The Preparation Of One-dimensional Functional Hydroxyapatite Nanomaterials And Their Applications In Biomedical Fields

Nano-hydroxyapatite（HAp） has attracted broad concern and research in the field of biological materials due to their highly similar chemical composition and structures to inorganic components of the human skeleton. The excellent biocompatibility, bioactivity and osteoconduction of HAp nanomaterials have been clinically applied to replace and repair aspects of hard tissues. Currently, there are various morphologies and surface properties of synthetic HAp nanomaterials that are also been studied for potential application in drug delivery systems. This is mainly attributed to their larger specific surface areas, which can absorb more chemotherapeutic agents. As a nanocarrier for drug loading, it can increase local drug concentration, prolong the effect of chemotherapy drugs and meanwhile reduce the damage to normal tissues and organs. Secondly, nano-HAp is in vivo biodegradable, and the calcium, phosphate ions from its degradation naturally exist in the body. That is one of the advantages of nano-HAp as drug nanocarriers. On the basis of the potential application of nanoHAp materials in the biomedical field, different morphologies of one-dimensional nano-HAp materials with luminescent properties were prepared via different methods in this paper, and their applications in drug delivery and in vitro imaging were also and other aspects of a series of exploratory basic research.Porous HAp composite nanofibers functionalized with Na（Y/Gd）F4:Yb³⁺,Er³⁺ nanocrystals have been fabricated via electrospinning. After introducing of Na（Y/Gd）F4:Yb³⁺,Er³⁺ nanocrystals, these composite nanofibers emit bright green light under 980 nm laser light excitation, which can be used as probes for cell imaging. In the meantime, the porous structure can be used as drug carriers for drugs loading. Therefore, the in vitro up-conversion luminescence imaging, T1- weighted MRI imaging and related cytotoxicity assays were evaluated. Also drug loading/release properties of these composite nanofibers were studied by using Indomethacin as a model drug, the study supported, and their cellular uptake behavior were investigated.Several rare earth ions Yb³⁺ /Er³⁺ / Gd³⁺ codoped HAp nanorods have been prepared via a solvothermal method. By replaced calcium ions with a certain proportion of these rare earth ions, HAp:Ln³⁺ nanorods could present green fluorescence under the excitation of 980 nm laser. This up-conversion luminescence can be used as an excellent probe for imaging cells. Meanwhile, these nanomaterials with doped Gd³⁺ ions could serve as T1 MRI contrast agent. MTT assay results show that these nanorods are of low toxicity. And the ability of HAp:Ln³⁺ nanorods as a carrier of BMP-2 to promote preosteoblasts differentiation of MC 3T3-E1 was investigated, which provides a favorable basis for these nanorods used as protein nanocarriers in bone repair.A series of evaluation and comparison of these as-prepared HAp nanomaterials with different morphologies were conducted to study their biocompatibility, mainly from the biodistribution in vivo, blood biochemical analysis and long-term toxicity evaluation. The results show that HAp nanomaterials by tail vein injected in healthy mice can be excreted gradually along with the time increasing via detection of in vivo distribution. By blood biochemical analysis, biochemical analysis and body weight fluctuation of these mice, it can be concluded that these two different morphologies of HAp nanomaterials both have no obvious toxicity to healthy mice, which show the possibility of these two one-dimensional nanomaterials for in vivo study. As a novel drug/protein nanocarrier, HAp nanomaterials show great potential in medical fields such as controlled drug delivery and disease treatment.