Ag¹³¹I Method Labeled PEG And Folic Acid Co-functionalized Graphene Oxide For Cervical Tumor Targeted Imaging

Objective:Cancer is the second leading cause of death throughout the world,with increasing incidence and mortality,Early diagnosis of cancer is extremely important.The rapid development of nanotechnology has made nano-targeted drugs show great application potential both in the field of tumor diagnosis and treatment.The advantages of small volume of graphene oxide?GO?,low cytotoxicity,good biocompatibility and easy modification make it an ideal nanocarrier.In order to study the application value of graphene oxide in the field of tumor imaging,in this paper,it is proposed to co-modify GO with polyethylene glycol?PEG?and folic acid?FA?to further improve its biocompatibility and tumor targeting ability,and use ¹³¹I labeled GO-PEG-FA to explore the application of graphene oxide in the field of tumor radionuclide imaging.In order to solve the shortcomings of traditional iodine labeling method,such as insufficient labeling rate and unstable product,this paper attempts to innovate the labeling of GO-PEG-FA by Ag¹³¹I method,and explore the feasibility of application of Ag¹³¹I/GO-PEG-FA in tumor nuclide imaging.Methods:In this thesis,GO was prepared by modified Hummers method,and characterized by UV-visible spectroscopy,infrared spectroscopy,dynamic light scattering and zeta potential.GO surface was functionalized by PEG or PEG and FA by amide bond to get polyethylene glycol modified graphene oxide?GO-PEG?and folic acid and polyethylene glycol co-modified graphene oxide?GO-PEG-FA?,and GO-PEG and GO-PEG-FA were obtained and characterized by UV-visible,infrared and Zeta potentials to confirm their structures.GO-PEG-?FA?was labeled by Ag¹³¹I method,and GO-PEG-?FA?was labeled by chloramine T method to compare the labeling rates of the two labeling methods.The cytotoxicity of GO-PEG and GO-PEG-FA with HEK293cells after 24 h and 48 h incubation was evaluated by MTS method,and the cytotoxicity of non-radioactive AgI/GO-PEG and AgI/GO-PEG-FA were also evaluated.The in vitro stability was evaluated by determining the labeling rate change of Ag¹³¹I/GO-PEG and Ag¹³¹I/GO-PEG-FA in physiological saline,PBS,BSA solution and various amino acids?alanine,arginine,glycine,serine and cysteine?for 24 h by paper chromatography.HeLa cells were incubated with Ag¹³¹I/GO-PEG and Ag¹³¹I/GO-PEG-FA for 4 h for cell uptake studies.Using HeLa tumor nude mice as a model,12 HeLa tumor-bearing nude mice were randomly divided into two groups.Ag¹³¹I/GO-PEG and Ag¹³¹I/GO-PEG-FA were injected into the tumor by tail vein injection and tumor in situ injection for4 h to study the SPECT imaging and biodistribution characteristics of HeLa tumor-bearing nude mice.Results:GO-PEG?-FA?was successfully prepared by functionalizing graphene oxide with folic acid and polyethylene glycol,and its structure was confirmed by UV-visible spectroscopy and Fourier transform infrared spectroscopy.GO-PEG and GO-PEG-FA were innovatively labeled by Ag¹³¹I method.Ag¹³¹I/GO-PEG and Ag¹³¹I/GO-PEG-FA with a labeling rate greater than 99%were obtained.The labeling rate was much higher than that of the chloramine T labeling method.Cytotoxicity experiments showed that GO-PEG and GO-PEG-FA had little cytotoxicity,and AgI/GO-PEG and AgI/GO-PEG-FA had controlled low cytotoxicity.Ag¹³¹I/GO-PEG and Ag¹³¹I/GO-PEG-FA have good stability in inorganic physiological media,but deiodination occurs in BSA solution.Further studies have found that the thiol group contained in the cysteine constituting the biological protein can replace¹³¹I in Ag¹³¹I.Comparison of SPECT imaging and biological results of HeLa tumor nude mice injected with Ag¹³¹I/GO-PEG and Ag¹³¹I/GO-PEG-FA via tail vein showed that FA modification significantly improved the targeting of tumors,Tumors of nude mice bearing HeLa tumors had strong uptake of Ag¹³¹I/GO-PEG-FA.The introduction of FA significantly improved the targeting of go derivatives on tumors with high FR expression.SPECT imaging and biodistribution results of in situ injection of Ag¹³¹I/GO-PEG and Ag¹³¹I/GO-PEG-FA in the tumor site of HeLa tumor-bearing nude mice showed that functionalized graphene oxide has a good retention effect in tumors.Conclusion:The Ag¹³¹I method has the advantage of high labeling rate to label functionalized graphene oxide.GO-PEG-FA has no obvious cytotoxicity,and AgI/GO-PEG-FA has controllable low cytotoxicity.The modification of folic acid increases the targeting of functionalized graphene oxide to tumors with high expression of FR.This study shows that Ag¹³¹I/GO-PEG-FA has potential clinical application prospects in tumor imaging and targeted therapy.