Preparation Of Macrophage-Mediated Gold Nanoflowers Embedded With Ultrasmall Iron Oxide For Enhance Molecular Imaging

With the increasement of incidence and recurrence rate year by year,cancer has put a lot of pressure on our lives,and it is essential to timely diagnosis and treatment.In recent years,the rapid development of nanomedicine has been promoted by the progress of nanoscience and technology.The successful preparation and application of multifunctional nanomaterials in the field of biomedicine also confirm this point.However,there are some limitations in the application of nanomaterials in biomedical field,such as insufficient aggregation and uneven distribution of nanomaterials in the tumor site.It is crucial to solve these problems of how to target cancer cells effectively and widely.It is common that targeted reagents have some limitations.They are usually targeting only part of the tumor models,and have no universality,so it is difficult to popularize.With the in-depth study of targeted reagents,more and more researchers have focused their attention on immune cells which are tumor-oriented.Immunocytes can deliver nanomaterials to tumors more accurately,and at the same time reduce the risk of removal of nanomaterials in vivo,increasing their infiltration into tumors,to improve the diagnostic effect of cancer.In this paper,we choose macrophages as transport carriers of nanomaterials,loaded with the final gold nanoflowers embedded with ultrasmall iron oxide nanoparticles for MR/CT imaging.This method can increase the concentration of contrast agent in the tumor area and enhance the contrast effect.In the second chapter,based on our previous work,we first obtain ultrasmall Fe₃O₄?USIO?with a higher r₁ relaxation rate by solvothermal method,and then activate the carboxyl groups on the surface of USIO.Then,the gold nanoflowers embedded with ultrasmall iron oxide nanoflowers?Fe₃O₄/Au DSNFs?were obtained by in-situ reduction.Finally,USIO was embedded in Au DSNPs by the reaction of amino groups on the surface of dendrimers with carboxyl groups of USIO.T Fe₃O₄/Au DSNFs were obtained by seed growth method.In the third chapter,the biocompatibility of Fe₃O₄/Au DSNFs was evaluated.CCK-8,Prussian blue staining,cell phagocytosis,Transwell and other experiments were used to evaluate whether the biological characteristics of the materials changed after co-incubation with cells.In the fourth chapter,the MR/CT imaging effect of the material in vitro and in vivo were validated.When using Fe₃O₄/Au DSNFs for in vitro imaging,USIO was selected as the control group for MR imaging in vitro,and the relaxation rates of the two groups were compared.When using MA@Fe₃O₄/Au DSNFs for in vivo MR imaging,Fe₃O₄/Au DSNFs was selected as the in vivo MR imaging control group,and the material was injected through the tail vein.In the mouse,MR imaging images and SNR values were observed.In the in vitro CT imaging using Fe₃O₄/Au DSNFs nanogold flower,iodulol was selected as the control group for CT imaging in vitro,and the HU values of the two groups were compared.When using MA@Fe₃O₄/Au DSNFs for in vivo CT imaging,Fe₃O₄/Au DSNFs was used as a CT imaging control group in vivo,and the material was passed through the tail.Intravenous injection into mice,observation of CT imaging images and HU values.The MR/CT imaging effects of macrophage-loaded nanomaterials were evaluated by the above experiments.In summary,we fabricated MA@Fe₃O₄/Au NFs,which can be used for multimodal imaging of tumors.Animal experiments can demonstrate the in vivo targeting of materials,to provide possibilities for accurate diagnosis.