title: Single carbon nanotube-based reversible regulation of biological motor activity.
abstract: 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.
authors.affiliation: †Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Aoba-ku, Sendai, 980-8577, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Inoue
authors.affiliation: †Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Aoba-ku, Sendai, 980-8577, Japan.
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Nagata
authors.affiliation: †Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Aoba-ku, Sendai, 980-8577, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Matsutaka
authors.affiliation: ‡Institute of Fluid Science, Tohoku University, Aoba-ku, Sendai, 980-8577, Japan.
authors.forename: Takeru
authors.initials: T
authors.lastname: Okada
authors.affiliation: †Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Aoba-ku, Sendai, 980-8577, Japan.
authors.forename: Masaaki K
authors.initials: MK
authors.lastname: Sato
authors.affiliation: †Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Aoba-ku, Sendai, 980-8577, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Ishijima
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D009218:Myosins / Q000737:chemistry* / Q000378:metabolism*; D036103:Nanotechnology / Q000379:methods*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D013814:Thermal Conductivity
chemical_list: D037742:Nanotubes, Carbon; D009218:Myosins
keywords: carbon nanotube; laser-induced heating; molecular motor; myosin; thermal conductivity