title: High-speed angle-resolved imaging of a single gold nanorod with microsecond temporal resolution and one-degree angle precision.
abstract: We developed two types of high-speed angle-resolved imaging methods for single gold nanorods (SAuNRs) using objective-type vertical illumination dark-field microscopy and a high-speed CMOS camera to achieve microsecond temporal and one-degree angle resolution. These methods are based on: (i) an intensity analysis of focused images of SAuNR split into two orthogonally polarized components and (ii) the analysis of defocused SAuNR images. We determined the angle precision (statistical error) and accuracy (systematic error) of the resultant SAuNR (80 nm × 40 nm) images projected onto a substrate surface (azimuthal angle) in both methods. Although both methods showed a similar precision of ∼1° for the azimuthal angle at a 10 μs temporal resolution, the defocused image analysis showed a superior angle accuracy of ∼5°. In addition, the polar angle was also determined from the defocused SAuNR images with a precision of ∼1°, by fitting with simulated images. By taking advantage of the defocused image method's full revolution measurement range in the azimuthal angle, the rotation of the rotary molecular motor, F1-ATPase, was measured with 3.3 μs temporal resolution. The time constants of the pauses waiting for the elementary steps of the ATP hydrolysis reaction and the torque generated in the mechanical steps have been successfully estimated. The high-speed angle-resolved SAuNR imaging methods will be applicable to the monitoring of the fast conformational changes of many biological molecular machines.
authors: Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo , Tokyo 113-8656, Japan.
authors: Sawako
authors: S
authors: Enoki
authors: Ryota
authors: R
authors: Iino
authors: Yamato
authors: Y
authors: Niitani
authors: Yoshihiro
authors: Y
authors: Minagawa
authors: Michio
authors: M
authors: Tomishige
authors: Hiroyuki
authors: H
authors: Noji
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001407:Bacillus / Q000201:enzymology*; D004867:Equipment Design; D006046:Gold / Q000737:chemistry*; D006868:Hydrolysis; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D008853:Microscopy / Q000295:instrumentation* / Q000379:methods; D008958:Models, Molecular; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure; D006180:Proton-Translocating ATPases / Q000032:analysis* / Q000378:metabolism
chemical_list: D006046:Gold; D000255:Adenosine Triphosphate; D006180:Proton-Translocating ATPases