Properties and performance of novel high-resolution/high-permeability ion-exchange media for protein chromatography

Ni(II) functionalized polyhedral oligomeric silsesquioxane based capillary monolith for purification of histidine-tagged proteins by immobilized metal affinity micro-chromatography

A new capillary monolithic stationary phase was synthesized for the purification of histidine tagged proteins by immobilized metal affinity micro-chromatography (μ-IMAC). For this purpose, mercaptosuccinic acid (MSA) linked-polyhedral oligomeric silsesquioxane [MSA@poly(POSS-MA)] monolith 300 μm in diameter was obtained by thiol-methacrylate polymerization using methacryl substituted-polyhedral oligomeric silsesquioxane (POSS-MA) and MSA as the thiol functionalized agent in a fused silica capillary tubing. Ni(II) cations were immobilized onto the porous monolith via metal-chelate complex formation with double carboxyl functionality of bound MSA segments. μ-IMAC separations aiming the purification of histidine tagged-green fluorescent protein (His-GFP) from Escherichia coli extract were carried out on Ni(II)@MSA functionalized-poly(POSS-MA) [Ni(II)@MSA@poly(POSS-MA)] capillary monolith. His-GFP was succesfully isolated by μ-IMAC on Ni(II)@MSA@poly(POSS-MA) capillary monolith with the isolation yield of 85 % and the purity of 92 % from E. coli extract. Higher His-GFP isolation yields were obtained with lower His-GFP feed concentrations and lower feed flow rates. The monolith was used for consecutive His-GFP purifications with a tolerable decrease in equilibrium His-GFP adsorption over five runs.

Characterization of a macroporous epoxy-polymer based resin for the ion-exchange chromatography of therapeutic proteins

This study investigated the adsorption capacity and mass transfer properties of a novel macroporous epoxy-polymer-based anion-exchanger, MPR Q, for the efficient separation of therapeutic proteins. MPR Q resin was prepared by phase separation based on spinodal decomposition followed by dextran grafting and ligand conjugation. Under static conditions, MPR Q exhibited a binding capacity of 49.8 mg-IgG/cm³-resin at pH 10, whereas the fastest adsorption was observed among the anion-exchanger resins tested. Inverse size-exclusion chromatography (iSEC) experiments revealed that the apparent pore diameter of MPR Q was approximately 90 nm, which was sufficiently large for the penetration of human IgG and bovine IgM. Moreover, the reduced height equivalent to a theoretical plate, h, of human IgG, determined using the linear gradient elution method was 65.8 and was not significantly changed in the range of linear velocities from 20.37 to 50.93 cm/min. The dynamic binding capacity at 10% breakthrough of MPR Q, determined by frontal analysis, exhibited a capacity of 43.8 mg/cm³ at 5.09 cm/min and 58% of DBC_10% was maintained even though the linear velocity was increased to 50.93 cm/min. Furthermore, a resolution for separation of IgG and BSA by MPR Q was 1.06 at 5.09 cm/min, while it was higher than that for the conventional resin at all linear velocities from 5.09 cm/min to 50.93 cm/min. Thus, it was suggested that the MPR Q developed in this study is a promising resin that can efficiently separate large biomacromolecules such as human IgG at higher velocities.

Downstream Processing Technologies/Capturing and Final Purification : Opportunities for Innovation, Change, and Improvement. A Review of Downstream Processing Developments in Protein Purification

Increased pressure on upstream processes to maximize productivity has been crowned with great success, although at the cost of shifting the bottleneck to purification. As drivers were economical, focus is on now on debottlenecking downstream processes as the main drivers of high manufacturing cost. Devising a holistically efficient and economical process remains a key challenge. Traditional and emerging protein purification strategies with particular emphasis on methodologies implemented for the production of recombinant proteins of biopharmaceutical importance are reviewed. The breadth of innovation is addressed, as well as the challenges the industry faces today, with an eye to remaining impartial, fair, and balanced. In addition, the scope encompasses both chromatographic and non-chromatographic separations directed at the purification of proteins, with a strong emphasis on antibodies. Complete solutions such as integrated USP/DSP strategies (i.e., continuous processing) are discussed as well as gains in data quantity and quality arising from automation and high-throughput screening (HTS). Best practices and advantages through design of experiments (DOE) to access a complex design space such as multi-modal chromatography are reviewed with an outlook on potential future trends. A discussion of single-use technology, its impact and opportunities for further growth, and the exciting developments in modeling and simulation of DSP rounds out the overview. Lastly, emerging trends such as 3D printing and nanotechnology are covered. Graphical Abstract Workflow of high-throughput screening, design of experiments, and high-throughput analytics to understand design space and design space boundaries quickly. (Reproduced with permission from Gregory Barker, Process Development, Bristol-Myers Squibb).

Preparation and recyclable catalysis performance of functional macroporous polyHIPE immobilized with gold nanoparticles on its surface

High internal phase emulsion polymerization was adopted for preparing macroporous polymeric monoliths, polyHIPE–Br (PHIPE–Br). Macroporous PHIPE–Br was used as the initiator to initiate the atom transfer radical polymerization (ATRP) of glycidyl methacrylate (GMA), resulting in a dense coating of polymers on the PHIPE surface and PHIPE–PGMA was obtained. Through a ring-opening addition reaction with TETA, a surface amino-polymer modified functional macroporous PHIPE–PGMA–TETA, was prepared conveniently. Gold nanoparticles could be easily in situ prepared and immobilized on the surface of PHIPE–PGMA–TETA. Characterization by scanning electron microscopy (SEM), EDX-mapping and TGA showed that PHIPE–PGMA–TETA was immobilized by the gold nanoparticles, and presented good catalytic properties. Moreover, the macroporous catalytic material, PHIPE–PGMA–TETA/Au NPs, presented recyclable catalytic performance without any decrease in activity. The materials and methods to form the monoliths and immobilize metal nanoparticles were simple and efficient, thus, opening new possibilities for highly porous PHIPE in catalysis applications.

The macroporous material PHIPE–PGMA–TETA/Au NPs has an open-cell and porous structure, and can effectively catalyze the reduction of 4-nitrophenol.

Surface glycopolymer-modified functional macroporous polyHIPE obtained by ATRP for the removal of boron in water

Macroporous polymeric monoliths PHIPE-PGAMA were obtained from polyHIPE with surface modification of PGAMA and used for boron removal.

Separation of proteins from complex bio-matrix samples using a double-functionalized polymer monolithic column

A double-functionalized polymer monolithic column was fabricated within the confines of a stainless-steel column (50 mm × 4.6 mm i.d.) via a facile method using iron porphyrin, ionic liquid (1-allyl-3-methylimidazolium chloride) and 1,10-decanediol dimethacrylate as tri-monomers; ethylene dimethacrylate as a crosslinker; polyethylene glycol 400 and N,N-dimethylformamide as co-porogens; benzoyl peroxide and N,N-dimethyl aniline as the redox initiation system. Results obtained from scanning electron microscopy, nitrogen adsorption-desorption, and mercury intrusion porosimetry confirmed the uniform pore structure and the pore size distribution of macro-pores. The home-made monolith was further characterized by elemental analysis to investigate the elemental composition of Fe supplied by iron porphyrin, confirming the synthetic process. The resulting optimized monolithic column was used as the stationary phase in high performance liquid chromatography for separating proteins, such as mixture of standard proteins, egg white, and human plasma, exhibiting good selectivity and high performance. It is worth noting that the home-made double-functionalized polymer monolithic column shows excellent selectivity for fractionation separation of human plasma proteins, and it is a promising separation tool for complex bio-samples in proteomic research.

Correlation of chromatographic performance with morphological features of organic polymer monoliths

Monoliths are considered to be a low pressure alternative to particle packed columns for liquid chromatography (LC). However, the chromatographic performance of organic monoliths, in particular, has still not reached the level of particle packed columns. Since chromatographic performance can be attributed to morphological features of the monoliths, in-situ characterization of the monolith structure in three dimensions would provide valuable information that could be used to help improve performance. In this work, serial sectioning and imaging were performed with a dual-beam scanning electron microscope for reconstruction and quantitative characterization of poly(ethylene glycol) diacrylate (PEGDA) monoliths inside a capillary column. Chord lengths, homogeneity factors, porosities and tortuosities were calculated from three-dimensional (3D) reconstructions of two PEGDA monoliths. Chromatographic efficiency was better for the monolith with smaller mean chord length (i.e., 5.23μm), porosity (i.e., 0.49) and tortuosity (i.e., 1.50) compared to values of 5.90μm, 0.59 and 2.34, respectively, for the other monolithic column. Computational prediction of tortuosity (2.32) was found to be in agreement with the experimentally measured value (2.34) for the same column. The monoliths were found to have significant radial heterogeneity since the homogeneity factor decreased from 5.39 to 4.89 (from center to edge) along the column radius.

Preparation of methacrylate-based monolith for capillary hydrophilic interaction chromatography and its application in determination of nucleosides in urine

A novel poly(N-acryloyltris(hydroxymethyl)aminomethane-co-pentaerythritol triacrylate) (NAHAM-co-PETA) monolith was prepared in the 100 μm i.d. capillary and investigated for capillary liquid chromatography (cLC). The polymer monolith was synthesized by in situ polymerization of NAHAM and PETA in the presence of polyethylene glycol (PEG) in dimethyl sulfoxide (DMSO) as the porogen. The porous structure of monolith was optimized by changing the ratio of NAHAM to PETA, the molecular weight and amount of PEG. To evaluate the separation performance of the resultant polymer monolith, several groups of model compounds (including nucleosides, benzoic acids and anilines) were selected to perform cLC separation. Our results showed that these model compounds can be baseline separated on the resultant poly(NAHAM-co-PETA) monolithic column with the optimized mobile phases. The column efficiency was estimated to be 87,000 plates/m for acrylamide. In addition, this monolithic column was coupled with on-line solid-phase microextraction (SPME) for the analysis of four nucleosides (uridine, adenosine, cytidine, guanosine) in urine. The limit of detection of the proposed method was in the range from 40 to 52 ng/mL. The method reproducibility was obtained by evaluating the intra- and inter-day precisions with relative standard deviations (RSDs) less than 8.3% and 10.2%, respectively. Recoveries of the target analytes from spiked urine samples were ranged from 86.5% to 106.8%.

Fabrication of high-permeability and high-capacity monolith for protein chromatography

A novel approach for the fabrication of macroporous poly(glycidyl methacrylate-ethylene glycol dimethacrylate) monolith is presented. The method involved the use of sodium sulfate granules and organic solvents as co-porogens. Compared with the conventional monoliths [ML-(1-3)] using organic solvents only as a porogen, the improved monoliths [MLS-(1-3)] showed not only higher column efficiency and dynamic binding capacity (DBC) for protein (bovine serum albumin, BSA), but also higher column permeability and lower back pressure. It is considered that the superpores introduced by the solid granules played an important role for the improvement of the monolith performance. Moreover, poly(glycidyl methacrylate-diethylamine) tentacles were grafted onto the pore surface of MLS-3 monolith. This has further increased the DBC of BSA to 74.7 mg/ml, about three times higher than that of the monoliths without the grafted tentacles. This grafting does not obviously decrease the column permeability, so a new monolith of high column permeability and binding capacity has been produced for high-performance preparative protein chromatography.

Assessing the macroporous structure of monolithic columns by transmission electron microscopy

A set of monolithic stationary phases representing a broad span of monomers and porogens have been characterized directly in their capillary chromatographic format by computational assessment of their pore structure from transmission electron micrographs obtained after in situ embedment of the monoliths in contrast resin, followed by dissolution of the fused-silica tubing, further encasement of the resin-embedded monolith, and microtomy. This technique has been compared to mercury intrusion, a more conventional technique for macroporosity estimation. Supplementing the embedding resin by lead methacrylate gave a negative staining, and the resulting micrographs showed a good contrast between the polymeric monoliths and the embedding resin that allowed studies on the pore formation and polymer development. The technique was also applied to a commercial monolithic silica column.

Dispersion effects in preparative polymethacrylate monoliths operated in radial-flow columns

Monolithic media have found widespread use as excellent tools for fast analytical separations of small molecules, proteins, pDNA and viruses. Polymethacrylate monoliths with large channels are attractive for capturing large molecules, like immunoglobulins, DNA, and viruses. For preparative purposes, these monoliths are operated in radial flow mode. Band spreading in monoliths is extremely low and mostly dominated by the contribution of extra column effects. The model used here had a single axial dispersion coefficient which lumps together extra column effects and the intrinsic band spreading of the monolithic material to characterize the adsorption of proteins and pDNA on polymethacrylate ion-exchange monoliths. Due to the fact that the performance of the monolith was unaffected by the velocity within the applied range, and due to highly favourable adsorption isotherms, a constant pattern model could be applied to predict preparative runs on radial flow units assuming axial flow for modelling.

Convective interaction media short monolithic columns: enabling chromatographic supports for the separation and purification of large biomolecules

New therapeutics that are being developed rely more and more on large and complex biomacromolecules like proteins, DNA, and viral particles. Manufacturing processes are being redesigned and optimized both upstream and downstream to cope with the ever-increasing demand for the above target molecules. In downstream processing, LC still represents the most powerful technique for achieving high yield and high purities of these molecules. In most cases, however, the separation technology relies on conventional particle-based technology, which has been optimized for the purification of smaller molecules. New technologies are, therefore, needed in order to push the downstream processing ahead and into the direction that will provide robust, productive, and easy to implement methods for the production of novel therapeutics. New technologies include the renaissance of membranes, various improvements of existing technologies, but also the introduction of a novel concept--the continuous bed or monolithic stationary phases. Among different introduced products, Convective Interaction Media short monolithic columns (SMC) that are based on methacrylate monoliths exhibit some interesting features that make them attractive for these tasks. SMC can be initially used for fast method development on the laboratory scale and subsequently efficiently transferred to preparative and even more importantly to industrial scale. A brief historical overview of methacrylate monoliths is presented, followed by a short presentation of theoretical considerations that had led to the development of SMC. The design of these columns, as well as their scale-up to large units, together with the methods for transferring gradient separations from one scale to another are addressed. Noninvasive methods that have been developed for the physical characterization of various batches of SMC, which fulfill the regulatory requirements for cGMP production, are discussed. The applications of SMC for the separation and purification of large biomolecules, which demonstrate the full potential of this novel technology for an efficient downstream processing of biomolecules, are also presented.

Monodisperse porous polymer particles with polyionic ligands for ion exchange separation of proteins

A new "grafting to" strategy was proposed for the preparation of polymer based ion exchange supports carrying polymeric ligands in the form of weak or strong ion exchangers. Monodisperse porous poly(glycidyl methacrylate-co-ethylene dimethacrylate), poly(GMA-co-EDM) particles 5.9 microm in size were synthesized by "modified seeded polymerization". Poly(2,3-dihydroxypropyl methacrylate-co-ethylene dimethacrylate), poly(DHPM-co-EDM) particles were then obtained by the acidic hydrolysis of poly(GMA-co-EDM) particles. The hydroxyl functionalized beads were treated with 3-(trimethoxysilyl)propyl methacrylate to have covalently linked methacrylate groups on the particle surface. The selected monomers carrying weak or strong ionizable groups (2-acrylamido-2-methyl-1-propane sulfonic acid, AMPS; 2-dimethylaminoethylmethacrylate, DMAEM and N-[3-(dimethylamino)propyl] methacrylamide, DMAPM) were subsequently grafted onto the particles via immobilized methacrylate groups. The final polymer based materials with polyionic ligands were tried as chromatographic packing in the separation of proteins by ion exchange chromatography. The proteins were successfully separated both in the anion and cation exchange mode with higher column yields with respect to the previously proposed materials. The plate heights obtained for poly(AMPS) and poly(DMAEM) grafted poly(DHPM-co-EDM) particles by using proteins as the analytes were 80 and 200 microm, respectively. Additionally, the plate height exhibited no significant increase with the increasing linear flow rate in the range of 1-20 cm/min. The most important property of the proposed strategy is to be applicable for the synthesis of any type of ion exchanger both in the strong and weak form.