant membrane. The permeate flux and HA rejection increased from 35.2 LMH and 55% for pristine PPSU membrane to 83 LMH and 96% for optimal membrane. For optimal membrane the flux recovery ratio (FRR) value of 96% and 93% determined for BSA and HA separation, respectively. Chemical stability examined and the results confirmed that the hydrogel‐coated membrane was more stable in acidic media compared with alkali media. In summary, the simultaneous presence of the interlayer and the grafted hydrogel had a great impact on the morphology, performance, anticlogging properties, and acid resistance of the modified membranes.

Improved Protein Removal Performance of PES Hollow-Fiber Ultrafiltration Membrane with Sponge-like Structure.

The research used polyethersulfone (PES) as a membrane material, polyvinylpyrrolidone (PVP) k30 and polyethylene glycol 400 (PEG 400) as water-soluble additives, and dimethylacetamide (DMAc) as a solvent to prepare hollow-fiber ultrafiltration membranes through a nonsolvent-induced phase separation (NIPS) process. The hydrophilic nature of PVP-k30 and PEG caused them to accumulate on the membrane surface during phase separation. The morphology, chemical composition, surface charge, and pore size of the PES membranes were evaluated by SEM, FTIR, zeta potential, and dextran filtration experiments. The paper also investigated how different spinning solution compositions affected membrane morphology and performance. The separation efficiency of membranes with four different morphologies was tested in single-protein and double-protein mixed solutions. The protein separation effectiveness of the membrane was studied through molecular weight cutoff, zeta potential, and static protein adsorption tests. In addition, the operating pressure and pH value were adjusted to improve ultrafiltration process conditions. The PES membrane with an intact sponge-like structure showed the highest separation factor of 11, making it a prime candidate membrane for the separation of bovine serum albumin (BSA) and lysozyme (LYS). The membrane had a minimal static protein adsorption capacity of 48 mg/cm2 and had excellent anti-fouling properties. When pH = 4, the BSA retention rate was 93% and the LYS retention rate was 23%. Furthermore, it exhibited excellent stability over a pH range of 1-13, confirming its suitability for protein separation applications.

Molecularly Imprinted Polymer with High Capacity and Selectivity for Separation of Bovine Serum Albumin

Molecularly Imprinted Polymer with High Capacity and Selectivity for Separation of Bovine Serum Albumin

Synthesis of a porous hollow magnetic molecularly imprinted microsphere by O/W/O composite emulsion polymerization for specifically recognizing bovine serum albumin

Molecular imprinting technology is highly successful for low-molecular-weight molecules, but is still confronted with many challenges for proteins. This study introduces a strategy to synthesize hollow magnetic molecularly imprinted microspheres (HMMIMs) under Fe3O4 magnetic nanoparticles matrix, by oil-in-water-in-oil composite emulsion polymerization with alkylphenol ethoxylates and Span-80 as emulsifiers. The synthesis conditions after optimization were 1.0 mmol thermo-sensitive functional monomer N-isopropylacrylamide, 1.0 mmol cross-linker N, N-methylene bisacrylamide, 2.0 wt% vinyl-modified silk fibroin, and 50 mg Fe3O4@COOH nanoparticles. The morphology structure and the forming process of the acquired HMMIMs were well characterized by POM, SEM, TEM and FT-IR. The HMMIMs were synthesized successfully with a porous structure and large specific surface area. The particle size of the obtained HMMIMs was at 10–20 µm. The obtained microspheres were superparamagnetic and thermo-responsive. The HMMIM adsorption capacity at 25 °C toward bovine serum albumin (BSA) was 89.9 mg/g and the BSA separation factor in BSA/BHb mixtures was 2.12. A good separation efficacy toward BSA was also observed in bovine whole blood. The prepared HMMIM possessed heterogeneous active sites, the BSA adsorption process on HMMIM was chemisorption controlled.

Synthesis of a gelatin based molecularly imprinted hydrogel with high selectivity on adsorbing bovine serum albumin

Molecularly imprinted polymers are confronted with many challenges during application to separating proteins, this study synthesized a molecularly imprinted hydrogel (MIP hydrogel) for specifically separating bovine serum albumin (BSA) with high selectivity. By using the ionic liquid [VAFMIM]Cl as the structure functional monomer and N-isopropylacrylamide (NIPAM) as the thermo-sensitive functional monomer, the obtained gelatin based MIP hydrogel was porous, showed good mechanical properties and outstanding swelling ability. The methacrylation of gelatin improved the MIP hydrogel greatly on mechanical strength. The employment of NIPAM enabled the obtained MIP hydrogel thermo-responsive on swelling ability and adsorption capacity. The BSA adsorption capacity of MIP hydrogel was as high as 150.18 mg/g when the BSA initial concentration was used at 0.5 mg/mL, and the imprinting factor of MIP hydrogel was achieved as high as 5.17. The selectivity coefficients against bovine hemoglobin and lysozyme achieved as high as 11.83 and 9.39, respectively. In BSA/BHb mixture, the MIP hydrogel separation factor toward BSA was still as high as 23.97, and the MIP hydrogel adsorption capacity toward BSA was 4.64-fold larger than that of NIP hydrogel. The adsorption kinetics and isotherm study demonstrated the surface of the synthesized MIP hydrogel was homogenous, the adsorbing active sites were identical with equal energy, the BSA molecules were adsorbed monolayer on MIP hydrogel, the adsorption process was chemisorption and diffusion-controlled. The prepared MIP hydrogel was favorable and showed high potentiality on specific separation of BSA.

Development of a 3D printed micro simulated moving bed chromatography system

In the 1960s, chromatography processes were revolutionized by the invention of simulated moving bed chromatography. This method not only enhances the separation performance and resin utilization in comparison to batch-chromatography, it has also a much lower buffer consumption. While simulated moving bed chromatography nowadays is applied for a wide range of industrial applications, it was never transferred to the micro-scale (in regards to column and system volume). In our opinion a micro simulated moving bed chromatography system (µSMB) would be a useful tool for many applications, ranging from early process development and long term studies to downstream processing of speciality products. We implemented such a µSMB with a 3D printed central rotary valve and a microfluidic flow controller as flow source. We tested the system with a four zone open loop setup for the separation of bovine serum albumin and ammonium sulfate with size exclusion chromatography. We used four process points and could achieve desalting levels of BSA ranging from 94% to 99%, with yields ranging form 65% to 88%. Thus, we were able to achieve comparable results to common lab scale processes. With a total dead volume of 358 µL, including all sensors, connections and the valve, this is, to the best of our knowledge, the smallest SMB system that was ever built and we were able to perform experiments with feed flow rates reaching as low as 15 µL/min.

Fabrication and characterization of cellulose acetate ultrafiltration membrane and its application for efficient bovine serum albumin separation

AbstractTo solve the easy contamination problem of ultrafiltration membranes during protein separation, a series of cellulose acetate (CA) ultrafiltration membranes with different pore morphology and structure were successfully prepared by combining solution casting, non‐solvent‐induced phase inversion, and pore‐forming agent leached out technologies. The effects of molecule weight and the content of porogen polyethylene glycol (PEG) on the pore morphology, chemical composition, and wettability of the CA ultrafiltration membrane were systematically studied. The feed permeability, bovine serum albumin rejection, and anti‐fouling ability were also investigated. The results showed that the CA10k membrane has the highest pure water flux of 877.5 L/m2h.bar, largest bovine serum albumin (BSA) rejection of 96.5% and flux recovery rate of 90.9% when the PEG molecule weight and content are 10 kDa and 10 wt%. Those results showed that the CA ultrafiltration membranes have great application prospects in the BSA separation area.

Preparation, enhancement of permeability, and anti-biofouling properties of PEES/nano-silver/PVP mixed-matrix membrane

This study investigated the separation of bovine serum albumin using a novel matrix mixed membrane composed of poly vinyl pyrrolidone and poly (phenylene ether ether sulfone)/Nano-silver. The responsive bare and modified PEES/Nano-silver membranes were evaluated using morphology, wettability, XRD and ATR-FTIR. The molecular weight cut-off (MWCO), water content, mean pore radius, porosity, and pure water flux were used to evaluate the presentation of mixed matrix membranes. The outcomes show that the membranes wettability is increased by the addition of PVP, which promotes the formation of hydrogen bonds. Its clear that the membranes are more hydrophilic than the PEES/Nano-silver membrane based on their performance. In addition, model foulants such bovine serum albumin (BSA) and E. coli were used to assess the efficacy of mixed matrix membranes anti-fouling properties. PVP loading results in more diversified surface morphology with asymmetric structure and higher water flux (4.35 × 10−5 ms−1) than the pristine membrane (2.23 × 10−5 ms−1) as a reference at 3.5 bar without compromising the rejection of membrane. The flux recovery ratio for PEES/PVP/Nano-Silver membranes is 97%, which is significantly higher than the ratio for PEES/Nano-Silver membranes (62%). Furthermore, The results of fluorescence microscopy showed that, compared to clean membranes, the modified membranes have biofouling activities.

Separation Mechanisms and Anti-Fouling Properties of a Microporous Polyvinylidene Fluoride-Polyacrylic Acid-Graphene Oxide (PVDF-PAA-GO) Composite Membrane with Salt and Protein Solutions.

This research demonstrates the preparation of composite membranes containing graphene oxide (GO) and investigates the separation mechanisms of various salts and bovine serum albumin (BSA) solutions. A microporous polyvinylidene fluoride-polyacrylic acid-GO (PVDF-PAA-GO) separation layer was fabricated on non-woven support. The GO-incorporating composite resulted in enlarged pore size (0.16 μm) compared with the control membrane (0.12 μm). The zeta potential of the GO composite was reduced to -31 from -19 mV. The resulting membranes with and without GO were examined for water permeability and rejection efficiency with single salt and BSA solutions. Using the non-woven/PVDF-PAA composite, the permeance values were 88-190 kg/m2hMPa, and the salt rejection coefficients were 9-28% for Na2SO4, MgCl2, MgSO4, and NaCl solutions. These salt removals were based on the Donnan exclusion mechanism considering the ion radii and membrane pore size. Incorporating GO into the separation layer exhibited limited impacts on the filtration of salt solutions, but significantly reduced BSA membrane adhesion and increased permeance. The negatively charged protein reached almost complete removal (98.4%) from the highly negatively charged GO-containing membrane. The GO additive improved the anti-fouling property of the composite membrane and enhanced BSA separation from the salt solution.

Preparation and Characterization of Protein Molecularly Imprinted Poly (Ionic Liquid)/Calcium Alginate Composite Cryogel Membrane with High Mechanical Strength for the Separation of Bovine Serum Albumin.

In order to improve the mechanical strength and imprinting efficiency, a novel bovine serum albumin (BSA) molecularly imprinted poly(ionic liquid)/calcium alginate composite cryogel membrane (MICM) was prepared. The results of the tensile test indicated that the MICM had excellent mechanical strength which could reach up to 90.00 KPa, 30.30 times higher than the poly (ionic liquid) membrane without calcium alginate; the elongation of it could reach up to 93.70%, 8.28 times higher than the poly (ionic liquid) membrane without calcium alginate. The MICM had a very high welling ratio of 1026.56% and macropore porosity of 62.29%, which can provide effective mass transport of proteins. More remarkably, it had a very high adsorption capacity of 485.87 mg g-1 at 20 °C and 0.66 mg mL-1 of the initial concentration of BSA. Moreover, MICM also had good selective and competitive recognition toward BSA, exhibiting potential utility in protein separation. This work can provide a potential method to prepare the protein-imprinted cryogel membrane with both high mechanical strength and imprinting efficiency.

Non-ionic deep eutectic solvents for membrane formation

Deep eutectic solvents (DES) have recently emerged as a new class of inexpensive biodegradable solvents and additives with diverse applications. In this study, a new family of non-ionic deep eutectic solvents (NIDES) is proposed for the first time for membrane preparation. Three types of NIDES, N-methylacetamide-acetamide (DES-1), N-methyl acetamide-N-methyl urea (DES-2), and N-methyl acetamide-N,N′-dimethyl urea (DES-3) were synthesized and used to dissolve polyvinylidene fluoride (PVDF) polymer. The effects of the additive polyvinylpyrrolidone (PVP) and the type of NIDES on the PVDF membrane characteristics, water permeability and bovine serum albumin (BSA) separation were studied. The membranes prepared with DES-1 and 2 wt% PVP exhibited a good water permeate flux (96.82 L/m2.h) and a high BSA separation factor (96.32%). High performance PVDF membranes can thus be efficiently prepared using biodegradable inexpensive NIDES.

Functional Nanoparticles with Magnetic 3D Covalent Organic Framework for the Specific Recognition and Separation of Bovine Serum Albumin.

Glutathione functionalized magnetic 3D covalent organic frameworks combined with molecularly imprinted polymer (magnetic 3D COF–GSH MIPs) were developed for the selective recognition and separation of bovine serum albumin (BSA). Ultrasonication was used to prepare magnetic 3D COFs with high porosity (~1 nm) and a large surface area (373 m2 g−1). The magnetic 3D COF–GSH MIP nanoparticles had an imprinting factor of 4.79, absorption capacity of 429 mg g−1, magnetic susceptibility of 32 emu g−1, and five adsorption–desorption cycles of stability. The proposed method has the advantages of a shorter equilibrium absorption time (1.5 h), higher magnetic susceptibility (32 emu g−1), and larger imprinting factor (4.79) compared with those reported from other studies. The magnetic 3D COF–GSH MIPs used with BSA had selectivity factors of 3.68, 2.76, and 3.30 for lysozyme, ovalbumin, and cytochrome C, respectively. The successful recognition and separation of BSA in a real sample analysis verified the capability of the magnetic 3D COF–GSH MIP nanoparticles.

Separation of Albumin from Bovine Serum Applying Ionic-Liquid-Based Aqueous Biphasic Systems

In this work, the extraction and separation of bovine serum albumin (BSA) from its original matrix, i.e., bovine serum, was performed using a novel ionic-liquid-based aqueous biphasic system (IL-based ABS). To this end, imidazolium-, phosphonium-, and ammonium-based ILs, combined with the anions’ acetate, arginate and derived from Good Buffers, were synthesized, characterized, and applied in the development of ABS with K2HPO4/KH2PO4 buffer aqueous solutions at pH 7. Initial studies with commercial BSA revealed a preferential migration of the protein to the IL-rich phase, with extraction efficiencies of 100% obtained in a single-step. BSA recovery yields ranging between 64.0% and 84.9% were achieved, with the system comprising the IL tetrabutylammonium acetate leading to the maximum recovery yield. With this IL, BSA was directly extracted and separated from bovine serum using the respective ABS. Different serum dilutions were further investigated to improve the separation performance. Under the best identified conditions, BSA can be extracted from bovine serum with a recovery yield of 85.6% and a purity of 61.2%. Moreover, it is shown that the BSA secondary structure is maintained in the extraction process, i.e., after being extracted to the IL-rich phase. Overall, the new ABS herein proposed may be used as an alternative platform for the purification of BSA from serum samples and can be applied to other added-value proteins.

Molecular imprinting of bovine serum albumin and lysozyme within the matrix of polyampholyte hydrogels based on acrylamide, sodium salt of 2-acrylamido-2-methyl-1-propanesulfonic acid and (3-acrylamidopropyl)trimethyl ammonium chloride

Molecularly-imprinted polyampholyte (MIP) hydrogels based on nonionic monomer – acrylamide (AAm), anionic monomer – sodium salt of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and cationic monomer – (3-acrylamidopropyl)trimethyl ammonium chloride (APTAC) were obtained by immobilization of bovine serum albumin (BSA) and lysozyme in situ polymerization conditions. It was found that the best amphoteric hydrogel for sorption of BSA is APTAC-75H while for sorption of lysozyme is AMPS-75H. The sorption capacity of APTAC-75H and AMPS-75H with respect to BSA and lysozyme is 305.7 and 64.1-74.8 mg per 1 g of hydrogel respectively. Desorption of BSA and lysozyme from MIP template performed by aqueous solution of 1M NaCl is equal to 82-88%. Separation of BSA and lysozyme from their mixture was performed on MIP templates. The results of adsorption-desorption cycles of BSA on adjusted to BSA polyampholyte hydrogel APTAC-75H and of lysozyme on adjusted to lysozyme polyampholyte hydrogel AMPS-75H show that the mixture of BSA and lysozyme can be selectively separated with the help of MIP hydrogels.

Halloysite Nanotube-Ferrihydrite Incorporated Polyethersulfone Mixed Matrix Membrane: Effect of Nanocomposite Loading on the Antifouling Performance.

Membrane filtration is an attractive process in water and wastewater treatment, but largely restricted by membrane fouling. In this study, the membrane fouling issue is addressed by developing polyethersulfone (PES)-based mixed matrix membranes (MMMs) with the incorporation of hydrophilic nanoparticles as an additive. Ultrafiltration MMMs were successfully fabricated by incorporating different loadings of halloysite nanotube-ferrihydrates (HNT-HFO) into a polyethersulfone (PES) matrix and their performance was evaluated for the separation of bovine serum albumin (BSA) solution and oil/water emulsion. The results show that wettability is endowed to the membrane by introducing the additive aided by the presence of abundant -OH groups from the HFO. The loading of additive also leads to more heterogeneous surface morphology and higher pure water fluxes (516.33–640.82 L/m2h) more than twice that of the pristine membrane as reference (34.69 L/m2h) without affecting the rejection. The MMMs also provide much enhanced antifouling properties. The filtration results indicate that the flux recovery ratio of the modified membrane reached 100% by washing with only distilled water and a total flux recovery ratio of >98% ± 0.0471 for HNT-HFO-loaded membranes in comparison with 59% ± 0.0169 for pristine PES membrane.

Effects of Gelatin and Nano‐ZnO on the Performance and Properties of Cellulose Acetate Water Membranes

AbstractBiodegradable cellulose acetate (CA) membranes were prepared via phase inversion induced by immersion precipitation method. Acetic acid and deionized water were used as solvent and non‐solvent, respectively. The modifying effect of gelatin and zinc oxide (ZnO) nanoparticles additives was investigated on the membranes in terms of water flux, protein rejection percentage, and fouling ability during two hours of bovine serum albumin separation from aqueous solution. Specimens were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), tensile test, contact angle technique, and porosity measurement. The incorporation of gelatin and ZnO nanoparticles into the CA matrix increased the porosity coefficient and hydrophilicity. Moreover, gelatin improved the tensile properties of the membrane.

Bovine serum albumin selective integral asymmetric isoporous membrane

Separation of bovine serum albumin (BSA) and hemoglobin (Hb), two proteins with almost identical molecular weight, has been a big challenge for more than two decades. Using traditional ultrafiltraion membranes separation of these proteins is possible only at the isoelectric point of one protein via electrostatic repulsion between the membrane and the other protein. Here we introduce an integral asymmetric isoporous membrane from polystyrene-block-poly(2-hydroxyethyl methacrylate-ran-2-(succinyloxy)ethyl methacrylate) (PS-b-P(HEMA-r-SEMA)) having random –OH and –COOH groups along the pore walls prepared by a method which combines solvent induced self-assembly of the block copolymer and nonsolvent induced phase separation (SNIPS). The membrane consists of soft isoporous channels due to swelling of the P(HEMA-r-SEMA) blocks in a hydrated state. The effective pore size of the membrane in a hydrated state is significantly lower compared to that in a dry state. These soft channels allow the permeation of BSA while retaining Hb at constant pH 7.4 where both proteins are negatively charged. In comparison to 22 commercial and in-house prepared membranes the PS-b-P(HEMA-r-SEMA) membrane presents unprecedented ideal selectivity of BSA over Hb (ψBSA/Hb=16). Unlike the conventional technique in this case the electroneutrality of one protein is not mandatory which will provide significantly easier handling.