Preparation And Characterization Of Iodine/Magnetite Hybryde Nanomaterials As CT/MRI Dual-functional Contrast Agents

X-ray computed tomography (CT) is one of the most frequently usedclinical imaging diagnosis means. It is mainly used for gastrointestinalimaging, cadiovascular imaging, liver imaging and tumor imaging. As anoninvasive diagnosis mean, CT has access to3D restructural image aswell as slicing the organ of interest. However, it is restricted by thedifficulty of differentiating soft-tissues. Magnetic resonance imaging (MRI)is another noninvasive method which is widely used in clinic. It isadvantageous in superior contrast between soft tissues but istime-consuming and costly. Thus, it calls for a necessity of combining CTand MRI to complement for each other, by which more accurate andvaluable images can be obtained.Currently, iodinated small molecular agents are normally employed inclinic to enhance sensitivity of CT. However，they are easily removed bykidney clearance, rendering a relatively short time for imaging. In recentyears, nanoparticles with iodine have received more and more attentiondue to their unique properties. They can enhance iodine concentrationswhile escaping from the kidney clearance, which is potential to be a newCT contrast agents in clinic.Currently, the clinically used MRI contrast agents are base onGadolinium and superparamagnetic iron oxide nanoparticles. The past fewyears witnessed the emerging of magnetic mesoporous silica nanoparticles,which possess not only superparamagnetism but also abundant mesoporesfor drug loading, rendering a potential to combine detecting and treatment.By combining iodinated oil with m SiO2@SPIONs or iron oxide nanoparticles, CT/MRI dual functional contrast agents could be achieved.In this dissertation, iodinated oil/mSiO2@SPIONs and iodinated oil/Fe3O4composites have been prepared as two kinds of novel CT/MRI dualfunctional contrast agents. The research mainly focused on three parts asfollows:1. Loading Iodinated oil into PEG-mSiO2@SPIONs andfmSiO2@SPIONsThe magnetic mesoporous silica nanoparticles（mSiO2@SPIONs）used in this study were provided by Professor Gu’s group,mSiO2@SPIONs were synthesised by template-directed silica growthmethod, mSiO2@SPIONs were further modified with PEG（PEG-mSiO2@SPIONs） or coupled by fluorochrome Cy5（fmSiO2@SPIONs）.As-synthesized mSiO2@SPIONs was first used for Natrii Diatrizoasloading. The highest loading efficiency in this research of64.48%has beenachieved. However, the release of loaded Natrii Diatrizoas was very fast inwater, which make it difficult for targeting imaging. Next, iodinated oilwas attempted to load into PEG-mSiO2@SPIONs and the loadingefficiency of more than80.0%was achieved in ethanol/water solution,which was tremendously enhanced by micro emulsion method. Finally, thepotential of iodinated oil loaded PEG-mSiO2@SPIONs for MRI and CTimaging both in vivo and in vitro was examined.2. Fabrication of iodinated oil/Fe3O4hybrid nanoclustersFirst, we prepared hydrophobic Fe3O4nanoparticles of about7nanometers by high-temperature decomposition route and then synthesizedMal-PEG-PLA (PEG Mw=5000; PLA Mw=5250).Subsequently, iodinated oil and hydrophobic Fe3O4nanoparticleswere assembled with the amphiphilic copolymers into nanoclusters, andthe clusters were carefully characterized.In summary, iodine/Fe3O4nano composites have been fabricated inthis study. The composites demonstrated great potential for CT/MRI dual modal imaging.