Improving tumor accumulation with SPIO-Loaded acoustic nanodroplets and magnetic targeting

Acoustic droplet vaporization (ADV) provides mechanical and chemical effects in tumor theranostic applications. Nano-sized droplets (NDs) could increase drug accumulation within tumor through the enhanced permeability and retention (EPR) effect. However, the high interstitial fluid pressure in solid tumor would resist NDs extravasation. In order to overcome this defect, NDs formulation which encapsulated super-paramagnetic iron oxide (SPIO) nanoparticles (SPIO-ND) was purposed in this study to enhance the local accumulation of NDs by external magnetism-assisted targeting (MT). The SPIO-NDs were fabricated by intensely sonicating lipids with perfluorocarbon and aliphatic-terminated SPIO. Vaporization features of SPIO-NDs and EPR effect were estimated by acousto-optical system on window chamber mice model. Vaporization efficiency of SPIO-NDs was calculated as 21.13% and the ADV process could be observed in intravital in vivo images. SPIO-NDs accumulation in the tumor via active MT was significantly higher than that though passive EPR effect. Future works include modifying specific targeting moieties on SPIO-NDs to increase intracellular drug accumulation, investigating the feasibility of SPIO-NDs for theranostic application on tumor intratissue drug release.