Department of Mechanical Engineering, University of Colorado, Boulder 80309, Colorado, United States.
Institute of Biomedical Engineering, Oxford University, Oxford OX3 7DQ, U.K.
Langmuir. 2021 Feb 23;37(7):2386-2396. doi: 10.1021/acs.langmuir.0c03349. Epub 2021 Feb 10.
Nanodrops comprising a perfluorocarbon liquid core can be acoustically vaporized into echogenic microbubbles for ultrasound imaging. Packaging the microbubble in its condensed liquid state provides some advantages, including activation of the acoustic signal, longer circulation persistence, and the advent of expanded diagnostic and therapeutic applications in pathologies which exhibit compromised vasculature. One obstacle to clinical translation is the inability of the limited surfactant present on the nanodrop to encapsulate the greatly expanded microbubble interface, resulting in ephemeral microbubbles with limited utility. In this study, we examine a biomimetic approach to stabilize an expanding gas surface by employing the lung surfactant replacement, beractant. Lung surfactant contains a suite of lipids and proteins that provide efficient shuttling of material from bilayer folds to the monolayer surface. We hypothesized that beractant would improve stability of acoustically vaporized microbubbles. To test this hypothesis, we characterized beractant surface dilation mechanics and revealed a novel biophysical phenomenon of rapid interfacial melting, spreading, and resolidification. We then harnessed this unique functionality to increase the stability and echogenicity of microbubbles produced after acoustic droplet vaporization for ultrasound imaging. Such biomimetic lung surfactant-stabilized nanodrops may be useful for applications in ultrasound imaging and therapy.
包含全氟碳液体芯的纳米液滴可以通过声学蒸发成声敏微泡用于超声成像。将微泡包装在其冷凝液体状态下提供了一些优势，包括激活声信号、延长循环持久性以及在表现出血管损伤的病理情况下扩展诊断和治疗应用。临床转化的一个障碍是纳米液滴上有限的表面活性剂无法包裹大大扩展的微泡界面，导致声敏微泡短暂存在，实用性有限。在这项研究中，我们通过使用肺表面活性剂替代物，牛肺表面活性剂，研究了一种稳定膨胀气体表面的仿生方法。肺表面活性剂包含一系列脂质和蛋白质，可有效地将物质从双层折叠转移到单层表面。我们假设牛肺表面活性剂会提高声蒸发微泡的稳定性。为了验证这一假设，我们对牛肺表面活性剂的表面扩张力学进行了表征，并揭示了一种快速界面熔化、铺展和再凝固的新物理现象。然后，我们利用这种独特的功能来提高声空化后产生的微泡的稳定性和超声成像的回声强度。这种仿生肺表面活性剂稳定的纳米液滴可能对超声成像和治疗应用有用。
