2006 Fiscal Year Final Research Report Summary
Photothermal and Photoionization Spectroscopies of Chemical Reactions in a Single Cell
| Project/Area Number |
16072213
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas
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| Allocation Type | Single-year Grants |
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| Review Section |
Science and Engineering
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| Research Institution | Kyushu University |
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Principal Investigator |
HARATA Akira Kyushu University, Faculty of Engineering Sciences, Professor (90222231)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Single Cell / Nonfluorescent Chemicals / Ultrahigh Sensitive Detection / Photothermal Spectroscopy / Microscopic Thermal Lens / Multi-color Excitation / Multiphoton Ionization / Chemical Imaging |
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| Research Abstract |
Most of biologically important chemicals such as amino acids, nucleotides and so on, are natively nonfluorescent, and a large part of them have optical absorption only at ultraviolet wavelengths. Photothermal and photoionization spectroscopic methods have a good potential for ultrahigh sensitive in-situ detection of these chemicals. We aim to develop ultrasensitive detection and imaging methods for nonfluorescent molecules in living cells.
A photothermal signal detector under multi-color excitation has been designed for ultrasensitive detection of biological chemicals, in which transient absorption is utilized for signal enhancement. Ultraviolet excitation-visible enhancement photothermal detection system has been constructed and applied to separation analysis in combination with a micro-HPLC system. A mixture of ultraviolet-absorbing chemicals were successfully separated and detected without any labeling procedure. Two-color excitation-induced enhancement of photothermal signal was successfully observed.
An ultraviolet-excitation photothermal microscope has been developed with the excitation of the third harmonics emission of a Ti-sapphire laser and the probe laser of its fundamental emission. Photothermal images of the yeast cells were obtained. In a photothermal amplitude image of the cells, features with the size of several micrometers are seen, corresponding to the size of the cells. It was observed that a strong photothermal signal excited with the 261-nm laser beam accompanied with a small intensity of the transmitted probe light at 784-nm.
Influences of laser irradiation on a physiological function of yeast cells were quantitatively evaluated using laser light at 220, 266, 355, 532, or 1064nm. It was found that the survival probability of yeast cells after 12 hours from irradiation by 532-nm light is 10 times larger than that by 355-nm light and 104 times larger than that by 266-nm light under the same energy density condition.
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