To meet the different application requirements in various fields, hydroxyapatite (HA) hollow microspheres with different surface charge were synthesized successfully by biomimetic method using Ca(NO3)2·4H2O and (NH4)2HPO4 in the presence of polyethylene glycol (PEG). Scanning electron microscopy (SEM), High-resolution TEM (HRTEM), X-ray powder diffraction (XRD), and Zeta PALS were used to characterize the obtained samples. The results indicated that the concentration of PEG and temperature significantly affect the morphology of the obtained samples. After incubation for 5 d, the HA hollow microspheres with positive surface charge, HA spherical nanoparticles with surface charge close to zero and calcium deficiency HA (d-HA) hollow microspheres with negative surface charge were obtained respectively in the presence of 5% PEG, 6% PEG and 7% PEG at 15 °C. Brunauer-Emmett-Teller (BET) revealed that the specific surface area of HA hollow microspheres reached 98.50 m2/g, while that of HA spherical nanoparticles were only 4.12 m2/g, hollow microspheres show a better application prospect. The possible formation mechanism was also discussed. Ca/P molar ratio >1.67, the surface charge of HA hollow microspheres inclines to be positive. Ca/P molar ratio <1.67, the surface charge of d-HA hollow microspheres tends to be negative.

中文翻译：

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仿生法制备表面电荷不同的羟基磷灰石空心微球及其机理

为满足不同领域的不同应用需求，在聚乙二醇（PEG）存在下，采用Ca（NO3）2·4H2O和（NH4）2HPO4仿生法成功合成了具有不同表面电荷的羟基磷灰石（HA）空心微球。使用扫描电子显微镜（SEM），高分辨率TEM（HRTEM），X射线粉末衍射（XRD）和Zeta PALS来表征获得的样品。结果表明PEG的浓度和温度显着影响所得样品的形态。孵育5 d后，分别在5％PEG的存在下，获得具有正表面电荷的HA中空微球，具有接近零表面电荷的HA球形纳米颗粒和具有负表面电荷的缺钙HA（d-HA）中空微球，在15°C下6％PEG和7％PEG。Brunauer-Emmett-Teller（BET）表明，HA中空微球的比表面积达到98.50 m2 / g，而HA球形纳米颗粒的比表面积仅为4.12 m2 / g，中空微球具有较好的应用前景。还讨论了可能的形成机理。Ca / P摩尔比> 1.67时，HA中空微球的表面电荷倾向于为正。当Ca / P摩尔比<1.67时，d-HA中空微球的表面电荷趋于为负。HA中空微球的表面电荷倾向于为正。当Ca / P摩尔比<1.67时，d-HA中空微球的表面电荷趋于为负。HA中空微球的表面电荷倾向于为正。当Ca / P摩尔比<1.67时，d-HA中空微球的表面电荷趋于为负。