Preparation Of Amorphous Calcium Phosphate / Magnetic Nanoparticle Composites By Coprecipitation Method And Their Biological Properties

Teeth are one of the vital of people, there are200million dental restoration cases in Untied States. Therefore, synthetic biology biological material with excellent performance is an important research content of oral studies. The main components of calcium phosphate are similar to tooth, so it has good biocompatibility. Amorphous calcium phosphate (ACP) is the only amorphous material of calcium phosphate. It is not only the intermediate state of liquid phase synthesis of calcium phosphate, but also an important precursor of biomineralization. In addition, it have bioactivity and biodegradability which are better than crystalline calcium phosphate. Magnetic nano-materials are widely used in biomedical, especially Fe3O4,which has the character of similar enzyme, can reduce the level of intracellular H2O2and promote the proliferation and differentiation of osteoblasts. In this paper, we synthsis the ACP/Fe3O4with co-precipitation method at room temperature. We will investigate the merits of its biological properties, the main research contents are as follows:1. We synthesised amorphous calcium phosphate by utilizing ethanol-water system at room temperature. We studied the influence of reaction concentration、 reaction time、reaction pH and ethanol content to determine the optimal synthesis conditions by means of X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The results showed that only reaction pH and the Degree of amorphization of calcium phosphate had linear correlation. We investigated the morphology and element of ACP under the observation of Scan Electron Microscopy(SEM)、Transmission Electron Microscopy(TEM) and Energy dispersive X-ray Spectroscopy.We found that ACP was spherical particles of about20nm, surrounding by a layer of absorbed water. There were no other impurity elements but Ca、P、C、O. By cell toxicity and cell adhesion experiments, we evaluated the biological properties of ACP:ACP toxicity rating were between0and1, showing good biocompatibility.2. We synthesised amorphous calcium phosphate by adding the stabilizer of polyethylene glycol (PEG) into the aqueous solution. We determined the content of PEG by using X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR):We obtained mass ratio of PEG and Ca(NO3)2-4H2O was0.25:1for conclusion; The Degree of amorphization of calcium phosphate declined with mass ratio deviating 0.25.The morphology of ACP synthesized by PEG consistent with the above mentioned material under the observation of SEM and TEM, which indicated PEG had no influence on the morphology of ACP. We observed morphology of different days, and found morphology didn’t change with the extension of time. We speculated ACP occurred phase chane by reorganization of Posner’s cluster. PEG could complex with Ca2+, which increased the resistance of the reorganization to delay the ACP phase transition time. By cell toxicity and cell adhesion experiments, we evaluated the biological properties of ACP. The results indicated PEG had hardly negative influence on biological properties of ACP. ACP toxicity rating were also between0and1, which was compliance with the performance requirements of the biomedical field.3. We doped Fe3O4modified by PEG into ACP in the process of prepareing ACP by co-precipitation method at room temperature. We studied the effect of Fe3O4on the formation of ACP by means of XRD. Fe3O4did’t affect the growth of calcium phosphate. ACP/Fe3O4was a core-shell structure, which Fe3O4was surrounded by ACP. elemental analysis and Multi-element distribution results showed that: Fe3O4were mainly concentrated in the center of the ACP.Cytotoxicity results showed that: the morphology of mouse embryonic fibroblasts (NIH3T3) had no distortion after co-cultured with ACP/Fe3O4composite. The OD values of MTT assay test were significantly higher than the OD values of aboved two chapters, indicated that ACP/Fe3O4composite had better biocompatible than ACP, and promote cell proliferation more effective, which relate to the spicy horseradish peroxidase property of Fe3O4. Cell adhesion experiments showed that, the number of cell adhesion revealed under confocal microscopy is more better after cells treated with Hoechst-33342staining, which reflected the good biological activity of Fe3O4.