A Simple Method To Control Morphology of Hydroxyapatite Nano- and Microcrystals by Altering Phase Transition Route

Abstract

Hydroxyapatite (HAp) particles with various morphologies such as sphere, rod, whisker, and platelet have attracted a great deal of scientific and technological interest for their broad utilization as reinforcing agents in bone cement, bone fillers, drug carriers, and adsorbents for chromatography. In this Article, a simple method to control the morphology of HAp particles by adjusting the initial pH of precursors and the amount of gelatin and urea additions is introduced. Initially formed calcium phosphate products such as octacalcium phosphate (OCP), hydroxyapatite (HAp), and amorphous calcium phosphate (ACP) are found to be altered by changing the pH of solutions, which induces variation of HAp morphology as well as phase transformation route to HAp. From the observation of HAp formation behavior, the addition of gelatin is revealed to retard HAp formation as well as to change the aspect ratio of HAp particles, which is ascribed to strong adsorption of gelatin on the surface of calcium phosphate. Also, urea is observed to boost HAp formation rate by enhancing hydrolysis reaction. Through the understanding of the influence of the aforementioned variables, the morphology of pure HAp particles is successfully controlled, and this enables the promotion of the applicability of HAp particles in various fields.

Evaluation of hydroxyapatite crystallization in a batch reactor for the valorization of alkaline phosphate concentrates from wastewater treatment plants using calcium chloride

“…The and 12 is ‫ܱܲܽܥ‬ ସ ି . Under this conditions it has been postulated a shift on the surface charge of the mineral leading to the precipitation of amorphous calcium phosphate [24],…”

“…Han et al [24] identified at pH 10, the precipitation of an amorphous calcium phosphate (ACP) phase at the initial reaction time and then it crystallized into Hap after 2h of reaction.…”

Effects of pore distribution of hydroxyapatite particles on their protein adsorption behavior

“…Han et al have reported a method for controlling the HAp nanoparticle morphology under hydrothermal treatment in the presence of urea and gelatin. They synthesized various HAp morphologies by altering the phase transition route by varying the initial pH and hydrothermal treatment time [23]. Kawachi [27,28].…”

Fabrication of a composite of nanocrystalline carbonated hydroxyapatite (cHAP) with polylactic acid (PLA) and its surface topographical structuring with direct laser writing (DLW)

“…11 Phase purity and crystal shape can also be controlled by adding organic can be obtained. 12 The crystallinity of the material is another important aspect, since it governs dissolution properties and subsequently effects the biodegradation/bioresorption. 14 Temperature and pH are two major parameters that determine the crystallinity of ceramic material produced by precipitation method.…”