In the present research, the mesoporous hydroxyapatite nanoparticles were synthesized by the chemical precipitation method in the absence and presence of different weight ratios (0, 0.1, and 0.3 g) of chitosan as an organic modifier. The effects of different weight ratios and pH values (8, 9, and 10) of chitosan on the structural characteristics of the mesoporous hydroxyapatite nanoparticles were also investigated. Then, all the prepared samples were calcined at 650 °C for 3 h and their structure, morphology, surface area, and pore size distribution were characterized by X-ray Diffraction (XRD) technique, Field Emission Scanning Electron and Transmission Electron Microscopy (FE-SEM & TEM), Fourier Transform Infrared spectroscopy (FT-IR), Energy Dispersive X-ray spectrometer (EDX), and finally Brunauer–Emmett–Teller (BET) technique. The XRD analysis showed that the crystalline size of the synthesized HA decreased from 38 to 24 nm at pH 8, 40 to 30 nm at pH 9 as well as from 48 to 32 nm at pH 10. The same trend of decrease in the crystalline size was observed when the chitosan concentration increased from 0.0 to 0.3 g. The results revealed that the crystalline size, pore size, and surface area of the synthesized HA can be controlled by adjusting the chitosan weight ratio in the initially prepared samples. Mesopores in HA were observed for the samples synthesized at different pH values, by removing the organic template. Furthermore, the pore size of the prepared chitosan/nHA samples was found to be 13–38 nm, which seems to be suitable for cell attachment and slow-release drug delivery, especially in treatment of osteoporosis.

中文翻译：

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壳聚糖作为有机改性剂合成孔径可控的介孔羟基磷灰石：研究壳聚糖的重量比和pH值对结构和形态性能的影响

在本研究中，在不存在和存在不同重量比（0、0.1和0.3 g）的壳聚糖作为有机改性剂的情况下，通过化学沉淀法合成了介孔羟基磷灰石纳米颗粒。还研究了壳聚糖的不同重量比和pH值（8、9和10）对介孔羟基磷灰石纳米粒子结构特征的影响。然后，将所有制备的样品在650°C下煅烧3 h，并通过X射线衍射（XRD）技术，场发射扫描电子和透射电子显微镜（FE）表征其结构，形态，表面积和孔径分布-SEM和TEM），傅里叶变换红外光谱（FT-IR），能量色散X射线光谱仪（EDX），最后是Brunauer-Emmett-Teller（BET）技术。XRD分析表明，合成的HA的晶体尺寸在pH 8时从38nm降低至24nm，在pH 9时从40nm降低至30nm，以及在pH 10时从48nm降低至32nm。晶体尺寸减小的趋势相同当壳聚糖的浓度从0.0增加到0.3 g时，观察到。结果表明，可以通过调节最初制备的样品中的壳聚糖重量比来控制合成的HA的晶体尺寸，孔径和表面积。通过去除有机模板，观察到在不同pH值下合成的样品中HA的中孔。此外，发现制备的壳聚糖/ nHA样品的孔径为13-38 nm，这似乎适用于细胞附着和缓释药物的输送，特别是在骨质疏松症的治疗中。