Preparation and characterization of single phase, biphasic and triphasic calcium phosphate whisker-like fibers by homogenous precipitation using urea

Abstract

Whisker−like calcium phosphate fibers were prepared by a homogenous precipitation method under refluxing conditions in solutions with a Ca/P molar ratio of 1.67 at 90°C and pH 3.0 using urea as additive. The precipitates were characterized by XRD, FTIR, SEM, and FE−SEM. The ICP spectroscopy and elemental analyzer were used to determine Ca/P ratio and carbonate content of products, respectively. The results indicate that the morphology and structural characteristics of the precipitates depend on the urea concentration and reaction time. Whisker−like biphasic monetite/hydroxyapatite (HA) fibers with a mean length of 60 µm and a mean width of 1.0 µm were obtained with the use of a low concentration of urea. Calcination of the biphasic calcium phosphate at 800 °C led to the formation of a triphasic mixture of HA/whitlockite (β−TCP)/calcium pyrophosphate (CPP) with a whisker−like morphology. The use of a higher concentration of urea was caused to form a mixed morphology of spherulites/whisker−like fibers consisting of octacalcium phosphate (OCP) and HA phases. When the reaction time was increased to 10 days, both the above biphasic calcium phosphates transformed to a single phase HA which its morphology and growth pattern were similar to those of a whisker, according to FE−SEM images. The HA whiskers produced by a lower amount of urea had a lower carbonate content compared to those obtained using a higher urea concentration.

Mechanically Robust 3D Graphene–Hydroxyapatite Hybrid Bioscaffolds with Enhanced Osteoconductive and Biocompatible Performance

“…The related peaks for CP composite are at 25.87°, 32.19°, 34.05°, and 50.49°, respectively, which are consistent with hydroxyapatite (HA) standard peaks (002), (112), (202), and (321) corresponding to JPCDS: 09-0432 [25]. The 2θ angles peaked at 25.85°, 29.22°, 30.74°, and 32.32° are consistent with octacalcium phosphate (OCP) standard peaks (−421), (−330), (6−11), and (−222) (JPCDS: 79-0423) [24], while the 2θ angle centered at 32.75° and 34.21° agrees with tricalcium phosphate (TCP) standard peaks (190) and (290) (JPCDS: 29-0359) [26]. In general, the CP composite obtained by electrodeposition under such condition is a mixture of OCP, TCP, and HA.…”

“…Furthermore, XRD was also utilized to characterize the crystal properties of the CP composite, which is coated on the surface of GF scaffold though electrochemical depositions, as shown in Figure 4. For each electrodeposition condition, a broad peak presents between the 2θ angles of 15 • [26]. In general, the CP composite obtained by electrodeposition under such condition is a mixture of OCP, TCP, and HA.…”

Bioactive monetite‐containing whisker‐like fibers reinforced chitosan scaffolds

“…The absorption band of 632 cm −1 was attributed to OH − group. The presence of group can be distinguished by the bands at 1107 and 1457 cm −1 . These bands were observed due to incorporation of carbonate from the urea hydrolysis into the structure of HA .…”

Small organic molecule-mediated hydrothermal synthesis of hierarchical porous hydroxyapatite microspheres by the incorporation of copper ions

“…The mixed constitution is similar to previous studies on the synthesis of calcium phosphate using a high concentration of urea as additive. 18 When IP6 was added in the solution, a mixture of microspheres (1-25 mm) and sheets was obtained (Fig. 1b).…”