Evaluation of Iminodiacetic Acid (IDA) as an Ionogenic Group for Adsorption of IgG1 Monoclonal Antibodies by Membrane Chromatography.

Iminodiacetic acid (IDA) is one of the chelating ligands most frequently employed in immobilized metal-ion affinity chromatography (IMAC) due to its ability to act as electron-pair donor, forming stable complexes with intermediate and borderline Lewis metal ions (electron acceptor). Thus, IDA can also be employed in ion exchange chromatography to purify positively charged proteins at neutral pH values. This study aimed to evaluate IDA as an ionogenic group (ion exchanger) immobilized on poly (ethylene vinyl alcohol) (PEVA) hollow fiber membranes for immunoglobulin G1 (IgG1) monoclonal antibody (MAb) purification. IDA-PEVA membranes showed considerable promise for MAb purification, since IgG1 was recovered in eluted fractions with traces of contaminants as confirmed by Western blotting and ELISA analysis. Quantification of IgG1 showed that a purity of 94.2% was reached in the elution step. Breakthrough curve and batch adsorption experiments showed that the MAb dynamic binding capacity (DBC) of 3.10 mg g-1 and the maximum adsorption capacity of 70 mg g-1 were of the same order of magnitude as those found in the literature. The results obtained showed that the IDA-PEVA hollow fiber membrane could be a powerful adsorbent for integrating large-scale processes for purification of MAb from cell culture supernatant.

Polyacrylamide-alginate (PAAm-Alg) and phospho-L-tyrosine-linked PAAm-Alg monolithic cryogels: Purification of IgG from human serum.

In recent decades cryogels as monolithic materials have gained interest as stationary phase in chromatography for purification of biomolecules. In this study, polyacrylamide-alginate (PAAm-Alg) monolithic cryogels were prepared by cryo-copolymerization of acrylamide and alginate monomers and methylene-bisacrylamide as crosslinker to be used as a matrix in affinity chromatography for purification of proteins. Ortho-phospho-L-tyrosine (P-Tyr) was covalently attached onto PAAm-Alg cryogels via bisoxirane-activation (PAAm-Alg-Bix-P-Tyr) and both derivatized and non-derivatized cryogels were utilized for the purification of immunoglobulin G (IgG) from human serum. Cryogels were characterized by scanning electron microscopy, swelling tests, elemental analysis, FTIR, and flow dynamics. The effects of buffer systems, conductivity, and pH on IgG adsorption were studied. Through breakthrough curve analysis a dynamic capacity of 9.2 mg IgG/mL with an IgG purity of 94% was obtained (based on ELISA analysis of IgG and albumin) for PAAm-Alg-Bix-P-Tyr cryogel when human serum was diluted in 10 mmol/L NaP buffer at pH 6.0. The adsorption isotherm data were well described by the Langmuir model with value of maximum adsorption capacity of 36.12 ±â€¯3.63 mg of IgG/g for PAAm-Alg-Bix-P-Tyr. The PAAm-Alg-Bix-P-Tyr cryogel provides an attractive alternative for adsorption of IgG from human serum.

Phospho-l-tyrosine-agarose chromatography: Adsorption of human IgG and its proteolytic fragments.

The behavior of human immunoglobulin G (IgG) and antigen-binding fragment (Fab fragment) adsorption onto phospho-l-tyrosine immobilized on agarose (P-Tyr-agarose) was evaluated by pseudoaffinity chromatography. The effects of buffer systems MES, MOPS, Bis-Tris, Tris-HCl and sodium phosphate (NaP) and pH on IgG adsorption were studied and high purity values were obtained (96%, based on ELISA analysis of albumin, transferrin and immunoglobulins A, G and M) when IgG was purified from human plasma diluted in 10 mmol L-1 NaP buffer at pH 6.0. The capture of IgG by the P-Tyr-agarose was also promising, since 91% of the IgG was adsorbed when plasma was diluted in 25 mmol L-1 MES buffer at pH 5.5, recommending its use for IgG depletion from human plasma under this condition. The experimental data on IgG adsorption kinetics were in agreement with the pseudo-second-order model. The adsorption isotherm data were well described by the Langmuir-Freundlich model with the value of parameter n being <1 (0.72), indicating negative cooperativity. Selectivity was achieved on P-Tyr-agarose from digested human IgG in HEPES 25 mmol L-1 buffer at pH 7.0 where Fab fragments were obtained in eluted fractions without Fc fragments (but with uncleaved IgG) with 86.2% recovery.

Separation of human IgG fragments using copper, nickel, zinc, and cobalt chelated to CM-Asp-agarose by positive and negative chromatography.

This study evaluated the feasibility of using immobilized metal-ion affinity chromatography (IMAC) for separation of human Fab fragments using four different transition metal ions copper, nickel, zinc, and cobalt chelated to CM-Asp (carboxymethylaspartate) immobilized on the agarose gel. The Fab and Fc fragments (from human IgG digested with papain) interacted differently with the chelates studied, depending on the adsorption buffer system. The interaction between chelate and Fc fragment is predominantly based on the coordination bonds using adsorption buffer containing NaCl. Negative chromatography was performed on Cu(II)-CM-Asp-agarose obtaining 2.9mg of Fab per mL of adsorbent in nonretained fractions (Fc fragment-free without uncleaved IgG). The adsorption of Fab fragments is governed by electrostatic forces in the absence of NaCl in the adsorption buffer. High selectivity was achieved on Co(II)-CM-Asp-agarose and 5.7mg of Fab per mL of adsorbent was obtained in eluted fractions without Fc fragments, although having uncleaved IgG. The results showed that chromatography on transition metal ions chetated to CM-Asp-agarose is a promising approach to separation of Fab fragments from papain-digested human IgG solution.

Behavior of human immunoglobulin G adsorption onto immobilized Cu(II) affinity hollow-fiber membranes.

Iminodiacetic acid (IDA) and tris(2-aminoethyl)amine (TREN) chelating ligands were immobilized on poly(ethylene vinyl alcohol) (PEVA) hollow-fiber membranes after activation with epichlorohydrin or butanediol diglycidyl ether (bisoxirane). The affinity membranes complexed with Cu(II) were evaluated for adsorption of human immunoglobulin G (IgG). The effects of matrix activation and buffer system on adsorption of IgG were studied. Isotherms of batch IgG adsorption onto finely cut membranes showed that neither of the chelates, IDA-Cu(II) or TREN-Cu(II), had a Langmuirean behavior with negative cooperativity for IgG binding. A comparison of equilibrium and dynamic maximum capacities showed that the dynamic capacity for a mini-cartridge in a cross-flow filtration mode (52.5 and 298.4 mg g(-1) dry weight for PEVA-TREN-Cu(II) and PEVA-IDA-Cu(II), respectively) was somewhat higher than the equilibrium capacity (9.2 and 73.3 mg g(-1) dry weight for PEVA-TREN-Cu(II) and PEVA-IDA-Cu(II), respectively). When mini-cartridges were used, the dynamic adsorption capacity of IDA-Cu(II) was the same for both mini-cartridge and agarose gel.

Sodium citrate and potassium phosphate as alternative adsorption buffers in hydrophobic and aromatic thiophilic chromatographic purification of plasmid DNA from neutralized lysate.

The number of studies on gene therapy using plasmid vectors (pDNA) has increased in recent years. As a result, the demand for preparations of pDNA in compliance with recommendations of regulatory agencies (EMEA, FDA) has also increased. Plasmid DNA is often obtained through fermentation of transformed Escherichia coli and purification by a series of unit operations, including chromatography. Hydrophobic interaction chromatography (HIC) and thiophilic aromatic chromatography (TAC), both using ammonium sulfate buffers, are commonly employed with success. This work was aimed at studying the feasibility of utilizing alternative salts in the purification of pDNA from neutralized lysate with phenyl-agarose (HIC) and mercaptopyrimidine-agarose (TAC) adsorbents. Their selectivity toward sc pDNA was evaluated through adsorption studies using 1.5 mol/L sodium citrate and 2.0 mol/L potassium phosphate as adsorption buffers. Chromatography with mercaptopyrimidine-agarose adsorbent and 1.5 mol/L sodium citrate was able to recover 91.1% of the pDNA with over 99.0% removal of gDNA and endotoxin. This represents a potential alternative for the primary recovery of sc pDNA. However, the most promising result was obtained using 2.0 mol/L potassium phosphate buffer and a mercaptopyrimidine-agarose column. In a single chromatographic step, this latter buffer/adsorbent system recovered 68.5% of the pDNA with 98.8% purity in accordance with the recommendations of regulatory agencies with regard to RNA and endotoxin impurity.

Evaluation of amino acid O-phosphoserine as ligand for the capture of immunoglubulin G from human serum.

The amino acid ortho-phosphoserine (OPS) immobilized on agarose gel was evaluated as a ligand for adsorption of polyclonal human immunoglobulin G (IgG) from human serum in the presence of low ionic strength buffers. Screening of buffer systems showed sodium phosphate as the buffer that exhibited higher IgG purity values. Through breakthrough curve analysis for agarose-OPS (feeding of 31.93 mg of total protein per mL of gel), a purification factor of 5.4 with an IgG purity of 89 % was obtained (based on IgG, IgM, IgA, HSA, and Trf nephelometric analysis). IgG adsorption equilibrium studies showed that these data followed the Langmuir-Freundlich model, with cooperativity parameter (n) equal to 1.74, indicating the presence of positive cooperativity, probably due to multipoint interactions. The maximum IgG binding capacity was 24.2 mg mL(-1), near the value for the bioaffinity ligand protein A. The agarose-OPS adsorbent provides an attractive alternative for capturing of IgG from human serum.

A new process of IgG purification by negative chromatography: adsorption aspects of human serum proteins onto omega-aminodecyl-agarose.

The adsorbent omega-aminodecyl-agarose was evaluated as to its feasibility for the adsorption of human serum and plasma proteins, aiming at the purification of immunoglobulin G (IgG). The contribution of electrostatic and hydrophobic interactions (mixed-mode) and the effects of buffer system on the adsorption of serum proteins were also studied. The adsorption isotherm parameters of human serum albumin (HSA) and IgG were evaluated, pointing to the existence of cooperative effects in the process. A positive (n=2.30+/-0.38) and negative cooperativity (n=0.63+/-0.12) were observed for IgG and HSA binding, respectively. High purity IgG was obtained (based on total protein concentration and nephelometric analysis of HSA, transferrin, and immunoglobulins A, G, and M) with a 75% recovery in Hepes 25 mmol L(-1) pH 6.8 feeding human serum. These results indicate that the use of omega-aminodecyl-agarose is a potential technique for purification of IgG from human serum.

Purification of human IgG by negative chromatography on omega-aminohexyl-agarose.

The omega-aminohexyl diamine immobilized as ligand on CNBr- and bisoxirane-activated agarose gel was evaluated for the purification of human immunoglobulin G (IgG) from serum and plasma by negative affinity chromatography. The effects of matrix activation, buffer system, and feedstream on recovery and purity of IgG were studied. A one-step purification process using Hepes buffer at pH 6.8 allowed a similar recovery (69-76%) of the loaded IgG in the nonretained fractions for both matrices, but the purity was higher for epoxy-activated gel (electrophoretically homogeneous protein with a 6.5-fold purification). The IgG and human serum albumin (HSA) adsorption equilibrium studies showed that the adsorption isotherms of IgG and HSA obeyed the Langmuir-Freundlich and Langmuir models, respectively. The binding capacity of HSA was high (210.4 mg mL(-1) of gel) and a positive cooperativity was observed for IgG binding. These results indicate that immobilizing omega-aminohexyl using bisoxirane as coupling agent is a useful strategy for rapid purification of IgG from human serum and plasma.

Adsorption of human serum proteins onto TREN-agarose: purification of human IgG by negative chromatography.

Tris(2-aminoethyl)amine (TREN) - a chelating agent used in IMAC - immobilized onto agarose gel was evaluated for the purification of IgG from human serum by negative chromatography. A one-step purification process allowed the recovery of 73.3% of the loaded IgG in the nonretained fractions with purity of 90-95% (based on total protein concentration and nephelometric analysis of albumin, transferrin, and immunoglobulins A, G, and M). The binding capacity was relatively high (66.63 mg of human serum protein/mL). These results suggest that this negative chromatography is a potential technique for purification of IgG from human serum.

Effect of IDA and TREN chelating agents and buffer systems on the purification of human IgG with immobilized nickel affinity membranes.

The purification of IgG from human plasma was studied by comparing two affinity membranes complexed with Ni(II), prepared by coupling iminodiacetic acid (IDA) and Tris(2-aminoethyl)amine (TREN) to poly(ethylenevinyl alcohol), PEVA, hollow fiber membranes. The Ni(II)-TREN-PEVA hollow fiber membrane had lower capacity for human IgG than the complex Ni(II)-IDA-PEVA, but with similar selectivity. The IgG in peak fractions eluted from the Ni(II)-IDA-PEVA with a stepwise concentration gradient of Tris-HCl pH 7.0 (100-700 mM) reached a purity of 98% (based on IgG, IgM, IgA, albumin, and transferrin nephelometric analysis). Adsorption IgG data at different temperatures (4-37 degrees C) were analyzed using Langmuir model resulting in a calculated maximum capacity at 25 degrees C of 204.6 mg of IgG/g of dry membrane. Decrease in Kd with increasing temperature (1.7x10(-5) to 5.3x10(-6) M) indicated an increase in affinity with increased temperature. The positive value of enthalpy change (26.2 kJ/mol) indicated that the adsorption of IgG in affinity membrane is endothermic. Therefore, lower temperature induces adsorption as verified experimentally.

Evaluation of IDA-PEVA hollow fiber membrane metal ion affinity chromatography for purification of a histidine-tagged human proinsulin.

Inabilities to process particulate material and to allow the use of high flow rates are limitations of conventional chromatography. Membranes have been suggested as matrix for affinity separation due to advantages such as allowing high flow rates and low-pressure drops. This work evaluated the feasibility of using an iminodiacetic acid linked poly(ethylenevinyl alcohol) membrane in the immobilized metal ion affinity chromatography (IMAC) purification of a human proinsulin(His)(6) of an industrial insulin production process. The screening of metal ions showed Ni(2+) as metal with higher selectivity and capacity among the Cu(2+), Ni(2+), Zn(2+) and Co(2+). The membrane showed to be equivalent to conventional chelating beads in terms of selectivity and had a lower capacity (3.68 mg/g versus 12.26 mg/g). The dynamic adsorption capacity for human proinsulin(His)(6) was unaffected by the mode of operation (dead-end and cross-flow filtration).

Protein L-agarose for adsorption of autoantibodies: a potential tool for extracorporeal treatment.

This work investigated the adsorption of autoantibodies such as anti-SS-A/Ro, anti-SS-B/La, anti-Sm, and anti-dsDNA on protein L-agarose gel. In order to determine better conditions for IgG adsorption on this matrix, some buffer systems were tested. Adsorption data were analyzed using the Langmuir and Langmuir-Freundlich isotherm models. The experimental isotherms were best described by the Langmuir-Freundlich model, which indicated negative and positive cooperativities for binding in the presence of PBS and HEPES buffers, respectively. The K(d) values for phosphate buffered saline solution (PBS) and hydroxyethylpiperazine ethanesulfonic acid (HEPES) were 2.8 x 10(-7) M and 3.2 x 10(-7) M, respectively, which indicate a high affinity between IgG and the immobilized protein L. The amount of protein adsorbed per amount of protein loaded was high for anti-Sm (44%) and anti-dsDNA (46%), but low for anti-SS-B/La (9%). The amount of albumin adsorbed was lower than 0.06 mg/mL, which may remove the need for a plasma replacement solution in clinical apheresis.

Evaluation of immobilized metal membrane affinity chromatography for purification of an immunoglobulin G1 monoclonal antibody.

The large scale production of monoclonal antibodies (McAbs) has gaining increased relevance with the development of the hybridoma cell culture in bioreactors creating a need for specific efficient bioseparation techniques. Conventional fixed bead affinity adsorption commonly applied for McAbs purification has the drawback of low flow rates and colmatage. We developed and evaluated a immobilized metal affinity chromatographies (IMAC) affinity membrane for the purification of anti-TNP IgG(1) mouse McAbs. We immobilized metal ions on a poly(ethylene vinyl alcohol) hollow fiber membrane (Me(2+)-IDA-PEVA) and applied it for the purification of this McAbs from cell culture supernatant after precipitation with 50% saturation of ammonium sulphate. The purity of IgG(1) in the eluate fractions was high when eluted from Zn(2+) complex. The anti-TNP antibody could be eluted under conditions causing no loss of antigen binding capacity. The purification procedure can be considered as an alternative to the biospecific adsorbent commonly applied for mouse IgG(1) purification, the protein G-Sepharose.