Introduction: β-TCP (β-tricalcium phosphate) is frequently used as bone repairing materials, drug carrier and other applications as biomedical materials because its chemical composition is close to natural bone, as well as its good bioactivity and biodegradability [1,2]. Mesoporous materials characterized having large surface area, large pore volume, unique surface, and a narrow pore size, which are crucial for developing new types of catalysts, adsorbents, drug delivery systems, and so on. Mesoporous β-TCP may be advance performance and wider application in biology. The aim of the present work is to investigate the feasibility of synthesizing mesoporous β-TCP powder by microemulsion technique.
Materials and Methods: The mesoporous β-tricalcium phosphate (β-TCP) powder was synthesized by using the microemulsion (hexadecyltrimethyl ammonium bromide (CTAB) / cyclohexane / n-octyl alcohol) system. The effects of pHs and calcination temperatures on the phase composition of the β-TCP powder were discussed. The effect of β-TCP powder with meso-structure on the proliferation of bone marrow mesenchymal stem cells (BMSCs) in vitro was studied. The phase composition, powder morphology, mesoporous structure, cell morphology and the optical density (OD) were characterized and confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), N2 adsorption-desorption isotherms, inverted phase contrast microscope and Multiskan Spectrum respectively.
Results and Discussion: The results indicated that the phase of β-calcium pyrophosphate (β-Ca2P2O7, β-CPP) was detected in the product when pH in the microemulsion system was changed from 5.0 to 6.0. The pH had an important influence on the phase composition of the final product. To obtain a purified β-TCP powder, the pH value of 7.0 was selecte. β-TCP powder was obtained at 800 °C. In the as-calcined and temperature range (200-600 °C), the products were mostly amorphous. HAP was found in the product when the calcination temperature was 700 °C that happens to be the phase transition temperature of HAP. The particles of sample seen in the picture were worm-like, irregular and aggregation partially. During the preparation process by microemulsion method, the surface morphology of β-TCP powder may be affected by the concentrations of surfactant, co-surfactant and oil phase, the stability of the microemulsion and calcination temperature. The isotherms exhibit a type IV isotherm for mesoporous materials with H3-type hysteresis loop, indicating the presence of non-uniform mesopores. The average pore size was 7.11 nm measured by the BJH method and the specific surface area calculated was 12.85 m2/g in the β-TCP powder. The cells on the mesoporous β-TCP powder spread and grew better compared to the non-mesoporous β-TCP powder, suggesting that the effect of mesoporous β-TCP powder on the activity of BMSCs was better than that of the non-mesoporous β-TCP powder. The OD values of different concentrations of the mesoporous β-TCP powder samples were higher than those non-mesoporous β-TCP powder samples after 1, 3 and 5 days in culture. These results suggested that the effect of mesoporous β-TCP powder on the proliferation of BMSCs was better than that of the non-mesoporous β-TCP powder.
Conclusions: The mesoporous β-TCP powder was prepared by microemulsion technique. The mesoporous β-TCP powder synthesized by the microemulsion technique in this study showed better effect on the proliferation of BMSCs than that of the non-mesoporous β-TCP powder.
Major Program of National Natural Science Foundation of China (No.81190133); Science and Technology Project of Wuhan (No. 2015060101010032)
References:
[1] Li Sha, Yuyan Liu, Qing Zhang, Min Hu, Yinshan Jiang, Microwave-assisted co-precipitation synthesis of high purity β-tricalcium phosphate crystalline powders, Materials Chemistry and Physics 129 (2011) 1138-1141
[2] J. Roman, M.V. Cabanas, J. Pena, J.C. Doadrio, M. Vallet-Regi, An optimized β-tricalcium phosphate and agarose scaffold fabrication technique，J. Biomed. Mater. Res. A 84 (2008) 99-107