Kress Holger, Stelzer Ernst H K, Griffiths Gareth, Rohrbach Alexander
European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany.
Phys Rev E Stat Nonlin Soft Matter Phys. 2005 Jun;71(6 Pt 1):061927. doi: 10.1103/PhysRevE.71.061927. Epub 2005 Jun 29.
We show how to control the relative radiation pressure and thereby the stable trap position of an optically trapped bead by variation of the mean incident axial photon momentum. The thermal position fluctuations of a trapped bead are recorded by a three-dimensional back-focal-plane interferometry. The interferometric detection signals are in agreement with predictions based on an extended Mie theory. Depending on the application, the unique and linear range of such a detection system can be optimized by controlling the trap position of the bead. We use this method to investigate in three dimensions the binding of beads to membranes of living cells during phagocytosis. We found that independent of the bead coating (IgG, complement, LPS, avidin) the most frequent initial mechanical response of the cell was a downward pulling of the bead into the cell. The time delay between binding and response was on average 2 s.
我们展示了如何通过改变平均入射轴向光子动量来控制相对辐射压力，从而控制光学捕获微珠的稳定捕获位置。通过三维背焦平面干涉测量法记录捕获微珠的热位置波动。干涉检测信号与基于扩展米氏理论的预测结果一致。根据应用需求，可通过控制微珠的捕获位置来优化这种检测系统独特的线性范围。我们使用这种方法在三个维度上研究吞噬作用过程中微珠与活细胞膜的结合。我们发现，无论微珠包被物（免疫球蛋白G、补体、脂多糖、抗生物素蛋白）如何，细胞最常见的初始机械反应是将微珠向下拉入细胞内。结合与反应之间的平均时间延迟为2秒。
