Matsuda Yu, Hanasaki Itsuo, Iwao Ryo, Yamaguchi Hiroki, Niimi Tomohide
Institute of Materials and Systems for Sustainability, Nagoya University , Furo-cho, Chikusa, Nagoya, Aichi 464-8603, Japan.
Department of Mechanical Systems Engineering, Tokyo University of Agriculture and Technology , Naka-cho 2-24-16, Koganei, Tokyo 184-8588, Japan.
Anal Chem. 2016 Apr 19;88(8):4502-7. doi: 10.1021/acs.analchem.6b00390. Epub 2016 Mar 28.
We focus on the issue of limited number of samples in the single particle tracking (SPT) when trying to extract the diffusion anisotropy that originates from the particle asymmetry. We propose a novel evaluation technique of SPT making use of the relation of the consecutive three steps. More specifically, the trend of the angle comprised of the three positions and the displacements are plotted on a scatter diagram. The particle anisotropy dependence of the shape of the scatter diagram is examined through the data from the standard numerical model of anisotropic two-dimensional Brownian motion. Comparison with the existing method reveals the faster convergence in the evaluation. In particular, our proposed method realizes the detection of diffusion anisotropy under the conditions of not only less number of data but also larger time steps. This is of practical importance not only when the abundant data is hard to achieve but also when the rotational diffusion is fast compared to the frame rate of the camera equipment, which tends to be more common for smaller particles or molecules of interest.
在尝试提取源于粒子不对称性的扩散各向异性时，我们关注单粒子追踪（SPT）中样本数量有限的问题。我们提出了一种利用连续三步关系的新型SPT评估技术。更具体地说，由三个位置和位移组成的角度趋势绘制在散点图上。通过来自各向异性二维布朗运动标准数值模型的数据，研究散点图形状的粒子各向异性依赖性。与现有方法的比较表明评估中的收敛更快。特别是，我们提出的方法不仅在数据量较少而且时间步长较大的条件下实现了扩散各向异性的检测。这不仅在难以获得大量数据时具有实际重要性，而且在旋转扩散相对于相机设备的帧率较快时也具有实际重要性，这对于较小的感兴趣粒子或分子来说往往更常见。
