Effect of Synthesis Temperature on the Crystallization and Growth of In Situ Prepared Nanohydroxyapatite in Chitosan Matrix

Abstract

Hydroxyapatite nanoparticles (nHA) have been used in different biomedical applications where certain particle size distribution and morphology are required. Chitosan/hydroxyapatite (CS/HA) nanocomposites were prepared using in situ coprecipitation technique and the effect of the reaction temperature on the crystallization and particle growth of the prepared nanohydroxyapatite particles was investigated. The composites were prepared at different synthesis temperatures (−10, 37, and 60°C). XRD, FTIR, thermal analysis, TEM and SEM techniques were used to characterize the prepared specimens. It was found that the increase in processing temperature had a great affect on particle size and crystal structure of nHA. The low temperature (−10°C) showed inhabitation of the HA growth in c-direction and low crystallinity which was confirmed using XRD and electron diffraction pattern of TEM. Molar ratio of the bone-like apatite layer (Ca/P) for the nanocomposite prepared at 60°C was higher was higher than the composites prepared at lower temperatures (37 and −10°C).

Wet chemical synthesis of nanocrystalline hydroxyapatite flakes: effect of pH and sintering temperature on structural and morphological properties

“…This implies that the samples improved their crystallinity and crystallite size ( figure 7 ) due to the reduction in strain and defect density of the crystals. The presence of CaHPO 4 was observed only for samples sintered at 700°C and 900°C, and it is due to the increase in the number of chemical reactions between the residual species [ 41 ], which resulted in agglomeration and formation of new compounds [ 42 , 43 ].…”

Injectable Scaffolds for Bone Regeneration

“…Where w p is the weight gain; K p is the kinetic constant of water penetration into the composite material; n p is the exponent describing the mechanism of water penetration. The disappearance of the band at 644 cm −1 (OH) and the shift of the CS signals from 1375 to 1413 cm −1 suggested that HA hydroxyl groups might interact with the hydroxyl groups of chitosan via the formation of hydrogen bonds 16,17 . Also the characteristic amino group band of the polysaccharide, at 1650cm −1 , almost disappeared while the amide I band at 1589cm −1 shifted to 1633 cm −1 and became less intense, indicating electrostatic interactions and hydrogen bonding is probably taking place between the PO 4 3− groups of HA and the NH 3 + groups of chitosan 18 .…”

Biomimetic matrix mediated room temperature synthesis and characterization of nano-hydroxyapatite towards targeted drug delivery

“…Previously explored methods of HA synthesis include plasma spraying [20], hydrothermal synthesis [21][22], freeze drying [23][24], sol-gel [25][26] phase transformation [27], mechanochemical synthesis [28], chemical precipitation [29], and precipitation in simulated body fluid (SBF) [30][31]. Further, most of these methods involve elevated temperatures and/ or extreme pH which results in larger crystal growth and an increase in coarseness of the microstructure limiting its bio application [33][34]. Further, most of these methods involve elevated temperatures and/ or extreme pH which results in larger crystal growth and an increase in coarseness of the microstructure limiting its bio application [33][34].…”