Nanoparticles with Multiple Perfluorocarbons for Controllable Ultrasonically Induced Phase Shifting

Abstract

In studying the feasibility of developing tissue-targeted contrast media that can be administered as liquids and vaporized by an external stimulus such as ultrasound, we have investigated the properties of emulsions of nanometer-size particles containing perfluoropentane and 2H,3H-perfluoropentane. We found that the ultrasound intensity required to induce echographically significant vaporization can be controlled by changing the ratio of 2H,3H-perfluoropentane to perfluoropentane and that the intensity threshold increases as this ratio increases. Significant azeotropic phenomena were not observed when the perfluorocarbon mixtures were heated, which indicates that mechanisms other than azotropy are involved in the threshold change. The vaporization of 2H,3H-perfluoropentane may have been due not only to ultrasound energy but also to the energy deposited by ultrasonically induced bubbles of perfluoropentane. Our results might lead to a phase-shift contrast agent with controllable ultrasound energy for phase shifting.

Ultrasound mediated destruction of multifunctional microbubbles for image guided delivery of oxygen and drugs

“…This observation is coincident with previous reports [27,28], except that the MAMs in our study can be activated at a relatively lower acoustic power density. It is believed that the cavitation effect of the therapeutic ultrasound pulses and the PFC thermodynamic changes after dissolving oxygen may contribute to the reduced acoustic energy threshold for droplet-to-bubble transition.…”

Thermal Activation of Superheated Lipid-Coated Perfluorocarbon Drops

“…[7][8][9][10] In principle, the vaporization condition of these metastable droplets can be tailored through the selection and mixing of the perfluorocarbon core material. 11,12 Sheeran et al 13 examined perfluoropropane (C 3 F 8 , T b = -37 °C) and perfluorobutane (C 4 F 10 , T b = -2 °C) as droplet core materials to develop phase-change ultrasound contrast agents that require minimal acoustic input at the physiological temperature (37 °C). Coincidentally, the PICASSO collaboration also utilized a mixture of these two perfluorocarbons in their neutrino detectors.…”

Enhancement of High-Intensity Focused Ultrasound Heating by Short-Pulse Generated Cavitation

“…To generate microbubbles containing slightly soluble gas inside a body, the usage of nanoparticles that can be vaporized into microbubbles by HIFU pulses or short bursts has been developed and investigated [23,[37][38][39]. Such phase change nanoparticles enable us to control the region of microbubbles induced by HIFU pulses.…”