Preparation And Properties Investigation Of Magnetic Targeted Drugs Carriers

The Fe₃O₄ nanoparticles?NPs?have been used for drugs/genes delivery systems due to their small size,superior magnetic properties,good biocompatibility and biodegradation,low toxicity and easy to be synthetic.Under the action of magnetic field,the magnetic nanoparticles carriers loaded drugs/genes could release the drugs/genes at disease sites,which can reduce the toxicity and side effects of the drug.However,the bare Fe₃O₄ nanoparticles tend to aggregate,which limit their employment in some fields.Thus,it is urgent need to modify the surface of the bare Fe₃O₄ nanoparticles with other inorganic or organic materials to prevent their aggregation as well as endow them new properties to obtain the multifunction targeted drugs/genes nano-carriers.Among which,SiO₂ nanoparticles have been extensive utilized for the modification of magnetic nanoparticles due to their non-toxicity,good stability,inert to chemical reaction and facile synthesis through the St?ber method.Meanwhile,the SiO₂ coating can not only protect magnetic nanoparticles against aggregation,but also supply attached points for further modification and the loading of drugs.Compared with the traditional non-degradable inorganic photothermal materials,the photothermal conversion polymer materials have drawn much attention because of their outstanding photothermal conversion efficiency,good photothermal stability,conductivity,biocompatibility,and easy synthesization.Among them,the polypyrrole?PPy?nanoparticles can be prepared through simple chemical or electrochemical polymerization process,meanwhile they have high conductivity,stability and the amine groups on the surface of polypyrrole nanopartices to provide conjugated sites for therapeutic agents.Nevertheless,when they are utilized for therapy systems,they lack a certain targeted properties.In this paper,the multifunction drug nano-carriers with magnetic targeted properties were obtained by combining Fe₃O₄nanoparticles with SiO₂ and PPy.The specific researches were carried out as follows:?1?Preparation of Fe₃O₄ nanoparticles:the Fe₃O₄ nanoparticles with small size and large size were prepared by co-precipitation and solvothermal methods,respectively.They were characterized by transmission electron microscope?TEM?,X-ray diffraction?XRD?,Fourier transform infrared spectroscopy?FTIR?,thermogravimetric analysis?TGA?and vibration sample magnetometer?VSM?.The Fe₃O₄ nanoparticles with small particle size of about 15nm and large size of about 180 nm were obtained respectively.?2?Synthesis of Fe₃O₄/SiO₂ nanoparticles:using the modified St?ber method,SiO₂ shell layers were coating on the surface of the above two types of Fe₃O₄ nanoparticles via sol-gel process under stirring at room temperature,the Fe₃O₄/SiO₂ core-shell composite nanoparticles with small and large size were prepared respectively.The TEM,XRD,FTIR,TGA and VSM were also applied for the characterization of the two types of Fe₃O₄/SiO₂ core-shell nanocomposites.The results show that in the small size Fe₃O₄/SiO₂ nanoparticles,the thickness of SiO₂ shell layer was 2.5 nm.The nanoparticles are also superparamagnetic,and the thermalstability has been improved well.Even after the TGA analysis from room temperature to 1000?,the mass of the nanoparticles is still maintained 94.44%.For the Fe₃O₄/SiO₂ nanoparticles with large size,the shell layer is about 6 nm after the functionalization with SiO₂,the obtained nanocomposites also possess large saturation magnetization and the thermalstability is also improved.?3?Synthesis of Fe₃O₄/SiO₂/PPy nanoparticles:the PPy shell were modified on the surface of two types obtained Fe₃O₄/SiO₂ core-shell nanocomposites by in-situ chemical polymerization process using a hydrothermal approach without any surfactant,and then the characterization of the two Fe₃O₄/SiO₂/PPy core-shell nanocomposites were carried out.The two obtained Fe₃O₄/SiO₂/PPy nanocomposites both have good dispersity and the thickness of polypyrrole shell layers are 5 nm and 19 nm,respectively.And the Fe₃O₄/SiO₂/PPy nanocomposites still exhibit excellent magnetic,which are suitable for targeted drug delivery.Simultaneously,they also display outstanding thermalstability,the two obtained Fe₃O₄/SiO₂/PPy nanocomposites still own 91.89%and 95.33%of mass respectively even after TGA from room temperature to 1000?.?4?The drug loading and release of Fe₃O₄/SiO₂ and Fe₃O₄/SiO₂/PPy nanoparticles:the drug loading and release behaviors of Ibuprofen?IBU?on the Fe₃O₄/SiO₂ and Fe₃O₄/SiO₂/PPy nanoparticles were investigated.In the drug loading experiment,a certain amount of Fe₃O₄/SiO₂ or Fe₃O₄/SiO₂/PPy nanocomposites were dissolved into IBU-ethanol solution and stirred for a long time.Then,the supernatant was removed by magnetic separation and the absorption intensity at 264 nm was measured by an ultraviolet-visible?UV-Vis?spectrophotometer,and then the amount of drug loading was obtained indirectly.The drug-loaded Fe₃O₄/SiO₂/PPy nanocomposites were dried for the release of IBU and dispersed into sodium hydrogen phosphate-sodium phosphate monobasic buffer solution?pH=7.4?.The IBU release was carried out under stirring or ultrasonication.Then,a certain amount of supernatant was extracted at regular intervals and replaced with equal amount of buffer solution,and the absorption intensity at 265 nm was measured via an UV-Vis spectrophotometer for the harvesting of drug release amount.The encapsulation efficiency was 51.01%.And the maximum loading capacity was up to 76.14%.The drug sustained-release could be realized under stirring and the drug release rate was accelerated obviously under ultrasonic trigger,and the maximum release amount was 91.82%within 65min.In brief,the Fe₃O₄/SiO₂ and Fe₃O₄/SiO₂/PPy nanocomposites with excellent core-shell structure were synthesized through a facile approach in this paper,and then their performances were characterized and the drug loading and liberated ability of them were also studied.Compared with other traditional drug release systems,the Fe₃O₄/SiO₂ and Fe₃O₄/SiO₂/PPy nanocomposites could realize the sustained release of drugs and the poisonous effects were depressed,thus the magnetic targeting drug carriers with outstanding performances were yielded.