Minimizing shear stress when using liquid handling systems

In this application note, Eppendorf presents experimental data on the impact of liquid handling-induced shear stress on the integrity of functional units like cells, DNA, and proteins, which has been a relatively understudied area. The study employs both computer simulations and laboratory experiments to investigate shear stress in different liquid handling systems. The research demonstrates that functional units do indeed experience shear stress during liquid handling, although the duration of this stress is very brief, primarily occurring at the tip's orifice. The number of pipetting steps is a critical factor influencing shear stress, with minimal effects on cell death and proliferation, even at maximum piston speed, for HEK 293 cells when using just one pipetting step. However, with iPSCs, the results become more complex, emphasizing that both the instrument and the tip together form a system that influences flow velocity.