Preparation And Properties Of Fe₃O₄@Cap Magnetic Nanohybrids By Biomineralization And Their Interaction With Bmscs

Iron oxide, especially iron oxide nanoparticle, is a very importantmagnetic material. It has been widely used in biomedical field for itsbiocompatibility, electrology and magnetism properties, which relates toparticle dimension and morphology. Calcium phosphates compounds （CaPs）,such as hydroxyapatite （HA）, dicalcium pyrophosphate dehydrate （DCPD） andtricalcium phosphate （α-TCP，β-TCP） etc., are biological ceramics owing totheir good biocompatibility and similar compositions with natural boneminerals. To develop a kind of Iron oxide nanobbrids with CaP coating, wouldcombine both the features of core and shell materials, and have potentialapplications in bone tissue engineering.In this thesis, Fe₃O₄magnetic nanoparticles were obtained byhydrothermal method, and then coated with CaP compounds viabiomineralization to form core-shell nanohybrids. Properties includingcrystallinity, composition, saturation magnetization and magnetism,morphology and dimension, and dispersibility in water were measured and analyzed by techniques as XRD, VSM, SEM and TEM. The results showedthat the crystallinity, magnetism and dimension of products could be improvedby elevating reaction temperature, prolonging reaction time and increasing theconcentration of PEG. When subjected to biomineralization with simulatedbody fluid （SBF）, the produced Fe₃O₄@CaP nanohybrids resulted in differentcrystal morphology and calcium-phosphorus ratio, which apparently dependedon the SBF used.SD rats bone mesenchymal stem cells （BMSCs） were cultured in thepresence of Fe₃O₄@CaP nanohybrids at different amounts, CCK-8and cellintake experiment were performed to evaluate the biocompatibility ofFe₃O₄@CaP nanohybrids. Then ALP activity and the content of calcium ion ofthe BMSCs with Fe₃O₄@CaP nanohybrids intake, were determined at3,7,14and21day after osteogenetically induced differentiation. The results exhibitedFe₃O₄@CaP nanohybrids had good biocompatibility, and could promote cellproliferation and differentiation. With the aid of external magnetic field, theBMSCs with Fe₃O₄@CaP nanohybrids intake could be made into a sort ofcompact cell-sheet with several layers of cells. The cells in the cell-sheet wereconfirmed viable and the cell sheet was expected to be used as scaffold-freeregeneration material for bone defects.