Biomimetic Carbonate–Hydroxyapatite Nanocrystals Prepared by Vapor Diffusion

Abstract

Biomimetic carbonate–hydroxyapatite (HA) nanocrystals have been synthesized by using the sitting drop vapor diffusion technique, for the first time. The method consists of diffusing vapors of an aqueous solution of NH4HCO3 through drops containing an aqueous mixture of (CH3COO)2Ca and (NH4)2HPO4 in order to increase slowly their pH. This synthesis has been performed in a crystallization mushroom, a glass device developed for protein and small molecules crystallization. The concentrations of the reagents, the final pH and the crystallization time have been optimized to produce pure carbonate–HA as a single phase. X‐Ray diffraction, Fourier transformed infrared spectroscopy, and transmission electron microscopy have been utilized to characterize the synthesized carbonated substituted HA crystals which display nanometric dimensions, plate‐like morphology, and low crystallinity degree, closely resembling the inorganic phase of bones, teeth, and many pathological calcifications. This novel method may prove to be suitable for the study of the interactions and/or the co‐crystallization of hydroxyapatite with minute amounts of biomolecules, polymers, or drugs.

Biomineralization on chemically synthesized collagen containing immobilized poly-γ-glutamic acid

“…After treatment, bands assigned to COO − symmetric stretching and OH bending of COOH became apparent at 1,400 and 1,250 cm −1 , respectively. On the other hand, the intensity of the band at 1,340 cm −1 assigned to C-OH stretch was significantly decreased 16,17) . These results mean that PGA was immobilized on the surface of the chemically synthesized collagen.…”

Nanodimensional and Nanocrystalline Calcium Orthophosphates

“…Furthermore, nanodimensional HA might be manufactured by a laser-induced fragmentation of HA targets in water [463][464][465][466][467] and in solvent-containing aqueous solutions [344,371,468], while dense nanocrystalline HA films might be produced by radio frequency magnetron sputtering [469,470]. An interesting approach using sitting drop vapor diffusion technique should be mentioned as well [471]. A comparison between the sol-gel synthesis and wet chemical precipitation technique was performed and both methods appeared to be suitable for synthesis of nanodimensional apatite [328].…”

Formation of calcium phosphates by vapour diffusion in highly concentrated ionic micro‐droplets

“…Despite the large number of synthetic strategies to synthesize nanoapatites, the preparation of HA with similar physico-chemical and morphological characteristics to those of the bone mineral phase, still remains an intellectual and technological challenge [4]. Recently, Iafisco et al reported a new methodology, based on the vapour diffusion sitting drop micro-method, to precipitate carbonate-substituted hydroxyapatite nanoparticles [5]. The method was developed by using an innovative device called the "crystallization mushroom" [6].…”