The nonlinear acoustic properties of microbubble ultrasound enhancing agents have allowed for the development of subharmonic, second harmonic, and contrast-pulse sequence ultrasound imaging modes, which enhance the quality, reduce the noise, and improve the diagnostic capabilities of clinical ultrasound. This study details acoustic scattering responses of perfluorobutane (PFB) microbubbles, an un-nested perfluoropentane (PFP) nanoemulsion, and two nested PFP nanoemulsions—one comprising a negatively charged phospholipid bilayer and another comprising a zwitterionic phospholipid bilayer—when excited at 1 or 2.25 MHz over a peak negative pressure range of 200 kPa to 4 MPa in the absence and presence of a 1-Hz, 1-V/cm electric field. The only sample that exhibited an increase in nonlinear activity in the presence of an electric field at both excitation frequencies was the negatively charged nested PFP nanoemulsion; the most pronounced effect was observed at an excitation of 2.25 MHz. Interestingly, the application of an electric field not only increased the nonlinear acoustic activity of the negatively charged nested PFP nanoemulsion but increased it beyond that seen when the nanoemulsion is un-nested and on the same scale as PFB microbubbles.

微泡超声增强剂的非线性声学特性促进了次谐波、二次谐波和对比脉冲序列超声成像模式的发展，从而提高了质量，降低了噪声，提高了临床超声的诊断能力。本研究详细介绍了全氟丁烷 (PFB) 微泡、未嵌套的全氟戊烷 (PFP​​) 纳米乳液和两种嵌套的 PFP 纳米乳液（一个包含带负电荷的磷脂双层，另一个包含两性离子磷脂双层）在 1 或 2.25 激发时的声学散射响应MHz 在 200 kPa 到 4 MPa 的峰值负压范围内，在 1 Hz、1 V/cm 电场不存在和存在的情况下。在两个激发频率的电场存在下表现出非线性活性增加的唯一样品是带负电荷的嵌套 PFP 纳米乳液；在 2.25 MHz 的激发下观察到最显着的效果。有趣的是，电场的应用不仅增加了带负电的嵌套式 PFP 纳米乳液的非线性声学活动，而且增加了超出纳米乳液未嵌套且与 PFB 微泡规模相同时所见的非线性声学活动。