Membrane Chromatography and Fractionation of Proteins from Whey—A Review

Membrane chromatography (MC) is an emerging bioseparation technology combining the principles of membrane filtration and chromatography. In this process, one type of molecule is adsorbed in the stationary phase, whereas the other type of molecule is passed through the membrane pores without affecting the adsorbed molecule. In subsequent the step, the adsorbed molecule is recovered by an elution buffer with a unique ionic strength and pH. Functionalized microfiltration membranes are usually used in radial flow, axial flow, and lateral flow membrane modules in MC systems. In the MC process, the transport of a solute to a stationary phase is mainly achieved through convection and minimum pore diffusion. Therefore, mass transfer resistance and pressure drop become insignificant. Other characteristics of MC systems are a minimum clogging tendency in the stationary phase, the capability of operating with a high mobile phase flow rate, and the disposable (short term) application of stationary phase. The development and application of MC systems for the fractionation of individual proteins from whey for investigation and industrial-scale production are promising. A significant income from individual whey proteins together with the marketing of dairy foods may provide a new commercial outlook in dairy industry. In this review, information about the development of a MC system and its applications for the fractionation of individual protein from whey are presented in comprehensive manner.

Selective detection of glufosinate using CuInS2 quantum dots as a fluorescence probe

This work designed a fluorescence “turn-off-on” probe to detect glufosinate.

Affinity chromatography: A versatile technique for antibody purification

Antibodies continue to be extremely utilized entities in myriad applications including basic research, imaging, targeted delivery, chromatography, diagnostics, and therapeutics. At production stage, antibodies are generally present in complex matrices and most of their intended applications necessitate purification. Antibody purification has always been a major bottleneck in downstream processing of antibodies, due to the need of high quality products and associated high costs. Over the years, extensive research has focused on finding better purification methodologies to overcome this holdup. Among a plethora of different techniques, affinity chromatography is one of the most selective, rapid and easy method for antibody purification. This review aims to provide a detailed overview on affinity chromatography and the components involved in purification. An array of support matrices along with various classes of affinity ligands detailing their underlying working principles, together with the advantages and limitations of each system in purifying different types of antibodies, accompanying recent developments and important practical methodological considerations to optimize purification procedure are discussed.

Methacryloylamidoglutamic acid having porous magnetic beads as a stationary phase in metal chelate affinity chromatography

We have prepared a novel magnetic metal-chelate adsorbent utilizing methacryloylamidoglutamic acid (MAGA) as a metal-chelating ligand. MAGA was synthesized by using methacryloyl chloride and L-glutamic acid dihydrochloride. Magnetic beads with an average diameter of 50-100 microm were produced by suspension polymerization of 2-hydroxyethyl methacrylate (HEMA) and MAGA in the presence of Fe3O4 particles carried out in an aqueous dispersion medium. Magnetic beads were charged with the Cu2+ ions directly via MAGA for the adsorption of cytochrome c (cyt c) from aqueous solutions. The maximum cyt c adsorption capacity of the Cu2+-chelated beads (0.86 mmol/g Cu2+ loading) was found to be 37 mg/g at pH 8.0 in phosphate buffer. Cyt c adsorption on the poly(HEMA-MAGA) beads was 15.4 mg/g. Cu2+ charging increased the cyt c adsorption significantly (37 mg/g). Cyt c adsorption decreased with increasing temperature. Cyt c molecules could be adsorbed and desorbed five times with these adsorbents without noticeable loss in their cyt c adsorption capacity. The resulting magnetic chelator beads posses excellent long term storage stability.

Protein-associated water and secondary structure effect removal of blood proteins from metallic substrates

Removing adsorbed protein from metals has significant health and industrial consequences. There are numerous protein-adsorption studies using model self-assembled monolayers or polymeric substrates but hardly any high-resolution measurements of adsorption and removal of proteins on industrially relevant transition metals. Surgeons and ship owners desire clean metal surfaces to reduce transmission of disease via surgical instruments and minimize surface fouling (to reduce friction and corrosion), respectively. A major finding of this work is that, besides hydrophobic interaction adhesion energy, water content in an adsorbed protein layer and secondary structure of proteins determined the access and hence ability to remove adsorbed proteins from metal surfaces with a strong alkaline-surfactant solution (NaOH and 5 mg/mL SDS in PBS at pH 11). This is demonstrated with three blood proteins (bovine serum albumin, immunoglobulin, and fibrinogen) and four transition metal substrates and stainless steel (platinum (Pt), gold (Au), tungsten (W), titanium (Ti), and 316 grade stainless steel (SS)). All the metallic substrates were checked for chemical contaminations like carbon and sulfur and were characterized using X-ray photoelectron spectroscopy (XPS). While Pt and Au surfaces were oxide-free (fairly inert elements), W, Ti, and SS substrates were associated with native oxide. Difference measurements between a quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance spectroscopy (SPR) provided a measure of the water content in the protein-adsorbed layers. Hydrophobic adhesion forces, obtained with atomic force microscopy, between the proteins and the metals correlated with the amount of the adsorbed protein-water complex. Thus, the amount of protein adsorbed decreased with Pt, Au, W, Ti and SS, in this order. Neither sessile contact angle nor surface roughness of the metal substrates was useful as predictors here. All three globular proteins behaved similarly on addition of the alkaline-surfactant cleaning solution, in that platinum and gold exhibited an increase, while tungsten, titanium, and stainless steel showed a decrease in weight. According to dissipation measurements with the QCM-D, the adsorbed layer for platinum and gold was rigid, while that for the tungsten, titanium, and stainless steel was much more flexible. The removal efficiency of adsorbed-protein by alkaline solution of SDS depended on the water content of the adsorbed layers for W, Ti, and SS, while for Pt and Au, it depended on secondary structural content. When protein adsorption was high (Pt, Au), protein-protein interactions and protein-surface interactions were dominant and the removal of protein layers was limited. Water content of the adsorbed protein layer was the determining factor for how efficiently the layer was removed by alkaline SDS when protein adsorption was low. Hence, protein-protein and protein-surface interactions were minimal and protein structure was less perturbed in comparison with those for high protein adsorption. Secondary structural content determined the efficient removal of adsorbed protein for high adsorbed amount.

Cellulose and Glass Fiber Affinity Membranes for the Chromatographic Separation of Biomolecules

Macroporous cellulose and glass membranes were prepared from filter paper and glass fiber filter, respectively. To enhance their stability, the cellulose membranes were crosslinked with epichlorohydrin, and the glass membranes were crosslinked with glutaraldehyde or organic bifunctional silanes. Several pathways for the modification, activation, and ligand immobilization were used and compared. For cellulose membranes, the diazotization method provided the best results, whereas the glutaraldehyde method provided the best performance for glass membranes, regarding both their stability and ligand immobilization capacity. The characterization of the membranes was made by using a triazine dye, bovine serum albumin, and trypsin as test ligands. The membrane morphologies and the uniformities of ligand distribution across the membrane cartridges were investigated. Numerous affinity ligands were immobilized onto the membranes, and the prepared affinity membranes have been used to separate or purify concanavalin A, peroxidase, protease inhibitors, globulin, fibronectin, and other biomolecules.

A New Metal Chelate Affinity Adsorbent for Cytochrome c

We have prepared a novel metal-chelate adsorbent utilizing N-methacryloyl-L-histidine methyl ester (MAH) as a metal-chelating ligand. MAH was synthesized by using methacryloyl chloride and l-histidine methyl ester dihydrochloride. Spherical beads with an average diameter of 75-125 microm were produced by suspension polymerization of 2-hydroxyethyl methacrylate (HEMA) and MAH carried out in an aqueous dispersion medium. Then, Cu(2+) ions were chelated directly on the chelating beads. Cu(2+)-chelated beads were used in the adsorption of cytochrome c (cyt c) from aqueous solutions. The maximum cyt c adsorption capacity of the Cu(2+)-chelated beads (658.2 micromol/g Cu(2+) loading) was found to be 31.7 mg/g at pH 10 in phosphate buffer. The nonspecific cyt c adsorption on the naked PHEMA beads was 0.2 mg/g. Cyt c adsorption increased with increasing Cu(2+) loading. Cyt c adsorption capacity was demonstrated for the buffer types with the effects in the order phosphate > HEPES > MOPS > MES > Tris-HCl. Cyt c molecules could be adsorbed and desorbed five times with these adsorbents without noticeable loss in their cyt c adsorption capacity.

Membrane adsorbers as purification tools for monoclonal antibody purification

Downstream purification processes for monoclonal antibody production typically involve multiple steps; some of them are conventionally performed by bead-based column chromatography. Affinity chromatography with Protein A is the most selective method for protein purification and is conventionally used for the initial capturing step to facilitate rapid volume reduction as well as separation of the antibody. However, conventional affinity chromatography has some limitations that are inherent with the method, it exhibits slow intraparticle diffusion and high pressure drop within the column. Membrane-based separation processes can be used in order to overcome these mass transfer limitations. The ligand is immobilized in the membrane pores and the convective flow brings the solute molecules very close to the ligand and hence minimizes the diffusional limitations associated with the beads. Nonetheless, the adoption of this technology has been slow because membrane chromatography has been limited by a lower binding capacity than that of conventional columns, even though the high flux advantages provided by membrane adsorbers would lead to higher productivity. This review considers the use of membrane adsorbers as an alternative technology for capture and polishing steps for the purification of monoclonal antibodies. Promising industrial applications as well as new trends in research will be addressed.

Modelling and simulation of affinity membrane adsorption

A mathematical model for the adsorption of biomolecules on affinity membranes is presented. The model considers convection, diffusion and adsorption kinetics on the membrane module as well as the influence of dead end volumes and lag times; an analysis of flow distribution on the whole system is also included. The parameters used in the simulations were obtained from equilibrium and dynamic experimental data measured for the adsorption of human IgG on A2P-Sartoepoxy affinity membranes. The identification of a bi-Langmuir kinetic mechanisms for the experimental system investigated was paramount for a correct process description and the simulated breakthrough curves were in good agreement with the experimental data. The proposed model provides a new insight into the phenomena involved in the adsorption on affinity membranes and it is a valuable tool to assess the use of membrane adsorbers in large scale processes.

Mathematical analysis of affinity membrane chromatography

A mathematical model including convection, diffusion and Freundlich adsorption is developed. To examine the validity of the model, the affinity membranes were prepared by coating chitosan on the nylon membranes, a ligand of poly-L-lysine was bound to the chitoan-coating membranes, and the adsorption behavior of bilirubin through the stacked affinity membranes was investigated. The agreements between the theoretical and experimental results are exceptional. Using our new model, we show that: (1) As Pe increases, the breakthrough curves become sharper. For Pe greater than 30, the effect of axial diffusion is insignificant; (2) As m increases, the time of total saturation is delayed and the loading capacity at the point of breakthrough is increased; (3) As n decreases, the time of total saturation is delayed and the loading capacity at the point of breakthrough is increased; (4) As r increases, both the time of total saturation and the loading capacity at the point of breakthrough are increased; (5) adsorption rate influences the time of total saturation strongly but contributes little to the loading capacity.

Evaluation of nonlinear chromatographic performance by frontal analysis using a simple multi-plate mathematical model

A multi-plate (MP) mathematical model was proposed by frontal analysis to evaluate nonlinear chromatographic performance. One of its advantages is that the parameters may be easily calculated from experimental data. Moreover, there is a good correlation between it and the equilibrium-dispersive (E-D) or Thomas models. This shows that it can well accommodate both types of band broadening that is comprised of either diffusion-dominated processes or kinetic sorption processes. The MP model can well describe experimental breakthrough curves that were obtained from membrane affinity chromatography and column reversed-phase liquid chromatography. Furthermore, the coefficients of mass transfer may be calculated according to the relationship between the MP model and the E-D or Thomas models.

Exploiting immobilized metal affinity membranes for the isolation or purification of therapeutically relevant species

Increasing reports regarding the isolation or purification of biospecies for therapeutic purpose using the immobilized metal affinity chromatography have been presented in recent years. At the same time, membrane chromatography technique has also gained more and more attention for their advantage in speeding the separation process. The immobilized metal affinity membrane technique developed by combining these two techniques may provide an alternative potential tool for separating the therapeutically relevant biospecies. In this review paper, the features of the immobilized metal affinity membranes are discussed and concentrated on three subtopics: membrane matrices, immobilized metal affinity method, and membrane module designs. Several examples of practically applying the immobilized metal affinity membranes on the purification of potential therapeutics reported in the literature are subsequently presented. Lastly, this review also provides an overall evaluation on the possible advantages and problems existing in this technique to point out opportunities and further improvements for more applied development of the immobilized metal affinity membranes.

Analysis of protein adsorption on regenerated cellulose-based immobilized copper ion affinity membranes

Immobilized metal affinity membranes (IMAMs) were prepared by immobilizing copper ions on microporous regenerated cellulose membranes through different types of chelating agents (dentate and triazine dye). The resulting chelator utilization percentages were 95% for iminodiacetic acid, 56% for N,N,N-tris(carboxymethyl)ethylenediamine, 52% for Cibacron blue 3GA, and 140% for Cibacron red 3BA. On the other hand, triazine dyes were slightly superior to dentate chelators on metal ion utilization for protein adsorption. In batch single-protein adsorptions, the protein adsorption capacity decreased with increasing molecular size and number of accessible surface histidine residues [lysozyme>bovine serum albumin(BSA)>gamma-globulin], while the binding strength order was the opposite (gamma-globulin>BSA>lysozyme). Moreover, the proportions of specific and nonspecific bindings were evaluated by varying pH and salt concentration conditions. A large fraction of the adsorption capacity was found to come from the nonspecific interactions for the prepared IMAMs. Lastly, batch three-protein adsorptions were performed and weak adsorption competition was observed.

Multivalent binding interaction of alcohol dehydrogenase on dye-metal affinity matrix

The optimization of a chromatographic process using immobilized metal affinity chromatography requires an understanding of the factors that govern the interaction between proteins and immobilized metal ions. Factors, such as concentrations of protein, NaCl and imidazole were investigated to elucidate kinetics of adsorption of alcohol dehydrogenase (ADH) onto a dye-iminodiacetic acid matrix (dye-IDA matrix). The results indicate that the adsorption of ADH onto a dye-IDA matrix occurs in the mode of multiple-site binding interactions between ADH and zinc ions immobilized on the dye-IDA matrix. The estimated average number of interaction sites was 4.5 and the association constant was 6 x 10(-9) mM(-n). The isotherm of ADH adsorption was well represented by a multivalent model of protein-zinc ion interactions. For the adsorption of ADH from clarified yeast homogenate, addition of imidazole as a protein competitor to adsorption buffer increased the adsorption specificity of ADH, thereby suppressing contaminant protein adsorption. It was also observed that the adsorption of ADH was better performed at high initial protein concentrations in the yeast homogenate. Consequently, these results may have important implications on the optimization of the strategy for immobilized metal affinity adsorption in packed and expanded bed systems.

Protein separation using membrane chromatography: opportunities and challenges

Some of the problems associated with packed bed chromatography can be overcome by using synthetic macroporous and microporous membranes as chromatographic media. This paper reviews the current state of development in the area of membrane chromatographic separation of proteins. The transport phenomenon of membrane chromatography is briefly discussed and work done in this area is reviewed. The various separation chemistries which have been utilised for protein separation, along with different applications, are also reviewed. The technical challenges facing membrane chromatography are highlighted and the scope for future work is discussed.

Purification of hepatocyte growth factor using polyvinyldiene fluoride-based immobilized metal affinity membranes: equilibrium adsorption study

Polyvinyldiene fluoride (PVDF)-based affinity membranes with immobilized copper ions were developed in this study. The resulting membranes were tested for their adsorption properties using a model protein, lysozyme, in batch mode. First, different lengths of diamine were utilized as spacer arms to immobilize the metal ions onto the membranes. It was found that the application of 1,8-diaminooctane as the spacer arm led to the highest adsorption capacity. Moreover, the effects of pH and salt concentration were investigated to distinguish the proportion of specific and nonspecific interactions. A big fraction of lysozyme adsorption capacity for the immobilized metal affinity membranes was considered to come from nonspecific electrostatic interactions, which could be reduced by increasing salt concentration. Lastly, the purification of hepatocyte growth factor (HGF) from insect cell supernatant was performed using the immobilized metal affinity membranes in batch mode. HGF was found in the elution condition using EDTA, indicating the successful purification of HGF.

Perspectives of immobilized-metal affinity chromatography

Immobilized Metal-Affinity Chromatography (IMAC) represents a relatively new separation technique that is primarily appropriate for the purification of proteins with natural surface-exposed histidine residues and for recombinant proteins with engineered histidine tags or histidine clusters. Because the method has gained broad popularity in recent years, the main recent developments in the field of new sorbents, techniques and possible applications are discussed in this article. Advantages of the method and new prospects are described as well as the problems and concerns that appear when the method is to be used for production of pharmaceutical-grade proteins.

Mathematical analysis of frontal affinity chromatography in particle and membrane configurations

The scaleup and optimization of large-scale affinity-chromatographic operations in the recovery, separation and purification of biochemical components is of major industrial importance. The development of mathematical models to describe affinity-chromatographic processes, and the use of these models in computer programs to predict column performance is an engineering approach that can help to attain these bioprocess engineering tasks successfully. Most affinity-chromatographic separations are operated in the frontal mode, using fixed-bed columns. Purely diffusive and perfusion particles and membrane-based affinity chromatography are among the main commercially available technologies for these separations. For a particular application, a basic understanding of the main similarities and differences between particle and membrane frontal affinity chromatography and how these characteristics are reflected in the transport models is of fundamental relevance. This review presents the basic theoretical considerations used in the development of particle and membrane affinity chromatography models that can be applied in the design and operation of large-scale affinity separations in fixed-bed columns. A transport model for column affinity chromatography that considers column dispersion, particle internal convection, external film resistance, finite kinetic rate, plus macropore and micropore resistances is analyzed as a framework for exploring further the mathematical analysis. Such models provide a general realistic description of almost all practical systems. Specific mathematical models that take into account geometric considerations and transport effects have been developed for both particle and membrane affinity chromatography systems. Some of the most common simplified models, based on linear driving-force (LDF) and equilibrium assumptions, are emphasized. Analytical solutions of the corresponding simplified dimensionless affinity models are presented. Particular methods for estimating the parameters that characterize the mass-transfer and adsorption mechanisms in affinity systems are described.

Affinity membrane chromatography for the analysis and purification of proteins

Affinity chromatography is unique among separation methods as it is the only technique that permits the purification of proteins based on biological functions rather than individual physical or chemical properties. The high specificity of affinity chromatography is due to the strong interaction between the ligand and the proteins of interest. Membrane separation allows the processing of a large amount of sample in a relatively short time owing to its structure, which provides a system with rapid reaction kinetics. The integration of membrane and affinity chromatography provides a number of advantages over traditional affinity chromatography with porous-bead packed columns, especially with regard to time and recovery of activity. This review gives detailed descriptions of materials used as membrane substrates, preparation of basic membranes, coupling of affinity ligands to membrane supports, and categories of affinity membrane cartridges. It also summarizes the applications of cellulose/glycidyl methacrylate composite membranes for proteins separation developed in our laboratory.

New affinity nylon membrane used for adsorption of gamma-globulin

Microporous polyamide membranes were first modified by acid hydrolysis and subsequently bound with hydroxy-ethylcellulose to amplify reactive groups and reduce nonspecific interactions with proteins. Then 1,6-diaminohexane as space arm and phenylalanine as ligand were immobilized onto the nylon membranes by s-triazine trichloride activation. Affinity membranes thus obtained were set in a stack and used to adsorb gamma-globulin. The adsorption capacity (qm) of the affinity membrane is 53 micro gamma-globulin per m2 membrane and the desorption constant (Kd) is 2.35 x 10(-6) mol/l. The effects of feed, washing and elution rates on adsorption and desorption behavior were investigated. The results showed that affinity purification through these membranes could not be operated at very high flow-rates. A stack of 20 membranes with 47 mm diameter can adsorb 7.8 mg gamma-globulin with a purity of 91.6% from 4 ml of human plasma in a single-pass mode.

Immobilized iminodiacetic acid (IDA)-type Cu2+ -chelating membrane affinity chromatography for purification of bovine liver catalase

A metal ion chelating membrane medium based on iminodiacetate-substituted modified short cotton cellulose was examined for the purification of bovine liver catalase (BLC). The effect of buffer pH, chelator surface density, initial concentration of crude enzyme and flow rate on BLC binding efficiency to the copper ion chelating membrane adsorbent were examined. Under the chromatographic conditions chosen, 67.7% recovery of BLC was attained with an overall 4.2-fold increase in specific activity in a single step. After performance of BLC purification, the chelating membrane adsorbent can be easily regenerated by imidazole or EDTA buffer with higher reviving effectiveness with the latter.

Effect of porous structure of macroporous polymer supports on resolution in high-performance membrane chromatography of proteins

The effect of porous structures of 2-mm thick diethylamine functionalized monolithic polymethacrylate discs on their chromatographic behavior in ion-exchange mode has been studied. Discs with small pores did not perform well because they exhibited high back pressure and substantial peak broadening. Discs characterized with pores larger than 1,000 nm did not provide good separations either because the time required for some protein molecules to traverse the length across the pore to reach the wall for adsorption/desorption process that is essential for the separation may be longer than their residence time within the matrix. Optimum pore size is centered at about 700 nm. Excellent separations have been achieved with these discs even at very steep gradients and high flow-rates which allow to shorten the separation times substantially.

Characterization and application of new macroporous membrane ion exchangers

A new ready-to-use unit for high-performance membrane chromatography has been characterized. Its dynamic capacity, resolving power and protein recovery were measured at different flow-rates. The binding capacity was 0.5-2 mg/cm2 with a 95% recovery at 10 ml/min irrespective of the protein concentration up to 10 mg/ml. For very-high flow-rates (50 and 100 ml/min) the recovery was 90% and 70%. At these flow-rates, the maximum back-pressure was about 0.1 MPa and was independent of the filtration area. By increasing the filtration area, a proportional capacity increase was obtained, indicating an easy scale-up. High flow-rates had only a slight effect on resolution. This new adsorber was able to purify IgM from supernatant of cell culture of a human hybridoma in less than 8 min with a high degree of purity (95%).

Preparation of magnetic immobilized metal affinity separation media and its use in the isolation of proteins

A new method of pseudobiospecific protein isolation is developed and tested, which employs both metal affinity and magnetism as the basis for isolation. The chelating group iminodiacetic acid (IDA) has been coupled to the surface of magnetic agarose, and when charged with metal ions (Cu2+ or Zn2+) is capable of binding model proteins which display metal affinity, and of separating protein mixtures. Magnetic properties of the medium facilitated the batch recovery of the adsorbent, as losses are minimized by concentrating and retaining the separation medium with the aid of a magnet. Model proteins were used to characterize protein adsorption, capacity, and stability of IDA magnetic agarose. Recovery from a cell lysate was demonstrated by protein isolation from extracts of E. coli containing a target protein. Overall, this study effectively illustrates the engineering of separation media which combine several desired properties for the development of a new branch of metal affinity-based bioseparation.