Key Laboratory of Modern Acoustics (MOE), Department of Physics, Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing 210093, China.
Key Laboratory of Modern Acoustics (MOE), Department of Physics, Collaborative Innovation Center of Advanced Microstructure, Nanjing University, Nanjing 210093, China; Wuxi Vocational Institute of Commerce, Wuxi 214153, Jiangsu, China.
Ultrason Sonochem. 2023 Mar;94:106312. doi: 10.1016/j.ultsonch.2023.106312. Epub 2023 Jan 25.
Phase-changeable contrast agents have been proposed as a next-generation ultrasound contrast agent over conventional microbubbles given its stability, longer circulation time and ability to extravasate. Safe vaporization of nanodroplets (NDs) plays an essential role in the practical translation of ND applications in industry and medical therapy. In particular, the exposure parameters for initializing phase change as well as the site of phase change are concerned to be controlled. Compared to the traditional optical vaporization or acoustic droplet vaporization, this study exhibited the potential of using simultaneous, single burst laser and ultrasound incidence as a means of activating phase change of NDs to generate cavitation nuclei with reduced fluence and sound pressure. A theoretical model considering the laser heating, vapor cavity nucleation and growth was established, where qualitative agreement with experiment findings were found in terms of the trend of combined exposure parameters in order to achieve the same level of vaporization outcome. The results indicate that using single burst laser pulse and 10-cycle ultrasound might be sufficient to lower the exposure levels under FDA limit for laser skin exposure and ultrasound imaging. The combination of laser and ultrasound also provides temporal and spatial control of ND vaporization and cavitation nucleation without altering the sound field, which is beneficial for further safe and effective applications of phase-changeable NDs in medical, environmental, food processing and other industrial areas.
相变型造影剂作为一种下一代超声造影剂，由于其稳定性、更长的循环时间和外渗能力，已被提出优于传统微泡。纳米液滴 (NDs) 的安全汽化在工业和医学治疗中实际应用 NDs 的转化中起着至关重要的作用。特别是，初始相变的暴露参数以及相变的位置被认为需要控制。与传统的光汽化或声空化相比，本研究展示了使用同时的、单次的激光和超声辐照作为一种激活 NDs 相变的手段的潜力，以产生具有降低的能量密度和声压的空化核。建立了一个考虑激光加热、蒸汽腔成核和生长的理论模型，根据实现相同汽化效果的组合暴露参数的趋势，发现实验结果与理论模型定性一致。结果表明，使用单个激光脉冲和 10 个周期的超声可能足以降低激光皮肤暴露和超声成像的 FDA 限制下的暴露水平。激光和超声的结合还提供了 ND 汽化和空化核形成的时间和空间控制，而不改变声场，这有利于在医学、环境、食品加工和其他工业领域进一步安全有效地应用相变型 NDs。
