Investigation of EDTA concentration on the size of carbonated flowerlike hydroxyapatite microspheres

Ethylenediamine tetraacetic acid (EDTA) is considered as an effective crystal growth modifier for template-assisted hydrothermal synthesis of hydroxyapatite (HA) materials. In this work, flowerlike carbonated HA (CHA) microspheres were synthesized using EDTA via a one-step hydrothermal route. The phase, functional groups, morphology, and particle size distribution of the products were examined by X-ray diffraction, Fourier transform infrared spectrometer, field-emission scanning electron microscopy as well as laser diffraction particle size analysis. Results show that the morphology of the products can be well controlled by adjusting the EDTA concentration. With an increase of the EDTA concentration, the particle size of flowerlike microspheres decreased from tens of microns down to a few microns. The underlying mechanism for the morphological transition of CHA microspheres with different concentrations of EDTA under the hydrothermal conditions was proposed. This work provides a simple way to controllably fabricate CHA microspheres with various sizes using the same synthesis system for biomedical applications, such as cell carriers and drug delivery.

乙二胺四乙酸（ethylenediamine tetraacetic acid，EDTA）被视为模板辅助水热合成羟基磷灰石（hydroxyapatite，HA）材料的高效晶体生长调控剂。本研究采用乙二胺四乙酸，通过一步水热法合成了花状碳酸化羟基磷灰石（carbonated HA，CHA）微球。研究采用X射线衍射（X-ray diffraction）、傅里叶变换红外光谱仪（Fourier transform infrared spectrometer）、场发射扫描电子显微镜（field-emission scanning electron microscopy）以及激光衍射粒度分析（laser diffraction particle size analysis），对产物的物相、官能团、形貌与粒径分布进行了表征。结果表明，通过调节乙二胺四乙酸的浓度可有效调控产物的形貌。随着乙二胺四乙酸浓度升高，花状微球的粒径从数十微米降至数微米。本研究提出了水热条件下不同浓度乙二胺四乙酸引发碳酸化羟基磷灰石微球形貌演变的潜在机制。本研究提供了一种简便策略，可在同一合成体系中可控制备不同粒径的碳酸化羟基磷灰石微球，可用于细胞载体、药物递送等生物医学应用场景。