Study On Preparation And Biological Properties Of Ferrite Nanoparticles

Magnetic nanoparticles are a kind of magnetic material with diameter of 1～100nm,which are made of transition metal and their oxide such as Fe,Co,Ni and so on.They are new type of functional materials with characterization of special effect,magnetic responsibility and bioaffinity, and have been one of hot spots in recent biomedicine research.Although many preparative methods about various magnetic nanoparticles have been reported,there have been some deficient such as justo major diameter, insufficient magnetic responsibility and biocompatibility,high cost price.In our study,we have prepared Zinc/Cobalt ferrite nanoparticle with microemulsion.After surface modified and encapsulate by different material, Zinc/Cobalt ferrite nanoparticle was reconstructed as arginine modified magnetic nanoparticles(AMMN),amino group modified silica/magnetic nanoparticles(AMSN),silver-loaded magnetic antimicrobial nanoparticles (SLMN) and magnetic chitosan silvernanoparticles(MCTSS).The physical and chemical properties of magnetic samples were characterized by element analysis,infrared spectroscopy(IR),scanning electron microscopy(SEM), X-ray diffractometry(XRD),vibrating sample magnetometer(VSM),and their biology properties had been also studied systematically.The main results were as follows:The new microemulsion system was made from cyclohexane as oil phase,TX-10 and AEO₉ as the surfactant,n-amylalcohol as consurfactant and Zn²⁺/Co²⁺,Fe³⁺ or NH₃·H₂O solution as water phase.The optimum conditions were as follows:the mass ratio of surfactants to cosurfactants is 2:1,the salinity was the mixture of 0.6 mol/L Fe³⁺ and 0.3 mol/L Zn²⁺/Co²⁺ and the solution of 0.6 mol/ L NH₃·H₂O respectively,the experimental temperature are 35℃.ZnFe₂O₄ and CoFe₂O₄ nanoparticles were synthesized on this microemulsion condition,respectively.The SEM results indicated that ferrite nanoparticles had narrow size distribution,less agglomeration and the size range of 15～25nm.The cobalt ferrite and zinc ferrite nanoparticles both showed paramagnetism.The results of XRD and IR showed that there is not any other except for the characteristic parameters of ferrite.Our results showed that we have prepared the Zinc/Cobalt ferrite nanoparticle with microemulsion successfully.This system has the advantage of low cost price,convenient preparation,small particle diameter and strong magnetic responsibility,which can be used to synthesize many kinds of ferrite nanoparticle.Ferrite nanoparticles were coated with silica,aminopropyl-triethoxy silane(APS) and argnine(Arg) respectively.A novel nanoparticle namely AMMN was prepared by this multilayer-coating method.Elemental analysis, IR and XRD analysis showed that APS had been bonded on silica through hydroxyl reaction and Arg had been bonded on ferrite nanoparticles with amide linkage.The SEM results indicated that AMMN was globular and well distributed with the size range of 20～35nm.The AMMN showed stronger acid resistance than SiO₂-coated ZnFe₂O₄ and ZnFe₂O₄ ferrite nanoparticles.With the positive electricity in the acid and neutral solution, the AMMN had the advantage of absorbing negatively charged DNA.The results of MTT showed that the nanoparticles were of low cytotoxicity to the liver cell lines.DNA binding assay showed that AMMN could bind DNA under physiological conditions.The DNA encapsuled inside the AMMN was protected from the external DNAase environment.Using reporter gene system,AMMN was demonstrated to transfer exogenous genes to cells and express encoded protein in vitro.Therefore,the AMMN show much potential as new vector candidates for safer and cost-effective DNA delivery. A novel amino group modified silica/magnetic nanoparticles(AMSN) were prepared by silica and amino-alkoxy group modification.Elemental analysis,TG-DTA thermal analysis and IR analysis proved that the organic Molecules with amino group had been linked on the SiO₂/CoFe₂O₄ ferrite nanoparticles.The result of atomic force microscopy(AFM) indicated that the AMSN was globular and dispersed,with average diameters of 30nm. Superparamagnetism was observed in the AMSN.The results of agarose gel showed that the AMSN could adsorb p53 gene strongly and resist blood serum digestion.The results of fluorescence microscope,RT-PCR and Western blotting showed the AMSN could transfer p53 gene into HepG2 cells and expressed in vitro.The in vivo experiment indicated that the AMSN-p53 could transfect to HepG2 induced tumor and inhibit its growth. Thus,the AMSN could be used as one of the ideal gene carriers for p53 gene delivery and hepatic hepatoma gene therapy.Silver-loaded Magnetic antimicrobial nanoparticles(SLMN) were prepared by reduction method of H₂ and sol-gel method.The characterizations of products were investigated using XRD,SEM,IR, energy dispersion spectrometry(SEM-EDS) and vibrating sample magnetometer(VSM).The results showed SLMN were approximately spherical particles with an average diameter of 75nm.The silica present in the products was amorphous and with simple silver phase based on the analyses of XRD.The results of the antibacterial tests showed that when the content of silver was more than 3.0%,the efficiency of sterilization of SLMN was above 99.9%against staphylococcus aureus and escherichia coli. The estimate of security and toxicology to samples proved that it belongs to innocuity reality.The samples took on non-stimulative to skins.Magnetic Chitosan Silver Nanoparticles(MCTSS) was prepared with ferrite nanoparticles,chitosan and Ag⁺,which had both magnetic and antibacterial activity.The optimum conditions were pH value of 4.5, temperature of 30℃,the time of reaction 25h,stirring speed of 500rpm.The adsorption of Ag(â… ) ions from aqueous solution by Magnetic crosslinked Chitosan nanoparticles(MCTS) were studied in a batch adsorption system.The adsorption capacities and rates of Ag(â… ) ions onto chitosan derivatives were evaluated.The adsorption isothermal data could be well interpreted by the Langmuir model.The kinetic experimental data properly correlated with the Lagergren pseudo-second-order kinetic model, which indicates that the chemical adsorption is the rate-limiting step.The characterizations of MCTSS were investigated using IR, SEM/EDS,XRD,Zeta potential and VSM.The result showed chitosan and Ag⁺ were coated on the surface of SCN,and the MCTSS exhibited the highest saturated magnetization.The results of the antibacterial tests showed that MCTSS had conspicuous inhibitory effect on E.coli,S.aureus and C.albicans.Acute oral toxicity tests showed that all the MCTSS samples were actually non-toxic.The estimate of security to samples proved that it also belonged to innocuity reality.So the MCTSS are a newly,steadily and secure magnetic antibacterial agent.