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首页> 外文期刊>IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control >Dynamics and fragmentation of thick-shelled microbubbles
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Dynamics and fragmentation of thick-shelled microbubbles

机译：厚壳微泡的动力学和破碎

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Localized delivery could decrease the systemic side effects of toxic chemotherapy drugs. The unique delivery agents we examine consist of microbubbles with an outer lipid coating, an oil layer, and a perfluorobutane gas core. These structures are 0.5-12 Μm in radius at rest. Oil layers of these acoustically active lipospheres (AALs) range from 0.3-1.5 Μm in thickness and thus the agents can carry a large payload compared to nano-scale drug delivery systems. We show that triacetin-based drug-delivery vehicles can be fragmented using ultrasound. Compared with a lipid-shelled contrast agent, the expansion of the drug-delivery vehicle within the first cycle is similar, and a subharmonic component is demonstrated at an equivalent radius, frequency, and driving pressure. For the experimental conditions explored here, the pulse length required for destruction of the drug-delivery vehicle is significantly greater, with at least five cycles required, compared with one cycle for the contrast agent. For the drug-delivery vehicle, the observed destruction mechanism varies with the initial radius, with microbubbles smaller than resonance size undergoing a symmetric collapse and producing a set of small, equal-sized fragments. Between resonance size and twice resonance size, surface waves become visible, and the oscillations become asymmetrical. For agents larger than twice the resonance radius, the destruction mechanism changes to a pinch-off, with one fragment containing a large fraction of the original volume.
机译：局部递送可以减少毒性化学治疗药物的全身副作用。我们检查的独特传递剂包括带有外部脂质涂层，油层和全氟丁烷气芯的微气泡。这些结构在静止时的半径为0.5-12μm。这些声学活性脂球（AAL）的油层厚度为0.3-1.5微米，因此与纳米级药物输送系统相比，这些药物可以携带大量有效负载。我们显示基于三醋精的药物递送工具可以使用超声破碎。与脂质壳造影剂相比，药物传递载体在第一个周期内的膨胀是相似的，并且在相同的半径，频率和驱动压力下表现出次谐波分量。对于此处探讨的实验条件，与造影剂的一个周期相比，销毁药物输送载体所需的脉冲长度明显更大，至少需要五个周期。对于药物输送载体，观察到的破坏机理随初始半径而变化，小于共振尺寸的微气泡会发生对称塌陷，并产生一组相等大小的小碎片。在共振大小和两倍共振大小之间，表面波变得可见，并且振荡变得不对称。对于比共振半径大两倍的试剂，破坏机理会变成夹断，一个碎片含有原始体积的很大一部分。

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