Effects of focused ultrasound and microbubbles on the vascular permeability of nanoparticles delivered into mouse tumors.

Ultrasound sonication with microbubbles (MBs) was evaluated for enhancement of the release of nanoparticles from vasculature to tumor tissues. In this study, tumor-bearing Balb/c mice were insonicated with focused ultrasound (FUS) in the tumors after the injection of MBs (SonoVue) and then lipid-coated quantum dot (LQD) nanoparticles (130 +/- 25 nm) were injected through the tail vein. We studied the effects of the injected MB dose (0-300 microL/kg), sonication duration (0-300 s) and treatment-procedure sequence on the accumulation of nanoparticles in the tumors 24 h after the treatment and the time response of the accumulation (0.5-24 h). After the treatment, the mice were sacrificed and perfused and then the tumor tissues were harvested for quantifying the amount of nanoparticles using graphite furnace atomic absorption spectrometry (GF-AAS). The results showed that pulsed-FUS sonication with MBs can effectively enhance the vascular permeability for LQD nanoparticle delivery into the sonicated tumors. It indicates that this technique is promising for a better nanodrug delivery for tumor chemotherapy.