Synthesis Of Hydroxyapatite Crystals Research Articles

Synthesis of Hydroxyapatite Crystals From Egg Shells

The aim of the review is to raise awareness to synthesise hydroxyapatite (HAp) crystals from eggshells. The development of hydroxyapatite crystals shows a systematic approach towards the development in various biomedical applications. The economic approach of the synthesis of crystalline hydroxyapatite crystals from the eggshells is done using ultrasound assisted technology. The study demonstrates the use of biowastes such as egg shells which is a promising technique to develop hydroxyapatite crystals due to its mechanical and osteogenic properties. The hydroxyapatite crystals are synthesised using biowastes such as egg shells which are rich in calcium and ammonium dihydrogen phosphate. This is a viable substitute for bone regeneration and orthodontic appliances due to its properties such as fracture toughness, mechanical strength, elastic modulus, osteoconductivity, bioactivity and differentiation. These minerals are similar to the inorganic content of the bone and are used widely for complete or partial bone augmentation, filling bone and teeth. They are used as coatings in orthopaedics and dental implants. The organic components of the matrix of the egg shells are mainly composed of mucopolysaccharides, proteins, mainly composed of chondroitin sulphate A and B, glucosamine, galactosamine, galactose, mannose, fructose and sialic acid. They are widely used as the matrix fibres have a strong influence on the mechanical strength of the entire egg shells. These crystals are characterised for bone tissue engineering due to the following properties such as biocompatibility, bioactivity and other mechanical properties without getting rejected by the immune system.

The synthesis of hydroxyapatite crystals with various morphologies via the solvothermal method using double surfactants

Hydroxyapatite (HA) crystals with arambola-like structures were prepared by supersaturated urea-assisted solvothermal synthesis using double-facile surfactants. The products were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, thermal gravimetric analysis, and scanning electron microscopy. Results revealed that the morphologies of the products, including micro-hexagonal prism, carambola-like structures, and microspheres could be well tailored by regulating the double-facile surfactants and reaction time. Na2EDTA exhibited a slight inhibitory effect on HA formation. Stearic acid adsorbs on the surface of HA to form a layer with long chains and act as mechanical barrier, indicating its excellent dispersibility.

Synthesis of hydroxyapatite crystals using carboxymethyl inulin for use as a delivery of ibuprofen

In the present study biodegradable, environmentally friendly polysaccharide-based polycarboxylate, carboxymethyl inulin (CMI), was used to produce hydroxyapatite (HAP) particles by wet chemical synthesis under controlled temperature, pH, and atmospheric conditions. The morphology and microstructure of the HAP nanoparticles were investigated by XRD, SEM, DTA–TGA and FTIR. CMI affects morphology, surface area, dimension and particle size distribution of the crystals. The reduction in size is greater in the direction of the c-axis. The increase in the polymer concentration to 7.5g/L resulted in the mixture of nanoparticles with particle sizes of less than 100nm. The SEM micrograph shows the formation of well-crystallized, agglomerated small particles of HAP. X-ray analysis has shown that the resulting particles have high thermal stability.The obtained crystals were used to produce tablets by direct compression of HAP. The influence of sample's CMI concentration on drug release profiles was investigated by using ibuprofen (C13H18O2) as a model drug. The model was used to determine the effective diffusion coefficient of the drug from the tablets. A good agreement between experimental data and model predictions was obtained as calculated in the present work. The values of the diffusion coefficients range from 1.62×10−7 to 4.72×10−7m2h−1.

Synthesis of Hydroxyapatite Crystals Using Amino Acid-Capped Gold Nanoparticles as a Scaffold

Inorganic composites are of special interest for biomedical applications such as in dental and bone implants wherein the ability to modulate the morphology and size of the inorganic crystals is important. One interesting possibility to control the size of inorganic crystals is to grow them on nanoparticles. We report here the use of surface-modified gold nanoparticles as templates for the growth of hydroxyapatite crystals. Crystal growth is promoted by a monolayer of aspartic acid bound to the surface of the gold nanoparticles; the carboxylate ions in aspartic acid are excellent binging sites for Ca(2+) ions. Isothermal titration calorimetry studies of Ca(2+) ion binding with aspartic acid-capped gold nanoparticles indicates that the process is entropically driven and that screening of the negative charge by the metal ions leads to their aggregation. The aggregates of gold nanoparticles are believed to be responsible for assembly of the platelike hydroxyapatite crystals into quasi-spherical superstructures. Control experiments using uncapped gold nanoparticles and pure aspartic acid indicate that the amino acid bound to the nanogold surface plays a key role in inducing and directing hydroxyapatite crystal growth.

Hydrothermal conversion of calcite crystals to hydroxyapatite

Hydroxyapatite (HAp) has been successfully synthesized by hydrothermal treatment of calcite crystals in H 3PO 4 suspensions at 120 or 180 °C. Synthesis of HAp crystals under different H 3PO 4 concentrations and time conditions were studied. The results showed that HAp can be produced by the hydrothermal conversion of calcite crystals in the presence of a neutral suspension consisted of Ca 50 mM and PO 4 60 mM, at 120 and 180 °C for 6 h. Unreacted CaCO 3 remained when PO 4 concentration was less than this at lower temperature. The major formation mechanism of HAp seems to be dissolution/precipitation.

Microwave‐ versus Conventional‐Hydrothermal Synthesis of Hydroxyapatite Crystals from Gypsum

Hydroxyapatite (HAp) crystals were synthesized from gypsum powder with diammonium hydrogen phosphate solution via microwave‐hydrothermal treatment at 100°C, and their properties were studied. Gypsum powder could be completely converted to fine HAp crystals 30‐300 nm long with 0.5M diammonium hydrogen phosphate at 100°C in 5 min. Compared to the formation of HAp crystals via conventional‐hydrothermal treatment, microwave‐hydrothermal treatment led to increased rate of formation (by two orders of magnitude).