The Preparation Of A Series Of The Controllable Degradation Coral-hydroxyapatite (SCHA-200R) And The Experiment Studies On Its Application As The Scaffold In Bone Tissue-engineering

Objective: The advancement of bone tissue engineering offers a new approach to repairing the clinical bone defects. One of those crucials in this field is the scaffold material. In my studies, the transformed-hydroxyapatite is made from the natural coral through hydrothermal reactions, and the feasibility of applying it as the scaffold material in bone tissue engineering is also observed.Methods: (Y)The natural coral undergo the chemical reaction with (NH4)2HPO4 in same temperature and same pressure for different time-lengths. X-ray diffraction analysis (XRD) and X-ray spectroscopy analysis (XRS) are employed to characterize a series of the controllable degradation coral-hydroxyapatite(SCHA-200R) and the outputs from the reaction. The effects of same temperatures, pressures and different time-lengths on the reaction are also observed. (2) Scanning electron microscopy (SEM) is employed to observe the spacial structure of the outputs in order to explore whether they have the needed network structure fit for the tissue-engineered scaffold material. (3) By inductively coupled plasma atomic emissionspectrometer (ICP-AES) , the contents of the metal elements in the natural coral are tested to assess the toxicity. The biocompatibility of the outputs of the reaction is also systematically investigated, which included haemolysis test, cell culture cytotoxicity assay and bone compatibility test. (4) The marrow stromal osteoblasts (MSOs) are cultured in vitro and combined with the outputs of the hydro-thermal reaction to form the MSO/CHA-200RM compound artificial bones . The MSO/CHA-200RM compound artificial bones are implanted into nude mice subcutaneously to observe their osteogenesis effects in immune-free animals.Results: (l)The results of the XRDand XRS analyses show that the chemical component of the natural coral is CaCO3 and the crystal type is aragonite. Under the condition of some temperature, pressure and different time-length, natural coral, together with (NH4)2HPO4, undergo a hydro-thermal reaction, and thus transform into hydroxyapatite-that is, a series of the controllable degradation coral-hydroxyapatite (SCHA-200R). (2) The rate of the chemical reaction depends on the temperature and the pressure. Under the condition of 180 C and 0.99MPa, and after 3-hour reaction, the rate of HA is 5%; after 4- hour, the rate is 10%; and after 5- hour, the rate is 20%.(3) The SEM observation shows that under the low magnification the SCHA-200R materials have the interconnected micro-porous network structures. (4)The rabbit haemolysis rates of the SCHA-200R are 0.004, 0.006and 0.004. The MSOs grow well in vitro with culture medium added with the extract of the SCHA-200R. These results show that SCHA-200R have good biocompatibility. (5)In nude mice, the ectopic osteogenesis of the MSO/CHA-200RM compound artificial bones is obvious and the new bone formation increases in pace with time.Conclusion: (1)The chemical component of the natural coral is CaCO3 and the crystal type is aragonite. (2)Under the condition of high temperatureand high pressure, natural coral can transform into hydroxyapatite. (3) Gradient HA (SCHA-200R) materials can be formed by adjusting the same temperature, same pressure and different time-length of the reaction. (4)The SCHA-200R has the interconnected micro-porous network structure. (5)The SCHA-200R has a good biocompatibility. (6) The osteogenesis of the MSO/CHA-200RM compound artificial bones is obvious when transplanted subcutaneously in nude mice. (7)The SCHA-200R is a potential candidate scaffold for bone tissue engineering.