| Summary: | 碩士 === 國立臺灣大學 === 生醫電子與資訊學研究所 === 102 === Photothermal therapy refers to the use of heating from electromagnetic radiation to treat various medical conditions, including cancer. For example, researchers have been using targeting gold nanoparticles to specific tumor sites as a therapeutic agent with the application of near infrared laser irradiation to induce heating and concomitant tumor cell necrosis. Comparing to other technologies, photothermal therapy can be highly effective with low side effects. It becomes clear that the quantity of gold nanoparticles that can be delivered and accumulated in the tumor is a key factor determining the therapeutic efficacy as well as an important research subject. One of the common approaches to enhancing delivery of the therapeutic agent is to employ micro bubbles as a carrier. Nonetheless, these microbubbles are generally not stable. Therefore, the hypothesis of this study is that by using nanodroplets as the carrier, the stability can be improved and thus the delivery can be enhanced. Moreover, we further hypothesize that by combining laser and ultrasound, liquid-to-gas phase change can be effectively induced and the subsequent bubble destruction can improve the cavitational effects and thus the delivery of therapeutic agent. To test these hypotheses, in vitro and in vivo experiments were conducted in this study. First, the in house therapeutic agents were characterized. Second, the inertial cavitation does was measured under various conditions to quantitatively represent the amount of the cavitational effects. Third, the delivery efficiency of gold nanoparticles between microbubbles and nanodroplets was compared. Finally, cell toxicity tests and animal experiments were conducted to evaluate photothermal therapeutic effects. Results show that the combination of laser with ultrasound provides stronger cavitational effects and synergistic treatment efficacy. Specifically, the destruction ratio of gold nanodroplets using both laser and ultrasound is approximately 45% and the optical density value representing the amount of gold delivered into the cells is 0.027, both are higher than those from gold microbubbles. Furthermore, the cell viability under both laser and ultrasound is 42%, which is also the lowest among all the treatment strategies that were included in this study. It is concluded that the use of gold nanodroplets and the combination of laser and ultrasound does have the potential to be an effective technology for plasmonic phothermal therapy.
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