Expanded bed adsorption/desorption of proteins with Streamline Direct CST I adsorbent

Theoretical Investigation of the Nonlinear General Rate Model with the Bi-Langmuir Adsorption Isotherm Using Core-Shell Adsorbents

Core-shell particles enable the separation of intricate mixtures in a highly efficient and rapid manner. The porous shell particles increased the separation efficiency with expedited flow rates due to an abatement in the pore volume accessible for longitudinal diffusion and a decrease in diffusion path length. This study focuses on the numerical approximation of a nonlinear isothermal general rate model applied to stationary bed columns that are replete with inert core adsorbents featuring double adsorption sites. The transport of solute in heterogeneous porous media can be modeled by a nonlinear convection acquiescent partial differential equation system together with a specific nonlinear algebraic relation: the bi-Langmuir adsorption isotherm. Therefore, it is important to develop accurate and reliable numerical techniques that can perform accurate numerical simulations of these models. We extended and implemented a second-order, semidiscrete, high-resolution finite volume method to simulate the governing equations of the model. Single solute flow and multi component mixture flows are assessed through a series of numerical experiments to theoretically illustrate the repercussions of intraparticle diffusion, film mass resistance, axial dispersion, and the size of the inert core radius upon simulated elution curves. Standard performance criteria are assessed to determine the optimal core radius fraction range for optimizing the separation performance.

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).

Experimental characterization of next-generation expanded-bed adsorbents for capture of a recombinant protein expressed in high-cell-density yeast fermentation

Expanded-bed adsorption (EBA) can be particularly useful in protein recovery from high-cell-density fermentation broth where conventional methods for harvest and clarification, such as continuous centrifugation and depth filtration, demand long processing times and are associated with high costs. In this work, the use of next-generation high-particle-density EBA adsorbents, including two mixed-mode resins, for the direct capture of a recombinant protein expressed in yeast at high cell densities is evaluated. Using classical experimental approaches and under different conditions (pH, salt, etc.), Langmuir isotherm parameters for these resins are obtained along with pore diffusivity values. Additional batch adsorption studies with Fastline® MabDirect, the resin that demonstrated the highest static binding capacity for the recombinant protein of interest under the conditions evaluated in this study, indicate competitive binding of nontarget proteins and approximately a 30% reduction in equilibrium binding capacity to 50 mg/mL settled bed in the presence of a 5%-10% cell concentration. Packed-bed (PB) dynamic binding capacities for the MabDirect resin (25-40 mg/mL PB) were significantly higher than for the Fastline® HSA resin and for the MabDirect MM resin in expanded-bed mode (5-10 mg/mL settled bed). Bed expansion behavior for the mMabDirect MM resin along with process yield and eluate purity are identified as a function of linear velocity and cell density, demonstrating process feasibility for pilot scale use.

Studies of lysozyme binding to histamine as a ligand for hydrophobic charge induction chromatography

Histamine was immobilized on Sepharose CL-6B (Sepharose) for use as a ligand of hydrophobic charge induction chromatography (HCIC) of proteins. Lysozyme adsorption onto Histamine-Sepharose (HA-S) was studied by adsorption equilibrium and calorimetry to uncover the thermodynamic mechanism of the protein binding. In both the experiments, the influence of salt (ammonium sulfate and sodium sulfate) was examined. Adsorption isotherms showed that HA-S exhibited a high salt tolerance in lysozyme adsorption. This property was well explained by the combined contributions of hydrophobic interaction and aromatic stacking. The isotherms were well fitted to the Langmuir equation, and the equilibrium parameters for lysozyme adsorption were obtained. In addition, thermodynamic parameters (DeltaH(ads), DeltaS(ads), and DeltaG(ads)) for the adsorption were obtained by isothermal titration calorimetry by titrating lysozyme solutions into the adsorbent suspension. Furthermore, free histamine was titrated into lysozyme solution in the same salt-buffers. Compared with the binding of lysozyme to free histamine, lysozyme adsorption onto HA-S was characterized by a less favorable DeltaG(ads) and an unfavorable DeltaS(ads) because histamine was covalently attached to Sepharose via a three-carbon-chain spacer. Consequently, the immobilized histamine could only associate with the residues on the protein surface rather than those in the hydrophobic pocket, causing a less favorable orientation between histamine and lysozyme. Further comparison of thermodynamic parameters indicated that the unfavorable DeltaS(ads) was offset by a favorable DeltaH(ads), thus exhibiting typical enthalpy-entropy compensation. Moreover, thermodynamic analyses indicated the importance of the dehydration of lysozyme molecule and HA-S during the adsorption and a substantial conformational change of the protein during adsorption. The results have provided clear insights into the adsorption mechanisms of lysozyme onto the new HCIC material.

Mathematical modeling and simulation of inulinase adsorption in expanded bed column

A mathematical model for an expanded bed column was developed to predict breakthrough curves for inulinase adsorption on Streamline SP ion-exchange adsorbent, using a crude fermentative broth with cells as the feedstock. The kinetics and mass transfer parameters were estimated using the PSO (particle swarm optimization) heuristic algorithm. The parameters were estimated for each expansion degree (ED) using three breakthrough curves at initial inulinase concentrations of 65.6UmL(-1). In sequence, the model parameters for an ED of 2.5 were validated using the breakthrough curve at an initial concentration of 114.4UmL(-1). The applicability of the validated model in process optimization was investigated, using the model as a process simulator and experimental design methodology to optimize the column and process efficiencies. The results demonstrated the usefulness of this methodology for expanded bed adsorption processes.

Mechanistic analysis on the effects of salt concentration and pH on protein adsorption onto a mixed-mode adsorbent with cation ligand

Streamline Direct HST is a new kind of mixed-mode adsorbent with cation exchange ligand, especially developed for the expanded bed adsorption process, which can capture target protein directly from the moderate ionic strength feedstock without the need of dilution or other additives. In this study, the isotherm adsorption behaviors and the isocratic retention factors of bovine serum albumin (BSA) on Streamline Direct HST were measured, and the corresponding adsorption mechanisms were also described. The results indicated that Streamline Direct HST shows the typical property of salt-independent adsorption and the maximum binding capacity of BSA occurs near the isoelectric point of BSA. When there are some amounts of electrostatic repulsion protein-adsorbent interactions, the multilayer adsorption could be found, and high salt concentration does not favor the adsorption of protein. A patch-controlled adsorption process and an oriented adsorption model are proposed for describing the adsorption behaviors under electrostatic repulsion condition.