| Project/Area Number |
12355009
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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 | 展開研究 |
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| Research Field |
Fluid engineering
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| Research Institution | Tohoku University |
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Principal Investigator |
TAKAYAMA Kazuyoshi Institute of Fluid Science, TOHOKU UNIVERSITY, PROFESSOR, 流体科学研究所, 教授 (40006193)
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| Co-Investigator(Kenkyū-buntansha) |
SAITO Tsutomu Institute of Fluid Science, TOHOKU UNIVERSITY, ASSOCIATE PROFESSOR, 流体科学研究所, 助教授 (00302224)
SASOH Akihiro Institute of Fluid Science, TOHOKU UNIVERSITY, PROFESSOR, 流体科学研究所, 助教授 (40215752)
IKOHAGI Toshiaki Institute of Fluid Science, TOHOKU UNIVERSITY, PROFESSOR, 流体科学研究所, 教授 (90091652)
TAKAHASHI Akira School of Medicine, TOHOKU UNIVERSITY, PROFESSOR, 医学系研究科, 教授 (40301048)
WADA Hiroshi Institute of Fluid Science, TOHOKU UNIVERSITY, PROFESSOR, 大学院・工学研究科, 教授 (30111264)
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| Project Period (FY) |
2000 – 2002
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| Keywords | Shock wave / Drug delivery / Shock wave therapy / Laser ablation / Hypersonic Stokes flow / Gene delivery / Micro-impact crater / Numerical simulation |
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| Research Abstract |
In the Interdisciplinary Shock Wave Research Center, Tohoku University, we have aimed to apply the shock wave phenomena to medicine. We have already finished the extracorporeal shock wave lithotripsy and now are working for the development of system for revascularization of cerebral thrombosis, which is expected to be completed in very near future. In these topics a shock wave plays always an important role*. When a Q-switched laser beam focused a spot on a metal foil surface, instantaneously a plasma cloud ejected from the spot and as its reaction a shock wave is generated inside the metal foil which propagate and reflected from the other surface. The plasma formation is called laser ablation. The reflected wave an expansion one and as a result of it the foil is instantaneously bulged at 2 to 5 km/s. When small* particles are attached on the metal surface these would be ejected at such a high speed at the moment laser beam irradiation. This principle has been applied to accelerate dry
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drug particles or metal particles* of the order of magnitude of one micron or so into human tissue. We have used Q-switched Nd:YAG laser focused on the surface of a 5 mm thick glass plate backed up with 0.1 mm this aluminum foil on which tungsten or gold particles were attached. We measured the particle ejection speed to be in the order of magnitude of 1 to 2 km/s. Injecting these particles against agarose cell, mouse liver, and mouse skin, we measured penetration depths against these and found the maximum penetration depth was about 6 mm for individual materials. The free flight of such small particles belongs to hypersonic Stokes flow which has never be discussed seriously in the field gas dynamics. We have developed numerical scheme to estimate particle free flight as well as penetration into soft tissues. We have examined with this method the penetration into cell lines in liquid solution and observed a beautiful penetration of a one micron tungsten particle into a cell. Based on these basic studies we concluded that this method is superior to the existing mechanical gene delivery systems and so robust and compact that it can be redesigned as a therapeutic device. We believe we have accomplished our main goal which we proposed at first. Less
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