| Magnetic resonance imaging (MRI) has become the essential medical imaging and detection tools due to its excellent characteristics of high functionality and non-injury. Magnetic nanoparticles (MNPs), as promising contrast agents for MRI and as carriers for drug delivery have been investigated intensively because of their unique magnetic properties and the easily functionalized ability at the cellular and molecular level of biological interactions. As a type of biomaterials, the development of MNPs ensures to provide human beings with a new medical method for diagnosis and treatment at the early stage of diseases and reduce the mortality of serious illness significantly. With recent advances in nanotechnology, conventional MNPs like iron oxide have been applied successfully in nanomedicine, not only in vitro (magnetic separation, magnetic sensing/detection, and magnetic transfection), but also in vivo (MRI, targeted drug delivery, and tissue engineering). However, low magnetic moment, low sensitivity and low cargo capacity have limited their further commercialization. Research and develop multifunctional MNPs that combined diagnosis and drug-delivery carriers for treatment may exhibit their significant applications in the healthcare in the near future.Because of its unique superparamagnetism, good biocompatibility, strong plasticity, easy to observe, iron oxide nanomaterial has attracted more and more attentions in recent years, both as contrast agents in MRI and carriers for drug delivery. At the same time, a kind of biomedical materials with both diagnosis and treatments is expected. Nowadays, a simplest and efficient form of NMPs is comprised of an inorganic nanoparticle core and a biocompatible surface coating. Such architecture can facilitate the NMPs to be stabilized under physiological conditions, and the surface to be functionalized with ligands as well. After modification, the NMPs will have multi-modal image, drug delivery, and real-time monitoring functionality simultaneously, which will help to build a set of MRI contrast agents with diagnosis and treatments.In this work, we carried out our experiments from the following aspects:(1)First, we get the dispersible FesO4NPs by using the thermal decomposition method. The Fe3O4NPs is monodisperse and has a uniform morphology, with the size of about20nm. NMR measurement shows that the R2relaxation rate can be up to651.38Fe mN-1S-1, and the R2relaxation rate of the Fe3O4NPs is only206.18Fe mM-1S-1, preparing by co-precipitation preparation;(2)Using self-assembly method to form Fe3O4clusters, which not only can transform the material from oil phase to water phase (facilitates to biological applications), but also increase the MRI effect, more than that of the Fe3O4NMPs;(3)Surface modified the Fe3O4clusters by using the electrostatic adsorption principle:coated polymer PAH and PSS on the Fe3O4surface, which can increase its water solubility and biocompatibility, and also can load positively charged anti-cancer drugs DOX to achieve the purpose of diagnosis and treatment;(4)Drug release in vitro experiments show that our preparation materials belong to the controlled release materials, and in the PH=5.0the release efficiency can reach up to80%, while only20%when PH=7.4, It has small damage to the normal cell in neutral environment, but for tumor cells in acidic condition it exhibits a greater lethality;(5)MTT experiments have been used to determine the influence of the materials for cell activity. The results show that the cytotoxicity of the Fe3O4clusters itself is very small without loading the anti-cancer drugs. However, after loading the anti-cancer drug DOX in a certain concentration range, cell activity is found a tendency decrease with the increase of the concentration of DOX and the material has certain lethality to the cancer cell;(6)The MRI proves the imaging properties of the synthesized materials, thus confirms that the material has the efficacy of diagnosis and treatment, as we have expected. |
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