Single carbon nanotube-based reversible regulation of biological motor activity
Inoue, Y.; Nagata, M.; Matsutaka, H.; Okada, T.; Sato, M.K.; Ishijima, A.
Acs Nano 9(4): 3677-3684
Because of their small size and high thermal conductivity, carbon nanotubes (CNTs) are excellent candidates for exploring heat transfer at the level of individual molecules in biological research. With a view toward examining the thermal regulation of single biomolecules, we here developed single CNTs as a new platform for observing the motile activity of myosin motors. On multiwall CNTs (diameter ∼170 nm; length ∼10 μm) coated with skeletal-muscle myosin, the ATP-driven sliding of single actin filaments was clearly observable. The normal sliding speed was ∼6 μm/s. Locally irradiating one end of the CNT with a red laser (642 nm), without directly irradiating the active myosin motors, accelerated the sliding speed to ∼12 μm/s, indicating the reversible activation of protein function on a single CNT in real time. The temperature along the CNT, which was estimated from the temperature-dependence of the sliding speed, decreased with the distance from the irradiated spot. Using these results with the finite element method, we calculated a first estimation of the thermal conductivity of multiwall CNTs in solution, as 1540 ± 260 (Wm(-1) K(-1)), which is consistent with the value estimated from the width dependency of multiwall CNTs and the length dependency of single-wall CNTs in a vacuum or air. The temporal regulation of local temperature through individual CNTs should be broadly applicable to the selective activation of various biomolecules in vitro and in vivo.