Characterization of cellular mechanical torque by rotation of ferromagnetic nanowire

Single cell's left-right biased motion, or chirality, is recent finding that may explain the origin of left right asymmetry at tissue development. Yet sufficient tools are lack to enrich our understanding toward this field. Here, to characterize cytoskeletal chirality, we use nanotechnology that offers spatial cues in the scale similar to the size of cells. We applied ferromagnetic nickel nanowires as the sensors attached to living cells. Within a uniform, horizontal magnetic field, cellular chirality rotates the nanowires and generates a mechanical torque. This cellular torque is eventually balanced with the magnetic torque created from the horizontal magnetic field at a clockwise of counter-clockwise angle. As such, this angular alignment reveals a quantifiable value of cytoskeletal chirality. Importantly, the exhibition of cellular chirality is dependent on cell type and time. Also, as the key factor of cytoskeleton, actin plays an important role in this feature. These findings demonstrate a new approach for future investigation of cell mechanics, with implication for tissue regeneration.