2006 Fiscal Year Final Research Report Summary
DEVELOPMENT OF A NOVEL DETECTION METHOD FOR SINGLE NONFLUORECSECT MOLECULES IN LIQUID SOLUTIONS
| Project/Area Number |
15205011
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Analytical chemistry
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| Research Institution | KYUSHU UNIVERCITY |
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Principal Investigator |
HARATA Akira Kyushu University, Faculty of Engineering Sciences, Professor, 大学院総合理工学研究院, 教授 (90222231)
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| Co-Investigator(Kenkyū-buntansha) |
FURUYA Kenji Kyushu University, Faculty of Engineering Sciences, Associate Professor, 大学院総合理工学研究院, 助教授 (70229128)
ISHIOKA Toshio Kyushu University, Faculty of Engineering Sciences, Research Associate, 大学院総合理工学研究院, 助手 (60304838)
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| Project Period (FY) |
2003 – 2006
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| Keywords | single molecule detection / nonfluorescent molecules / separation analysis / photothermal spectroscopy / thermal lens / multi-color enhancement / transient absorption / nonradiative relaxation |
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| Research Abstract |
One of the ultimate goals of analytical chemistry is to detect certain target molecules in liquid solutions and to observe molecular behavior in-situ. Although techniques based on single molecule detection of biological species begin to provide a variety of new and essential information on the way life works recently, the target molecules are limited to exceptionally highly fluorescent species even for molecule detection in a simple solution. The greater parts of biologically and environmentally important chemicals, such as amino acids, nucleotides, proteins, hormones and so on, are natively nonfluorescent. Thus, we aim to develop ultrasensitive detection methods for nonfluorescent molecules in liquid solutions by improving performance of photothermal spectroscopic techniques. Photothermal spectroscopy is one of the most sensitive detection methods of nonfluorescent chemical species in a liquid solution, and we have reported that photothermal signal is enhanced by two-color exaction, b
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ased on transient absorption and nonradiative relaxation of photoabsorbing molecules. We have experimentally examined absorption spectra of biologically important chemicals, amino acids and nucleotides, and theoretically estimated transient absorption spectra of these chemicals. It is concluded that simultaneous excitation by ultraviolet light and visible or near infrared light could cause photothermal signal enhancement. We proposed that a crossed beam configuration as a suitable optical setup for the ultraviolet-visible simultaneous excitation, and experimentally confirmed that photothermal signal enhancement by the two-color excitation is observed in the crossed beam excitation configuration. We have designed and constructed the ultraviolet-visible two-color excitation photothermal detector and experimentally demonstrated the photothermal signal enhancement for amino acids and some medicines in liquid solutions. In a combination with a micro-HPLC and the detector, we have demonstrated a sensitive separation analysis of nonfluorescent biological specimens. These results are and are being published in scientific literatures. Less
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