Ginebra M P, Driessens F C M, Planell J A
Research Centre in Biomedical Engineering, Biomaterials Division, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), Av. Diagonal 647, E08028 Barcelona, Spain.
Biomaterials. 2004 Aug;25(17):3453-62. doi: 10.1016/j.biomaterials.2003.10.049.
The aim of this work is to investigate the possibility of controlling the final micro and nanostructural features of a calcium phosphate cement by modifying the particle size of the starting powder, and to study the effect of this parameter on the kinetics of the setting reaction. The development of calcium phosphate materials with tailored structures at the micro and nanoscale levels could allow the modulation of some specific responses in biologic phenomena such as protein adsorption and cell adhesion, which strongly depend on the nano-sized roughness of the interface. It is shown that the higher specific surface, produced by the reduction of the particle size of the powder, strongly accelerates the hydrolysis of the alpha-TCP into calcium-deficient hydroxyapatite. The higher degree of supersaturation attained in the solution favours the nucleation of smaller crystals. Thus, by increasing the specific surface of the starting powder in a factor of 5, the size of the precipitated crystals is strongly reduced, and the specific surface of the set cement increases by a factor of 2. The reduction of the particle size produces a substantial decrease of the setting time and accelerates the hardening of the cement without significantly affecting the final strength attained. The mechanical strength achieved by the cement cannot be univocally related to the degree of reaction, without considering the microstructural features.
这项工作的目的是研究通过改变起始粉末的粒径来控制磷酸钙水泥最终微观和纳米结构特征的可能性，并研究该参数对凝固反应动力学的影响。开发在微观和纳米尺度上具有定制结构的磷酸钙材料，可以调节生物现象中的一些特定反应，如蛋白质吸附和细胞粘附，这些反应强烈依赖于界面的纳米级粗糙度。结果表明，粉末粒径减小产生的较高比表面积强烈加速了α-TCP水解为缺钙羟基磷灰石。溶液中达到的较高过饱和度有利于较小晶体的成核。因此，将起始粉末的比表面积增加5倍，沉淀晶体的尺寸会大幅减小，凝固水泥的比表面积会增加2倍。粒径的减小会使凝固时间大幅缩短，并加速水泥的硬化，而不会显著影响最终达到的强度。如果不考虑微观结构特征，水泥所达到的机械强度与反应程度并非唯一相关。
