MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, South China Normal University, Guangzhou 510631, China.
Nanoscale. 2019 Nov 28;11(46):22222-22229. doi: 10.1039/c9nr06549k.
Microwave-induced thermoacoustic imaging (MTAI) utilizes the high dielectric contrast of tissues in the microwave range, and, combined with the high resolution of ultrasound imaging, can noninvasively obtain anatomical and functional structure information. However, adequate contrast in certain indications (e.g., breast tumor in their early stages) can be difficult to achieve due to the minimal dielectric difference in the target tissues. A tumor specific targeting nanoparticle with high dielectric loss would enhance MTAI contrast in such applications. In this work, we propose a physics-principle-based technique that increases the dielectric loss of a nanoparticle by increasing its atomic defect to generate an amplified thermoacoustic signal. In principle, bovine serum albumin loaded on graphene oxide (GO) serves as a reductant to create additional vacancies in GO to produce more electric dipoles. Upon pulsed microwave irradiation, the defect dipoles are polarized repeatedly, causing transient heating and thermoelastic expansion, and ultimately generating an amplified acoustic wave. This hypothesis was tested in vitro and in vivo with a breast tumor animal model. The results demonstrate that the nanoparticle can effectively enhance the MTAI contrast of breast tumors. The physics-principle-based technique is likely to contribute to early breast tumor imaging.
微波诱导热声成象（MTAI）利用了微波范围内组织的高介电对比度，并结合超声成象的高分辨率，能够非侵入式地获得解剖和功能结构信息。然而，在某些适应症中（例如早期乳腺癌），由于目标组织中的介电差异很小，因此很难获得足够的对比度。具有高介电损耗的肿瘤特异性靶向纳米颗粒将增强此类应用中的 MTAI 对比度。在这项工作中，我们提出了一种基于物理原理的技术，通过增加纳米颗粒的原子缺陷来增加其介电损耗，从而产生放大的热声信号。原则上，负载在氧化石墨烯（GO）上的牛血清白蛋白充当还原剂，在 GO 中产生更多的空位以产生更多的电偶极子。在微波脉冲辐照下，缺陷偶极子被反复极化，导致瞬态加热和热弹性膨胀，最终产生放大的声波。这一假设在体外和乳腺癌动物模型中进行了测试。结果表明，纳米颗粒可以有效增强乳腺癌的 MTAI 对比度。基于物理原理的技术可能有助于早期乳腺癌成像。
