Preparation And Characterization Of New Magnetic Resonance Nanocontrast Agent Based On Trimanganese Tetraoxide

Objective A magnetic resonance nano-contrast agent containing trimanganese tetroxide was synthesized,its characterization was explored,and its contrast efficiency and safety performance were explored.Methods Polyacrylic acid（PAA）was used as a p H-responsive polymer to react with manganese sulfate to obtain nanoparticles.The molecular formula of the synthesized nanoparticles was determined by X-ray photoelectron spectroscopy and X-ray diffractometer.Transmission electron microscopy,particle size analyzer,inductance Coupled plasma emission spectroscopy and 7.0T magnetic resonance imaging instruments were used to study the morphology,magnetic resonance properties,cell biocompatibility,and material stability of nanoparticles.Results Manganese oxide samples were obtained by the reaction of glutathione,polyacrylic acid and Mn SO₄.The sample was observed under transmission electron microscopy as petal-shaped nanoparticles with a diameter of about 100～200 nm.X-ray photoelectron spectroscopy and X-rays The diffractometer results all show that its composition is Mn₃O₄;at p H 4.5,the 24h Mn²⁺release is still less than 0.5%,which proves its good stability and safety;magnetic resonance imaging results show that the p H is acidic Under the conditions,the manganese oxide nanoparticles have extremely high contrast performance.When the p H is 4.5,the longitudinal relaxation rate reaches13.0 mmol^-1·S^-1,indicating that it can respond to the tumor microenvironment;CCK-8showed that co-cultivation of the manganese oxide nanoparticles with gingival fibroblasts（HGF）for 24h and 48h did not produce cytotoxicity,proving that the material has good biocompatibility.Conclusion A new nano-contrast agent with trimanganese tetroxide was successfully synthesized,which has good biocompatibility and the highest contrast efficiency under acidic conditions,providing a basis for its further clinical research.