Collaboration on “Formation of millimeter scale liquid-like domain of glycine by a focused laser beam” and invited presentation on “Laser-induced crystallization ad crystal growth of amino acids and proteins in solution” in 11th Japan-Belgium Symposium on Polymer Science (Nov. 8-11, 2009, Tokyo)
金額 69,298.-
November 5-7; Left Hsinchu and arrived at Nara Institute of Science and Technology (NAIST), and extended collaboration experiment with Associate Professor Teruki Sugiyama, Mr. Kei Ishiguro, and Mr. Ken-ichi Yuyama.
November 8-10; Attended the 11th Japan-Belgium Symposium on Polymer Science in Tokyo Institute of Technology, presented an invited paper on “Laser–induced Crystallization and Crystal Growth of Amino Acids and Proteins in Solution”, and discussed on the relevant topics with Japanese and Belgian scientists. Also chaired the 1st morning session of Nov. 10.
November 11; Left Tokyo and arrived back at Hsinchu 二、 心得（可含照片）
(1) Collaboration experiment
In this collaboration, we have succeeded in the formation of a mm-scale liquid-like cluster of glycine by focusing a laser beam at a different focal position, a glass/solution interface of the solution. We examine and consider the formation process of the large cluster on the basis of the results of direct observation and surface height measurement.
附件 V
A 40 µl portion of glycine D2O solution (3.6 M) was put on a cover glass with a highly hydrophilic surface, where a thin solution layer with 120-160 µm thickness was prepared. A near-infrared CW laser beam of the linear polarization (λ = 1064 nm) with varying the intensity from 0.7 to 1.4 W was focused at a glass/solution interface via an objective lens (60× magnification, NA=0.90). The surrounding area at the focal spot was directly observed under halogen light irradiation, and the images were captured from the obliquely upward of a sample using a CCD camera. The temporal change of the solution surface height during 10 min-laser irradiation was monitored by a laser confocal displacement meter every 50 ms.
Before laser irradiation, only the top of the objective lens was observed as a dark disk through a petri dish and the solution in Fig. 1a (1). After 30 sec-laser irradiation, we clearly identified about 2 mm-sized and circular area (white dashed line) around the focal spot by CCD camera as shown in Fig. 1a (2), which had higher refractive index than that of the surrounding solution. For further laser irradiation, the area gradually became larger until 210 sec, and eventually it grew to the size with a few mm in diameter, as could be seen even by the naked eye as in Fig. 1a (3). However, at 225 sec the area suddenly disappeared in Figure 1a (4). During the area formation, temporal change of the solution surface height simultaneously measured. The result in Fig. 1b shows that the solution surface elevation is followed with the area growth observed directly. Surprisingly the height became higher than the initial position. We consider that this area with a high refractive index is produced by gathering the small liquid-like cluster. As far as we know this is the first demonstration of the formation of the mm-scale liquid-like cluster, which is much larger than the focal spot. Note that the focal point was moved to the surface of the large cluster after it formed, the crystallization was immediately induced. Thus, the large cluster is expected to be the precursor of the crystal, and the understanding will lead us the elucidation of nucleation and crystallization process.
Fig.1 (a) CCD camera images around the focal spot.
(b) Temporal change of the solution surface height during laser irradiation.
The images shown in Fig.1(a) were captured at each point in the graph.
(2) Invited paper and chair
The content of my lecture is concerned with new frontiers in molecular science opened by intense laser irradiation, particularly with laser-induced crystallization and crystal growth of molecules in solution. I talked as follows.
In 2002 we reported for the first time lysozyme crystallization triggered by femtosecond laser ablation of its saturated aqueous solution. The ablation induces shockwave propagation, and generation and collapse of tiny bubbles, leading to local convection in solution, and thus we call this phenomenon “Laser Tsunami
Now we have been extending the studies on the underlying dynamics and mechanism by time-resolved spectroscopy and imaging.
In 2007 we succeeded in crystallization of glycine by photon pressure of a focused CW near IR laser beam and now we call this crystallizaiton “Laser Trapping Crystallization” and explore the relevant behaviors. An intense CW laser beam of 1064 nm was introduced into an inverted microscope and focused into a thin film of super-saturated heavy water solution of glycine with an objective lens of 40 x magnification and NA of 0.9. The irradiation position is important and single crystal formation was observed only upon focusing the beam at an air/solution interface. The crystal grew up to a few tens μm and dependences of the crystallization on laser power and laser polarization are now being examined.
When laser irradiation was performed at a solution/glass interface of the glycine solution, no crystallization was observed, and instead millimeter-sized liquid-like domain was formed. It is surprising to see that the size of the domain is extremely larger than the focal point, while the crystallization through this domain was also confirmed.
In addition it was demonstrated that growth of a spontaneously prepared (not by laser) glycine crystal can be controlled by irradiation at the solution/glass interface with the trapping laser.
These results show high potential of laser trapping method in molecular, supramolecular, and polymer sciences, while we expect our approach will contribute to understand crystallization mechanism of amino acids and proteins in solution.
Also I chaired two speakers ; Th. Verbiest (Belgium) and H. Takezoe (Japan).
三、 考察參觀活動(無是項活動者，或前已敘述者可省略此項) None
四、 建議
The collaboration topic is extremely unique and will give a strong impact upon different two research fields of laser trapping and crystallization mechanism. Systematic and detailed study is necessary and will be developed in NCTU and NAIST.
The intimate relation between Japan and Belgium has been grown up since 1982. Under this situation I have participated from NCTU and discussed on many topics of mutual interests with Japanese and Belgian scientists. I am sure my presence will contribute to setup of future collaboration of NCTU with Japanese and Belgian Universities.
五、 攜回資料名稱及內容
A copy of program and some information of 11th Japan-Belgium Symposium on Polymer Science
六、其他 None