Strohm Eric, Rui Min, Gorelikov Ivan, Matsuura Naomi, Kolios Michael
Biomed Opt Express. 2011 Jun 1;2(6):1432-42. doi: 10.1364/BOE.2.001432. Epub 2011 May 4.
Micron-sized liquid perfluorocarbon (PFC) droplets are currently being investigated as activatable agents for medical imaging and cancer therapy. After injection into the bloodstream, superheated PFC droplets can be vaporized to a gas phase for ultrasound imaging, or for cancer therapy via targeted drug delivery and vessel occlusion. Droplet vaporization has been previously demonstrated using acoustic methods. We propose using laser irradiation as a means to induce PFC droplet vaporization using a method we term optical droplet vaporization (ODV). In order to facilitate ODV of PFC droplets which have negligible absorption in the infrared spectrum, optical absorbing nanoparticles were incorporated into the droplet. In this study, micron-sized PFC droplets loaded with silica-coated lead sulfide (PbS) nanoparticles were evaluated using a 1064 nm laser and ultra-high frequency photoacoustic ultrasound (at 200 and 375 MHz). The photoacoustic response was proportional to nanoparticle loading and successful optical droplet vaporization of individual PFC droplets was confirmed using photoacoustic, acoustic, and optical measurements. A minimum laser fluence of 1.4 J/cm(2) was required to vaporize the droplets. The vaporization of PFC droplets via laser irradiation can lead to the activation of PFC agents in tissues previously not accessible using standard ultrasound-based techniques.
微米级液态全氟碳化物（PFC）液滴目前正作为用于医学成像和癌症治疗的可激活剂进行研究。注入血液后，过热的PFC液滴可汽化为气相用于超声成像，或通过靶向药物递送和血管闭塞用于癌症治疗。液滴汽化此前已通过声学方法得到证实。我们提出使用激光照射作为一种手段，通过一种我们称为光滴汽化（ODV）的方法来诱导PFC液滴汽化。为了促进在红外光谱中吸收可忽略不计的PFC液滴的ODV，将光吸收纳米颗粒掺入液滴中。在本研究中，使用1064 nm激光和超高频光声超声（200和375 MHz）对负载有二氧化硅包覆硫化铅（PbS）纳米颗粒的微米级PFC液滴进行了评估。光声响应与纳米颗粒负载量成正比，并使用光声、声学和光学测量方法证实了单个PFC液滴成功实现了光滴汽化。汽化这些液滴需要的最小激光能量密度为1.4 J/cm²。通过激光照射使PFC液滴汽化可导致PFC剂在以前使用基于标准超声的技术无法到达的组织中被激活。
