2007 Fiscal Year Final Research Report Summary
Novel Technology for Cryopreservation of Biological Tissue by Utilizing Ultrasonic lrradiation
| Project/Area Number |
18560195
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thermal engineering
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| Research Institution | Kanazawa University |
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Principal Investigator |
TADA Yukio Kanazawa University, Graduate School of Natural Science and Technology, Associate Professor (20179708)
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| Co-Investigator(Kenkyū-buntansha) |
TAKIMOTO Akira Kanazawa University, Graduate School of Natural Science and Technology, Professor (20019780)
ONISHI Hajime Kanazawa University, Graduate School of Natural Science and Technology, Assistant Professor (80334762)
YOSHIOKA Hideaki Toyama National College of Technology, Department of Maritime Technology, Associate Professor (80259845)
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| Project Period (FY) |
2006 – 2007
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| Keywords | Freezing / Ultrasound / Ice formation / Ultrasonic cavitation / Biological tissue |
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| Research Abstract |
Freezing can slow down or stop some biological reactions for preserving biological cell. It is also true that the freezing is lethal to the living system. During freezing, the extra- and intra-cellular ice formation, osmotic water permeation through cell membrane, deformation of the cell and other behavior occur at microscale and they bring serious injuries connecting to life-and-death of living cell.
A method to actively controlling crystallization is one of promising technique for cryopreservation. The object of this project is to study the effects of ultrasonic irradiation on ice formation during freezing of biological materials. In the experiments, agar gel was frozen under various irradiation methods of ultrasound at frequency of 28 kHz. The measurements of temperature and the microscopic observation of ice crystals by using fluorescent indicator were carried out.
Firstly, it was found that ultrasound released the supercooling states, and reduced ice crystal size in the tissue. However, the fattning of ice crystal was observed by irradiation of higher ultrasonic power, since the cooling rate was reduced due to absorption of the ultrasonic wave. The ice crystal size in the tissue was clarified in relation to ultrasonic power and tissue size. Secondly, various irradiation methods were tested. It was found that the pulsed irradiation is useful for reducing ice crystal size, since the fattening of ice crystal due to absorption of ultrasonic wave is reduced. The mechanism of sonocrystallization in biological tissue was discussed in relation to ultrasonic power, on-off frequency and irradiation duration.
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