Biomolecular Nano-Flow-Sensor to Measure Near-Surface Flow

We have proposed and experimentally demonstrated that the measurement of the near-surface flow at the interface between a liquid and solid using a 10 nm-sized biomolecular motor of F(1)-ATPase as a nano-flow-sensor. For this purpose, we developed a microfluidic test-bed chip to precisely control the liquid flow acting on the F(1)-ATPase. In order to visualize the rotation of F(1)-ATPase, several hundreds nanometer-sized particle was immobilized at the rotational axis of F(1)-ATPase to enhance the rotation to be detected by optical microscopy. The rotational motion of F(1)-ATPase, which was immobilized on an inner surface of the test-bed chip, was measured to obtain the correlation between the near-surface flow and the rotation speed of F(1)-ATPase. As a result, we obtained the relationship that the rotation speed of F(1)-ATPase was linearly decelerated with increasing flow velocity. The mechanism of the correlation between the rotation speed and the near-surface flow remains unclear, however the concept to use biomolecule as a nano-flow-sensor was proofed successfully. (See supplementary material 1)