Preparation and in vitro imaging of a magnetic heating phasetransition multimodal ultrasound contrast agent

Objective To prepare a novel magnetic heating phasetransition nanoparticle contrast agent (PFH-HIONS), and to study its performance on enhancing photoacoustic imaging, magnetic resonance imaging and ultrasound imaging after phasetransition by magnetic-thermo in vitro. Methods Firstly, the superparamagnetic nano hollow iron spheres (HIONS) were prepared by a one-pot solvothermal method, and then the phasetransition liquid perfluorocarbon (PFH) was loaded on the HIONS by vacuum adsorption to obtain PFH-HIONS. After characterization of the nanoparticles, photoacoustic imaging, magnetic resonance imaging and ultrasound imaging after phasetransition with magnetic-thermo were performed in vitro, and the results were analyzed by a software. Results PFH-HIONS was successfully prepared with uniform particle size of (537.3±24.8)nm. PFH-HIONS could apparently enhance photoacoustic imaging and magnetic resonance imaging in vitro. In an alternating magnetic field, it could significantly increase the temperature, which promotes phasetransion of the PFH to produce microbubbles, thereby enhancing ultrasound imaging. Furthermore, as the concentration increased, the imaging intensity was enhanced, and the differences in imaging intensity between different concentration groups were statistically significant (P<0.05). Conclusions The PFH-HIONS can enhance the multimodal imaging including ultrasound, photoacoustic and magnetic resonance, and it also has obvious magnetic heating performance. It provides a new and efficient research platform for theranostics based on molecular imaging, therefore it has promising application prospects. Key words: Magnetic heating; Phasetransition; Contrast agent; Multimodal