Flexural rigidity of a single microtubule

Microtubules, which are flexible biopolymers, can be used for nanotechnology applications (e.g., nano-actuator) as they have a rigidity similar to that of plexyglass and other plastic materials. The flexural rigidity, or bending stiffness, of nucrotubules was measured using a laser trapping technique and dark-field microscopy. One end of a microtubule rod was chemically bound to a glass microsphere, while the other end was bound to a silica glass substrate. Then, the microsphere was lasertrapped and manipulated to exert three different deformation modes on the microtubule. The values of flexural rigidity for these deformations were between 10^-25 and 10^-23 Nm² as measured for the 5-25 μm length microtubules. The origin of the length dependence of the flexural rigidity of microtubules is discussed.