The Preparation And Characterization Of Tumor Targeting CT Contrast Agent Based On Iopamidol

Objective:Malignant tumors are the common serious diseases which are threatening the health and life of human being for a long time.Computed Tomography?CT?has become an essential instrument in clinical tumor diagnosis for its unique characteristics of high efficiency,high spatial resolution.In this study,a nanoscale CT contrast agent containing iodine was prepared,and the properties of contrast agent was also studied,which greatly improved the diagnostic accuracy of tumor.Content:The RGD modified iodinated nanoparticles were prepared successfully by multi-steps and labeled with fluorescent markers Cy5.5,including the synthesis of monomeric compound containing iodine,the preparation of iodinated nanoparticles,the modification of PEG and RGD and the label of fluorescent markers Cy5.5.We studied their characters by ¹H-NMR and MS,Fourier transform infrared spectrometer?FT-IR?,Inductively Coupled Plasma Optical Emission Spectrometer?ICP-OES?,transmission electron microscope?TEM?,dynamic laser scattering?DLS?and ultraviolet-visible spectrophotometer?UV-Vis?etc.The cellular uptake was examined by flow cytometer?FCM?andLSCM,Meanwhile,the cytotoxicity was evaluated with MTT assay in vitro.Mice with breast cancer were used as animal model and assessed by small animal imaging system and CT scanner after the injection of nanoparticles to evaluate the imaging capability in vivo.Methods:The methacrylated iopamidol?MAI?was first synthesised from iopamidol via multi-step polymerization.The monomer compound was MAI and the poly methacrylated iopamidol?PMAI?were prepared through precipitation polymerization.The PMAI-PEG nanoparticles was prepared by esterification reaction between PMAI and polyethylene glycol?PEG?.The RGD was modified on the surface of nanoparticles by the reaction between the thiol groups on RGD and the maleimide group on PEG to form the resultant nanoparticles PMAI-PEG-RGD.Next,We studied the structure of material made in this study.The structure of the monomer was determined by nuclear magnetic resonance spectroscopy?¹H-NMR?,and the molecular weight of monomer was determined by MS.FT-IR was used to characterize the chemical structure of the nanoparticles and determine whether PEG was modified on the surface of the nanoparticles successfully.TEM was used to investigate the size and surface morphology and DLS was used to investigate the size,dispersibility and surface charges of the nanoparticles.ICP-OES was used to detect the iodine content of the nanoparticles.UV-vis was used to investigate the change of absorbance of nanoparticle solution under redox conditions to investigated the degradation property.MTT assay was used to investigate the cytotoxicity of PMAI-PEG-RGD nanoparticles,and the cell uptake capacity was examined by flow cytometry and CLSM.Whole-body fluorescent imaging system and CT scanner were used to investigate the X-ray absorption capacity and CT imaging performance of nanoparticles in vivo.Results:The structure of the various compounds in each step and the monomer MAI was confirmed by ¹H-NMR spectrum and MS spectrum.FT-IR spectroscopy confirms that the PEG was successfully modified on the surface of nanoparticles.The results of TEM and DLS showed the smooth surface,uniform particle size,good dispersity and narrow particle size distribution of the nanoparticles from each step.The average particle size of the PMAI-PEG-RGD nanoparticles was 89 nm.The Zeta potential of PMAI,PMAI-PEG,PMAI-PEG-RGD were-9.6 mV,-13.6 mV and-27.6 mV,This displayed that the materials were modified successful and the physical stability of the nanoparticles could be maintained by electrostatic interactions.The result of ICP-OES showed that the iodine content in PMAI-PEG-RGD nanoparticles was 30%.We used the MTT assay to explore the cellular viability of nanoparticles.When the concentration of iodine was 1000?g·mL^-1,the low cytotoxicity and the nanoparticles had no obvious effect on the normal growth of cells.The results of FCM and CLSM indicated that PMAI-PEG-RGD nanoparticles showed the better cell uptake capacity.TheresultofWhole-bodyfluorescentimagingsystemshownedthat PMAI-PEG-RGD nanoparticles have better tumor targeting capability and can increase the accumulation of nanomaterials at the tumor site.In addition,The CT imaging result showed that the PMAI-PEG-RGD nanoparticles have strong X-ray.it could be heaped in the tumor and enhanced the CT imaging of the tumor.Conclusion:PMAI-PEG-RGD nanoparticles were successfully prepared in this study.The results in study showed that the nanoparticles have redox-responsive degradation characteristics,excellent cell uptake capacity,low cytotoxicity and X-ray attenuation property.PMAI-PEG-RGD nanoparticles could be heaped in the tumor and enhance the imaging effect.The nanoparticles have potential value of applications in tumor-targeted CT imaging diagnosis.