Selectivity of monolithic supports under overloading conditions and their use for separation of human plasma and isolation of low abundance proteins

Sample displacement chromatography of monoclonal antibody charge variants and aggregates

The rise of biosimilar monoclonal antibodies has renewed the interest in monoclonal antibody (mAb) charge variants composition and separation. The sample displacement chromatography (SDC) has the potential to overcome the low separation efficiency and productivity associated with bind-elute separation of mAb charge variants. SDC in combination with weak cation exchanging macroporous monolithic chromatographic column was successfully implemented for a separation of charge variants and aggregates of monoclonal IgG under overloading conditions. The charge variants composition was at-line monitored by a newly developed, simple and fast analytical method, based on weak cation exchange chromatography. It was proven that basic charge variants acted as displacers of IgG molecules with lower pI, when the loading was performed 1 to 1.5 pH unit below the pI of acidic charge variants. The efficiency of the SDC process is flow rate independent due to a convection-based mass transfer on the macroporous monolith. The productivity of the process at optimal conditions is 35 mg of purified IgG fraction per milliliters of monolithic support with 75-80% recovery. As such, an SDC approach surpasses the standard bind-elute separation in the productivity for a factor of 3, when performed on the same column. The applicability of the SDC approach was confirmed for porous particle-based column as well, but with 1.5 lower productivity compared to the monoliths.

A conjoint multi metal-ion iminodiacetic acid monolith microfluidic chip for structural-based protein pre-fractionation

PDMS-based multichannel microfluidic chip was designed and fabricated in a simple approach using readily available tools. UV-initiated in situ polymerization of poly(2-hydroxy ethyl methacrylate-co-di(ethylene glycol) diacrylate-co-N,N'-diallyl l-tartardiamide) in an Eppendorf tube was achieved within 40 min. This polymerization process was successfully translated to a microfluidic chip format without any further modifications. Iminodiacetic acid was successfully immobilized on aldehyde functional monoliths via Schiff base reaction and confirmed by FT-IR spectroscopy. Four transition metal ions (Co (II), Zn (II), Ni (II), and Cu (II)) were chelated individually on four IDA-monolith microfluidic chips. The conjoint metal-ion monolith microfluidic chip has displayed high permeability (9.40 × 10^-13  m² ) and a porosity of 32.8%. This affinity microfluidic chip has pre-fractioned four human plasma proteins (fibrinogen, immunoglobulin, transferrin, and human serum albumin) based on their surface-exposed histidine surface topography. A protein recovery of approximately 95% (Bradford assay data) was achieved. The multimonolith microchip can be reusable even after three protein adsorption-desorption cycles.

Combinatorial peptides: A library that continuously probes low-abundance proteins

After a decade of experimental applications, it is the objective of this review to make a point on combinatorial peptide ligand libraries dedicated to low-abundance proteins from animals to plants and to microorganism proteomics. It is, thus, at the light of the recent technical developments and applications that we will examine the state of the art, its usage within the scientific community, and its openness to unexplored fields. The improvements of the methodology and its implementation in connection with analytical determinations of combinatorial peptide ligand library (CPLL)-treated samples are extensively reviewed and commented upon. Relevant examples covering few critical aspects describe the performance of the technology. Finally, a reflection on the technological future is attempted in particular by involving new concepts adapted to the limited availability of certain biological samples.

Process development exploiting competitive adsorption-based displacement effects in monoclonal antibody aggregate removal-A new high-throughput screening procedure for membrane chromatography

High-throughput screening (HTS) approaches are commonly used to accelerate downstream process development. Although most HTS approaches use batch isothermal data (K_P screen) or bind and elute mode as screening procedure, different or new process designs are rarely investigated. In this paper, a mechanistic model case study for the separation of two different two-component solutions was conducted and confirmed prior evidence. With these outcomes, a novel HTS screening procedure was developed including the determination of competitive adsorption-based displacement effects and key parameter identification. The screening procedure employing an overload bind and elute (OBE) mode is presented in a case study dealing with IgG aggregate removal in a typical monoclonal antibody purification step, applying a Sartobind® S membrane adsorber (MA). Based on a MA scale down device, the OBE mode allows the determination of classical process parameters and dynamic effects, such as displacement effects. Competitive adsorption-based displacement effects are visualized by introducing a displacement identifier leading to a displacement process map. Based on this map, the approach is transferred to and confirmed by the OBE recycle experiments with 4.6 and 8.2 ml benchtop scsale devices resulting in 45% reduced IgG monomer and 88% increased higher molecular weight species binding capacities.

Sample Displacement Batch Chromatography of Proteins

In downstream processing, large-scale chromatography plays an important role. For its development, screening experiments followed by pilot-plant chromatography are mandatory steps. Here we describe fast, simple, and inexpensive methods for establishing a preparative chromatography for the separation of complex protein mixtures, based on sample displacement batch chromatography. The methods are demonstrated by anion-exchange chromatography of a human plasma protein fraction (Cohn IV-4), including the screening step and upscaling of the chromatography by a factor of one hundred. The results of the screening experiments and the preparative chromatography are monitored by SDS-PAGE electrophoresis. In summary, we provide a protocol, which should be easily adaptable for the chromatographic large-scale purification of other proteins, in the laboratory as well as in the manufacturing of biopharmaceuticals. These protocols cover the initial piloting steps for establishing a large-scale sample batch chromatography. The results from the piloting steps may also be applied for packed columns for performing simulated-moving-bed (SMB) chromatography rather than batch chromatography.

Fabrication of an ionic-liquid-based polymer monolithic column and its application in the fractionation of proteins from complex biosamples

An ionic-liquid-based polymer monolithic column was synthesized by free radical polymerization within the confines of a stainless-steel column (50 mm × 4.6 mm id). In the processes, ionic liquid and stearyl methacrylate were used as dual monomers, ethylene glycol dimethacrylate as the cross-linking agent, and polyethylene glycol 200 and isopropanol as co-porogens. Effects of the prepolymerization solution components on the properties of the resulting monoliths were studied in detail. Scanning electron microscopy, nitrogen adsorption-desorption measurements, and mercury intrusion porosimetry were used to investigate the morphology and pore size distribution of the prepared monoliths, which showed that the homemade ionic-liquid-based monolith column possessed a relatively uniform macropore structure with a total macropore specific surface area of 44.72 m² /g. Compared to a non-ionic-liquid-based monolith prepared under the same conditions, the ionic-liquid-based monolith exhibited excellent selectivity and high performance for separating proteins from complex biosamples, such as egg white, snailase, bovine serum albumin digest solution, human plasma, etc., indicating promising applications in the fractionation and analysis of proteins from the complex biosamples in proteomics research.

Simultaneous depletion of immunoglobulin G and albumin from human plasma using novel monolithic cryogel columns

In this study, we aimed to develop an alternative matrix able to deplete the albumin (Alb) and immunoglobulin G (IgG) from blood plasma simultaneously to prepare plasma samples for large-scale applications of blood-related proteomics. As a first step, nano-protein A nanoparticles (nanoProA) were prepared and characterized. Subsequently, cibacron blue F3GA (CB) was immobilized onto the nanoProA's to enhance their specific affinity for Alb molecules. Finally, both nanoparticles, specifically, nanoProA and CB-nanoProA, were separately embedded into cryogel structures to combine advantages of the nanoparticles with those of the cryogels. The protein adsorption was optimized using aqueous Alb and IgG solutions separately. Subsequently, competitive protein adsorption was performed using a protein mixture prepared with Alb and IgG adhering to their plasma protein ratios. Because of the CB-immobilization, the Alb depletion performance of the cryogels increased whereas the IgG depleting performance decreased. Using the nanoProA, embedded cryogel removed 99.3% of the IgG, while using the CB-nanoProA embedded cryogel removed 97.5% of the Alb content. The simultaneous depletion performances of the cryogels for Alb and IgG were characterized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In this study, the monolithic cryogel-based adsorbents were classified as an alternative matrix to prepare plasma samples for proteomics applications at the preparative scale.

Separation of proteins from human plasma by sample displacement chromatography in hydrophobic interaction mode

Sample displacement chromatography (SDC) in reversed-phase and ion-exchange modes was introduced approximately 20 years ago. This method was first used for the preparative purification of peptides and proteins. Recently, SDC in ion-exchange mode was also successfully used for enrichment of low-abundance proteins from human plasma. In this paper, the use of SDC for the separation of plasma proteins in hydrophobic interaction mode is demonstrated. By use of two or more columns coupled in series during sample application, and subsequent elution of detached columns in parallel, additional separation of bound proteins was achieved. Further low-abundance, physiologically active proteins could be highly enriched and detected by ESI-MS/MS.

Sample displacement chromatography as a method for purification of proteins and peptides from complex mixtures

Sample displacement chromatography (SDC) in reversed-phase and ion-exchange modes was introduced approximately twenty years ago. This method takes advantage of relative binding affinities of components in a sample mixture. During loading, there is a competition among different sample components for the sorption on the surface of the stationary phase. SDC was first used for the preparative purification of proteins. Later, it was demonstrated that this kind of chromatography can also be performed in ion-exchange, affinity and hydrophobic-interaction mode. It has also been shown that SDC can be performed on monoliths and membrane-based supports in both analytical and preparative scale. Recently, SDC in ion-exchange and hydrophobic interaction mode was also employed successfully for the removal of trace proteins from monoclonal antibody preparations and for the enrichment of low abundance proteins from human plasma. In this review, the principals of SDC are introduced, and the potential for separation of proteins and peptides in micro-analytical, analytical and preparative scale is discussed.