Temperature dependence of microtubule-based active fluid

Kinesin molecular motors step along microtubules in cells to transport cargos with a stepping speed that increases with temperature. This temperature-dependent speed was reported to follow the Arrhenius Law. Kinesin was also used to drive microtubule-based active fluid; however, whether the flow of the fluid follows the Arrhenius Law to accelerate with temperature remains unclear. Here, we systematically characterized the flow speed of kinesin-driven active fluid as a function of temperature, followed by fitting the data to the Arrhenius equation. We characterized the temperature dependence of the flow speed in three different motor systems: (1) processive motors, (2) non-processive motors, and (3) an even mixture of both, finding that these systems followed the Arrhenius Law and developed faster flows with increasing temperature. However, we found that the relation between the flow speed and temperature could be reversed by introducing a depleting agent that had a temperature-dependent micelle formation, causing the active fluid to flow more slowly when heated. Finally, we heated and cooled the fluid repeatedly to accelerate and decelerate the flow sequentially, demonstrating the ability to control the flow speed in real time.