[18p-A201-1~11] 3.1 光学基礎・光学新領域（旧3.2「材料・機器光学」と統合）

▲ [18p-A201-6] Two-Stage Optical Trapping Mechanism of Protein at its Air/Solution Interface

Po-Wei Yi^1,2、Wei-Hsiang Chiu¹、Shuichi Toyouchi¹、Roger Bresoli-Obach^1,3,4、Johan Hofkens^3,5、Eri Chatani⁶、Yoichiroh Hosokawa²、Teruki Sugiyama^1,2、〇(P)Hiroshi Masuhara¹ (1.Nat'l Yang Ming Chiao Tung Univ., Taiwan、2.NAIST、3.KULeuven, Belgium、4.Univ. Ramon Llull, Spain、5.Max-Planck Inst., Germany、6.Kobe Univ.)

キーワード：Optical trapping, Protein assembly, Interface

Optical trapping by a single focused laser beam is used as a tool to manipulate individual microparticles and living cells, while nanoparticles are trapped as a single small assembly in solution. However, the picture is completely different at interface.¹⁾ The nano- and micro-particles are gathered along the interface, giving a single extremely large disk-like assembly. Its size reaches a few ten micrometers, which is interpreted in terms of scattering and propagation of the trapping laser along the interface. Recently we reported that a similar behavior is induced for protein lysozyme solution and its assembly size is a sub-millimeter in diameter and a few ten micrometers in depth.²⁾
Here we apply simultaneous transmission and fluorescence imaging and elucidate no-linear assembling nature with respect to trapping laser power and protein concentration. Upon irradiation a “white ring” appears from the focus in the transmission image and expands to the outside over a few ten micrometers. The fluorescence imaging of a dye-bonded lysozyme directly reveals the assembling behavior, while it is visualized by monitoring the movement of added polystyrene microparticles. Based on these results, we propose a two-stage mechanism; 1) formation and widening of a shallow lysozyme layer and 2) the later trapping of lysozyme clusters expelling the lysozyme layer from the focus.
1. H. Masuhara, K. Yuyama, Annu. Rev. Phys. Chem., 2021, 72, 565-589
2. P.-W. Yi et al., J. Phys. Chem. C, 2021, 125, 18988-18999