Physicochemical properties and cytocompatibility of biomimetically precipitated nanocrystalline calcium phosphate granules / 中国组织工程研究

ABSTRACT

BACKGROUND:Artificially synthesized hydroxyapatite ceramic granules are widely used in clinical practice to repair large-volume bone defects.However,the osteogenic effect of hydroxyapatite ceramic granules prepared by high-temperature sintering is limited by their low degradability and bioactivity. OBJECTIVE:To prepare biomimetically precipitated nanocrystalline calcium phosphate granules by a novel low-temperature deposition technique,and to characterize their physicochemical properties and cytocompatibility. METHODS:Biomimetically precipitated nanocrystalline calcium phosphate granules were prepared using a modified supersaturated calcium phosphate mineralization solution and a repeated settling and decantation washing method.Hydroxyapatite bioceramic granules were used as the control.The morphology and phase composition of the granules were characterized by scanning electron microscopy,X-ray diffraction,and Fourier transform infrared spectroscopy.The specific surface area,porosity distribution,hardness and hydrophilicity of the granules were characterized by BET-N2 method,hardness test,and contact angle test.The adsorption properties of the granules for bovine serum albumin and fetal bovine serum protein were determined by bicinchoninic acid assay.The two kinds of granules or granule extracts were co-cultured with human umbilical cord mesenchymal stem cells,and the cell proliferation was detected by MTT assay. RESULTS AND CONCLUSION:(1)Scanning electron microscopy showed that the surface of the two kinds of particles was slightly rough and accompanied by tiny particles,the surface of the hydroxyapatite bioceramic particles was dense and smooth,and the biomimetically precipitated nanocrystalline calcium phosphate granules were mainly composed of needle/plate crystals with non-uniform nanometer size,and formed a nanopore structure between the crystals.X-ray diffraction and Fourier transform infrared spectroscopy exhibited that compared with hydroxyapatite bioceramic granules,biomimetically precipitated nanocrystalline calcium phosphate granules had smaller crystalline particles,lower crystallinity,and more binding water and carbonic acid groups.Compared with hydroxyapatite bioceramic granules,biomimetically precipitated nanocrystalline calcium phosphate granules had higher specific surface area,better hydrophilicity,lower hardness,and higher protein adsorption capacity.(2)The results of MTT assay showed that the two kinds of granule extracts had no cytotoxicity,human umbilical cord mesenchymal stem cells survived well on the surface of the two kinds of granules,and the biomimetically precipitated nanocrystalline calcium phosphate granules had stronger cell proliferation activity.(3)These findings indicate that compared with hydroxyapatite bioceramic granules,biomimetically precipitated nanocrystalline calcium phosphate granules have better physicochemical properties and cytocompatibility.