Scale‐down characterization of post‐centrifuge flocculation processes for high‐throughput process development

Abstract

AbctractFlocculation unit operations are being revisited as a strategy to ease the burden posed on clarification and purification operations by the increasingly high cell density cultures used in the biopharmaceutical industry. The purpose of this study was to determine the key process parameters impacting flocculation scale-up and use this understanding to develop an automated ultra-scale down (USD) method for the rapid characterization of flocculation at the microliter scale. The conditions under which flocculation performance of a non-geometrically similar vessel three orders of magnitude larger can be mimicked by the USD platform are reported. Saccharomyces cerevisiae clarified homogenate was flocculated with poly(ethyleneimine) (PEI) to remove the residual solids remaining in the centrate. Flocculant addition time modulated flocculation performance depending on the predominant mixing time scale (i.e. macro-, meso- or micromixing). Particle growth and breakage was mimicked at the two flocculation scales by the average turbulent energy dissipation (εavg) and impeller tip speed (vtip) scale-up bases. The results obtained were used to develop an USD method. The USD method proposed uses constant εavg as the scale-up basis under a micromixing controlled regime. These conditions mimicked the STR flocculation performance within a ±5% error margin. Operation in the mesomixing regime led to particle size deviations between the flocculation scales of ≤50 %. These results, in addition to the microscopic observations made, demonstrate the USD system presented in this work can produce process-relevant flocculated material at the microliter scale under the correct operating conditions.

Procedure to Evaluate the Efficiency of Flocculants for the Removal of Dispersed Particles from Plant Extracts

“…The method described here can easily be adapted to other feed stocks and is therefore also relevant for scientists and engineers developing clarification strategies for mammalian cell cultures and food/feed production processes. Especially plant-based processes will benefit from the intermediate sample volumes suggested here because plant extracts can contain particles up to 1 mm in diameter which are incompatible with microplate formats 21 , e.g. because the mixing dynamics differ due to a particle diameter to vessel diameter ratio that is not representative of the process scale.…”

A modular approach for the ultra-scale-down of depth filtration

“…pH, conductivity, etc.). Screening of filtration conditions could be integrated with existing high throughput harvest, particle conditioning, and clarification workflows [3,[10][11][12][13][14][15][16]. Laboratory qualification of clinical production processes could be expedited and concluded with less material.…”

The microscale flocculation test (MFT)—A high-throughput technique for optimizing separation performance

“…For example, Kang et al [11] developed a novel cell culture flocculation process using a stimulus-responsive polymer to streamline antibody purification processes via a full-factorial DOE study at a 5 mL culture scale. A recent study developed an automated scaled-down method for optimizing the flocculation of pre-clarified cell broths [12]. These innovations are being driven primarily by the need within the biotechnology industry to minimize the occurrence of process bottlenecks and to bring the pace of development of downstream separation processes in line with the upstream product discoveries [13].…”