(182a) Design and Control of Novel Droplet-Based System for Estimating Protein Crystallization Kinetics

Packed-bed chromatography is the most common bioseparation process for biopharmaceutical manufacturing because of its high resolution. However, even with recent technologies for operational improvements [1], chromatographic purification scales linearly with production rate and is a substantial proportion of the manufacturing costs. Chromatography has become more than half of the cost of goods for some biotherapeutic proteins such as monoclonal antibodies (mAbs) [2], which will increase as titers and product demands continue to increase [3–6]. Among alternative non-chromatography separation methods, crystallization is already widely used for the purification of small-molecule pharmaceutical compounds due to its cost-effectiveness. Crystallization has operating costs that scale sub-linearly with throughput [3,7].

Crystallization technology for large-molecule therapeutic proteins is much less mature than for small molecules and is mostly still in research and development other than a few isolated products [1,3,6,7]. Protein crystallization is mainly studied by micro-batch scale protein crystallization experiments, focused on high-throughput protein crystallization screening. Few studies consider operation at the production scale. Crystallization kinetics are required for the design and control of such process but only a limited quantity of protein is available during the initial stage of process development.

This presentation describes the design of a droplet-based evaporative system for the evaluation of candidate crystallization conditions and the estimation of kinetics using only a minimum quantity of protein. The temperature and humidity of air are controlled for evaporation and rehydration of the droplet, which are used for manipulating supersaturation. Multi-angle images of the droplet are taken and analyzed on-line to obtain the droplet volume and crystal sizes. Crystallization kinetics are estimated based on a first-principles process model and experimental data. Tight control of temperature and humidity of the air, fast and accurate image analysis, and accurate estimation of crystallization kinetics are experimentally demonstrated for a model protein lysozyme.

References:

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