Size Control Synthesis of Hydroxyapatite Plates and Their Application in the Preparation of Highly Oriented Films

Abstract

Hydroxyapatite (HAp) plates were successfully synthesized using dodecanedioic acid (DDDA). Following the preparation of an ethanolic solution of DDDA, solutions of calcium and phosphate were added in succession to produce a white slurry upon mixing. Subsequent processing of this slurry under hydrothermal conditions provided HAp plates of various sizes. Indeed, the plate size could be changed by varying the quantity of DDDA employed in the synthesis, with larger particles being obtained in the presence of larger quantities of DDDA. It was confirmed that a calcium–DDDA complex (Ca-DDD, calcium dodecanedioate) was formed upon mixing of the DDDA and calcium solutions. The observed morphological control could potentially be accounted for by the formation of Ca-DDD. More specifically, during crystal growth, Ca-DDD plays the role of a nucleation substrate (template), a pH buffer, and a calcium reservoir. Finally, we demonstrated that the obtained HAp plates could be employed to prepare a HAp film with high crystallographic orientation.

On the Crystallization of Hydroxyapatite under Hydrothermal Conditions: Role of Sebacic Acid as an Additive

“… 25 , 26 In addition, among the fatty acids having a carboxylic acid group, naturally occurring fatty acids having a dicarboxylic acid group are used as additives. 27 , 28 The dicarboxylic acid provides the nucleation site, and the hydrocarbon chain might induce oriented crystal growth of HAp during the hydrothermal process. In addition, organic acids with carboxyl groups are chemisorbed onto the surface of growing crystal grains under hydrothermal conditions, which help the crystals grow in a specific orientation.…”

An oriented hydroxyapatite film with arrayed plate‐like particles enhance chondrogenic differentiation of ATDC5 cells

“…HAp nanoparticles were synthesized via a hydrothermal method as described previously with some modifications (Horiuchi et al, ). Briefly, 0.1 M calcium chloride (10 mL) was added to 2 mmol dodecanedioic acid (DD, Sigma‐Aldrich, MO) or 20 mmol oleic acid (OA, Sigma‐Aldrich) in ethanol.…”

“…HAp nanoparticles were synthesized via a hydrothermal method as described previously with some modifications (Horiuchi et al, 2018).…”

“…Biologically formed HAp forms plate-like crystals (Shen, Horiuchi, Miyashin, Yamashita, & Nagai, 2017;Suzuki, Kamakura, & Katagiri, 2006). We recently successfully synthesized c-axis-oriented HAp platelets via a hydrothermal method, using fatty acids as the template (Horiuchi et al, 2018). To obtain HAp resembling the natural bone minerals, studies have attempted to regulate the directed growth of HAp Zhuang et al, 2013).…”

“…To obtain HAp resembling the natural bone minerals, studies have attempted to regulate the directed growth of HAp (Aizawa et al, ; Zhuang et al, ). We recently successfully synthesized c‐axis‐oriented HAp platelets via a hydrothermal method, using fatty acids as the template (Horiuchi et al, ).…”