Papers by Keyword: Calcium Phosphate

Abstract: The usage of iron alloys for bone fractures treatment has been limited due to its high density and elastic modulus, as compared to bone. In contrast, the use of tricalcium phosphate (TCP), a ceramic that promotes bone healing, is mostly limited by its brittle nature. In the present work the fracture mechanism of a novel iron-TCP interpenetrated composite fabricated by spark plasma sintering was studied. Specimens were subjected to a diametral tensile-strength-test. The work of fracture was determined by indirect tensile loading conditions using the diametral tensile strength test. The results revealed that iron has a clear toughening effect on the microstructure of tricalcium phosphate specimens consolidated by spark plasma sintering. This is a promising result to overcome the limited usage of tricalcium phosphate to treat only non-load bearing bone defects.

Abstract: The fabrication of a composite material based on magnesium (Mg) and tricalcium phosphate is reported in this work. Rods of β-tricalcium phosphate (β-TCP) were processed and consolidated together with pure Mg powder through spark plasma sintering (SPS). The microstructure at the interface, the chemical composition and transformation of the components and the microhardness were analysed. The microstructure of the composite shows two zones with well-defined and continuous interface between them: a ceramic zone composed by β-TCP filled with Mg and the metallic zone constituted by Mg and Mg rich eutectic. Vickers hardness shows the excellent mechanical interaction between the two zones.

Abstract: α-Tricalcium phosphate is an important ingredient of calcium phosphate bone cements, which are used for bone defect augmentation and repair. In this study sub-micrometre sized α­tricalcium phosphate particles were synthesized by heat treating amorphous calcium phosphate. Size of synthesized particles depended on duration and temperature of heat treatment. Longer duration and higher temperatures produced larger particles. The reactivity of synthesized particles did not correlate with particle size – the smallest particles did not have the highest reactivity. The most reactive particles were prepared at 700-800 °C. The prepared particles were more reactive than those of conventionally synthesized α-tricalcium phosphate.

Abstract: The combination of calcium phosphate compounds and hyaluronan is expected to have advantages of both materials to be used as optimal scaffold for bone tissue engineering. It possesses the fundamental necessary characteristics such as bioactivity, biomechanical similarity, processability, and biodegradability. Preparation technology and properties of hyaluronan acid and calcium phosphate composites (HA/CaP) are described in the current study, and for the first time composites with high, up to 0.43 HA/CaP mass ratio are synthesized using chemical cross-linking method.HA/CaP hydrogels were prepared using fixed cross-linker amount at different HA concentrations. Swelling properties of prepared HA/CaP hydrogels were investigated as function of the HA content in composite. The swelling properties of hydrogels were studied in phosphate-buffered saline (PBS) at pH 7.4. It was observed that HA reinforcement with CaP particles increases hydrogel stability, and prepared HA/CaP hydrogels maintained their integrity up to 4 weeks.

Abstract: Failures, infections, tumors are some bone defects causes. To repair these defects, studies show calcium phosphate bioceramics, which have been chemical and crystallographic similarity with the human bone and are biocompatible, favoring the interaction of these with vivo organisms, for bone repair. These biomaterials can be obtained from different synthesis methods. The powders, in this study, were obtained by wet method, using alternative raw material calcium carbonate from fossilized calcareous shells. The present paper aimed to elaborate and characterize different calcium phosphate ratio compositions: (i)1.4; (ii)1.6 and (iii)1.7 molar, sintered for 2 hours at 1100°C and 1200°C, further these powders were compressed in forms of cylinders. The characterization was realized by X-Ray Fluorescence (XFR), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffractometry (XRD). The chemical and physical results shown small variations according to the Ca/P molar ratio and temperature increases.

Abstract: The calcium phosphate bioceramics are characterized by chemical and crystallographic similarity with the human skeleton. The wet synthesis method was used in the preparation of hydrated calcium phosphate nanostructured powders and biphasic compositions of calcium phosphate matrix. This study aimed the synthesis and characterization of a hydrated calcium phosphate matrix in the ratio Ca/P 1.67 molar and two biphasic compositions of hydrated calcium phosphate matrix, with 1% MgO and 5% α-Al₂O₃. Scanning Electron Microscopy (SEM) helped with the powders morphological characterization, X-ray diffractometry (XRD) served for crystallographic characterization of powders and Fourier Transformed Infrared Spectroscopy (FTIR) gave support to the identification of H₂O, CO₃^2- and PO₄^3- grouping vibrational bands. The work showed that the presence of 1% MgO inside the hydrated calcium phosphate matrix provided brushite formation and the presence of 5% α-Al₂O₃ in the matrix provided the hydrated calcium phosphate powder.

Abstract: Calcium phosphates bioceramics are a broad class of biomaterials, known by properties like biocompatibility and bioactivity in living tissues. The aim of this paper was the synthesis by wet method and characterization of nanostructured calcium phosphate powders in the Ca/P ratio of 1.67molar and rheological evaluation of the colloidal suspension during the synthesis: suspension viscosity with variable shear rate. Morphological characterization was performed for the hydrated nanostructured calcium phosphate powder by scanning electron microscopy with field effect, crystallography by X-Ray diffractometry, chemical characterization by Fourier Transformed Infrared Spectroscopy. The results demonstrated that varying the shear rate has a direct influence on the viscosity values according to time. This result may contribute to the development of a synthesis methodology for nanostructured calcium phosphate powders.

Abstract: Calcium phosphate bioceramics obtained from raw materials are potential bone substitutes in orthopedic and dental applications. Calcium phosphates attained from calcareous shells using wet methods provide an interconnected microporous framework, shown to be promising and contribute to cell adhesion and proliferation. This study aimed to characterize three different calcium phosphate ratio compositions: (i)1.4, (ii)1.6 and (iii)1.7 molar, sintered for 2 hours at 1100°C and 1200°C. Scanning electron microscopy field effect [FEG] and confocal were used to assess microstructural characterization and Arthur method to determine open porosity. FEG and confocal analyses showed good grain coalescence, sinterability and well defined interfaces for all Ca/P molar at 1100°C and 1200°C. Open porosity and hydrostatic density exhibit better results when using Ca/P molar ratio (iii)1.7 at 1100°C. The results showed that open porosity is related to Ca/P ratio and by temperature. As the Ca/P increases so does the open porosity. Inversely occurs for temperature. As the temperature increases the porosity decreases and in parallel, the grain size increases.

Abstract: The development of the calcium phosphate ceramics (CPC) using natural materials such as coral, eggshell, bovine bone, fish bone etc., from Indian origin have been reviewed. The CPCs from natural sources has the benefit that they inherit some of the properties of the raw materials such as the macro-and micro-pore structure, optimal composition, similar morphology etc., as well as the advantage of unlimited world wide availability at a very low raw material cost. Hydroxyapatite (HA), carbonated HA and fluorapatite from natural coral genus "Goniopora” has been obtained. Growth factor loaded coralline HA has been found to significantly accelerate early-stage bone formation in in vivo rabbit model studies. Sea shells have been tested as the source of calcium for electrochemical deposition of HA on titanium implants. Deproteinized hydroxyl carbonate apatite phase was formed by heating adult bovine tibia at 500o C. As eggshell could be easily procured, a great deal of effort has been made to utilize this resource as value-added CPCs including nanocrystalline HA (OHA), calcium deficient HA (CDHA), TCP, tetracalcium phosphate (TTCP) etc., which are the most widely used bone substitutes. Also OHA showed higher antibiotic delivery and more controlled protein release profile compared to the synthetic apatites. Eggshell derived CPCs were also found to have minor amount of Mg, Sr, Si and Na ions inherited from the eggshell. As these ions are crucial for bio-mineralization of eggshell, the influence of multi-ions substituted CPCs as a potential bioceramic for bone regenerative applications has been emphasised.

Abstract: Bioceramics draw attention in bone tissue engineering field since their biomimetic properties regarding bone attribute. In this context, a concept of smart bioceramics granules made of Hydroxyapatite have been set up, enhancing surface area available to body fluids containing proteins and cell adhesion for bone forming respectively thanks to microporosities and macropore concavities. New “hollow shell” granules were developed and assessed by physico-chemical characterizations, in-vitro experiments and in-vivo implantation in comparison with classical round granules. This new original galenic formulation showed promising potential in cell carrying and osteoconduction matter.