20 February 2014 Optical fiber-based photomechanical molecular delivery system
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Molecular delivery based on nanosecond pulsed laser-induced photomechanical waves (PMWs) enables endoscopic application by using an optical fiber for laser transmission. In our previous fiber system, a laser target, which was a black natural rubber film as a laser absorbing material covered with an optically transparent polyethylene terephthalate disk to confine the laser-induced plasma, was attached to the output end of a 1 mm core diameter quartz fiber. There were two problems in that system: 1) the outer diameter was large (~2.7 mm) and 2) available peak pressure rapidly decreased with increasing pulse number. In this study, we developed a new fiber delivery system to overcome these problems. As a laser absorbing material, we used a cap-type silicone rubber containing carbon black, into which the fiber output end can simply be inserted. The fiber end surface works to confine the laser-induced plasma. The outer diameter of the fiber system was reduced to ~1.4 mm. At an output laser fluence of 1.2 J/cm2, peak pressure of the first PMW pulse exceeded ~40 MPa. With successive 10 laser pulses, decreasing rate of the peak pressure was 22%, which was considerably lower than that with the previous fiber system (82%), enabling generation of at least successive 30 pulses of PMW with the same cap-type target. With this fiber system, we attempted transfer of plasmid DNA encoding EGFP (enhanced green fluorescence protein) to the rat skin as a test tissue in vivo, showing site-selective efficient gene expression.
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Koki Nakano, Koki Nakano, Shunichi Sato, Shunichi Sato, Satoko Kawauchi, Satoko Kawauchi, Hiroshi Ashida, Hiroshi Ashida, Izumi Nishidate, Izumi Nishidate, "Optical fiber-based photomechanical molecular delivery system", Proc. SPIE 8938, Optical Fibers and Sensors for Medical Diagnostics and Treatment Applications XIV, 89381J (20 February 2014); doi: 10.1117/12.2040904; https://doi.org/10.1117/12.2040904

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