Use of operating windows in the assessment of integrated robotic systems for the measurement of bioprocess kinetics.

This study examines the utility of an automated liquid handling robot integrated with a microwell plate reader to enable the rapid acquisition of bioprocess kinetic data. The relationship between the key parameters for liquid handling accuracy and precision and the sample detection period has been characterized for typical low-viscosity (<2.0 mPa x s) aqueous and organic phases and for a high-viscosity aqueous phase (60 mPa x s), all exhibiting Newtonian rheology. The use of a simple graphical method enables the suitability of a given automation platform to be assessed once the user has determined the minimum sample detection period and the minimum accurate and precise dispense volume. This provides for a reduction in the duration of any experiment by maximizing well usage within each microwell plate. The suitability of employing an integrated automation platform to gather kinetic data for systems typical of those encountered in bioprocessing is analyzed via a series of case studies. Application to alkaline cell lysis, where disruption is complete within 120 s, showed that the range of available dispense volumes and the number of wells that can be utilized is limited. In contrast, analysis of a system exhibiting slow process kinetics, the fermentation of Escherichia coli TOP10 pQR239 in microwell plates, demonstrated that, for a typical sample detection period of 30 min, the only restrictions on the degree of well utilization are the liquid handling accuracy and precision and the volume capacity of the liquid handling robot. Finally, liquid-liquid extraction, an example of a kinetically independent operation, was also examined. In this case, only a single equilibrium measurement is required, which means that the only restrictions to the utilization of the integrated devices are the liquid handling accuracy and precision. Integrated automation platforms represent a powerful process development tool over traditional experimental methods used for bioprocess development. Smaller volumes of reagent and sample can be used to achieve greater throughput, while high levels of reproducibility and sensitivity are maintained.