Recent developments in chromatographic purification of biopharmaceuticals

Hydrophobic interaction chromatography in continuous flow-through mode for product-related variant removal

Product-related impurities are challenging to remove during monoclonal antibody (mAb) purification process due to molecular similarity. Frontal chromatography on hydrophobic interaction resins has demonstrated its capability to effectively remove such impurities. However, process improvements geared towards purity level comes as a trade-off with the yield loss. In this work, we present a hydrophobic interaction chromatography process using multicolumn continuous chromatography (MCC) concept and frontal analysis to remove a high prevalence product related impurity. This design uses a two-column continuous system where the two columns are directly connected during product chase step to capture product wash loss without any in-process adjustment. This polish MCC operation resulted in a 10 % increase in yield while maintaining 99 % purity, despite the presence of 20 % product-related impurities in the feed material. One challenge associated with polish MCC design is that the accumulation of the impurities renders a non-steady state recycling. To surmount this issue and ensure a robust process, a mechanistic model was developed and validated to predict multicomponent breakthrough. This model was capable to predict multiple cycle behavior and accounts for increased impurity concentration. Assisted by the model, the optimized operation parameters and conditions can be determined to account for variation in product load quality. The simulated results demonstrate an effective doubling of productivity compared to conventional batch chromatography.

Clear insight into complex multimodal resins and impurities to overcome recombinant protein purification challenges: A review

Increasing attention has been paid to the purity of therapeutic proteins imposing extensive costs and challenges to the downstream processing of biopharmaceuticals. One of the efforts, that has been exerted to overcome such limitations, was developing multimodal or mixed-mode chromatography (MMC) resins for launching selective, orthogonal, non-affinity purification platforms. Despite relatively extensive usage of MMC resins, their real potential and fulfillment have not been extensively reviewed yet. In this work, the explanation of practical and key aspects of downstream processing of recombinant proteins with or without MMC resins was debated, as being useful for further purification process development. This review has been written as a step-by-step guide to deconvolute both inherent protein purification and MMC complexities. Here, after complete elucidation of the potential of MMC resins, the effects of frequently used additives (mobile phase modifiers) and their possible interactions during the purification process, the critical characteristics of common product-related impurities (e.g., aggregates, charge variants, fragments), host-related impurities (e.g., host cell protein and DNA) and process related impurities (e.g., endotoxin, and viruses) with solved or unsolved challenges of traditional and MMC resins have been discussed. Such collective experiences which are reported in this study could be considered as an applied guide for developing successful downstream processing in challenging conditions by providing a clear insight into complex MMC resins and impurities.

Using the reactive/transport dispersive models to simulate a monolithic anion exchanger: Experimental parameter determination, simultaneous model evaluation, and validation

Selecting an adequate model to represent the mass transfer mechanisms occurring in a chromatographic process is generally complicated, which is one of the reasons why monolithic chromatography is scarcely simulated. In this study, the chromatographic separation of model proteins bovine serum albumin (BSA), β-lactoglobulin-A, and β-lactoglobulin-B on an anion exchange monolith was simulated based on experimental parameter determination, simultaneous model testing, and validation under three statistical criteria: retention time, dispersion accuracies, and Pearson correlation coefficient. Experimental characterization of morphologic, physicochemical, and kinetic parameters was performed through volume balances, pressure drop analysis, breakthrough curve analysis, and batch adsorptions. Free Gibbs energy indicated a spontaneous adsorption process for proteins and counterions. Dimensionless numbers were estimated based on height equivalent to a theoretical plate analysis, finding that pore diffusion controlled β-lactoglobulin separation, whereas adsorption/desorption kinetics was the dominant mechanism for BSA. The elution profiles were modeled using the transport dispersive model and the reactive dispersive model coupled with steric mass action (SMA) isotherms because these models allowed to consider most of the mass transport mechanisms that have been described. RDM-SMA presented the most accurate simulations at pH 6.0 and at low (250 mM) and high (400 mM) NaCl concentrations. This simulation will be used as reference to forecast the purification of these proteins from bovine whey waste and to extrapolate this methodology to other monolith-based separations using these three statistical criteria that have not been used previously for this purpose.

Advances in high-throughput, high-capacity nonwoven membranes for chromatography in downstream processing: A review

Nonwoven membranes are highly engineered fibrous materials that can be manufactured on a large scale from a wide range of different polymers, and their surfaces can be modified using a large variety of different chemistries and ligands. The fiber diameters, surface areas, pore sizes, total porosities, and thicknesses of the nonwoven mats can be carefully controlled, providing many opportunities for creative approaches for the development of novel membranes with unique properties to meet the needs of the future of downstream processing. Fibrous membranes are already finding use in ultrafiltration, microfiltration, depth filtration, and, more recently, in membrane chromatography for product capture and impurity removal. This article summarizes the various methods of manufacturing nonwoven fabrics, and the many methods available for the modification of the fiber surfaces. It also reviews recent studies focused on the use of nonwoven fabric devices in membrane chromatography and provides some perspectives on the challenges that need to be overcome to increase binding capacities, decrease residence times, and reduce pressure drops so that eventually they can replace resin column chromatography in downstream process operations.

Toward microfluidic continuous-flow and intelligent downstream processing of biopharmaceuticals

Biopharmaceuticals have emerged as powerful therapeutic agents, revolutionizing the treatment landscape for various diseases, including cancer, infectious diseases, autoimmune and genetic disorders. These biotherapeutics pave the way for precision medicine with their unique and targeted capabilities. The production of high-quality biologics entails intricate manufacturing processes, including cell culture, fermentation, purification, and formulation, necessitating specialized facilities and expertise. These complex processes are subject to rigorous regulatory oversight to evaluate the safety, efficacy, and quality of biotherapeutics prior to clinical approval. Consequently, these drugs undergo extensive purification unit operations to achieve high purity by effectively removing impurities and contaminants. The field of personalized precision medicine necessitates the development of novel and highly efficient technologies. Microfluidic technology addresses unmet needs by enabling precise and compact separation, allowing rapid, integrated and continuous purification modules. Moreover, the integration of intelligent biomanufacturing systems with miniaturized devices presents an opportunity to significantly enhance the robustness of complex downstream processing of biopharmaceuticals, with the benefits of automation and advanced control. This allows seamless data exchange, real-time monitoring, and synchronization of purification steps, leading to improved process efficiency, data management, and decision-making. Integrating autonomous systems into biopharmaceutical purification ensures adherence to regulatory standards, such as good manufacturing practice (GMP), positioning the industry to effectively address emerging market demands for personalized precision nano-medicines. This perspective review will emphasize on the significance, challenges, and prospects associated with the adoption of continuous, integrated, and intelligent methodologies in small-scale downstream processing for various types of biologics. By utilizing microfluidic technology and intelligent systems, purification processes can be enhanced for increased efficiency, cost-effectiveness, and regulatory compliance, shaping the future of biopharmaceutical production and enabling the development of personalized and targeted therapies.

Phase separation methods for protein purification: A meta-analysis of purification performance and cost-effectiveness

Protein purifications based on phase separations (e.g., precipitation and liquid-liquid extraction) have seen little adoption in commercial protein drug production. To identify barriers, we analyzed the purification performance and economics of 290 phase separation purifications from 168 publications. First, we found that studies using Design of Experiments for optimization achieved significantly greater mean yield and host cell protein log10 removal values than those optimizing one factor at a time (11.5% and 53% increases, respectively). Second, by modeling each reported purification at scales from 10 to 10,000 kg product/year and comparing its cost-effectiveness versus chromatography, we found that cost-effectiveness depends strongly on scale: the fraction of phase separations predicted to be cost-effective at the 10, 100, and 1000 kg/year scales was 8%, 15%, and 43%, respectively. Total cost per unit product depends inversely on input purity, with phase separation being cheaper than chromatography at the 100 kg/year scale in 100% of cases where input purity was ≤ 1%, compared to about 25% of cases in the dataset as a whole. Finally, we identified a simple factor that strongly predicts phase separation process costs: the mass ratio of reagents versus purified product (the "direct materials usage rate"), which explains up to 58% of variation in cost per unit of purified product among all 290 reports, and up to 98% of variation within particular types of phase separation.

Structural and biofunctional diversity of sulfated polysaccharides from the genus Codium (Bryopsidales, Chlorophyta): A review

It is believed that polysaccharides will become a focal point for future production of food, pharmaceuticals, and materials due to their ubiquitous and renewable nature, as well as their exceptional properties that have been extensively validated in the fields of nutrition, healthcare, and materials. Sulfated polysaccharides derived from seaweed sources have attracted considerable attention owing to their distinctive structures and properties. The genus Codium, represented by the species C. fragile, holds significance as a vital economic green seaweed and serves as a traditional Chinese medicinal herb. To date, the cell walls of the genus Codium have been found to contain at least four types of sulfated polysaccharides, specifically pyruvylated β-d-galactan sulfates, sulfated arabinogalactans, sulfated β-l-arabinans, and sulfated β-d-mannans. These sulfated polysaccharides exhibit diverse biofunctions, including anticoagulant, immune-enhancing, anticancer, antioxidant activities, and drug-carrying capacity. This review explores the structural and biofunctional diversity of sulfated polysaccharides derived from the genus Codium. Additionally, in addressing the impending challenges within the industrialization of these polysaccharides, encompassing concerns regarding scale-up production and quality control, we outline potential strategies to address these challenges from the perspectives of raw materials, extraction processes, purification technologies, and methods for quality control.

Evaluation of dynamic control of continuous capture with periodic counter-current chromatography under feedstock variations

Multi-column periodic counter-current chromatography is a promising technology for continuous antibody capture. However, dynamic changes due to disturbances and drifts pose some potential risks for continuous processes during long-term operation. In this study, a model-based approach was used to describe the changes in breakthrough curves with feedstock variations in target proteins and impurities. The performances of continuous capture of three-column periodic counter-current chromatography under ΔUV dynamic control were systematically evaluated with modeling to assess the risks under different feedstock variations. As the concentration of target protein decreased rapidly, the protein might not breakthrough from the first column, resulting in the failure of ΔUV control. Small reductions in the concentrations of target proteins or impurities would cause protein losses, which could be predicted by the modeling. The combination of target protein and impurity variations showed complicated effects on the process performance of continuous capture. A contour map was proposed to describe the comprehensive impacts under different situations, and nonoperation areas could be identified due to control failure or protein loss. With the model-based approach, after the model parameters are estimated from the breakthrough curves, it can rapidly predict the process stability under dynamic control and assess the risks under feedstock variations or UV signal drifts. In conclusion, the model-based approach is a powerful tool for continuous process evaluation under dynamic changes and would be useful for establishing a new real-time dynamic control strategy.

Precipitation and Extraction Methods for Protein Purification: A Meta-Analysis of Purification Performance and Cost-Effectiveness

For protein drug purification, packed-bed chromatography often remains both the predominant method and a bottleneck for cost and scalability. Accordingly, extensive efforts have been made to develop alternatives, such as precipitation and liquid-liquid extraction. Despite decades of development, such methods have been slow to see adoption in commercial processes. To diagnose the key barriers to implementation and guide future work, we have systematically reviewed studies of protein precipitation and liquid-liquid extraction. We classify the products, methods, and results of 168 publications representing 290 unique purification operations and analyze these operations in terms of both process economics and purification performance. Whereas it is generally assumed that precipitation and extraction methods will have lower costs than chromatography, we find that this is only the case under specific process conditions such as at a large manufacturing scale and low initial sample purity. Furthermore, we find that only a small number of the many precipitation and extraction methods reported to date have shown readiness for implementation in protein drug purification processes. Finally, we identify key factors governing both the economic and purification performance of this class of methods: first, that operating costs are almost entirely predictable by the ratio between the mass of phase-forming materials used and the mass of product protein yielded; second, that use of modern optimization techniques such as Design of Experiments is associated with significantly better purification performance and cost-effectiveness.

Highlights

Alternative separation purification methods are not always cheaper than chromatographyThe use of a combination of phase separating agents remains largely underexplored/underutilizedLower initial purity and increasing production scale favor phase-separation over chromatographyThe direct material usage rate is an important predictor of alternative separation cost-effectivenessCurrent alternative separation method development has largely ignored optimization of direct material usage rate.

Model-assisted process development, characterization and design of continuous chromatography for antibody separation

Continuous manufacturing in monoclonal antibody production has generated increased interest due to its consistent quality, high productivity, high equipment utilization, and low cost. One of the major challenges in realizing continuous biological manufacturing lies in implementing continuous chromatography. Given the complex operation mode and various operation parameters, it is challenging to develop a continuous process. Due to the process parameters being mainly determined by the breakthrough curves and elution behaviors, chromatographic modeling has gradually been used to assist in process development and characterization. Model-assisted approaches could realize multi-parameter interaction investigation and multi-objective optimization by integrating continuous process models. These approaches could reduce time and resource consumption while achieving a comprehensive and systematic understanding of the process. This paper reviews the application of modeling tools in continuous chromatography process development, characterization and design. Model-assisted process development approaches for continuous capture and polishing steps are introduced and summarized. The challenges and potential of model-assisted process characterization are discussed, emphasizing the need for further research on the design space determination strategy and parameter robustness analysis method. Additionally, some model applications for process design were highlighted to promote the establishment of the process optimization and process simulation platform.

Messenger RNA chromatographic purification: advances and challenges

Messenger RNA (mRNA) technologies have shown great potential in prophylactic vaccines and therapeutic medicines due to their adaptability, rapidity, efficacy, and safety. The purity of mRNA determines the efficacy and safety of mRNA drugs. Though chromatographic technologies are currently employed in mRNA purification, they are facing challenges, mainly arising from the large size, relatively simple chemical composition, instability, and high resemblance of by-products to the target mRNA. In this review, we will first make a comprehensive analysis of physiochemical properties differences between mRNA and proteins, then the major challenges facing in mRNA purification and general considerations are highlighted. A detailed summary of the state-of-arts in mRNA chromatographic purification will be provided, which are mainly classified into physicochemical property-based (size, charge, and hydrophobicity) and chemical structure-based (phosphate backbone, bases, cap structure, and poly A tail) technologies. Efforts in eliminating dsRNA byproducts via post in vitro transcript (IVT) purification and by manipulating the IVT process to reduce the generation of dsRNA are highlighted. Finally, a brief summary of the current status of chromatographic purification of the emerging circular mRNA (circRNA) is provided. We hope this review will provide some useful guidance for the Quality by Design (QbD) of mRNA downstream process development.

Analyzing and understanding the robustness of bioprocesses

The robustness of bioprocesses is becoming increasingly important. The main driving forces of this development are, in particular, increasing demands on product purities as well as economic aspects. In general, bioprocesses exhibit extremely high complexity and variability. Biological systems often have a much higher intrinsic variability compared with chemical processes, which makes the development and characterization of robust processes tedious task. To predict and control robustness, a clear understanding of interactions between input and output variables is necessary. Robust bioprocesses can be realized, for example, by using advanced control strategies for the different unit operations. In this review, we discuss the different biological, technical, and mathematical tools for the analysis and control of bioprocess robustness.

Valuable pigments from microalgae: phycobiliproteins, primary carotenoids, and fucoxanthin

Phycobiliproteins, carotenoids and fucoxanthin are photosynthetic pigments extracted from microalgae and cyanobacteria with great potential biotechnological applications, as healthy food colorants and cosmetics. Phycocyanin possesses a brilliant blue color, with fluorescent properties making it useful as a reagent for immunological essays. The most important source of phycocyanin is the cyanobacterium Arthrospira platensis, however, recently, the Rhodophyta Galdieria sulphuraria has also been identified as such. The main obstacle to the commercialization of phycocyanin is represented by its chemical instability, strongly reducing its shelf-life. Moreover, the high level of purity needed for pharmaceutical applications requires several steps which increase both the production time and cost. Microalgae (Chlorella, Dunaliella, Nannochloropsis, Scenedesmus) produce several light harvesting carotenoids, and are able to manage with oxidative stress, due to their free radical scavenging properties, which makes them suitable for use as source of natural antioxidants. Many studies focused on the selection of the most promising strains producing valuable carotenoids and on their extraction and purification. Among carotenoids produced by marine microalgae, fucoxanthin is the most abundant, representing more than 10% of total carotenoids. Despite the abundance and diversity of fucoxanthin producing microalgae only a few species have been studied for commercial production, the most relevant being Phaeodactylum tricornutum. Due to its antioxidant activity, fucoxanthin can bring various potential benefits to the prevention and treatment of lifestyle-related diseases. In this review, we update the main results achieved in the production, extraction, purification, and commercialization of these important pigments, motivating the cultivation of microalgae as a source of natural pigments.

Proteomics Methodologies: The Search of Protein Biomarkers Using Microfluidic Systems Coupled to Mass Spectrometry

Protein biomarkers have been the subject of intensive studies as a target for disease diagnostics and monitoring. Indeed, biomarkers have been extensively used for personalized medicine. In biological samples, these biomarkers are most often present in low concentrations masked by a biologically complex proteome (e.g., blood) making their detection difficult. This complexity is further increased by the needs to detect proteoforms and proteome complexity such as the dynamic range of compound concentrations. The development of techniques that simultaneously pre-concentrate and identify low-abundance biomarkers in these proteomes constitutes an avant-garde approach to the early detection of pathologies. Chromatographic-based methods are widely used for protein separation, but these methods are not adapted for biomarker discovery, as they require complex sample handling due to the low biomarker concentration. Therefore, microfluidics devices have emerged as a technology to overcome these shortcomings. In terms of detection, mass spectrometry (MS) is the standard analytical tool given its high sensitivity and specificity. However, for MS, the biomarker must be introduced as pure as possible in order to avoid chemical noise and improve sensitivity. As a result, microfluidics coupled with MS has become increasingly popular in the field of biomarker discovery. This review will show the different approaches to protein enrichment using miniaturized devices and the importance of their coupling with MS.

Optimization of fluid flow in membrane chromatography devices using computational fluid dynamic simulations

Flow uniformity within the device is critically important in membrane chromatography. Recent studies have shown that the design of the device has a significant impact on flow uniformity, and thereby on separation efficiency. The main premise of this work is that computational fluid dynamics (CFD) could serve as a fast and inexpensive tool for preliminary optimization of the design of a membrane chromatography device. CFD also helps in identifying factors that affect flow uniformity. In this paper, CFD is used to compare the fluidic attributes of conventional membrane chromatography devices such as the stacked disc and radial flow devices with those of more recently developed ones such as the different versions of the laterally-fed membrane chromatography (LFMC) device. These are compared based on pulse tracer solute dispersion, which is a useful metric for measuring flow uniformity, and is thereby a good predictor of chromatographic separation performance. The poor separation performance typically observed with conventional membrane chromatography devices could be attributed to the high degree of solute dispersion within these devices. CFD is then used to analyze the impact of factors such as membrane aspect ratio, and channel dimensions on the performance of z²-laterally-fed membrane chromatography (z²LFMC) devices. The results discussed in the paper demonstrate that CFD could indeed serve as a powerful optimization and performance prediction tool for membrane chromatography.

Cationised Fibre-Based Cellulose Multi-Layer Membranes for Sterile and High-Flow Bacteria Retention and Inactivation

Low-cost, readily available, or even disposable membranes in water purification or downstream biopharma processes are becoming attractive alternatives to expensive polymeric columns or filters. In this article, the potential of microfiltration membranes prepared from differently orientated viscose fibre slivers, infused with ultrafine quaternised (qCNF) and amino-hydrophobised (aCNF) cellulose nanofibrils, were investigated for capturing and deactivating the bacteria from water during vacuum filtration. The morphology and capturing mechanism of the single- and multi-layer structured membranes were evaluated using microscopic imaging and colloidal particles. They were assessed for antibacterial efficacy and the retention of selected bacterial species (Escherichia coli, Staphylococcus aureus, Micrococcus luteus), differing in the cell envelope structure, hydrodynamic biovolume (shape and size) and their clustering. The aCNF increased biocidal efficacy significantly when compared to qCNF-integrated membrane, although the latter retained bacteria equally effectively by a thicker multi-layer structured membrane. The retention of bacterial cells occurred through electrostatic and hydrophobic interactions, as well as via interfibrous pore diffusion, depending on their physicochemical properties. For all bacterial strains, the highest retention (up to 100% or log 6 reduction) at >50 L/h∗bar∗m2 flow rate was achieved with a 4-layer gradient-structured membrane containing different aCNF content, thereby matching the performance of industrial polymeric filters used for removing bacteria.

Implementation of Novel Affinity Ligand for Lentiviral Vector Purification

The use of viral vectors as therapeutic products for multiple applications such as vaccines, cancer treatment, or gene therapies, has been growing exponentially. Therefore, improved manufacturing processes are needed to cope with the high number of functional particles required for clinical trials and, eventually, commercialization. Affinity chromatography (AC) can be used to simplify purification processes and generate clinical-grade products with high titer and purity. However, one of the major challenges in the purification of Lentiviral vectors (LVs) using AC is to combine a highly specific ligand with a gentle elution condition assuring the preservation of vector biological activity. In this work, we report for the first time the implementation of an AC resin to specifically purify VSV-G pseudotyped LVs. After ligand screening, different critical process parameters were assessed and optimized. A dynamic capacity of 1 × 1011 total particles per mL of resin was determined and an average recovery yield of 45% was found for the small-scale purification process. The established AC robustness was confirmed by the performance of an intermediate scale providing an infectious particles yield of 54%, which demonstrates the scalability and reproducibility of the AC matrix. Overall, this work contributes to increasing downstream process efficiency by delivering a purification technology that enables high purity, scalability, and process intensification in a single step, contributing to time-to-market reduction.

Current research approaches in downstream processing of pharmaceutically relevant proteins

Biopharmaceuticals and their production are on the rise. They are needed to treat and to prevent multiple diseases. Therefore, an urgent need for process intensification in downstream processing (DSP) has been identified to produce biopharmaceuticals more efficiently. The DSP currently accounts for the majority of production costs of pharmaceutically relevant proteins. This short review gathers essential research over the past 3 years that addresses novel solutions to overcome this bottleneck. The overview includes promising studies in the fields of chromatography, aqueous two-phase systems, precipitation, crystallization, magnetic separation, and filtration for the purification of pharmaceutically relevant proteins.

Circular Geometry in Molecular Stream Separation to Facilitate Nonorthogonal Field-to-Flow Orientation

Molecular stream separation (MSS) is a promising complement for continuous-flow synthesis. MSS is driven by forces exerted on molecules by a field applied at an angle to the stream-carrying flow. MSS has only been performed with a 90° field-to-flow angle because of a rectangular geometry of canonic MSS; the second-order rotational symmetry of a rectangle prevents any other angle. Here, we propose a noncanonic circular geometry for MSS, which better aligns with the polar nature of MSS and allows changing the field-to-flow. We conducted in silico and experimental studies of circular geometry for continuous-flow electrophoresis (CFE, an MSS method). We proved two advantages of circular CFE over its rectangular counterpart. First, circular CFE can support better flow and electric-field uniformity than rectangular CFE. Second, the nonorthogonal field-to-flow orientation, achievable in circular CFE, can result in a higher stream resolution than the orthogonal one. Considering that circular CFE devices are not more complex in fabrication than rectangular ones, we foresee that circular CFE will serve as a new standard and a testbed for the investigation and creation of new CFE modalities.

Matrices and Affinity Ligands for Antibody Purification and Corresponding Applications in Radiotherapy

Antibodies have become an important class of biological products in cancer treatments such as radiotherapy. The growing therapeutic applications have driven a demand for high-purity antibodies. Affinity chromatography with a high affinity and specificity has always been utilized to separate antibodies from complex mixtures. Quality chromatographic components (matrices and affinity ligands) have either been found or generated to increase the purity and yield of antibodies. More importantly, some matrices (mainly particles) and affinity ligands (including design protocols) for antibody purification can act as radiosensitizers or carriers for therapeutic radionuclides (or for radiosensitizers) either directly or indirectly to improve the therapeutic efficiency of radiotherapy. This paper provides a brief overview on the matrices and ligands used in affinity chromatography that are involved in antibody purification and emphasizes their applications in radiotherapy to enrich potential approaches for improving the efficacy of radiotherapy.

Conversion of recombinant human ferritin light chain inclusion bodies into uniform nanoparticles in Escherichia coli for facile production

Prokaryotic expression systems are widely used to produce many types of biologics because of their extreme conveniences and unmatchable cost. However, production of recombinant human ferritin light chain (rhFTL) protein is largely restrained because its expression in Escherichia coli tends to form inclusion bodies (IBs). In this study, a prokaryotic expression vector (FTL-pBV220) harboring the rhFTL gene was constructed using a pBV220 plasmid. The tag-free rhFTL was highly expressed and almost entirely converted to soluble form, and thus the rhFTL was successfully self-assembled into uniform nanoparticles in E. coli. To establish a simplified downstream process, a precipitation procedure based on the optimized incubation temperature, pH condition, and ionic strength was developed to remove impurities from the crude lysate supernatant. The rhFTL retained in the clarified supernatant was subsequently purified in a single step using Capto Butyl column resulting in a considerable recovery and high purity. The purified rhFTL was characterized and verified by mass spectrometry and spectral and morphological analyses. The results revealed that rhFTL exhibited highly ordered and fairly compact structures and the spherical structures were preserved.

Ultrahigh speed, ultrahigh resolution preparative separation of protein biopharmaceuticals using membrane chromatography

This paper discusses ultrahigh speed, ultrahigh resolution preparative protein separation using an in-house designed membrane chromatography device. The performance of the membrane chromatography device was systematically compared with an equivalent resin-packed preparative column. Experiments carried out using model proteins showed that membrane chromatography gave more than 4-times greater resolution than the preparative column, while at the same time being more than 19-times faster. Membrane chromatography was therefore a better option, not only in terms of higher productivity, but also in terms of higher product purity. Membrane chromatography was also superior in terms of resolving and presenting tracer impurity peaks in the chromatogram. Experiments carried out using monoclonal antibody samples showed that membrane chromatography was suitable to ultrahigh speed, ultrahigh resolution fractionation of charge variants. This paper highlights and explains the need for proper device design for enabling the use of membrane chromatography for efficient purification of protein biopharmaceuticals. This article is protected by copyright. All rights reserved.

Solution design to extend the pH range of the pH-responsive precipitation of a CspB fusion protein

Cell surface protein B (CspB) from Corynebacterium glutamicum has been developed as a reversible pH-responsive tag for protein purification. CspB fusion proteins precipitate at acidic pH, after that they completely dissolve at neutral pH. This property has been used in a non-chromatographic protein purification method named pH-responsive Precipitation-Redissolution of CspB tag Purification (pPRCP). However, it is difficult to apply pPRCP to proteins that are unstable under acidic conditions. In an effort to shift the precipitation pH to a milder range, we investigated the solution conditions of CspB-fused Teriparatide (CspB50TEV-Teriparatide) during the process of pH-responsive precipitation using pPRCP. The purified CspB50TEV-Teriparatide in buffer without additives precipitated at pH 5.3. By contrast, CspB50TEV-Teriparatide in buffer with 0.5 M Na₂SO₄ precipitated at pH 6.6 because of the kosmotropic effect. Interestingly, the pH at which precipitation occurred was independent of the protein concentration. The precipitated CspB50TEV-Teriparatide was fully redissolved at above pH 8.0 in the presence or absence of salt. The discovery that proteins can be precipitated at a mild pH will allow pPRCP to be applied to acid-sensitive proteins.

Efficient Isolation of Bacterial RNAs Using Silica-Based Materials Modified with Ionic Liquids

High quality nucleic acids (with high integrity, purity, and biological activity) have become indispensable products of modern society, both in molecular diagnosis and to be used as biopharmaceuticals. As the current methods available for the extraction and purification of nucleic acids are laborious, time-consuming, and usually rely on the use of hazardous chemicals, there is an unmet need towards the development of more sustainable and cost-effective technologies for nucleic acids purification. Accordingly, this study addresses the preparation and evaluation of silica-based materials chemically modified with chloride-based ionic liquids (supported ionic liquids, SILs) as potential materials to effectively isolate RNAs. The investigated chloride-based SILs comprise the following cations: 1-methyl-3-propylimidazolium, triethylpropylammonium, dimethylbutylpropylammonium, and trioctylpropylammonium. All SILs were synthesized by us and characterized by solid-state ¹³C Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy (SEM), elemental analysis, and zeta potential measurements, confirming the successful covalent attachment of each IL cation with no relevant changes in the morphology of materials. Their innovative application as chromatographic supports for the isolation of recombinant RNA was then evaluated. Adsorption kinetics of transfer RNA (tRNA) on the modified silica-based materials were investigated at 25 °C. Irrespective to the immobilized IL, the adsorption experimental data are better described by a pseudo first-order model, and maximum tRNA binding capacities of circa 16 µmol of tRNA/g of material were achieved with silica modified with 1-methyl-3-propylimidazolium chloride and dimethylbutylpropylammonium chloride. Furthermore, the multimodal character displayed by SILs was explored towards the purification of tRNA from Escherichia coli lysates, which in addition to tRNA contain ribosomal RNA and genomic DNA. The best performance on the tRNA isolation was achieved with SILs comprising 1-methyl-3-propylimidazolium chloride and dimethylbutylpropylammonium chloride. Overall, the IL modified silica-based materials represent a more efficient, sustainable, and cost-effective technology for the purification of bacterial RNAs, paving the way for their use in the purification of distinct biomolecules or nucleic acids from other sources.

Avdović E, Radulović M, Xiao J, A. Prieto M, Simal-Gandara J. Seaweed Protein Hydrolysates and Bioactive Peptides: Extraction, Purification, and Applications

Seaweeds are industrially exploited for obtaining pigments, polysaccharides, or phenolic compounds with application in diverse fields. Nevertheless, their rich composition in fiber, minerals, and proteins, has pointed them as a useful source of these components. Seaweed proteins are nutritionally valuable and include several specific enzymes, glycoproteins, cell wall-attached proteins, phycobiliproteins, lectins, or peptides. Extraction of seaweed proteins requires the application of disruptive methods due to the heterogeneous cell wall composition of each macroalgae group. Hence, non-protein molecules like phenolics or polysaccharides may also be co-extracted, affecting the extraction yield. Therefore, depending on the macroalgae and target protein characteristics, the sample pretreatment, extraction and purification techniques must be carefully chosen. Traditional methods like solid-liquid or enzyme-assisted extraction (SLE or EAE) have proven successful. However, alternative techniques as ultrasound- or microwave-assisted extraction (UAE or MAE) can be more efficient. To obtain protein hydrolysates, these proteins are subjected to hydrolyzation reactions, whether with proteases or physical or chemical treatments that disrupt the proteins native folding. These hydrolysates and derived peptides are accounted for bioactive properties, like antioxidant, anti-inflammatory, antimicrobial, or antihypertensive activities, which can be applied to different sectors. In this work, current methods and challenges for protein extraction and purification from seaweeds are addressed, focusing on their potential industrial applications in the food, cosmetic, and pharmaceutical industries.

Purification of Modified Therapeutic Proteins Available on the Market: An Analysis of Chromatography-Based Strategies

Proteins, which have inherent biorecognition properties, have long been used as therapeutic agents for the treatment of a wide variety of clinical indications. Protein modification through covalent attachment to different moieties improves the therapeutic's pharmacokinetic properties, affinity, stability, confers protection against proteolytic degradation, and increases circulation half-life. Nowadays, several modified therapeutic proteins, including PEGylated, Fc-fused, lipidated, albumin-fused, and glycosylated proteins have obtained regulatory approval for commercialization. During its manufacturing, the purification steps of the therapeutic agent are decisive to ensure the quality, effectiveness, potency, and safety of the final product. Due to the robustness, selectivity, and high resolution of chromatographic methods, these are recognized as the gold standard in the downstream processing of therapeutic proteins. Moreover, depending on the modification strategy, the protein will suffer different physicochemical changes, which must be considered to define a purification approach. This review aims to deeply analyze the purification methods employed for modified therapeutic proteins that are currently available on the market, to understand why the selected strategies were successful. Emphasis is placed on chromatographic methods since they govern the purification processes within the pharmaceutical industry. Furthermore, to discuss how the modification type strongly influences the purification strategy, the purification processes of three different modified versions of coagulation factor IX are contrasted.

A cuboid chromatography device having short bed-height gives better protein separation at a significantly lower pressure drop than a taller column having the same bed-volume

Simultaneously reducing the bed-height and increasing the area of cross-section, while keeping the bed-volume the same, would substantially reduce the pressure drop across a process chromatography column. This would minimize problems such as resin compaction and non-uniformity in column packing, which are commonly faced when using soft chromatographic media. However, the increase in macroscale convective dispersion due to the increase in column diameter, and the resultant loss in resolution would far outweigh any potential benefit. Cuboid-packed bed devices have lower macroscale convective dispersion compared to their equivalent cylindrical columns. In this paper, we discuss how and why a flat cuboid chromatography device having a short bed-height gives better protein separation, at a significantly lower pressure drop, than a taller column having the same bed-volume. First, we explored this option based on computational fluid dynamic (CFD) simulations. Depending on the flow rate, the pressure drop across the flat cuboid device was lower than that in the tall column by a factor of 6.35 to 6.4 (i.e. less than 1/6^th the pressure). The CFD results also confirmed that the macroscale convective dispersion within the flat cuboid device was significantly lower. Head-to-head separation experiments using a 1 mL flat cuboid device having a bed-height of 10 mm, and a 1 mL tall column having a bed-height of 25.8 mm, both packed with the same chromatographic media, were carried out. The number of theoretical plates per unit bed-height was on an average, around 2.5 time times greater with the flat cuboid device, while the total number of theoretical plates in the two devices were comparable. At any given superficial velocity, the height equivalent of a theoretical plate in the tall column was on an average, higher by a factor 2.5. Binary protein separation experiments showed that at any given flow rate, the resolution obtained using the flat cuboid device was significantly higher than that obtained with the tall column. This work opens up the possibility of designing and developing short bed-height chromatography devices for carrying out high-resolution biopharmaceutical purifications, at very low pressures.

High-Throughput Process Development: I-Process Chromatography

Chromatographic separation serves as "a workhorse" for downstream process development and plays a key role in the removal of product-related, host-cell-related, and process-related impurities. Complex and poorly characterized raw materials and feed material, low feed concentration, product instability, and poor mechanistic understanding of the processes are some of the critical challenges that are faced during the development of a chromatographic step. Traditional process development is performed as a trial-and-error-based evaluation and often leads to a suboptimal process. A high-throughput process development (HTPD) platform involves the integration of miniaturization, automation, and parallelization and provides a systematic approach for time- and resource-efficient chromatographic process development. Creation of such platforms requires the integration of mechanistic knowledge of the process with various statistical tools for data analysis. The relevance of such a platform is high in view of the constraints with respect to time and resources that the biopharma industry faces today.This protocol describes the steps involved in performing the HTPD of chromatography steps. It describes the operation of a commercially available device (PreDictor™ plates from GE Healthcare). This device is available in 96-well format with 2 or 6 μL well size. We also discuss the challenges that one faces when performing such experiments as well as possible solutions to alleviate them. Besides describing the operation of the device, the protocol also presents an approach for statistical analysis of the data that are gathered from such a platform. A case study involving the use of the protocol for examining ion exchange chromatography of the Granulocyte Colony Stimulating Factor (GCSF), a therapeutic product, is briefly discussed. This is intended to demonstrate the usefulness of this protocol in generating data that are representative of the data obtained at the traditional lab scale. The agreement in the data is indeed very significant (regression coefficient 0.93). We think that this protocol will be of significant value to those involved in performing the high-throughput process development of the chromatography process.

Protein Purification Technologies

Protein Biotechnology is an exciting and fast- growing area of research, with numerous industrial applications. The growing demand for developing efficient and rapid protein purification methods is driving research and growth in this area. Advances and progress in the techniques and methods of protein purification have been such that one can reasonably expect that any protein of a given order of stability may be purified to currently acceptable standards of homogeneity. However, protein manufacturing cost remains extremely high, with downstream processing constituting a substantial proportion of the overall cost. Understanding of the methods and optimization of the experimental conditions have become critical to the manufacturing industry in order to minimize production costs while satisfying the quality as well as all regulatory requirements. New purification processes exploiting specific, effective and robust methods and chromatographic materials are expected to guide the future of the protein purification market.

Polysaccharide-based chromatographic adsorbents for virus purification and viral clearance

Viruses still pose a significant threat to human and animal health worldwide. In the fight against viral infections, high-purity viral stocks are needed for manufacture of safer vaccines. It is also a priority to ensure the viral safety of biopharmaceuticals such as blood products. Chromatography techniques are widely implemented at both academic and industrial levels in the purification of viral particles, whole viruses and virus-like particles to remove viral contaminants from biopharmaceutical products. This paper focuses on polysaccharide adsorbents, particulate resins and membrane adsorbers, used in virus purification/removal chromatography processes. Different chromatographic modes are surveyed, with particular attention to ion exchange and affinity/pseudo-affinity adsorbents among which commercially available agarose-based resins (Sepharose®) and cellulose-based membrane adsorbers (Sartobind®) occupy a dominant position. Mainly built on the development of new ligands coupled to conventional agarose/cellulose matrices, the development perspectives of polysaccharide-based chromatography media in this antiviral area are stressed in the conclusive part.

Magnetic Precipitation: A New Platform for Protein Purification

One of the trends in downstream processing comprises the use of "anything-but-chromatography" methods to overcome the current downfalls of standard packed-bed chromatography. Precipitation and magnetic separation are two techniques already proven to accomplish protein purification from complex media, yet never used in synergy. With the aim to capture antibodies directly from crude extracts, a new approach combining precipitation and magnetic separation is developed and named as affinity magnetic precipitation. A precipitation screening, based on the Hofmeister series, and a commercial precipitation kit are tested with affinity magnetic particles to assess the best condition for antibody capture from human serum plasma and clarified cell supernatant. The best conditions are obtained when using PEG3350 as precipitant at 4 °C for 1 h, reaching 80% purity and 50% recovery of polyclonal antibodies from plasma, and 99% purity with 97% recovery yield of anti-TNFα mAb from cell supernatants. These results show that the synergetic use of precipitation and magnetic separation can represent an alternative for the efficient capture of antibodies.

Mechanistic Modeling of Preparative Column Chromatography for Biotherapeutics

Chromatography has long been, and remains, the workhorse of downstream processing in the production of biopharmaceuticals. As bioprocessing has matured, there has been a growing trend toward seeking a detailed fundamental understanding of the relevant unit operations, which for some operations include the use of mechanistic modeling in a way similar to its use in the conventional chemical process industries. Mechanistic models of chromatography have been developed for almost a century, but although the essential features are generally understood, the specialization of such models to biopharmaceutical processing includes several areas that require further elucidation. This review outlines the overall approaches used in such modeling and emphasizes current needs, specifically in the context of typical uses of such models; these include selection and improvement of isotherm models and methods to estimate isotherm and transport parameters independently. Further insights are likely to be aided by molecular-level modeling, as well as by the copious amounts of empirical data available for existing processes.

Affinity purification of Car9-tagged proteins on silica-derivatized spin columns and 96-well plates

The Car9 affinity tag is a dodecameric silica-binding peptide that can be fused to the N- and C-termini of proteins of interest to enable their rapid and inexpensive purification on underivatized silica in a process that typically relies on l-lysine as an eluent. Here, we show that silica paper spin columns and borosilicate multi-well plates used for plasmid DNA purification are suitable for recovering Car9-tagged proteins with high purity in a workflow compatible with high-throughput experiments. Spin columns typically yield 100 μg of biologically active material that can be recovered in minutes with low concentrations of lysine. Because of their short bed length, spin columns also offer unique advantages, as evidenced by the selective recovery of functional Car9-tagged tobacco etch virus (TEV) protease from a fused and auto-cleaved maltose binding protein (MBP) folding partner that nonspecifically binds to silica in the presence of NaCl. These additional purification modalities should increase the versatility and appeal of the Car9 tag for affinity protein purification.

Recent Developments in Bioprocessing of Recombinant Proteins: Expression Hosts and Process Development

Infectious diseases, along with cancers, are among the main causes of death among humans worldwide. The production of therapeutic proteins for treating diseases at large scale for millions of individuals is one of the essential needs of mankind. Recent progress in the area of recombinant DNA technologies has paved the way to producing recombinant proteins that can be used as therapeutics, vaccines, and diagnostic reagents. Recombinant proteins for these applications are mainly produced using prokaryotic and eukaryotic expression host systems such as mammalian cells, bacteria, yeast, insect cells, and transgenic plants at laboratory scale as well as in large-scale settings. The development of efficient bioprocessing strategies is crucial for industrial production of recombinant proteins of therapeutic and prophylactic importance. Recently, advances have been made in the various areas of bioprocessing and are being utilized to develop effective processes for producing recombinant proteins. These include the use of high-throughput devices for effective bioprocess optimization and of disposable systems, continuous upstream processing, continuous chromatography, integrated continuous bioprocessing, Quality by Design, and process analytical technologies to achieve quality product with higher yield. This review summarizes recent developments in the bioprocessing of recombinant proteins, including in various expression systems, bioprocess development, and the upstream and downstream processing of recombinant proteins.

Emerging biomaterials for downstream manufacturing of therapeutic proteins

Downstream processing is considered one of the most challenging phases of industrial manufacturing of therapeutic proteins, accounting for a large portion of the total production costs. The growing demand for therapeutic proteins in the biopharmaceutical market in addition to a significant rise in upstream titers have placed an increasing burden on the downstream purification process, which is often limited by high cost and insufficient capacities. To achieve efficient production and reduced costs, a variety of biomaterials have been exploited to improve the current techniques and also to develop superior alternatives. In this work, we discuss the significance of utilizing traditional biomaterials in downstream processing and review the recent progress in the development of new biomaterials for use in protein separation and purification. Several representative methods will be highlighted and discussed in detail, including affinity chromatography, non-affinity chromatography, membrane separations, magnetic separations, and precipitation/phase separations. STATEMENT OF SIGNIFICANCE: Nowadays, downstream processing of therapeutic proteins is facing great challenges created by the rapid increase of the market size and upstream titers, starving for significant improvements or innovations in current downstream unit operations. Biomaterials have been widely used in downstream manufacturing of proteins and efforts have been continuously devoted to developing more advanced biomaterials for the implementation of more efficient and economical purification methods. This review covers recent advances in the development and application of biomaterials specifically exploited for various chromatographic and non-chromatographic techniques, highlighting several promising alternative strategies.

Improved monovalent TNF receptor 1-selective inhibitor with novel heterodimerizing Fc

The development of alternative therapeutic strategies to tumor necrosis factor (TNF)-blocking antibodies for the treatment of inflammatory diseases has generated increasing interest. In particular, selective inhibition of TNF receptor 1 (TNFR1) promises a more precise intervention, tackling only the pro-inflammatory responses mediated by TNF while leaving regenerative and pro-survival signals transduced by TNFR2 untouched. We recently generated a monovalent anti-TNFR1 antibody fragment (Fab 13.7) as an efficient inhibitor of TNFR1. To improve the pharmacokinetic properties of Fab 13.7, the variable domains of the heavy and light chains were fused to the N-termini of newly generated heterodimerizing Fc chains. This novel Fc heterodimerization technology, designated "Fc-one/kappa" (Fc1κ) is based on interspersed constant Ig domains substituting the CH3 domains of a γ1 Fc. The interspersed immunoglobulin (Ig) domains originate from the per se heterodimerizing constant CH1 and CLκ domains and contain sequence stretches of an IgG1 CH3 domain, destined to enable interaction with the neonatal Fc receptor, and thus promote extended serum half-life. The resulting monovalent Fv-Fc1κ fusion protein (Atrosimab) retained strong binding to TNFR1 as determined by enzyme-linked immunosorbent assay and quartz crystal microbalance, and potently inhibited TNF-induced activation of TNFR1. Atrosimab lacks agonistic activity for TNFR1 on its own and in the presence of anti-human IgG antibodies and displays clearly improved pharmacokinetic properties.

Development of L-Asparaginase Biobetters: Current Research Status and Review of the Desirable Quality Profiles

L-Asparaginase (ASNase) is a vital component of the first line treatment of acute lymphoblastic leukemia (ALL), an aggressive type of blood cancer expected to afflict over 53,000 people worldwide by 2020. More recently, ASNase has also been shown to have potential for preventing metastasis from solid tumors. The ASNase treatment is, however, characterized by a plethora of potential side effects, ranging from immune reactions to severe toxicity. Consequently, in accordance with Quality-by-Design (QbD) principles, ingenious new products tailored to minimize adverse reactions while increasing patient survival have been devised. In the following pages, the reader is invited for a brief discussion on the most recent developments in this field. Firstly, the review presents an outline of the recent improvements on the manufacturing and formulation processes, which can severely influence important aspects of the product quality profile, such as contamination, aggregation and enzymatic activity. Following, the most recent advances in protein engineering applied to the development of biobetter ASNases (i.e., with reduced glutaminase activity, proteolysis resistant and less immunogenic) using techniques such as site-directed mutagenesis, molecular dynamics, PEGylation, PASylation and bioconjugation are discussed. Afterwards, the attention is shifted toward nanomedicine including technologies such as encapsulation and immobilization, which aim at improving ASNase pharmacokinetics. Besides discussing the results of the most innovative and representative academic research, the review provides an overview of the products already available on the market or in the latest stages of development. With this, the review is intended to provide a solid background for the current product development and underpin the discussions on the target quality profile of future ASNase-based pharmaceuticals.