Magnetite Nanoparticles Can Be Coupled to Microbubbles to Support Multimodal Imaging

Abstract

Microbubbles (MBs) are commonly used as injectable ultrasound contrast agent (UCA) in modern ultrasonography. Polymer-shelled UCAs present additional potentialities with respect to marketed lipid-shelled UCAs. They are more robust; that is, they have longer shelf and circulation life, and surface modifications are quite easily accomplished to obtain enhanced targeting and local drug delivery. The next generation of UCAs will be required to support not only ultrasound-based imaging methods but also other complementary diagnostic approaches such as magnetic resonance imaging or computer tomography. This work addresses the features of MBs that could function as contrast agents for both ultrasound and magnetic resonance imaging. The results indicate that the introduction of iron oxide nanoparticles (SPIONs) in the poly(vinyl alcohol) shell or on the external surface of the MBs does not greatly decrease the echogenicity of the host MBs compared with the unmodified one. The presence of SPIONs provides enough magnetic susceptibility to the MBs to accomplish good detectability both in vitro and in vivo. The distribution of SPIONs on the shell and their aggregation state seem to be key factors for the optimization of the transverse relaxation rate.

Analysis of polyvinyl alcohol microbubbles in human blood plasma using capillary electrophoresis

“…The highest concentration is similar to the concentration injected in in vivo studies on rats [5]. The corresponding total peak area had the average value of 468, 1586, 4774, and 7829 mAUs for the different concentrations, and the RSDs for the total peak areas ranged between 7 and 17%.…”

Biodistribution, kinetics, and biological fate of SPION microbubbles in the rat

“…38 Large gas-filled microbubbles provide additional ultrasound contrast. 39,40 The present investigation addresses how larger vehicles would affect the distribution and half-life of the iron oxide signal using MR imaging. Microscopic tissue sample analysis confirmed rapid uptake of SPION microbubbles in the lungs and their redistribution to the liver and spleen over time.…”

Crucial factors and emerging concepts in ultrasound-triggered drug delivery

“…PLGA nanoparticles [51], magnetic nanoparticles [52], liposomes and lipoplexes [53], gold nanoparticles and silica nanoparticles [54] were used in combination with microbubbles and ultrasound. Through encapsulating the drug molecules in nanoscopic particles they become well protected against degradation, which is a major challenge, especially for biological drugs.…”