Integrin ?v?3 Targeted Fe₃O₄-DiD@PLGA-RGD Nanospheres For Magnetic Resonance And Fluorescence Imaging Of Glioma

Purpose:The aim of this study is to achieve accurate diagnosis of glioma through magnetic resonance and fluorescence dual-modal imaging utilizing ?v?3 targeted Fe₃O₄-DiD@PLGA-RGD nanospheres as targeted contrast agent.Methods:Firstly,PLGA loaded with 3.5 nm Fe₃O₄ nanoparticles and DiD was processed by an oil-in-water emulsion solvent evaporation method,forming Fe₃O₄-DiD@PLGA nanospheres.Secondly,c?RGDfk?peptides were conjugated to the surface of these nanospheres through carbodiimide-mediated amide bond formation,forming Fe₃O₄-DiD@PLGA-RGD nanospheres.Their structure and properties were characterized with state-of-art facilities.Then the biocompatibility of Fe₃O₄-DiD@PLGA-RGD was assessed by MTT cytotoxicity test.After that,in vitro magnetic resonance and fluorescence imaging performance of Fe₃O₄-DiD@PLGA-RGD nanospheres was tested on glioma cells.Finally,in vivo magnetic resonance and fluorescence imaging performance was tested on subcutaneous glioma models.Results:The size of Fe₃O₄-DiD@PLGA-RGD nanospheres is 97.1±27.1 nm,and the average hydrated particle size is 168.0nm.It is stable in ultrapure water,PBS buffer,normal saline and 10%FBS within 6 days.T1 relaxation rate of Fe₃O₄-DiD@PLGA-RGD is 0.28±0.04 mM^-1s^-1.T2 relaxation rate is 121.24±0.69 mM^-1s^-1 It is suitable for serving as magnetic resonance T2 weighted imaging contrast agent.Fe₃O₄-DiD@PLGA-RGD has a maximum excitation wavelength of 651 nm and a maximum emission wavelength of 676 nm.Red fluorescence can be emitted under excitation.Cytotoxicity test shows the agent has biosecurity.Cell viability is greater than 80%when the iron concentration is less than 100?g/mL.Perls-stain test shows the experimental group has more blue-stained iron oxide particles than the control group.Laser confocal fluorescence microscope shows the experimental group has more red fluorescence than the control group.Both in vitro and in vivo images show Fe₃O₄-DiD@PLGA-RGD have a more pronounced accumulation at the tumor site than Fe₃O₄-DiD@PLGA.Conclusion:Fe₃O₄-DiD@PLGA-RGD have not only biocompatibility,but also good magnetic resonance and fluorescence dual-modal targeted imaging capability.As contract agent,it has important prospects for accurate diagnosis of glioma.