Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC, USA.
Department of Radiology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
Ultrasound Med Biol. 2022 Sep;48(9):1720-1732. doi: 10.1016/j.ultrasmedbio.2022.04.216. Epub 2022 Jun 10.
Polyethylene glycol (PEG) is often added to the lipid coating of a contrast microbubble to prevent coalescence and improve circulation. At high surface density, PEG chains are known to undergo a transition from a mushroom configuration to an extended brush configuration. We investigated the effects of PEG chain configuration on attenuation and dissolution of microbubbles by varying the molar ratio of the PEGylated lipid in the shell with three (0%, 2% and 5%) in the mushroom configuration and two (10% and 20%) in the brush configuration. We measured attenuation through the bubble suspensions and used it to obtain the characteristic rheological properties of their shells according to two interfacial rheological models. The interfacial elasticity was found to be significantly lower in the brush regime (∼0.6 N/m) than in the mushroom regime (∼1.3 N/m), but similar in value within each regime. The dissolution behavior of microbubbles under acoustic excitation inside an air-saturated medium was studied by measuring the time-dependent attenuation. Total attenuation recorded a transient increase because of growth resulting from air influx and an eventual decrease caused by dissolution. Microbubble shell composition with varying PEG concentrations had significant effects on dissolution dynamics.
聚乙二醇（PEG）通常添加到对比微泡的脂质涂层中，以防止聚结并改善循环。在高表面密度下，PEG 链已知会从蕈状构型转变为扩展刷状构型。我们通过改变壳中 PEG 化脂质的摩尔比（在蕈状构型下为 0%、2%和 5%，在刷状构型下为 10%和 20%）来研究 PEG 链构型对微泡衰减和溶解的影响。我们通过气泡悬浮液测量衰减，并根据两种界面流变模型使用它来获得其壳的特征流变性质。在刷状构型下（约 0.6 N/m），界面弹性明显低于蕈状构型（约 1.3 N/m），但在每个构型内的数值相似。通过测量声激发下空气饱和介质中微泡的时变衰减来研究微泡的溶解行为。由于空气流入导致的生长，总衰减记录了瞬态增加，并且最终由于溶解而导致衰减。具有不同 PEG 浓度的微泡壳组成对溶解动力学有显著影响。
