(1360-A) Quantitative evaluation of pipetting parameters in cell suspension by liquid handling system

Abstract: Pipetting for liquid handling is one of the most fundamental operations in biological experiments. Among various experimental materials, animal cells are particularly sensitive to physical perturbations, requiring careful handling to avoid unexpected effects. However, most experimental protocols describe procedures only in qualitative terms, such as "mix slowly," leading to inevitable variations in technique among persons. In contrast, robots, including liquid dispensers, can operate with higher spatiotemporal repeatability (in mm and msec units) than humans. In this study, we quantitatively evaluated the impact of physical parameters in liquid handling on experimental results, using cultured cell operations as a subject.

We used the OT-2 liquid handling system (Opentrons Labworks Inc.) for preparing and aliquoting cell suspensions, assessing the impact of its parameters. We prepared suspensions of HEK293T cells and aliquoted them from a predetermined depth in the microplate well at regular intervals for cell counting, quantifying the rate of cell sedimentation over time. Furthermore, we set various combinations of pipetting parameters (flow rate, mixing volume, and number of mixes) when resuspending cell pellet under certain conditions and evaluated the uniformity of suspension achieved. These results provide insights into the effects of physical parameters that are not controllable by manual human operation. They also serve as a proof of concept for digitizing experimental procedures, previously handled with vague expressions, using affordable robots.