Force Measurement and Modeling for Motor Proteins Be- Tween Microsphere and Microfluidic Channel Surface

This paper reports a fundamental study on a force measurement and mechanical modeling of a microbead coated with multiple motor proteins, kinesins, which moves on a cytoskeletal filament, microtubules (MTs). We utilized a laminar flow in a microfluidic channel to apply torque  and drag force FD to the bead, whose values can be derived theoretically. As a result, the adhesion force FAdh was determined based on the mechanical modeling. Here, the flow rate necessary to break kinesin-MT bindings was experimentally measured, and two models were applied to derive fluid forces that was also calculated by a simulation software, FLUENT. Consequently, adhesion forces of 363 pN and 31 pN were obtained under no ATP and 1 mM ATP conditions, respectively. The proposed measurement methodology is advantageous in analyzing multiple microbeads transported by kinesin-MT interaction in a microfluidic system.