Controllable preparation and formation mechanism of highly ordered hydroxyapatite nanofibers: Effect of PO43−/CO32-

Abstract

Hydroxyapatite (HAP), as an inorganic material with the biocompatible and bioactive, widely exists in hard tissues such as teeth and bones of mammals. However, the inherent brittleness of traditional HAP severely limits its clinical applications in load-bearing. HAP ultralong nanofibers with good flexibility can overcome this problem due to their high aspect ratio. In this work, the highly ordered HAP nanofibers are successfully synthesized by the calcium oleate precursor solvothermal method. The effects of ratio of PO43− and CO32− on the microstructure, orientation degree, and properties are researched. The results show that the arrangement of HAP nanofibers first changes from loose state to ordered dense structure, then to ordered loose form, and finally to disordered nanofibers with the increase of the PO43−/CO32− ratio. Meanwhile, the chemical composition, crystallinity, and thermal stability also change because of various PO43−/CO32−. In addition, the formation mechanism of highly ordered HAP nanofibers is explored as well in this work. Besides, the HAP ultralong nanofibers prepared by solvothermal method can be designed into advanced functional materials with highly ordered structures, which is expected to overcome the limitation of its difficult application in the load-bearing field.

Keywords

• Hydroxyapatite nanofibers
• Solvothermal method
• Highly ordered
• Crystal structure
• Surface energy