The Distribution Of Iron Oxide Nanoparticles In Rat Brain And Its Application As A Drug Carrier

In this work,iron?II?acetylacetonate was used as iron source to synthesize superparamagnetic iron oxide nanoparticles?SPIONs?by"one-pot"thermal decomposition method.The morphology and size distribution of the samples were observed by field emission transmission electron microscopy?TEM?.X-ray diffraction analyzer?XRD?was used to measure the crystal form of the samples.The size and the zeta potential are measured by a nanoparticle zeta potential analyzer.Inductively coupled plasma atomic emission spectrometry?ICP-OES?was used tomeasure the concentration of Fe³⁺.Fourier transform infrared spectroscopy?FT-IR?,UV-visible spectrophotometer and high performance liquid chromatography?HPLC?are used to analyze the organics,drugs and functional groups on the surface of rhe nanoparticles.The weight of each component of the sample was analyzed by thermogravimetry?TG?.SQUID was used to test the magnetic properties ofthe samples.The elements and element valence of the organics on the surface of the nanoparticles weremeasured by X-ray photoelectron spectroscopy?XPS?analysis.The cytotoxicity of the samples was measured by MTT method.The distribution of the sample in rat brain was observed with TEM.The specific research contents are as follows:?1?Fe?acac?₃ was thermally decomposed into SPIONs by using polyethylene glycol?PEG?as reducing agent,solvent and modifier.The SPIONs modified with PEG was grafted with transferrin?Tf?by coupling with maleic anhydride?Mal?using EDC-NHS method.The TEM results showed that the shape of nanoparticles coated with transferrin was uniform and the average particle size was 7.5±1.0 nm.XRD result shows that the main phase of the sample is well-crystallized Fe₃O₄.The hydration kinetic particle size of Tf-modified SPIONs was 96 nm,the zeta potential was 2.3 mV,the modification amount of Tf was 32.7wt%and the saturation magnetization was 43 emu/g.FTIR analysis,XPS and Brandford method were used to detect the protein.The results showed that Tf was modified on the surface of SPIONs.Modifiers give the nanoparticles a good water dispersibility.Tf-modified nanoparticles were injected into substantia nigras of rat brains using rat brain stereotaxic instrument.Brains were taken 24 hours later.ICP-OES was used to detect the content of iron in various brain regions of rats.The results showed that the content of iron in each brain region of rats was similar,which was significantly higher than that of the saline group,indicating that nanoparticles were diffused into olfactory bulb,prefrontal cortex,thalamus,temporal lobe,brainstem,and hippocampus.Take ultra-thin sections of the substantia nigra,observed under TEM.Most iron oxide particles are present in myelin or axons.?2?Ferric acetylacetonate?Fe?acac?₃?was thermally decomposed to SPIONs by using polyethylene glycol?PEG?,polyethyleneimine?PEI?as reducing agents,solvent and modifiers.Folic acid?FA?was grafted onto SPIONs using the EDC-NHS method.Docetaxel?DTX?was coated on the surface of SPIONs by physical adsorption.TEM was used to observe the morphology of the grains.The results showed that the shape of the nanoparticles was regular and distributed evenly with a particle size of 12.9±2.2 nm.The hydration kinetic particle size of DTX-coated SPIONs was 263 nm and the Zeta potential was 3.64 mV.Thermogravimetry data showed the modification rate of FA is 7.9 wt%and the DTX modification rate is 8.4 wt%.The saturation magnetization of the modified FA nanoparticles was 41 emu/g,and the saturation magnetization of the modified DTX nanoparticles was 36 emu/g.UV spectrophotometer and high performance liquid chromatography analyzing results show that FA and DTX were coated on thesurface of SPIONs.The final entrapment efficiency of DTX with different drug concentration within a certain range between 75%-78%.The thermogravimetry data showed that the drug loading rate was 8.4%.In vitro release data showed that the cumulative release rate was higher at low pH and the cumulative release rate of drug-loaded nanoparticles at different pH was significantly lower than that of free DTX control group.?3?SPIONs were synthesized by thermal decomposition of Fe?acac?₃ with polyethylene glycol?PEG?,polyethyleneimine?PEI?as reducing agents,solvent and modifiers.Carboxylated chitosan?CCH?was grafted on the surface of SPIONs by the amide bond conbining with the amino group of PEI by means of EDC-NHS method.The morphology of the nanoparticles coated with CCH observed under TEM showed a spherical shape with an approximately regular distribution with an average particle size of 11.9±1.6 nm.The hydration kinetic particle size and Zeta potential of the nanoparticles of the nanoparticles before and after the CCH modification were 28.8 nm,29.8 mV and 98.5 nm,-38.8 mV,respectively.The thermogravimetry data showed that the modification rate of CCH was29.8 wt%and the SQUID results showed that the nanoparticles had superparamagnetism and the saturation magnetization before and after modification of CCH were 45 emu/g and22 emu/g,respectively.The XPS data showed that CCH was modified on the surface of nanoparticles.The in vitro cytotoxicity of the samples was detected by MTT assay.After incubated with C6 cells for 24 h or 48 h,the cell viability ismore than 85%,indicating that the sample cytotoxicity is low.CCH-modified superparamagnetic iron oxide nanoparticles are expected to be used as drug carriers for targeting tumor cells.