Rapid hydrothermal flow synthesis and characterisation of carbonate- and silicate-substituted calcium phosphates

PubMed Central

Knowles, Jonathan C; Rehman, Ihtesham; Darr, Jawwad A

2013-01-01

A range of crystalline and nano-sized carbonate- and silicate-substituted hydroxyapatite has been successfully produced by using continuous hydrothermal flow synthesis technology. Ion-substituted calcium phosphates are better candidates for bone replacement applications (due to improved bioactivity) as compared to phase-pure hydroxyapatite. Urea was used as a carbonate source for synthesising phase pure carbonated hydroxyapatite (CO3-HA) with ≈5 wt% substituted carbonate content (sample 7.5CO3-HA) and it was found that a further increase in urea concentration in solution resulted in biphasic mixtures of carbonate-substituted hydroxyapatite and calcium carbonate. Transmission electron microscopy images revealed that the particle size of hydroxyapatite decreased with increasing urea concentration. Energy-dispersive X-ray spectroscopy result revealed a calcium deficient apatite with Ca:P molar ratio of 1.45 (±0.04) in sample 7.5CO3-HA. For silicate-substituted hydroxyapatite (SiO4-HA) silicon acetate was used as a silicate ion source. It was observed that a substitution threshold of ∼1.1 wt% exists for synthesis of SiO4-HA in the continuous hydrothermal flow synthesis system, which could be due to the decreasing yields with progressive increase in silicon acetate concentration. All the as-precipitated powders (without any additional heat treatments) were analysed using techniques including Transmission electron microscopy, X-ray powder diffraction, Differential scanning calorimetry, Thermogravimetric analysis, Raman spectroscopy and Fourier transform infrared spectroscopy. PMID:22983020

Hydroxyapatite, fluor-hydroxyapatite and fluorapatite produced via the sol-gel method: bonding to titanium and scanning electron microscopy.

PubMed

Tredwin, Christopher J; Georgiou, George; Kim, Hae-Won; Knowles, Jonathan C

2013-05-01

Hydroxyapatite (HA), fluor-hydroxyapatite (FHA) with varying levels of fluoride ion substitution and fluorapatite (FA) production has been characterised and optimised by the sol-gel method and the dissolution and biological properties of these materials were investigated. It was the objective of this study to investigate the potential bond strength and interaction of these materials with titanium. HA, FHA and FA were synthesised by a sol-gel method. Calcium nitrate and triethyl phosphite were used as precursors under an ethanol-water based solution. Different amounts of ammonium fluoride (NH4F) were incorporated for the preparation of the FHA and FA sol-gels. Using a spin coating technique the sol-gels were coated onto commercially pure titanium disks and crystallised at various temperatures. Using scanning electron microscopy (SEM) and elemental analysis, the surface characteristics, coating thickness and interaction of the Ti substrate and coating were investigated. The bond strengths of the coating to the Ti were investigated using an Instron Universal Load Testing Machine. Statistical analysis was performed with a two-way analysis of variance and post hoc testing with a Bonferroni correction. (1) Coating speed inversely influenced the coating thickness. (2) Increasing fluoride ion substitution and heating temperature significantly increased bond strength and (3) increasing fluoride ion substitution increased the coating thickness. FHA and FA synthesised using the sol-gel technique may offer a superior alternative to coating titanium implants with HA and plasma spraying. HA, FHA and FA materials synthesised by the sol-gel method may also have a use as bone grafting materials. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Preparation of hydroxyapatite from animal bones.

PubMed

Sobczak, Agnieszka; Kowalski, Zygmunt; Wzorek, Zbigniew

2009-01-01

This paper presents the method of obtaining hydroxyapatite from animal bones. Bone sludge and calcined products were characterized by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Calcium concentration was determined with titration, and phosphorus--spectrophotometrically. Making use of the AAS and ICP methods the content of microelements was determined. In all the products, hydroxyapatite was the only crystalline phase indicated. The FT-IR spectra confirmed that calcination removed the total of organic substances. Calcium and phosphorus contents were 38% and 18%, respectively, which corresponded to the Ca/P molar ratio of nonstoichiometric hydroxyapatite. The specific surfaces of products were measured by BET method. The volume of micro- and mesopores was determined.

The precursors effects on biomimetic hydroxyapatite ceramic powders.

PubMed

Yoruç, Afife Binnaz Hazar; Aydınoğlu, Aysu

2017-06-01

In this study, effects of the starting material on chemical, physical, and biological properties of biomimetic hydroxyapatite ceramic powders (BHA) were investigated. Characterization and chemical analysis of BHA powders were performed by using XRD, FT-IR, and ICP-AES. Microstructural features such as size and morphology of the resulting BHA powders were characterized by using BET, nano particle sizer, pycnometer, and SEM. Additionally, biological properties of the BHA ceramic powders were also investigated by using water-soluble tetrazolium salts test (WST-1). According to the chemical analysis of BHA ceramic powders, chemical structures of ceramics which are prepared under different conditions and by using different starting materials show differences. Ceramic powders which are produced at 80°C are mainly composed of hydroxyapatite, dental hydroxyapatite (contain Na and Mg elements in addition to Ca), and calcium phosphate sulfide. However, these structures are altered at high temperatures such as 900°C depending on the features of starting materials and form various calcium phosphate ceramics and/or their mixtures such as Na-Mg-hydroxyapatite, hydroxyapatite, Mg-Whitlockit, and chloroapatite. In vitro cytotoxicity studies showed that amorphous ceramics produced at 80°C and ceramics containing chloroapatite structure as main or secondary phases were found to be extremely cytotoxic. Furthermore, cell culture studies showed that highly crystalline pure hydroxyapatite structures were extremely cytotoxic due to their high crystallinity values. Consequently, the current study indicates that the selection of starting materials which can be used in the production of calcium phosphate ceramics is very important. It is possible to produce calcium phosphate ceramics which have sufficient biocompatibility at physiological pH values and by using appropriate starting materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Alternate Spray-coating for the Direct Fabrication of Hydroxyapatite Films without Crystal Growth Step in Solution.

PubMed

Watanabe, Satoshi; Kashiwagi, Rei; Matsumoto, Mutsuyoshi

2017-03-01

We discuss an alternate spray-coating technique for the direct fabrication of hydroxyapatite films using metal masks, suction-type spray nozzles and two calcification solutions of calcium hydroxide and phosphoric acid aqueous solutions. Hydroxyapatite films were formed only on the hydrophobic surface of the substrates. Scanning electron microscopy and energy dispersive X-ray spectroscopy showed that the spray-coated films consisted of hydroxyapatite nanoparticles. The Ca/P ratio was estimated to be about 1.26. X-ray diffraction patterns of the spray-coated films almost coincided with those of the hydroxyapatite powders, showing that the spray-coated films consisted of hydroxyapatite nanoparticles. Dot arrays of hydroxyapatite films at a diameter of 100 μm were formed by tuning the concentrations of calcium hydroxide and phosphoric acid aqueous solutions. This technique allows for the direct fabrication of the hydroxyapatite films without crystal growth process in hydroxyapatite precursors, the scaffolds of crystal growth such as biocompatibility SiO 2 -CaO glasses, or electrophoresis processes. By using this technique, large-area ceramic films with biocompatibility will be micropatterned with minimized material consumption, short fabrication time, and reduced equipment investments.

The Effects of Diet Calcium, Protein and Acidity on Calcium Retention in the Rat, Particularly as Related to the Inner and Outer Surfaces of Tubular Bone: A Possible Model for the Treatment or Prevention of Osteoporosis

DTIC Science & Technology

1979-10-01

transformed, by dissolution and reprecipitation, Into the crystalline constituent (85). It has also been suggested that crystalline hydroxyapatite ...a Ca:P molar ratio of 8:6), and finally hydroxyapatite (115). The apatites of bone are primarily hydroxvapatite which has the composition Ca 1 0 (P0...Thus bone always contains a large variety of materials other than those which compose hydroxyapatite . ____ ____ ___..~rr? - -- lt- - -11- The amount

A process for the development of strontium hydroxyapatite

NASA Astrophysics Data System (ADS)

Zahra, N.; Fayyaz, M.; Iqbal, W.; Irfan, M.; Alam, S.

2014-06-01

A procedure for the preparation of Strontium Hydroxyapatite is adapted to produce high purity and better homogeneity ceramic with good Crystallinity. The strontium substituted bone cement has potential for use in orthopedic surgeries. Ionic Strontium (Sr) in humans shares the same physiological pathway as calcium and can be deposited in the mineral structure of the bone. In the present study, a novel concept of preparing Sr-contained Hydroxyapatite bone cement by using a precipitation method is proposed to get an ideal biomaterial that possesses potential degradability and more excellent pharmacological effect. Chemical analysis, Fourier Transform Infra Red analysis and Thermogravimetric/ Differential Scanning Calorimetric studies were conducted on prepared Strontium Hydroxyapatite sample to characterize the incorporation of 15% Sr2+ into the crystal lattice of Hydroxyapatite. Strontium was quantitatively incorporated into Hydroxyapatite where its substitution for calcium provoked a linear shift of the infrared absorption bands of the hydroxyl and phosphate groups. Thus, the formation of Sr-HAp was confirmed by Chemical Analysis, FT-IR and TGA/DSC results.

Nucleation of hydroxyapatite by bone sialoprotein.

PubMed Central

Hunter, G K; Goldberg, H A

1993-01-01

Bone sialoprotein (BSP) and osteopontin, the major phosphorylated proteins of mammalian bone, have been proposed to function in the initiation of mineralization. To test this hypothesis, the effects of BSP and osteopontin on hydroxyapatite crystal formation were determined by using a steady-state agarose gel system. At low calcium phosphate concentrations, no accumulation of calcium and phosphate occurred in control gels or gels containing osteopontin. Gels containing BSP at 1-5 micrograms/ml, however, exhibited a visible precipitation band and significantly elevated Ca + PO4 contents. By powder x-ray diffraction, the precipitate formed in the presence of BSP was shown to be hydroxyapatite. These findings suggest that bone sialoprotein may be involved in the nucleation of hydroxyapatite at the mineralization front of bone. Images Fig. 4 PMID:8397409

Effect of Calcium-Infiltrated Hydroxyapatite Scaffolds on the Hematopoietic Fate of Human Umbilical Vein Endothelial Cells.

PubMed

Zhang, Qinghao; Gerlach, Jörg C; Schmelzer, Eva; Nettleship, Ian

2017-01-01

Foamed hydroxyapatite offers a three-dimensional scaffold for the development of bone constructs, mimicking perfectly the in vivo bone structure. In vivo, calcium release at the surface is assumed to provide a locally increased gradient supporting the maintenance of the hematopoietic stem cells niche. We fabricated hydroxyapatite scaffolds with high surface calcium concentration by infiltration, and used human umbilical vein endothelial cells (HUVECs) as a model to study the effects on hematopoietic lineage direction. HUVECs are umbilical vein-derived and thus possess progenitor characteristics, with a prospective potential to give rise to hematopoietic lineages. HUVECs were cultured for long term on three-dimensional porous hydroxyapatite scaffolds, which were either infiltrated biphasic foams or untreated. Controls were cultured in two-dimensional dishes. The release of calcium into culture medium was determined, and cells were analyzed for typical hematopoietic and endothelial gene expressions, surface markers by flow cytometry, and hematopoietic potential using colony-forming unit assays. Our results indicate that the biphasic foams promoted a hematopoietic lineage direction of HUVECs, suggesting an improved in vivo-like scaffold for hematopoietic bone tissue engineering. © 2017 S. Karger AG, Basel.

Electrospinning of calcium carbonate fibers and their conversion to nanocrystalline hydroxyapatite.

PubMed

Holopainen, Jani; Santala, Eero; Heikkilä, Mikko; Ritala, Mikko

2014-12-01

Calcium carbonate (CaCO3) fibers were prepared by electrospinning followed by annealing. Solutions consisting of calcium nitrate tetrahydrate (Ca(NO3)2·4H2O) and polyvinylpyrrolidone (PVP) dissolved in ethanol or 2-methoxyethanol were used for the fiber preparation. By varying the precursor concentrations in the electrospinning solutions CaCO3 fibers with average diameters from 140 to 290 nm were obtained. After calcination the fibers were identified as calcite by X-ray diffraction (XRD). The calcination process was studied in detail with high temperature X-ray diffraction (HTXRD) and thermogravimetric analysis (TGA). The initially weak fiber-to-substrate adhesion was improved by adding a strengthening CaCO3 layer by spin or dip coating Ca(NO3)2/PVP precursor solution on the CaCO3 fibers followed by annealing of the gel formed inside the fiber layer. The CaCO3 fibers were converted to nanocrystalline hydroxyapatite (HA) fibers by treatment in a dilute phosphate solution. The resulting hydroxyapatite had a plate-like crystal structure with resemblance to bone mineral. The calcium carbonate and hydroxyapatite fibers are interesting materials for bone scaffolds and bioactive coatings. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of precursor concentration and spray pyrolysis temperature upon hydroxyapatite particle size and density.

PubMed

Cho, Jung Sang; Lee, Jeong-Cheol; Rhee, Sang-Hoon

2016-02-01

In the synthesis of hydroxyapatite powders by spray pyrolysis, control of the particle size was investigated by varying the initial concentration of the precursor solution and the pyrolysis temperature. Calcium phosphate solutions (Ca/P ratio of 1.67) with a range of concentrations from 0.1 to 2.0 mol/L were prepared by dissolving calcium nitrate tetrahydrate and diammonium hydrogen phosphate in deionized water and subsequently adding nitric acid. Hydroxyapatite powders were then synthesized by spray pyrolysis at 900°C and at 1500°C, using these calcium phosphate precursor solutions, under the fixed carrier gas flow rate of 10 L/min. The particle size decreased as the precursor concentration decreased and the spray pyrolysis temperature increased. Sinterability tests conducted at 1100°C for 1 h showed that the smaller and denser the particles were, the higher the relative densities were of sintered hydroxyapatite disks formed from these particles. The practical implication of these results is that highly sinterable small and dense hydroxyapatite particles can be synthesized by means of spray pyrolysis using a low-concentration precursor solution and a high pyrolysis temperature under a fixed carrier gas flow rate. © 2015 Wiley Periodicals, Inc.

Biomimetic Mineralization on a Macroporous Cellulose-Based Matrix for Bone Regeneration

PubMed Central

Petrauskaite, Odeta; Gomes, Pedro de Sousa; Fernandes, Maria Helena; Juodzbalys, Gintaras; Maminskas, Julius

2013-01-01

The aim of this study is to investigate the biomimetic mineralization on a cellulose-based porous matrix with an improved biological profile. The cellulose matrix was precalcified using three methods: (i) cellulose samples were treated with a solution of calcium chloride and diammonium hydrogen phosphate; (ii) the carboxymethylated cellulose matrix was stored in a saturated calcium hydroxide solution; (iii) the cellulose matrix was mixed with a calcium silicate solution in order to introduce silanol groups and to combine them with calcium ions. All the methods resulted in a mineralization of the cellulose surfaces after immersion in a simulated body fluid solution. Over a period of 14 days, the matrix was completely covered with hydroxyapatite crystals. Hydroxyapatite formation depended on functional groups on the matrix surface as well as on the precalcification method. The largest hydroxyapatite crystals were obtained on the carboxymethylated cellulose matrix treated with calcium hydroxide solution. The porous cellulose matrix was not cytotoxic, allowing the adhesion and proliferation of human osteoblastic cells. Comparatively, improved cell adhesion and growth rate were achieved on the mineralized cellulose matrices. PMID:24163816

Influence of solution conditions on deposition of calcium phosphate on titanium by NaOH-treatment

NASA Astrophysics Data System (ADS)

Feng, Q. L.; Cui, F. Z.; Wang, H.; Kim, T. N.; Kim, J. O.

2000-03-01

The present paper demonstrated a biomimetic method to coat calcium phosphate (Ca-P) on the surface of titanium induced by NaOH-treatment from a simple supersaturated hydroxyapatite solution (SHS). The influence of pH value and calcium ions concentration on the precipitation process was investigated. It is necessary for the solution to be supersaturated than the critical concentration of octacalcium phosphate (OCP) to get Ca-P coatings on titanium surface. In the precipitating process, it seems that amorphous calcium phosphate (ACP) precipitated first, then OCP, and finally hydroxyapatite (HA). The system was in continuous evolution and the phase transitions occurred in sequence.

Characterisation of Suspension Precipitated Nanocrystalline Hydroxyapatite Powders

NASA Astrophysics Data System (ADS)

Mallik, P. K.; Swain, P. K.; Patnaik, S. C.

2016-02-01

Hydroxyapatite (HA) is a well-known biomaterial for coating on femoral implants, filling of dental cavity and scaffold for tissue replacement. Hydroxyapatite possess limited load bearing capacity due to their brittleness. In this paper, the synthesis of nanocrystalline hydroxyapatite powders was prepared by dissolving calcium oxide in phosphoric acid, followed by addition of ammonia liquor in a beaker. The prepared solution was stirred by using magnetic stirrer operated at temperature of 80°C for an hour. This leads to the formation of hydroxyapatite precipitate. The precipitate was dried in oven for overnight at 100°C. The dried agglomerated precipitate was calcined at 800°C in conventional furnace for an hour. The influence of calcium oxide concentration and pH on the resulting precipitates was studied using BET, XRD and SEM. As result, a well-defined sub-rounded morphology of powders size of ∼41 nm was obtained with a salt concentration of 0.02 M. Finally, it can be concluded that small changes in the reaction conditions led to large changes in final size, shape and degree of aggregation of the hydroxyapatite particles.

Effect of substrate nature on the electrochemical deposition of calcium-deficient hydroxyapatites

NASA Astrophysics Data System (ADS)

Gualdrón-Reyes, A. F.; Domínguez-Vélez, V.; Morales-Morales, J. A.; Cabanzo, R.; Meléndez, A. M.

2017-01-01

Calcium phosphates were obtained by reducing nitrate ions to produce hydroxide ions on TiO2/stainless steel and TiO2/titanium electrodes. TiO2 coatings on metallic substrates were prepared by sol-gel dip-coating method. The morphology of deposits was observed by FESEM. Chemical nature of calcium phosphate deposits was identified by Raman micro-spectroscopy and FESEM/EDS microanalysis. Electrochemical behavior of nitrate and nitrite reduction on stainless steel and titanium electrodes was studied by linear sweep voltammetry. In addition, voltammetric study of the calcium phosphate electrodeposition on both electrodes was performed. From these measurements was selected the potential to form a calcium phosphate. A catalytic current associated to nitrate reduction reaction was obtained for stainless steel electrode, leading to significant deposition of calcium phosphate. Ca/P ratio for both substrates was less than 1.67. The formation of calcium deficient hydroxyapatite was confirmed by Raman spectroscopy.

Strontium hydroxyapatite and strontium carbonate as templates for the precipitation of calcium-phosphates in the absence and presence of fluoride

NASA Astrophysics Data System (ADS)

Sternitzke, Vanessa; Janousch, Markus; Heeb, Michèle B.; Hering, Janet G.; Johnson, C. Annette

2014-06-01

The heterogeneous precipitation of calcium-phosphates on calcium hydroxyapatite (Ca10(PO4)6(OH)2 or HAP) in the presence and absence of fluoride is important in the formation of bone and teeth, protection against tooth decay, dental and skeletal fluorosis and defluoridation of drinking water. Strontium hydroxyapatite (Sr10(PO4)6(OH)2 or SrHAP) and strontium carbonate (SrCO3) were used as calcium-free seed templates in precipitation experiments conducted with varying initial calcium-to-phosphate (Ca/P) or calcium-to-phosphate-to-fluoride (Ca/P/F) ratios. Suspensions of SrHAP or SrCO3 seed templates (which were calcium-limited for both templates and phosphate-limited in the case of SrCO3) were reacted at pH 7.3 (25 °C) over 3 days. The resulting solids were examined with Scanning Transmission Electron Microscopy (STEM), X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), and X-ray Photoelectron Spectroscopy (XPS), X-ray Absorption Near Edge Structure (XANES), and Extended X-ray Absorption Fine Structure spectroscopy (EXAFS). Calcium apatite was the predominant phase identified by all techniques independent of the added Ca/P ratios and of the presence of fluoride. It was not possible to make an unambiguous distinction between HAP and fluorapatite (Ca10(PO4)6F2, FAP). The apatite was calcium-deficient and probably contained some strontium.

[Experimental research on the effect of nanophase ceramics on osteoblasts functions].

PubMed

Wen, Bo; Chen, Zhiqing; Jiang, Yinshan; Yang, Zhengwen; Xu, Yongzhong

2005-06-01

In order to study the cytocompatibility of nanophase hydroxyapatite ceramic in vitro, we prepared hydroxyapatite by use of the wet chemistry techniques. The grain size of hydroxyapatite of interest to the present study was determined by scanning electron microscopy and atomic force microscopy with image analysis software. Primary culture of osteoblast from rat calvaria was established. Protein content, synthesis of alkaline phosphatase and deposition of calcium-containing mineral by osteoblasts cultured on nanophase hydroxyapatite ceramics and on conventional hydroxyapatite ceramics for 7, 14, 21 and 28 days were examined. The results showed that the average surface grain size of the nanophase and that of the conventional HA compact formulations was 55 (nanophase) and 780 (conventional) nm, respectively. More importantly, compared to the synthesis of alkaline phosphatase and deposition of calcium-containing mineral by osteoblasts cultured on nanophase was significantly greater than that on conventional ceramics after 21 and 28 days. The cytocompatibility was significantly greater on nanophase HA than on conventional formulations of the same ceramic.

Influence of pulse ratio on codeposition of copper species with calcium phosphate coatings on titanium by means of electrochemically assisted deposition.

PubMed

Wolf-Brandstetter, Cornelia; Oswald, Steffen; Bierbaum, Susanne; Wiesmann, Hans-Peter; Scharnweber, Dieter

2014-01-01

Aim of this study was to combine the well-known biocompatibility and ostoeconductivity of thin calcium phosphate coatings on titanium with proangiogenic signals from codeposited copper species. Copper species could be integrated in mineral layers based on hydroxyapatite by means of electrochemically assisted deposition from electrolytes containing calcium, phosphate, and copper ions. Different combinations of duration and intensity of galvanostatic pulses result in different amounts of deposited calcium phosphate and of copper species even for the same applied total charge. Absolute amounts of copper varied between 2.1 and 6.9 μg/cm², and the copper was distributed homogeneously as shown by EDX mapping. The presence of copper did not change the crystalline phase of deposited calcium phosphate (hydroxyapatite) but provoked a significant decrease in deposited amounts by factor 3 to 4. The copper was deposited mainly as Cu(I) species with a minor fraction of basic copper phosphates. Reduction of copper occurred not only at the surface of titanium but also within the hydroxyapatite coating due to the reaction with hydrogen produced by the electrolysis of water during the cathodic polarization of the substrate. Copyright © 2013 Wiley Periodicals, Inc.

Setting characteristics and mechanical behaviour of a calcium phosphate bone cement containing tetracycline.

PubMed

Ratier, A; Gibson, I R; Best, S M; Freche, M; Lacout, J L; Rodriguez, F

2001-05-01

Calcium phosphate cements are used for bone defect filling and they may also be used as delivery systems for active agents. The physicochemical behaviour of an ionic cement, with a final composition of hydroxyapatite, containing tetracycline hydrochloride was investigated. Chemical characterisation, X-ray diffraction analysis, compressive strength and tensile strength were performed. It is known that the antibiotic can be adsorbed on calcium phosphate compounds and the presence of chloride ions can strongly influence the behaviour of the cement. Adding more than 1% (w/w) of 95% pure tetracycline hydrochloride in the solid phase led to a cement with poor mechanical properties, but which, in addition to hydroxyapatite, contained residual starting reagents. For this reason, experiments were also performed with tetracycline previously treated with a calcium sulphate solution. Using a treated tetracycline, it was possible to introduce at least 7% (w/w) of active ingredient whilst still allowing the reaction to proceed to completion i.e. the formation of hydroxyapatite with good mechanical properties. Therefore, treating the tetracycline HCI with calcium sulphate solution prior to reaction conserved the activity of the antibiotic, limited the influence of the antibiotic on the cement evolution and retained the physical properties of the cement.

BoneSource hydroxyapatite cement: a novel biomaterial for craniofacial skeletal tissue engineering and reconstruction.

PubMed

Friedman, C D; Costantino, P D; Takagi, S; Chow, L C

1998-01-01

BoneSource-hydroxyapatite cement is a new self-setting calcium phosphate cement biomaterial. Its unique and innovative physical chemistry coupled with enhanced biocompatibility make it useful for craniofacial skeletal reconstruction. The general properties and clinical use guidelines are reviewed. The biomaterial and surgical applications offer insight into improved outcomes and potential new uses for hydroxyapatite cement systems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Pei; Wei, Pingpin; Li, Pengjian

Calcium silicate possessed excellent biocompatibility, bioactivity and degradability, while the high brittleness limited its application in load-bearing sites. Hydroxyapatite whiskers ranging from 0 to 30 wt.% were incorporated into the calcium silicate matrix to improve the strength and fracture resistance. Porous scaffolds were fabricated by selective laser sintering. The effects of hydroxyapatite whiskers on the mechanical properties and toughening mechanisms were investigated. The results showed that the scaffolds had a uniform and continuous inner network with the pore size ranging between 0.5 mm and 0.8 mm. The mechanical properties were enhanced with increasing hydroxyapatite whiskers, reached a maximum at 20more » wt.% (compressive strength: 27.28 MPa, compressive Young's modulus: 156.2 MPa, flexural strength: 15.64 MPa and fracture toughness: 1.43 MPa·m{sup 1/2}) and then decreased by addition of more hydroxyapatite whiskers. The improvement of mechanical properties was due to whisker pull-out, crack deflection and crack bridging. Moreover, the degradation rate decreased with the increase of hydroxyapatite whisker content. A layer of bone-like apatite was formed on the scaffold surfaces after being soaked in simulated body fluid. Human osteoblast-like MG-63 cells spread well on the scaffolds and proliferated with increasing culture time. These findings suggested that the calcium silicate scaffolds reinforced with hydroxyapatite whiskers showed great potential for bone regeneration and tissue engineering applications. - Highlights: • HA whiskers were incorporated into CS to improve the properties. • The scaffolds were successfully fabricated by SLS. • Toughening mechanisms was whisker pull-out, crack deflection and bridging. • The scaffolds showed excellent apatite forming ability.« less

The comparison study of bioactivity between composites containing synthetic non-substituted and carbonate-substituted hydroxyapatite.

PubMed

Borkowski, Leszek; Sroka-Bartnicka, Anna; Drączkowski, Piotr; Ptak, Agnieszka; Zięba, Emil; Ślósarczyk, Anna; Ginalska, Grażyna

2016-05-01

Apatite forming ability of hydroxyapatite (HAP) and carbonate hydroxyapatite (CHAP) containing composites was compared. Two composite materials, intended for filling bone defects, were made of polysaccharide polymer and one of two types of hydroxyapatite. The bioactivity of the composites was evaluated in vitro by soaking in a simulated body fluid (SBF), and the formation of the apatite layer was determined by scanning electron microscopy with energy-dispersive spectrometer and Raman spectroscopy. The results showed that both the composites induced the formation of apatite layer on their surface after soaking in SBF. In addition, the sample weight changes and the ion concentration of the SBF were scrutinized. The results showed the weight increase for both materials after SBF treatment, higher weight gain and higher uptake of calcium ions by HAP containing scaffolds. SBF solution analysis indicated loss of calcium and phosphorus ions during experiment. All these results indicate apatite forming ability of both biomaterials and suggest comparable bioactive properties of composite containing pure hydroxyapatite and carbonate-substituted one. Copyright © 2016 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li Chengfeng

Calcium phosphate powders with nano-sized crystallinity were synthesized by neutralization using calcium hydroxide and orthophosphoric acid with the assistance of citric acid. The influence of processing parameters, such as free or additive citric acid, synthetic temperature and ripening time, on the crystallinity of hydroxyapatite were investigated. The results of X-ray diffraction and microstructure observations showed that the crystallinity and morphology of nano-sized hydroxyapatite particles were influenced by the presence or absence of citric acid. It was found that the crystallinities and crystallite sizes of hydroxyapatite powders prepared with the additive citric acid increased with increasing synthetic temperature and ripening time.more » Especially, the crystallinities of (h k 0) planes were raised and more homogeneously grown particles were obtained with increasing synthetic temperature.« less

Evolving application of biomimetic nanostructured hydroxyapatite

PubMed Central

Roveri, Norberto; Iafisco, Michele

2010-01-01

By mimicking Nature, we can design and synthesize inorganic smart materials that are reactive to biological tissues. These smart materials can be utilized to design innovative third-generation biomaterials, which are able to not only optimize their interaction with biological tissues and environment, but also mimic biogenic materials in their functionalities. The biomedical applications involve increasing the biomimetic levels from chemical composition, structural organization, morphology, mechanical behavior, nanostructure, and bulk and surface chemical–physical properties until the surface becomes bioreactive and stimulates cellular materials. The chemical–physical characteristics of biogenic hydroxyapatites from bone and tooth have been described, in order to point out the elective sides, which are important to reproduce the design of a new biomimetic synthetic hydroxyapatite. This review outlines the evolving applications of biomimetic synthetic calcium phosphates, details the main characteristics of bone and tooth, where the calcium phosphates are present, and discusses the chemical–physical characteristics of biomimetic calcium phosphates, methods of synthesizing them, and some of their biomedical applications. PMID:24198477

Local induction of calcium phosphate formation on TiO2 coatings on titanium via surface treatment with a CO2 laser.

PubMed

Moritz, N; Jokinen, M; Peltola, T; Areva, S; Yli-Urpo, A

2003-04-01

Sol-gel-derived TiO(2) coatings are known to promote bonelike hydroxyapatite formation on their surfaces in vitro and in vivo. Hydroxyapatite integrates into bone tissue. In some clinical applications, the surface of an implant is simultaneously interfaced with soft and hard tissues, so it should match the properties of both. A new method is introduced for treating the coatings locally in a controlled manner. The local densification of sol-gel-derived titania coatings on titanium substrates with a CO(2) laser was studied in terms of the in vitro calcium phosphate-inducting properties. CO(2)-laser-treated multilayer coatings were compared with furnace-fired coatings prepared with the same recipe and previously shown to be bioactive. Additionally, local areas of furnace-fired multilayer coatings (previously shown to be bioactive in vitro) were further laser-treated to achieve various properties in the same implant. Topological surface properties were examined with atomic force microscopy. The formation of hydroxyapatite was studied with Fourier transform infrared and scanning electron microscopy energy-dispersive X-ray analysis. The results show that calcium phosphate formation can be adjusted locally by laser treatment. Calcium phosphate is a bonelike hydroxyapatite. The local treatment of sol-gel-derived coatings with a CO(2) laser is a promising technique for creating implants with various properties to interface different tissues and a possible way of coating implants that do not tolerate furnace firing. Copyright 2003 Wiley Periodicals, Inc.

A novel biphasic calcium phosphate derived from fish otoliths

NASA Astrophysics Data System (ADS)

Montañez-Supelano, N. D.; Sandoval-Amador, A.; Estupiñan-Durán, H. A.; Y Peña-Ballesteros, D.

2017-12-01

Calcium phosphates are bioceramics that have been widely used as bone substitutes because they encourage the formation of bone on their surface and can improve the healing of the bone. Hydroxyapatite HA (calcium/phosphorus ratio of 1.67) and tricalcium phosphate TCP (calcium/phosphorus ratio of 1.50) are the most common calcium phosphates. Natural materials have begun to be tested to make HA or TCP such as shells of cardiidae (family of mollusks) and eggshells. The calcium phosphate obtained has a high ability to precipitate apatite. In this work, the mixed phase ceramic of beta-Tri-calcium phosphate / hydroxyapatite (β-TCP/HA) was synthesized by aqueous precipitation from fish otoliths, which are monomineralic species composed of aragonite. Otoliths of the specie Plagioscion squamosissimus, commonly called the river croaker, were used. Techniques such as DRX, Raman spectroscopy and SEM-EDS were used to characterize the raw material and the obtained material. X-ray diffraction analysis revealed the presence of two crystalline phases of calcium phosphates with 86.2% crystallinity. SEM micrographs showed agglomeration of particles with porous structure and submicron particle sizes.

Porous hydroxyapatite and biphasic calcium phosphate ceramics promote ectopic osteoblast differentiation from mesenchymal stem cells

NASA Astrophysics Data System (ADS)

Zhang, Lingli; Hanagata, Nobutaka; Maeda, Megumi; Minowa, Takashi; Ikoma, Toshiyuki; Fan, Hongsong; Zhang, Xingdong

2009-04-01

Because calcium phosphate (Ca-P) ceramics have been used as bone substitutes, it is necessary to investigate what effects the ceramics have on osteoblast maturation. We prepared three types of Ca-P ceramics with different Ca-P ratios, i.e. hydroxyapatite (HA), beta-tricalcium phosphate (β-TCP), and biphasic calcium phosphate (BCP) ceramics with dense-smooth and porous structures. Comprehensive gene expression microarray analysis of mouse osteoblast-like cells cultured on these ceramics revealed that porous Ca-P ceramics considerably affected the gene expression profiles, having a higher potential for osteoblast maturation. In the in vivo study that followed, porous Ca-P ceramics were implanted into rat skeletal muscle. Sixteen weeks after the implantation, more alkaline-phosphatase-positive cells were observed in the pores of hydroxyapatite and BCP, and the expression of the osteocalcin gene (an osteoblast-specific marker) in tissue grown in pores was also higher in hydroxyapatite and BCP than in β-TCP. In the pores of any Ca-P ceramics, 16 weeks after the implantation, we detected the expressions of marker genes of the early differentiation stage of chondrocytes and the complete differentiation stage of adipocytes, which originate from mesenchymal stem cells, as well as osteoblasts. These marker gene expressions were not observed in the muscle tissue surrounding the implanted Ca-P ceramics. These observations indicate that porous hydroxyapatite and BCP had a greater potential for promoting the differentiation of mesenchymal stem cells into osteoblasts than β-TCP.

Open-Porous Hydroxyapatite Scaffolds for Three-Dimensional Culture of Human Adult Liver Cells

PubMed Central

Schmelzer, Eva; Over, Patrick; Nettleship, Ian; Gerlach, Joerg C.

2016-01-01

Liver cell culture within three-dimensional structures provides an improved culture system for various applications in basic research, pharmacological screening, and implantable or extracorporeal liver support. Biodegradable calcium-based scaffolds in such systems could enhance liver cell functionality by providing endothelial and hepatic cell support through locally elevated calcium levels, increased surface area for cell attachment, and allowing three-dimensional tissue restructuring. Open-porous hydroxyapatite scaffolds were fabricated and seeded with primary adult human liver cells, which were embedded within or without gels of extracellular matrix protein collagen-1 or hyaluronan. Metabolic functions were assessed after 5, 15, and 28 days. Longer-term cultures exhibited highest cell numbers and liver specific gene expression when cultured on hydroxyapatite scaffolds in collagen-1. Endothelial gene expression was induced in cells cultured on scaffolds without extracellular matrix proteins. Hydroxyapatite induced gene expression for cytokeratin-19 when cells were cultured in collagen-1 gel while culture in hyaluronan increased cytokeratin-19 gene expression independent of the use of scaffold in long-term culture. The implementation of hydroxyapatite composites with extracellular matrices affected liver cell cultures and cell differentiation depending on the type of matrix protein and the presence of a scaffold. The hydroxyapatite scaffolds enable scale-up of hepatic three-dimensional culture models for regenerative medicine applications. PMID:27403430

Microstructural Improvement of Hydroxyapatite-ZrO2 Composite Ceramics via Thermal Precipitation Techniques.

NASA Astrophysics Data System (ADS)

Sangmala, A.; Limsuwan, P.; Kaewwiset, W.; Naemchanthara, K.

2017-09-01

Hydroxyapatite-ZrO2 composite ceramic were synthesized using a thermal precipitation techniques. The chemical precursors were prepared from di-ammonium hydrogen orthophosphate, calcium oxide (CaO) derived from chicken eggshell, zirconium dioxide (ZrO2) and distilled water. The mixture were heated at the various temperatures from 100 to 700 °C in the furnace with an incremental temperature of 100 °C. The ZrO2 contents in the composite ceramic were varied from 0 to 15 percent weight of CaO. The prepared composites were then annealed at 300, 600 and 700 °C for 4 h in air. The crystal structure, function group and morphology of all samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and universal testing machine (UTM), respectively. The results indicated that the undoped-ZrO2 samples hydroxyapatite phase with a hexagonal structure. However, the hydroxyapatite was transformed to the tri-calcium phosphate after thermal treatment at 700 °C. For the doped-ZrO2 samples, the hydroxyapatite and ZrO2 phases were found. Moreover, the result showed that the compressive strength of hydroxyapatite-ZrO2 composite ceramic increased with increasing the ZrO2 content.

Breast Microcalcification Detection Using Super-Resolution Ultrasound Image Reconstruction

DTIC Science & Technology

2010-09-01

microcalcifications often occur as one of two types: calcium oxalate dihydrate or calcium hydroxyapatite. Their sizes range approximately from 0.1 mm to 0.5 mm...super-resolution imaging, ultrasound imaging, wave equation. 1. INTRODUCTION Microcalcifications, tiny specks of mineral deposits ( calcium ), are the

Biodegradation and biocompatability of a calcium sulphate-hydroxyapatite bone substitute.

PubMed

Nilsson, M; Wang, J S; Wielanek, L; Tanner, K E; Lidgren, L

2004-01-01

An injectable material consisting of calcium sulphate mixed with hydroxyapatite was investigated as a possible alternative to autograft in the restoration of bone defects. The material was studied both in vitro in simulated body fluid (SBF) and in vivo when implanted in rat muscles and into the proximal tibiae of rabbits. Variation in the strength and weight of the material during ageing in SBF was measured. Tissue response, material resorption and bone ingrowth were studied in the animal models. A good tissue response was observed in both the rat muscles and rabbit tibiae without inflammatory reactions or the presence of fibrous tissue. Ageing in SBF showed that during the first week carbonated hydroxyapatite precipitated on the surfaces of the material and this may enhance bone ingrowth.

Hydrothermal synthesis of porous triphasic hydroxyapatite/(alpha and beta) tricalcium phosphate.

PubMed

Vani, R; Girija, E K; Elayaraja, K; Prakash Parthiban, S; Kesavamoorthy, R; Narayana Kalkura, S

2009-12-01

A novel, porous triphasic calcium phosphate composed of nonresorbable hydroxyapatite (HAp) and resorbable tricalcium phosphate (alpha- and beta-TCP) has been synthesized hydrothermally at a relatively low temperature. The calcium phosphate precursor for hydrothermal treatment was prepared by gel method in the presence of ascorbic acid. XRD, FT-IR, Raman analyses confirmed the presence of HAp/TCP. The surface area and average pore size of the samples were found to be 28 m2/g and 20 nm, respectively. The samples were found to be bioactive in simulated body fluid (SBF).

Situ formation of apatite for sequestering radionuclides and heavy metals

DOEpatents

Moore, Robert C.

2003-07-15

Methods for in situ formation in soil of a permeable reactive barrier or zone comprising a phosphate precipitate, such as apatite or hydroxyapatite, which is capable of selectively trapping and removing radionuclides and heavy metal contaminants from the soil, while allowing water or other compounds to pass through. A preparation of a phosphate reagent and a chelated calcium reagent is mixed aboveground and injected into the soil. Subsequently, the chelated calcium reagent biodegrades and slowly releases free calcium. The free calcium reacts with the phosphate reagent to form a phosphate precipitate. Under the proper chemical conditions, apatite or hydroxyapatite can form. Radionuclide and heavy metal contaminants, including lead, strontium, lanthanides, and uranium are then selectively sequestered by sorbing them onto the phosphate precipitate. A reducing agent can be added for reduction and selective sequestration of technetium or selenium contaminants.

Influence of calcium precursors on the morphology and crystallinity of sol gel-derived hydroxyapatite nanoparticles

NASA Astrophysics Data System (ADS)

Vijayalakshmi Natarajan, U.; Rajeswari, S.

2008-10-01

Nanosized hydroxyapatite (HAP) particles were prepared by sol-gel method from the water-based solution of calcium and phosphorus precursor. In this study, two calcium precursors such as calcium nitrate tetrahydrate and calcium acetate were chosen as calcium precursors. The influence of aging period, pH, viscosity and sintering temperature on crystallinity and morphology of the HAP particles were investigated for the two calcium precursors with triethyl phosphate precursor. The morphology of nano-HAP towards phosphorous precursor was dependent on the type of calcium precursor used. The HAP prepared from calcium nitrate and triethyl phosphate was spherically shaped whereas the one from calcium acetate was found to be fibrous in structure. Both HAPs were stable up to 1200 °C and their crystallinity increased with respect to the sintering temperature. The obtained sample was characterized through X-ray diffraction (XRD), P 31 nuclear magnetic resonance (NMR), scanning electronic microscopy (SEM) and TEM analysis. The sol derived from the optimized aging period for the two different calcium precursors was coated on 316L stainless-steel (SS) implant and its corrosion resistivity during long-term implantation was studied by cyclic polarization in Ringer's solution. Both HAPs have their own desirable qualities and were found to be corrosion resistive.

Use of ossein-hydroxyapatite complex in the prevention of bone loss: a review.

PubMed

Castelo-Branco, C; Dávila Guardia, J

2015-02-01

The ossein-hydroxyapatite complex (OHC) is a microcrystalline form of calcium which provides a number of additional minerals (magnesium, phosphorus, potassium, zinc), and proteins (osteocalcin, type I collagen, type I insulin growth factor I and II, transforming growth factor beta) associated with bone metabolism. The objective of this review is to examine the role of OHC in preventing bone loss in different conditions. A review of clinical trials assessing the relationship between OHC and bone loss was made using the following data sources: Medline (from 1966 to December 2013), the Cochrane Controlled Clinical Trials Register, Embase (up to December 2013), contact with companies marketing the supplements studied, and reference lists. Different randomized, clinical trials and meta-analysis suggest that OHC is more effective than calcium supplements in maintaining bone mass in postmenopausal women and in different conditions related to bone loss. In addition, OHC improves pain symptoms and accelerates fracture consolidation in patients with osteopenia or osteoporosis. The ossein-hydroxyapatite complex is significantly more effective in preventing bone loss than calcium carbonate.

Titanium surface modification by microarc oxidation in electrolyte based on wollastonite and hydroxyapatite

NASA Astrophysics Data System (ADS)

Sharkeev, Yu. P.; Sedelnikova, M. B.; Komarova, E. G.; Khlusov, I. A.

2015-11-01

An investigation of titanium surface modification by microarc oxidation in the electrolyte based on wollastonite and hydroxyapatite was presented. The dependences of the coating properties on the microarc oxidation parameters were found. A variation of the process parameters allowed producing wollastonite-calcium phosphate coatings with aplate-like structure, thickness 25-30 µm, roughness 2.5-5.0 µm, and adhesion strength 57 MPa. The optimum microarc oxidation parameters such as the electrical voltage of 150 V, process duration of 5-10 min, and pulse duration of 100-300 µs were revealed. The wollastonite addition to the electrolyte based on the aqueous solution of phosphoric acid and hydroxyapatite allowed us to form wollastonite-calcium phosphate coatings on the titanium surface by the microarc oxidation method with enhanced strength properties and an increased ability to osseointegration.

Surface modification of calcium-copper hydroxyapatites using polyaspartic acid

NASA Astrophysics Data System (ADS)

Othmani, Masseoud; Aissa, Abdallah; Bachoua, Hassen; Debbabi, Mongi

2013-01-01

Mixed calcium-copper hydroxyapatite (Ca-CuHAp), with general formula Ca(10-x)Cux(PO4)6(OH)2, where 0 ≤ x ≤ 0.75 was prepared in aqueous medium in the presence of different concentrations of poly-L-aspartic acid (PASP). XRD, IR, TG-DTA, TEM-EDX, AFM and chemical analyses were used to characterize the structure, morphology and composition of the products. All techniques show the formation of new hybrid compounds Ca-CuHAp-PASP. The presence of the grafting moiety on the apatitic material is more significant with increasing of copper amount and/or organic concentration in the starting solution. These increases lead to the affectation of apatite crystallinity. The IR spectroscopy shows the conservation of (Psbnd OH) band of (HPO4)2- groups, suggesting that PASP acid was interacted only with metallic cations of hydroxyapatite.

Preparation and bioactive properties of nanocrystalline hydroxyapatite thin films obtained by conversion of atomic layer deposited calcium carbonate.

PubMed

Holopainen, Jani; Kauppinen, Kyösti; Mizohata, Kenichiro; Santala, Eero; Mikkola, Esa; Heikkilä, Mikko; Kokkonen, Hanna; Leskelä, Markku; Lehenkari, Petri; Tuukkanen, Juha; Ritala, Mikko

2014-09-01

Nanocrystalline hydroxyapatite thin films were fabricated on silicon and titanium by atomic layer deposition (ALD) of CaCO3 and its subsequent conversion to hydroxyapatite by diammonium hydrogen phosphate (DAP) solution. The effects of conversion process parameters to crystallinity and morphology of the films were examined. DAP concentration was found to be critical in controlling the crystal size and homogeneity of the films. The hydroxyapatite phase was identified by XRD. ToF-elastic recoil detection analysis studies revealed that the films are calcium deficient in relation to hydroxyapatite with a Ca/P ratio of 1.39 for films converted with 0.2 M DAP at 95 °C. The coatings prepared on titanium conformally follow the rough surface topography of the substrate, verifying that the good step coverage of the ALD method was maintained in the conversion process. The dissolution tests revealed that the coating was nondissolvable in the cell culture medium. Annealing the coated sample at 700 °C for 1 h seemed to enhance its bonding properties to the substrate. Also, the biocompatibility of the coatings was confirmed by human bone marrow derived cells in vitro. The developed method provides a new possibility to produce thin film coatings on titanium implants with bone-type hydroxyapatite that is biocompatible with human osteoblasts and osteoclasts.

Calcium to phosphate ratio measurements in calcium phosphates using LIBS

NASA Astrophysics Data System (ADS)

Tariq, U.; Haider, Z.; Chaudhary, K.; Hussain, R.; Ali, J.

2018-05-01

In this study, we report the measurement of Ca/P ratio of hydroxyapatite using LIBS. Hydroxyapatite was prepared by wet chemical precipitation method with different stoichiometric ratios of Ca and P (1.5, 1.6, 1.67, 1.70, 1.80). Samples were then pelletized using KBr as a binder under a hydraulic press. Samples were irradiated with a laser beam and corresponding spectra were recorded. Spectra were further analyzed to calculate the Ca/P ratio which was then compared with the EDX for validation. LIBS results showed promise with a deviation of < 5% with the Stoichiometric ratios and EDX results.

Comparison of characteristics of hydroxyapatite powders synthesized from cuttlefish bone via precipitation and ball milling techniques

NASA Astrophysics Data System (ADS)

Faksawat, K.; Kaewwiset, W.; Limsuwan, P.; Naemchanthara, K.

2017-09-01

The aim of this work was to compare characteristics of hydroxyapatite synthesized by precipitation and ball milling techniques. The cuttlefish bone powder was a precursor in calcium source and the di ammonium hydrogen orthophosphate powders was a precursor in phosphate source. The hydroxyapatite was synthesized by the both techniques such as precipitation and ball milling techniques. The phase formation, chemical structure and morphology of the both hydroxyapatite powders have been examined by X-ray diffractometer (XRD), Fourier transform infrared spectroscope (FTIR) and field emission scanning electron microscope (FESEM), respectively. The results show that the hydroxyapatite synthesized by precipitation technique formed hydroxyapatite phase slower than the hydroxyapatite synthesized by ball milling technique. The FTIR results show the chemical structures of sample in both techniques are similar. The morphology of the hydroxyapatite from the both techniques were sphere like shapes and particle size was about in nano scale. The average particle size of the hydroxyapatite by ball milling technique was less than those synthesized by precipitation technique. This experiment indicated that the ball milling technique take time less than the precipitation technique in hydroxyapatite synthesis.

Surface modification of calcium hydroxyapatite by grafting of etidronic acid

NASA Astrophysics Data System (ADS)

Othmani, Masseoud; Aissa, Abdallah; Bac, Christophe Goze; Rachdi, Férid; Debbabi, Mongi

2013-06-01

The surface of prepared calcium hydroxyapatite CaHAp has been modified by grafting the etidronic acid (ETD). For that purpose, CaHAp powders have been suspended in an aqueous etidronate solution with different concentrations. The obtained composites CaHAp-(ETD) were characterized by TEM and AFM techniques to determinate morphological properties and were also characterized by XRD, IR, NMR and chemical and thermal analysis to determinate their physico-chemical properties and essentially the nature of the interaction between the inorganic support and the grafted organic ETD. After reaction with ETD, XRD powder analysis shows that the apatitic structure remains unchanged with slight affectation of its crystallinity. The presence of etidronate fragment bounded to hydroxyapatite was confirmed by IR and solid-state NMR spectroscopy. TEM and AFM techniques indicate that the presence of etidronate changes the morphology of the particles. Basing on the obtained results, a reactional mechanism was proposed to explain the formation of covalent Casbnd Osbnd Porg bonds on the hydroxyapatite surface between the superficial hydroxyl groups (tbnd Casbnd OH) of the apatite and phosphonate group (Psbnd OH) of etidronate.

Micro arc oxidized HAp-TiO 2 nanostructured hybrid layers-part I: Effect of voltage and growth time

NASA Astrophysics Data System (ADS)

Abbasi, S.; Bayati, M. R.; Golestani-Fard, F.; Rezaei, H. R.; Zargar, H. R.; Samanipour, F.; Shoaei-Rad, V.

2011-05-01

Micro arc oxidation was employed to grow hydroxyapatite-TiO 2 nanostructured porous composite layers. The layers were synthesized on the titanium substrates in the electrolytes consisting of calcium acetate and sodium β-glycerophosphate salts under different applied voltages for various times. SEM and AFM investigations revealed a porous structure and rough surface where the pores size and the surface roughness were respectively determined as 70-650 nm and 9.8-12.7 nm depending on the voltage and time. Chemical composition and phase structure of the layers were evaluated using EDX, XPS, and XRD methods. The layers consisted of the hydroxyapatite, anatase, α-TCP, and calcium titanatephases with a varying fraction depending on the growth conditions. The hydroxyapatite crystalline size was also determined as ˜42 nm. The sample fabricated under the voltage of 350 V for 3 min exhibited the most appropriate Ca/P ratio (˜1.60) as well as the highest amount of the hydroxyapatite phase. This sample had a fine surface morphology and a high pores density.

An Overview of the Percutaneous Antibiotic Delivery Technique for Osteomyelitis Treatment and a Case Study of Calcaneal Osteomyelitis.

PubMed

Karr, Jeffrey C

2017-11-01

A percutaneous antibiotic delivery technique (PAD-T) used for the adjunctive management of osteomyelitis is presented. This surgical technique incorporates a calcium sulfate and hydroxyapatite (calcium phosphate) bone void filler acting as a carrier vehicle with either an antibiotic or an antifungal medicine, delivering this combination directly into the area of osteomyelitis. The benefit of the PAD-T is reviewed with a case presentation of a successfully treated calcaneal osteomyelitis. No previously reported PAD-T using a simple bone cortex incision in the adjunctive treatment of osteomyelitis has been reported. The PAD-T safely and effectively uses a calcium sulfate and hydroxyapatite bone void filler carrier vehicle to deliver either an antibiotic or an antifungal medicine directly into the area of osteomyelitis.

Reinforcing of a calcium phosphate cement with hydroxyapatite crystals of various morphologies.

PubMed

Neira, Inés S; Kolen'ko, Yury V; Kommareddy, Krishna P; Manjubala, Inderchand; Yoshimura, Masahiro; Guitián, Francisco

2010-11-01

A series of biocomposite materials was successfully prepared by reinforcing advanced calcium phosphate cement with hydroxyapatite fibrous and elongated plate-like particles. Powder X-ray diffraction showed that ball-milled biocomposite precursors (dicalcium and tetracalcium phosphates) entirely transform to a single phase hydroxyapatite end product within 7 h at 37 °C. Electron microscopy showed that the resultant biocomposites are constituted of nanoscaled cement particles intimately associated with the reinforcement crystals. The influence of shape, size, and concentration of the hydroxyapatite filler on the compression strength of reinforced cements is discussed. The best compression strength of 37 ± 3 MPa (enhancement of ∼50% compared to pure cement) was achieved using submicrometer-sized hydroxyapatite crystals with complementary shapes. Nanoindentation revealed that averaged elastic modulus and hardness values of the cements are consistent with those reported for trabecular and cortical human bones, indicating a good match of the micromechanical properties for their potential use for bone repair. The stiffness of the biocomposites was confirmed to gradate-compliant cement matrix, cement-filler interface, and stiff filler-as a result of the structuring at the nanometer-micrometer level. This architecture is critical in conditioning the final mechanical properties of the functional composite biomaterial. In vitro cell culture experiments showed that the developed biomaterial system is noncytotoxic.

A study of the formation of amorphous calcium phosphate and hydroxyapatite on melt quenched Bioglass using surface sensitive shallow angle X-ray diffraction.

PubMed

Martin, R A; Twyman, H; Qiu, D; Knowles, J C; Newport, R J

2009-04-01

Melt quenched silicate glasses containing calcium, phosphorous and alkali metals have the ability to promote bone regeneration and to fuse to living bone. These glasses, including 45S5 Bioglass((R)) [(CaO)(26.9)(Na(2)O)(24.4)(SiO(2))(46.1)(P(2)O(5))(2.6)], are routinely used as clinical implants. Consequently there have been numerous studies on the structure of these glasses using conventional diffraction techniques. These studies have provided important information on the atomic structure of Bioglass((R)) but are of course intrinsically limited in the sense that they probe the bulk material and cannot be as sensitive to thin layers of near-surface dissolution/growth. The present study therefore uses surface sensitive shallow angle X-ray diffraction to study the formation of amorphous calcium phosphate and hydroxyapatite on Bioglass((R)) samples, pre-reacted in simulated body fluid (SBF). Unreacted Bioglass((R)) is dominated by a broad amorphous feature around 2.2 A(-1) which is characteristic of sodium calcium silicate glass. After reacting Bioglass((R)) in SBF a second broad amorphous feature evolves ~1.6 A(-1) which is attributed to amorphous calcium phosphate. This feature is evident for samples after only 4 h reacting in SBF and by 8 h the amorphous feature becomes comparable in magnitude to the background signal of the bulk Bioglass((R)). Bragg peaks characteristic of hydroxyapatite form after 1-3 days of reacting in SBF.

Effects of sintering temperature on electrical properties of sheep enamel hydroxyapatite

NASA Astrophysics Data System (ADS)

Dumludag, F.; Gunduz, O.; Kılıc, O.; Kılıc, B.; Ekren, N.; Kalkandelen, C.; Oktar, F. N.

2017-12-01

Bioceramics, especially calcium phosphate based bioceramics, whose examples are hydroxyapatite, and calcium phosphate powders have been widely used in the biomedical engineering applications. Hydroxyapatite (HA) is one of the most promising biomaterials, which are derived from natural sources, chemical method, animal like dental enamel and corals. The influence of sintering temperature on the electrical properties (i.e. DC conductivity, AC conductivity) of samples of sintered sheep enamel (SSSE) was studied in air and in vacuum ambient at room temperature. The sheep enamel were sintered at varying temperatures between 1000°C and 1300°C. DC conductivity results revealed that while dc conductivity of the SSSE decreases with increasing the sintering temperature in air ambient the values increased with increasing the sintering temperature in vacuum ambient. AC conductivity measurements were performed in the frequency range of 40 Hz - 105 Hz. The results showed that ac conductivity values decrease with increasing the sintering temperature.

Calcium hydroxyapatite crystal deposition with intraosseous penetration involving the posterior aspect of the cervical spine: a previously unreported cause of neck pain.

PubMed

Urrutia, Julio; Contreras, Oscar

2017-05-01

Calcific tendinitis is a frequent disorder caused by hydroxyapatite crystal deposition; however, bone erosions from calcific tendinitis are unusual. The spinal manifestation of this disease is calcific tendinitis of the longus colli muscle; this disease has never been described in the posterior aspect of the spine. We report a case of calcium hydroxyapatite crystal deposition involving the posterior cervical spine eroding the bone cortex. A 57-year-old woman presented with a 5-month history of left-sided neck pain. Radiographs showed C4-C5 interspinous calcification with lytic compromise of the posterior arch of C4. Magnetic resonance imaging confirmed a lytic lesion of the posterior arch of C4, with a soft tissue mass extending to the C4-C5 interspinous space; calcifications were observed as very low signal intensity areas on T1 and T2 sequences, surrounded by gadolinium-enhanced soft tissues. A computed tomography (CT) scan confirmed the bone erosions and the soft tissue calcifications. A CT-guided needle biopsy was performed; it showed vascularized connective tissue with inflammatory histiocytic infiltration and multinucleated giant cells; Alizarin Red stain confirmed the presence of hydroxyapatite crystals. The patient was treated with anti-inflammatories for 2 weeks. She has been asymptomatic in a 6-month follow-up; a CT scan at the last follow-up revealed reparative remodeling of bone erosions. This is the first report of calcium hydroxyapatite crystal deposition with intraosseous penetration involving the posterior aspect of the cervical spine. Considering that this unusual lesion can be misinterpreted as a tumor or infection, high suspicion is required to avoid unnecessary surgical procedures.

Resorption kinetics of four hydroxyapatite-based ceramics by particle induced X-ray emission and neutron activation analysis

NASA Astrophysics Data System (ADS)

Jallot, E.; Irigaray, J. L.; Oudadesse, H.; Brun, V.; Weber, G.; Frayssinet, P.

1999-05-01

From the viewpoint of hard tissue response to implant materials, calcium phosphates are probably the most compatible materials presently known. During the last few years, much attention has been paid to hydroxyapatite and β-tricalcium phosphate as potential biomaterials for bone substitute. A good implantation of biomaterials in the skeleton is to reach full integration of non-living implant with living bone. The aim of this study is to compare the resorption kinetics of four kinds of calcium phosphate ceramics: hydroxyapatite (Ca{10}(PO4)6(OH)2), hydroxyapatite doped with manganese or zinc and a composite material of 75% hydroxyapatite and 25% β-tricalcium phosphate (Ca3(PO4)2). Cylinders (5 6 mm in diameter) of these ceramics were packed into holes made in the femur diaphysis of mature ovine. At 2, 4, 8, 12, 16, 20, 28, 36 and 48 weeks after the operation, bone/implant interface was embedded in polymethylmethacrylate. We used the PIXE method (particle induced X-ray emission) to measure the distribution of mineral elements (Ca, P, Sr, Zn, Mn and Fe) at the bone/implant interface. At 4, 8, 16, 28 and 48 weeks after implantation we studied a biopsy of the ceramics by neutron activation method. Then, we have a global measurement of mineral elements in the biomaterial. The results showed that the resorption kinetics of hydroxyapatite doped with zinc was faster than that of the three other bioceramics.

Response of Human Osteoblast to n-HA/PEEK—Quantitative Proteomic Study of Bio-effects of Nano-Hydroxyapatite Composite

NASA Astrophysics Data System (ADS)

Zhao, Minzhi; Li, Haiyun; Liu, Xiaochen; Wei, Jie; Ji, Jianguo; Yang, Shu; Hu, Zhiyuan; Wei, Shicheng

2016-03-01

Nano-sized hydroxyapatite (n-HA) is considered as a bio-active material, which is often mixed into bone implant material, polyetheretherketone (PEEK). To reveal the global protein expression modulations of osteoblast in response to direct contact with the PEEK composite containing high level (40%) nano-sized hydroxyapatite (n-HA/PEEK) and explain its comprehensive bio-effects, quantitative proteomic analysis was conducted on human osteoblast-like cells MG-63 cultured on n-HA/PEEK in comparison with pure PEEK. Results from quantitative proteomic analysis showed that the most enriched categories in the up-regulated proteins were related to calcium ion processes and associated functions while the most enriched categories in the down-regulated proteins were related to RNA process. This enhanced our understanding to the molecular mechanism of the promotion of the cell adhesion and differentiation with the inhibition of the cell proliferation on n-HA/PEEK composite. It also exhibited that although the calcium ion level of incubate environment hadn’t increased, merely the calcium fixed on the surface of material had influence to intracellular calcium related processes, which was also reflect by the higher intracellular Ca2+ concentration of n-HA/PEEK. This study could lead to more comprehensive cognition to the versatile biocompatibility of composite materials. It further proves that proteomics is useful in new bio-effect discovery.

Cuttlefish bone scaffold for tissue engineering: a novel hydrothermal transformation, chemical-physical, and biological characterization.

PubMed

Battistella, Elisa; Mele, Silvia; Foltran, Ismaela; Lesci, Isidoro Giorgio; Roveri, Norberto; Sabatino, Piera; Rimondini, Lia

2012-09-27

Natural resources are receiving growing interest because of their possible conversion from a cheap and easily available material into a biomedical product. Cuttlefish bone from Sepia Officinalis was investigated in order to obtain an hydroxyapatite porous scaffold using hydrothermal transformation. Complete conversion of the previous calcium carbonate (aragonite) phase into a calcium phosphate (hydroxyapatite) phase was performed with an hydrothermal transformation at 200 °C (~ 15 atm), for four hours, with an aqueous solution of KH2PO4 in order to set the molar ratio Ca/P = 10/6 in a reactor (Parr 4382). The complete conversion was then analyzed by TGA, ATR-FTIR, x-ray diffraction, and SEM. Moreover, the material was biologically investigated with MC3T3-E1 in static cultures, using both osteogenic and maintenance media. The expression of osteogenic markers as ALP and osteocalcin and the cell proliferation were investigated. Cuttlefish bone has been successfully transformed from calcium carbonate into calcium phosphate. Biological characterization revealed that osteogenic markers are expressed using both osteogenic and maintenance conditions. Cell proliferation is influenced by the static culture condition used for this three-dimensional scaffold. The new scaffold composed by hydroxyapatite and derived for a natural source presents good biocompatibility and can be used for further investigations using dynamic cultures in order to improve cell proliferation and differentiation for bone tissue engineering.

Response of Human Osteoblast to n-HA/PEEK--Quantitative Proteomic Study of Bio-effects of Nano-Hydroxyapatite Composite.

PubMed

Zhao, Minzhi; Li, Haiyun; Liu, Xiaochen; Wei, Jie; Ji, Jianguo; Yang, Shu; Hu, Zhiyuan; Wei, Shicheng

2016-03-09

Nano-sized hydroxyapatite (n-HA) is considered as a bio-active material, which is often mixed into bone implant material, polyetheretherketone (PEEK). To reveal the global protein expression modulations of osteoblast in response to direct contact with the PEEK composite containing high level (40%) nano-sized hydroxyapatite (n-HA/PEEK) and explain its comprehensive bio-effects, quantitative proteomic analysis was conducted on human osteoblast-like cells MG-63 cultured on n-HA/PEEK in comparison with pure PEEK. Results from quantitative proteomic analysis showed that the most enriched categories in the up-regulated proteins were related to calcium ion processes and associated functions while the most enriched categories in the down-regulated proteins were related to RNA process. This enhanced our understanding to the molecular mechanism of the promotion of the cell adhesion and differentiation with the inhibition of the cell proliferation on n-HA/PEEK composite. It also exhibited that although the calcium ion level of incubate environment hadn't increased, merely the calcium fixed on the surface of material had influence to intracellular calcium related processes, which was also reflect by the higher intracellular Ca(2+) concentration of n-HA/PEEK. This study could lead to more comprehensive cognition to the versatile biocompatibility of composite materials. It further proves that proteomics is useful in new bio-effect discovery.

Evaluation of a setting reaction pathway in the novel composite TiHA-CSD bone cement by FT-Raman and FT-IR spectroscopy

NASA Astrophysics Data System (ADS)

Paluszkiewicz, Czesława; Czechowska, Joanna; Ślósarczyk, Anna; Paszkiewicz, Zofia

2013-02-01

The aim of this study was to determine a setting reaction pathway in a novel, surgically handy implant material, based on calcium sulfate hemihydrate (CSH) and titanium doped hydroxyapatite (TiHA). The previous studies confirmed superior biological properties of TiHA in comparison to the undoped hydroxyapatite (HA) what makes it highly attractive for future medical applications. In this study the three types of titanium modified HA powders: untreated, calcined at 800 °C, sintered at 1250 °C and CSH were used to produce bone cements. The Fourier Transform-InfraRed (FT-IR) spectroscopy and Raman spectroscopy were applied to evaluate processes taking place during the setting of the studied materials. Our results undoubtedly confirmed that the reaction pathways and the phase compositions differed significantly for set cements and were dependent on the initial heat treatment of TiHA powder. Final materials were multiphase composites consisting of calcium sulfate dihydrate, bassanite, tricalcium phosphate, hydroxyapatite and calcium titanate (perovskite). The FT-IR and Scanning Electron Microscopy (SEM) measurements performed after the incubation of the cement samples in the simulated body fluid (SBF), indicate on high bioactive potential of the obtained bone cements.

Experimental and in silico investigations of organic phosphates and phosphonates sorption on polymer-ceramic monolithic materials and hydroxyapatite.

PubMed

Pietrzyńska, Monika; Zembrzuska, Joanna; Tomczak, Rafał; Mikołajczyk, Jakub; Rusińska-Roszak, Danuta; Voelkel, Adam; Buchwald, Tomasz; Jampílek, Josef; Lukáč, Miloš; Devínsky, Ferdinand

2016-10-10

A method based on experimental and in silico evaluations for investigating interactions of organic phosphates and phosphonates with hydroxyapatite was developed. This quick and easy method is used for determination of differences among organophosphorus compounds of various structures in their mineral binding affinities. Empirical sorption evaluation was carried out using liquid chromatography with tandem mass spectrometry or UV-VIS spectroscopy. Raman spectroscopy was used to confirm sorption of organic phosphates and phosphonates on hydroxyapatite. Polymer-ceramic monolithic material and bulk hydroxyapatite were applied as sorbent materials. Furthermore, a Polymer-ceramic Monolithic In-Needle Extraction device was used to investigate both sorption and desorption steps. Binding energies were computed from the fully optimised structures utilising Density Functional Theory (DFT) at B3LYP/6-31+G(d,p) level. Potential pharmacologic and toxic effects of the tested compounds were estimated by the Prediction of the Activity Spectra of Substances using GeneXplain software. Copyright © 2016 Elsevier B.V. All rights reserved.

Behavior of osteoblast-like cells on calcium-deficient hydroxyapatite ceramics composed of particles with different shapes and sizes.

PubMed

Kamitakahara, Masanobu; Uno, Yuika; Ioku, Koji

2014-01-01

In designing the biomaterials, it is important to control their surface morphologies, because they affect the interactions between the materials and cells. We previously reported that porous calcium-deficient hydroxyapatite (HA) ceramics composed of rod-like particles had advantages over sintered porous HA ceramics; however, the effects of the surface morphology of calcium-deficient HA ceramics on cell behavior have remained unclear. Using a hydrothermal process, we successfully prepared porous calcium-deficient HA ceramics with different surface morphologies, composed of plate-like particles of 200-300, 500-800 nm, or 2-3 μm in width and rod-like particles of 1 or 3-5 μm in width, respectively. The effects of these surface morphologies on the behavior of osteoblast-like cells were examined. Although the numbers of cells adhered to the ceramic specimens did not differ significantly among the specimens, the proliferation rates of cells on the ceramics decreased with decreasing particle size. Our results reveal that controlling the surface morphology that is governed by particle shape and size is important for designing porous calcium-deficient HA ceramics.

Osteoblast response to zirconia-hybridized pyrophosphate-stabilized amorphous calcium phosphate

PubMed Central

Whited, Bryce M.; Skrtic, Drago; Love, Brian J.

2006-01-01

Calcium phosphate bioceramics, such as hydroxyapatite, have long been used as bone substitutes because of their proven biocompatibility and bone binding properties in vivo. Recently, a zirconia-hybridized pyrophosphate-stabilized amorphous calcium phosphate (Zr-ACP) has been synthesized, which is more soluble than hydroxyapatite and allows for controlled release of calcium and phosphate ions. These ions have been postulated to increase osteoblast differentiation and mineralization in vitro. The focus of this work is to elucidate the physicochemical properties of Zr-ACP and to measure cell response to Zr-ACP in vitro using a MC3T3-E1 mouse calvarial-derived osteoprogenitor cell line. Cells were cultured in osteogenic medium and mineral was added to culture at different stages in cell maturation. Culture in the presence of Zr-ACP showed significant increases in cell proliferation, alkaline phosphatase activity (ALP), and osteopontin (OPN) synthesis, whereas collagen synthesis was unaffected. In addition, calcium and phosphate ion concentrations and medium pH were found to transiently increase with the addition of Zr-ACP, and are hypothesized to be responsible for the osteogenic effect of Zr-ACP. PMID:16278876

Improvement of the stability of hydroxyapatite through glass ceramic reinforcement.

PubMed

Ha, Na Ra; Yang, Zheng Xun; Hwang, Kyu Hong; Kim, Tae Suk; Lee, Jong Kook

2010-05-01

Hydroxyapatite has achieved significant application in orthopedic and dental implants due to its excellent biocompatibility. Sintered hydroxyapatites showed significant dissolution, however, after their immersion in water or simulated body fluid (SBF). This grain boundary dissolution, even in pure hydroxyapatites, resulted in grain separation at the surfaces, and finally, in fracture. In this study, hydroxyapatite ceramics containing apatite-wollastonite (AW) or calcium silicate (SG) glass ceramics as additives were prepared to prevent the dissolution. AW and SG glass ceramics were added at 0-7 wt% and powder-compacted uniaxially followed by firing at moisture conditions. The glass phase was incorporated into the hydroxyapatite to act as a sintering aid, followed by crystallization, to improve the mechanical properties without reducing the biocompatibility. As seen in the results of the dissolution test, a significant amount of damage was reduced even after more than 14 days. TEM and SEM showed no decomposition of HA to the secondary phase, and the fracture toughness increased, becoming even higher than that of the commercial hydroxyapatite.

Preparation of hydroxyapatite/collagen injectable bone paste with an anti-washout property utilizing sodium alginate. Part 1: influences of excess supplementation of calcium compounds.

PubMed

Sato, Taira; Kikuchi, Masanori; Aizawa, Mamoru

2017-03-01

The anti-washout property, viscosity, and cytocompatibility to an osteoblastic cell line, MG-63, of anti-washout pastes were investigated. Mixing a hydroxyapatite/collagen bone-like nanocomposite (HAp/Col), an aqueous solution of sodium alginate (Na-Alg), which is a paste hardening and lubricant agent, and supplementation of calcium carbonate or calcium citrate (Ca-Cit) as a calcium resource for the hardening reaction realized an injectable bone paste. Adding Ca-Cit at a concentration greater than eight times the Ca 2+ ion concentration to Na-Alg improved the anti-washout property. Although the viscosity test indicated a gradual increase in the paste viscosity as the calcium compounds increased, pastes with excess supplementation of calcium compounds exhibited injectability through a syringe with a 1.8 mm inner diameter, realizing an injectable bone filler. Furthermore, the anti-washout pastes with Ca-Cit had almost the same cell proliferation rate as that of the HAp/Col dense body. Therefore, HAp/Col injectable anti-washout pastes composed of the HAp/Col, Na-Alg, and Ca-Cit are potential candidates for bioresorbable bone filler pastes.

Hydroxyapatite growth on cotton fibers modified chemically

NASA Astrophysics Data System (ADS)

Varela Caselis, J. L.; Reyes Cervantes, E.; Landeta Cortés, G.; Agustín Serrano, R.; Rubio Rosas, E.

2014-09-01

We have prepared carboxymethyl cellulose fibers (CMC) by chemically modifying cotton cellulose with monochloroacetic acid and calcium chloride solution. This modification favored the growth of hydroxyapatite (HAP) on the surface of the CMC fibers in contact with simulated body fluid solutions (SBF). After soaking in SBF for periods of 7, 14 and 21 days, formation of HAP was observed. Analysis by scanning electron microscopy and X-ray diffraction showed that crystallinity, crystallite size, and growth of HAP increased with the soaking time. The amount of HAP deposited on CMC fibers increased greatly after 21 days of immersion in the SBF, while the substrate surface was totally covered with hemispherical aggregates with the size of the order of 2 microns. Elemental analysis showed the presence of calcium and phosphate, with calcium/phosphate atomic ratio of 1.54. Fourier transform infrared spectroscopy bands confirmed the presence of HAP. The results suggest that cotton modified by calcium treatment has a nucleating ability and can accelerate the nucleation of HAP crystals.

Evaluation of calcination temperature and phase composition ratio for new hyroxyapatite

NASA Astrophysics Data System (ADS)

Salimi, M. N. Ahmad; Chin, H. S.

2017-10-01

The demand of production of hydroxyapatite (HA) has been increasing for the purpose of medical and dental application. HA possesses the excellent properties leads to the priority choice for ceramic bone replacement. Synthesis route by wet chemical precipitation is commonly practised in industrial scale. Calcium hydroxide and Orthophosphoric acid are the precursors for production scale. The synthesis of HA is conducted by varying the synthetic condition: stirring rate, calcium-phosphate and calcination temperature. This paper is focused on the properties of HA produced by regulating the synthetic condition so that the qualities of HA can be well performed. Characterization studies were also carried out by Fourier Transform Infrared Spectroscopy (FT-IR) for functional group identification, Scanning Electron Microscope (SEM) for surface morphology analysis and X-Ray Diffraction (XRD) for phase composition and crystallinity respectively. Narrow particle size distribution contributed to better quality of hydroxyapatite for bone replacement. Both calcium-phosphate ratio and calcination temperature would affect the phase composition of calcium phosphate.

Effect of silver additive on physicochemical properties of hydroxyapatite applied to reconstructive surgery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhuk, I. V., E-mail: zhukiv1993@mail.ru; Rasskazova, L. A., E-mail: ly-2207@mail.ru; Korotchenko, N. M., E-mail: korotch@mail.ru

The effect of silver adding to hydroxyapatite (HA) in its solubility in physiological solution and biological activity was investigated. Samples of HA containing silver (AgHA) obtained by liquid-phase method in the conditions of microwave exposure. Solubility (C{sub Ca}{sup 2+}·10{sup 3}, mol/l) of the powders AgHA was determined by chemical methods according trilonometric titration of the calcium ions in physiological solution at 25 and 37 °C. To investigate the biological activity of the samples, a series of experiments on the formation of the calcium-phosphate layer on the surface of the SBF-solution at 37 °C for 28 days. Electronic micrographs of samplesmore » taken at the end of each 7 days of the experiment, indicate the formation of calcium-phosphate layer (CPL) in the samples, the kinetics of which is shown as a function of cumulative concentrations of calcium and magnesium ions from time.« less

Synthesis of Ag doped calcium phosphate particles and their antibacterial effect as additives in dental glass ionomer cements.

PubMed

Chen, Song; Gururaj, Satwik; Xia, Wei; Engqvist, Håkan

2016-11-01

Developing dental restorations with enhanced antibacterial properties has been a constant quest for materials scientists. The aim of this study was to synthesize silver doped calcium phosphate particles and use them to improve antibacterial properties of conventional glass ionomer cement. The Ag doped monetite (Ag-DCPA) and hydroxyapatite (Ag-HA) were synthesized by precipitation method and characterized using X-ray diffraction, scanning electron microscope and X-ray fluorescence spectroscopy. The antibacterial properties of the cements aged for 1 day and 7 days were evaluated by direct contact measurement using staphylococcus epidermis Xen 43. Ion concentrations (F - and Ag + ) and pH were measured to correlate to the results of the antibacterial study. The compressive strength of the cements was evaluated with a crosshead speed of 1 mm/min. The glass ionomer cements containing silver doped hydroxyapatite or monetite showed improved antibacterial properties. Addition of silver doped hydroxyapatite or monetite did not change the pH and ion release of F - . Concentration of Ag + was under the detection limit (0.001 mg/L) for all samples. Silver doped hydroxyapatite or monetite had no effect on the compressive strength of glass ionomer cement.

Development and optimisation of atorvastatin calcium loaded self-nanoemulsifying drug delivery system (SNEDDS) for enhancing oral bioavailability: in vitro and in vivo evaluation.

PubMed

Kassem, Abdulsalam M; Ibrahim, Hany M; Samy, Ahmed M

2017-05-01

The objective of this study was to develop and optimise self-nanoemulsifying drug delivery system (SNEDDS) of atorvastatin calcium (ATC) for improving dissolution rate and eventually oral bioavailability. Ternary phase diagrams were constructed on basis of solubility and emulsification studies. The composition of ATC-SNEDDS was optimised using the Box-Behnken optimisation design. Optimised ATC-SNEDDS was characterised for various physicochemical properties. Pharmacokinetic, pharmacodynamic and histological findings were performed in rats. Optimised ATC-SNEDDS resulted in droplets size of 5.66 nm, zeta potential of -19.52 mV, t 90 of 5.43 min and completely released ATC within 30 min irrespective of pH of the medium. Area under the curve of optimised ATC-SNEDDS in rats was 2.34-folds higher than ATC suspension. Pharmacodynamic studies revealed significant reduction in serum lipids of rats with fatty liver. Photomicrographs showed improvement in hepatocytes structure. In this study, we confirmed that ATC-SNEDDS would be a promising approach for improving oral bioavailability of ATC.

Investigating the addition of SiO₂-CaO-ZnO-Na₂O-TiO₂ bioactive glass to hydroxyapatite: Characterization, mechanical properties and bioactivity.

PubMed

Yatongchai, Chokchai; Placek, Lana M; Curran, Declan J; Towler, Mark R; Wren, Anthony W

2015-11-01

Hydroxyapatite (Ca10(PO4)6(OH)2) is widely investigated as an implantable material for hard tissue restoration due to its osteoconductive properties. However, hydroxyapatite in bulk form is limited as its mechanical properties are insufficient for load-bearing orthopedic applications. Attempts have been made to improve the mechanical properties of hydroxyapatite, by incorporating ceramic fillers, but the resultant composite materials require high sintering temperatures to facilitate densification, leading to the decomposition of hydroxyapatite into tricalcium phosphate, tetra-calcium phosphate and CaO phases. One method of improving the properties of hydroxyapatite is to incorporate bioactive glass particles as a second phase. These typically have lower softening points which could possibly facilitate sintering at lower temperatures. In this work, a bioactive glass (SiO2-CaO-ZnO-Na2O-TiO2) is incorporated (10, 20 and 30 wt%) into hydroxyapatite as a reinforcing phase. X-ray diffraction confirmed that no additional phases (other than hydroxyapatite) were formed at a sintering temperature of 560 ℃ with up to 30 wt% glass addition. The addition of the glass phase increased the % crystallinity and the relative density of the composites. The biaxial flexural strength increased to 36 MPa with glass addition, and there was no significant change in hardness as a function of maturation. The pH of the incubation media increased to pH 10 or 11 through glass addition, and ion release profiles determined that Si, Na and P were released from the composites. Calcium phosphate precipitation was encouraged in simulated body fluid with the incorporation of the bioactive glass phase, and cell culture testing in MC-3T3 osteoblasts determined that the composite materials did not significantly reduce cell viability. © The Author(s) 2015.

Surface modification of calcium fluoro and hydroxyapatite by 1-octylphosphonic dichloride

NASA Astrophysics Data System (ADS)

Aissa, Abdallah; Agougui, Hassen; Debbabi, Mongi

2011-08-01

The reactivity of the surface of calcium hydroxyapatite (CaHAp) and fluorapatite (CaFAp) was tested and compared by grafting the 1-octylphosphonic dichloride (C 8H 17OPCl 2) using a molar ratio x = 2 or 4, x = n(organic)/ n(apatite). Successful synthesis was confirmed by different characterisation techniques such as X-ray powder diffraction patterns, IR spectroscopy, MAS-NMR ( 1H and 31P) and chemical analysis. The difference between their specific surface area (SSA: 57.46 for HAp and 12.09 m 2/g for FAp), the percentage of carbon measured after treatment with (C 8H 17OPCl 2) and the intensities of IR bands attributed to the grafted moiety suggests that the surface of hydroxyapatite is more reactive than that of fluorapatite. The 31P CP-MAS-NMR spectra of treated fluorapatite show a significant change in isotropic signal due to the protonation and deprotonation of superficial phosphate group. This can be explained by the difference in the nature of inorganic material.

Reduction of orthophosphates loss in agricultural soil by nano calcium sulfate.

PubMed

Chen, Dong; Szostak, Paul; Wei, Zongsu; Xiao, Ruiyang

2016-01-01

Nutrient loss from soil, especially phosphorous (P) from farmlands to natural water bodies via surface runoff or infiltration, have caused significant eutrophication problems. This is because dissolved orthophosphates are usually the limiting nutrient for algal blooms. Currently, available techniques to control eutrophication are surprisingly scarce. Calcium sulfate or gypsum is a common soil amendment and has a strong complexation to orthophosphates. The results showed that calcium sulfate reduced the amount of water extractable P (WEP) through soil incubation tests, suggesting less P loss from farmlands. A greater decrease in WEP occurred with a greater dosage of calcium sulfate. Compared to conventional coarse calcium sulfate, nano calcium sulfate further reduced WEP by providing a much greater specific surface area, higher solubility, better contact with the fertilizer and the soil particles, and superior dispersibility. The enhancement of the nano calcium sulfate for WEP reduction is more apparent for a pellet- than a powdered- fertilizer. At the dosage of Ca/P weight ratio of 2.8, the WEP decreased by 31±5% with the nano calcium sulfate compared to 20±5% decrease with the coarse calcium sulfate when the pellet fertilizer was used. Computation of the chemical equilibrium speciation shows that calcium hydroxyapatite has the lowest solubility. However, other mineral phases such as hydroxydicalcium phosphate, dicalcium phosphate dihydrate, octacalcium phosphate, and tricalcium phosphate might form preceding to calcium hydroxyapatite. Since calcium sulfate is the major product of the flue gas desulfurization (FGD) process, this study demonstrates a potential beneficial reuse and reduction of the solid FGD waste. Copyright © 2015 Elsevier B.V. All rights reserved.

Specialized probes based on hydroxyapatite calcium for heart tissues research by atomic force microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhukov, Mikhail, E-mail: cloudjyk@yandex.ru; Golubok, Alexander; Institute for Analytical Instrumentation, Russian Academy of Sciences

The new specialized AFM-probes with hydroxyapatite structures for atomic force microscopy of heart tissues calcification were created and studied. A process of probe fabrication is demonstrated. The adhesive forces between specialized hydroxyapatite probe and endothelium/subendothelial layers were investigated. It was found that the adhesion forces are significantly higher for the subendothelial layers. We consider that it is connected with the formation and localization of hydroxyapatite in the area of subendothelial layers of heart tissues. In addition, the roughness analysis and structure visualization of the endothelial surface of the heart tissue were carried out. The results show high efficiency of createdmore » specialized probes at study a calcinations process of the aortic heart tissues.« less

Regenerated cellulose/wool blend enhanced biomimetic hydroxyapatite mineralization.

PubMed

Salama, Ahmed; El-Sakhawy, Mohamed

2016-11-01

The current article investigates the effect of bioactive cellulose/wool blend on calcium phosphate biomimetic mineralization. Regenerated cellulose/wool blend was prepared by dissolution-regeneration of neat cellulose and natural wool in 1-butyl-3-methyl imidazolium chloride [Bmim][Cl], as a solvent for the two polymers. Crystalline hydroxyapatite nanofibers with a uniform size, shape and dimension were formed after immersing the bioactive blend in simulated body fluid. The cytotoxicity of cellulose/wool/hydroxyapatite was studied using animal fibroblast baby hamster kidney cells (BHK-21) and the result displayed good cytocompatability. This research work presents a green processing method for the development of novel cellulose/wool/hydroxyapatite hybrid materials for tissue engineering applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of hydroxyapatite derived from Indian coral.

PubMed

Sivakumar, M; Kumar, T S; Shantha, K L; Rao, K P

1996-09-01

A simple method of converting the calcium carbonate skeleton of the corals available in the Indian coast into hydroxyapatite granules has been developed. By heating the coral to 900 degrees C, the organic materials were eliminated. Powder X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) were employed to characterize the coral and to optimize the processing parameters as well as to confirm the hydroxyapatite formation. The coral used exhibits the presence of both aragonite and calcite phases (dimorphism). At a temperature of 900 degrees C the coral was found to decompose all the carbonate phases. The pre-heated coral is converted into hydroxyapatite by a chemical exchange reaction with di-ammonium phosphate under hydrothermal conditions. The hydroxyapatite obtained was in powder form and does not contain any impurities. The in vitro solubility test of the apatite granules performed in Gomoris, Michalelis, Sorensens, Ringer's and phosphate buffer of pH 7.2 and de-ionized water indicated the stability of the coralline hydroxyapatite.

Injectable Microsphere Gel Progressively Improves Global Ventricular Function, Regional Contractile Strain, and Mitral Regurgitation after Myocardial Infarction

PubMed Central

McGarvey, Jeremy R; Kondo, Norihiro; Witschey, Walter RT; Takebe, Manabu; Aoki, Chikashi; Burdick, Jason A.; Spinale, Francis G; Gorman, Joseph H; Pilla, James J; Gorman, Robert C

2014-01-01

Background There is continued need for therapies which reverse or abate the remodeling process following myocardial infarction (MI). In this study, we evaluate the longitudinal effects of calcium hydroxyapatite microsphere gel on regional strain, global ventricular function, and mitral regurgitation (MR) in a porcine MI model. Methods Twenty five Yorkshire swine were enrolled. Five were dedicated weight-matched controls. Twenty underwent posterolateral infarction by direct ligation of the circumflex artery and its branches. Infarcted animals were randomly divided into four groups: one week treatment, one week control, four week treatment, and four week control. Following infarction, animals received either twenty 150μl calcium hydroxyapatite gel or saline injections within the infarct. At their respective timepoints, echocardiograms, cardiac MRI, and tissue were collected for evaluation of MR, regional and global left ventricular function, wall thickness, and collagen content. Results Global and regional LV function were depressed in all infarcted subjects at one week compared to healthy controls. By four weeks post-infarction, global function had significantly improved in the calcium hydroxyapatite group compared to infarcted controls (EF 48.5±1.9% vs. 38.0±1.7%, p<0.01). Similarly, regional borderzone radial contractile strain (16.3±1.5% vs. 11.2±1.5%, p=0.04), MR grade (0.4±0.2 vs. 1.2±0.2, p=0.04), and infarct thickness (7.8±0.5mm vs. 4.5±0.2mm, p<0.01) were improved at this timepoint in the treatment group compared to infarct controls. Conclusions Calcium hydroxyapatite injection following MI progressively improves global LV function, borderzone function, and mitral regurgitation. Using novel biomaterials to augment infarct material properties is viable alternative in the current management of heart failure. PMID:25524397

Effect of the calcium to phosphorus ratio on the setting properties of calcium phosphate bone cements.

PubMed

Vlad, M D; Gómez, S; Barracó, M; López, J; Fernández, E

2012-09-01

α-Tricalcium phosphate (α-TCP) has become the main reactant of most experimental and commercial ceramic bone cements. It has calcium-to-phosphorus (Ca/P) ratio of 1.50. The present study expands and reports on the microstructures and mechanical properties of calcium phosphate (CP) cements containing sintered monolithic reactants obtained in the interval 1.29 < Ca/P < 1.77. The study focuses on their cement setting and hardening properties as well as on their microstructure and crystal phase evolution. The results showed that: (a) CP-cements made with reactants with Ca/P ratio other than 1.50 have longer setting and lower hardening properties; (b) CP-cements reactivity was clearly affected by the Ca/P ratio of the starting reactant; (c) reactants with Ca/P < 1.50 were composed of several phases, calcium pyrophosphate and α- and β-TCP. Similarly, reactants with Ca/P > 1.50 were composed of α-TCP, tetracalcium phosphate and hydroxyapatite; (d) only the reactant with Ca/P = 1.50 was monophasic and was made of α-TCP, which transformed during the setting into calcium deficient hydroxyapatite; (e) CP-cements developed different crystal microstructures with specific features depending on the Ca/P ratio of the starting reactant.

Simple and Rapid Synthesis of Magnetite/Hydroxyapatite Composites for Hyperthermia Treatments via a Mechanochemical Route

PubMed Central

Iwasaki, Tomohiro; Nakatsuka, Ryo; Murase, Kenya; Takata, Hiroshige; Nakamura, Hideya; Watano, Satoru

2013-01-01

This paper presents a simple method for the rapid synthesis of magnetite/hydroxyapatite composite particles. In this method, superparamagnetic magnetite nanoparticles are first synthesized by coprecipitation using ferrous chloride and ferric chloride. Immediately following the synthesis, carbonate-substituted (B-type) hydroxyapatite particles are mechanochemically synthesized by wet milling dicalcium phosphate dihydrate and calcium carbonate in a dispersed suspension of magnetite nanoparticles, during which the magnetite nanoparticles are incorporated into the hydroxyapatite matrix. We observed that the resultant magnetite/hydroxyapatite composites possessed a homogeneous dispersion of magnetite nanoparticles, characterized by an absence of large aggregates. When this material was subjected to an alternating magnetic field, the heat generated increased with increasing magnetite concentration. For a magnetite concentration of 30 mass%, a temperature increase greater than 20 K was achieved in less than 50 s. These results suggest that our composites exhibit good hyperthermia properties and are promising candidates for hyperthermia treatments. PMID:23629669

In situ fabrication of hollow hydroxyapatite microspheres by phosphate solution immersion

NASA Astrophysics Data System (ADS)

Wang, Yingchun; Yao, Aihua; Huang, Wenhai; Wang, Deping; zhou, Jun

2011-07-01

Hollow hydroxyapatite (HAP) microspheres with pores on their surfaces were prepared by converting Li 2O-CaO-B 2O 3 (LCB) glass microspheres in phosphate solution. The structure, phase composition, surface morphology, and porosity of the hollow HAP microspheres were characterized by SEM, SEM-EDS, XRD, FTIR, ICP-AES, and N 2 adsorption-desorption techniques. The formation and conversion mechanism of the hollow HAP microspheres during immersion process were discussed. The as-prepared microspheres consisted of calcium deficient carbonated hydroxyapatite, which is biomimetic. FTIR spectra indicated that the resulting apatite were B-type CO 3HAP, in which carbonate ions occupied the phosphate sites. After 600 °C heating treatment, hollow microspheres were completely composed of calcium deficient hydroxyapatite crystals including CO32-. The pore size distribution of the as-prepared hollow HAP microspheres were mainly the mesopores in the range of 2-40 nm with the pore volume 0.5614 cm 3/g, and the mean pore size 10.5 nm, respectively. The results confirmed that LCB glass were transformed to hydroxyapatite without changing the external shape and dimension of the original glass object and the resulting microspheres possessed good hollow structures. Once immersed in phosphate solution, Ca-P-OH hydrates were in situ formed on the surface of the glass and precipitated in the position occupied by Ca 2+, while the pores were formed in the position occupied by Li + and B 3+. These hollow HAP microspheres with such structures may be used as promising drug delivery devices.

Intramuscular migration of calcium hydroxyapatite crystal deposits involving the rotator cuff tendons of the shoulder: report of 11 patients.

PubMed

Pereira, Bruno P G; Chang, Eric Y; Resnick, Donald L; Pathria, Mini N

2016-01-01

The intent of the study is to describe an unusual pattern of intramuscular migration of calcific deposits related to hydroxyapatite deposition disease (HADD) involving the rotator cuff, to illustrate the characteristic imaging features of this phenomenon, and to discuss the clinical significance of such migration. A series of cases of intramuscular accumulation of calcium hydroxyapatite crystals collected over a 7-year period at multiple hospitals within the same academic institution were retrospectively reviewed. The patient group was composed of seven men and four women, ranging in age from 51 to 79 years, with a mean age of 63 years. All subjects presented with acute shoulder pain. The majority of subjects reported the spontaneous onset of the symptoms (64%), while others reported weight lifting (27%) and a fall on the arm (9%) as the mechanisms of injury. The right shoulder was affected in 73% of the subjects. The supraspinatus was the most commonly affected muscle (82%), followed by the infraspinatus muscle (36%). Knowledge of the imaging features of intramuscular migration of hydroxyapatite deposits is important in order to avoid the erroneous diagnosis of other causes of muscle edema and inflammation such as myotendinous injury, myositis, subacute denervation, and neoplasm.

Femtosecond laser ablation of enamel

NASA Astrophysics Data System (ADS)

Le, Quang-Tri; Bertrand, Caroline; Vilar, Rui

2016-06-01

The surface topographical, compositional, and structural modifications induced in human enamel by femtosecond laser ablation is studied. The laser treatments were performed using a Yb:KYW chirped-pulse-regenerative amplification laser system (560 fs and 1030 nm) and fluences up to 14 J/cm2. The ablation surfaces were studied by scanning electron microscopy, grazing incidence x-ray diffraction, and micro-Raman spectroscopy. Regardless of the fluence, the ablation surfaces were covered by a layer of resolidified material, indicating that ablation is accompanied by melting of hydroxyapatite. This layer presented pores and exploded gas bubbles, created by the release of gaseous decomposition products of hydroxyapatite (CO2 and H2O) within the liquid phase. In the specimen treated with 1-kHz repetition frequency and 14 J/cm2, thickness of the resolidified material is in the range of 300 to 900 nm. The micro-Raman analysis revealed that the resolidified material contains amorphous calcium phosphate, while grazing incidence x-ray diffraction analysis allowed detecting traces of a calcium phosphate other than hydroxyapatite, probably β-tricalcium phosphate Ca3), at the surface of this specimen. The present results show that the ablation of enamel involves melting of enamel's hydroxyapatite, but the thickness of the altered layer is very small and thermal damage of the remaining material is negligible.

Synthesis of fluorapatite–hydroxyapatite nanoparticles and toxicity investigations

PubMed Central

Montazeri, N; Jahandideh, R; Biazar, Esmaeil

2011-01-01

In this study, calcium phosphate nanoparticles with two phases, fluorapatite (FA; Ca10(PO4)6F2) and hydroxyapatite (HA; Ca10(PO4)6(OH)2), were prepared using the solgel method. Ethyl phosphate, hydrated calcium nitrate, and ammonium fluoride were used, respectively, as P, Ca, and F precursors with a Ca:P ratio of 1:72. Powders obtained from the sol-gel process were studied after they were dried at 80°C and heat treated at 550°C. The degree of crystallinity, particle and crystallite size, powder morphology, chemical structure, and phase analysis were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Zetasizer experiments. The results of XRD analysis and FTIR showed the presence of hydroxyapatite and fluorapatite phases. The sizes of the crystallites estimated from XRD patterns using the Scherrer equation and the crystallinity of the hydroxyapatite phase were about 20 nm and 70%, respectively. Transmission electron microscope and SEM images and Zetasizer experiments showed an average size of 100 nm. The in vitro behavior of powder was investigated with mouse fibroblast cells. The results of these experiments indicated that the powders were biocompatibile and would not cause toxic reactions. These compounds could be applied for hard-tissue engineering. PMID:21499417

Bioceramics synthesis of hydroxyapatite from red snapper fish scales biowaste using wet chemical precipitation route

NASA Astrophysics Data System (ADS)

Ulfyana, D.; Anugroho, F.; Sumarlan, S. H.; Wibisono, Y.

2018-03-01

Fish scales biowaste contain high collagens and calcium phosphates, therefore have considerable potential as raw material for value-added biomaterial such as hydroxyapatite (HAp). HAp is the main constituent component of hard tissue such as bone and teeth in the human body and is known as bioceramic materials. In this work, wet chemical precipitation method was used to syntesize HAp from Red Snapper Fish (Lutjanus campechanus) Scales. Two variations of calcination temperatures of 600°C (FHAp1) and 800°C (FHAp2) were conducted for 5 hours. The results showed calcium content from biowaste of red snapper fish scale was 83.62%. FTIR result shows that PO4 3-, OH-, and CO3 2- functional groups presence as indicates the formation of HAp. XRD result showed the degree of crystallinity for FHAp1 and FHAp2 were 75.52% and 79.20%, respectively. The degree of crystallinity is in accordance with ISO 13779-2:2000 standard in which the minimum degree of crystallinity of hydroxyapatite used for biomedical materials is 45%. Finally, Particle Size Analyzer (PSA) results show that the particle size distribution is evenly distributed, with the size of micro-scale hydroxyapatite particles, ranging from 5.76 μm to 132.64 μm.

Hydroxyapatite formation on titania-based materials in a solution mimicking body fluid: Effects of manganese and iron addition in anatase.

PubMed

Shin, Euisup; Kim, Ill Yong; Cho, Sung Baek; Ohtsuki, Chikara

2015-03-01

Hydroxyapatite formation on the surfaces of implanted materials plays an important role in osteoconduction of bone substitutes in bone tissues. Titania hydrogels are known to instigate hydroxyapatite formation in a solution mimicking human blood plasma. To date, the relationship between the surface characteristics of titania and hydroxyapatite formation on its surface remains unclear. In this study, titania powders with varying surface characteristics were prepared by addition of manganese or iron to examine hydroxyapatite formation in a type of simulated body fluid (Kokubo solution). Hydroxyapatite formation was monitored by observation of deposited particles with scale-like morphology on the prepared titania powders. The effect of the titania surface characteristics, i.e., crystal structure, zeta potential, hydroxy group content, and specific surface area, on hydroxyapatite formation was examined. Hydroxyapatite formation was observed on the surface of titania powders that were primarily anatase, and featured a negative zeta potential and low specific surface areas irrespective of the hydroxy group content. High specific surface areas inhibited the formation of hydroxyapatite because calcium and phosphate ions were mostly consumed by adsorption on the titania surface. Thus, these surface characteristics of titania determine its osteoconductivity following exposure to body fluid. Copyright © 2014 Elsevier B.V. All rights reserved.

Fractionated-combustion analysis of carbonate-containing phases in composite materials of the hydroxyapatite-calcium carbonate system

NASA Astrophysics Data System (ADS)

Goldberg, M. A.; Shibaeva, T. V.; Smirnov, V. V.; Kutsev, S. V.; Barinov, S. M.; Grigorovich, K. V.

2012-12-01

Materials in the hydroxyapatite (HA)-calcium carbonate (CC) system were synthesized by a precipitation method from aqueous solutions. According to the data of X-ray phase analysis and IR spectroscopy, the powders consisted of CC and AB-type carbonate-substituted HA (CHA). In order to determine the content of carbonate-containing phases in materials, the temperature-temporal mode of fractionated-combustion analysis of carbon was developed. The quantitative phase ratios and the degree of substitution of carbonate groups in CHA were determined. It was shown that the degree of substitution of carbonate groups in CHA increased from 2.47 to 5.31 wt % as the CC content increased from 13.50 to 88.33 wt %.

Hydrothermal fabrication of hydroxyapatite on the PEG-grafted surface of wood from Chinese Glossy Privet

NASA Astrophysics Data System (ADS)

Wang, Ning; Cai, Chuanjie; Cai, Dongqing; Cheng, Junjie; Li, Shengli; Wu, Zhengyan

2012-10-01

Wood-hydroxyapatite composite material was developed by depositing hydrated calcium hydrogen phosphate (HCHP) on the surface of wood from Chinese Glossy Privet (CGP) with polyethylene glycol (PEG, HO(CH2CH2O)nH) as the grafting agent and subsequent hydrothermal vapor treatment. The results illustrated that HCHP could adhere quickly and strongly on the PEG-grafted wood surface. Moreover, this HCHP could be efficiently transformed to hydroxyapatite (HA, Ca10(PO4)6(OH)2) by hydrothermal vapor treatment. IR, XRD analysis and SEM observation indicated that the fabricated hydroxyapatite was pure and its morphology was uniform and microporous. This work provides a new fabricating approach of biocompatible material which may have some potential applications as bone-repairing material.

Intramuscular migration of calcific tendinopathy in the rotator cuff: ultrasound appearance and a review of the literature.

PubMed

Becciolini, Marco; Bonacchi, Giovanni; Galletti, Stefano

2016-09-01

Calcific tendinopathy of the shoulder is a common condition caused by calcium hydroxyapatite crystals, affecting the tendons of the rotator cuff. Among uncommon complication, one is the migration of the calcium in the subacromion-subdeltoid bursa. More rare is the intraosseous migration. We present four cases of an even more rare condition, not well described in literature yet, the intramuscular migration of calcium.

Crystallization of carbonate hydroxyapatite in the presence of strontium ranelate

NASA Astrophysics Data System (ADS)

Izmailov, R. R.; Golovanova, O. A.

2015-11-01

The influence of strontium ranelate on the crystallization of carbonate hydroxyapatite from a prototype of synovial fluid of humans has been investigated. The synthesis products are studied by IR Fourier spectroscopy, X-ray diffraction, and differential thermal analysis. The amount of strontium in the samples is determined by atomic emission analysis. The sizes of crystallites in the synthesized phases are calculated from the Selyakov-Scherrer formula; the lattice parameters are also determined. The phases obtained are found to be species of calcium-deficient strontium-containing carbonate hydroxyapatite of mixed A and B types. Schemes of chemical reactions occurring during heat treatment are proposed.

Nanocrystalline hydroxyapatite ceramics prepared by hydrolysis in polyol medium

NASA Astrophysics Data System (ADS)

Mechay, Abderrahmen; Feki, Hafed E. L.; Schoenstein, Fréderic; Jouini, Noureddine

2012-07-01

This Letter describes a new approach for the synthesis of hydroxyapatite nanoparticles, which involves precipitation and hydrolysis reactions conducted in polyol medium. In fact, ammonium-hydrogen phosphate and calcium nitrate were dissolved in polyol, and then heated at the boiling point of the polyol (ethane1, 2diol or propane1, 2diol). Besides, the phase and composition of the polycrystalline were studied by TGA/DTA, FT-IR, TEM and XRD techniques. The nanoparticles thus obtained present interesting morphological characters varying from needle to very thin platelet. Moreover, the hydroxyapatite prepared in ployol shows higher cristallinity in comparison with that obtained by other 'chimie douce' methods.

In-situ hybridization of calcium silicate and hydroxyapatite-gelatin nanocomposites enhances physical property and in vitro osteogenesis.

PubMed

Chiu, Chi-Kai; Lee, Dong Joon; Chen, Hsin; Chow, Laurence C; Ko, Ching-Chang

2015-02-01

Low mechanical strengths and inadequate bioactive material-tissue interactions of current synthetic materials limit their clinical applications in bone regeneration. Here, we demonstrate gelatin modified siloxane-calcium silicate (GEMOSIL-CS), a nanocomposite made of gelatinous hydroxyapatite with in situ pozzolanic formation of calcium silicate (CS) interacting among gelatin, silica and Calcium Hydroxide (Ca(OH)2). It is shown the formation of CS matrices, which chemically bonds to the gelatinous hydroxyapatite, provided hygroscopic reinforcement mechanism and promoted both in vitro and in vivo osteogenic properties of GEMOSIL-CS. The formation of CS was identified by Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffraction. The interfacial bindings within nanocomposites were studied by FTIR and thermogravimetric analysis. Both gelatin and CS have been found critical to the structure integrity and mechanical strengths (93 MPa in compressive strength and 58.9 MPa in biaxial strength). The GEMOSIL-CS was biocompatible and osteoconductive as result of type I collagen secretion and mineralized nodule formation from MC3T3 osteoblasts. SEM and TEM indicated the secretion of collagen fibers and mineral particles as the evidence of mineralization in the early stage of osteogenic differentiation. In vivo bone formation capability was performed by implanting GEMOSIL-CS into rat calvarial defects for 12 weeks and the result showed comparable new bone formation between GEMOSIL-CS group (20%) and the control (20.19%). The major advantage of GEMOSIL-CS composites is in situ self-hardening in ambient or aqueous environment at room temperature providing a simple, fast and cheap method to produce porous scaffolds.

Preparation and characterization of composites based on the blends of collagen, chitosan and hyaluronic acid with nano-hydroxyapatite.

PubMed

Sionkowska, Alina; Kaczmarek, Beata

2017-09-01

3D porous composites based on the blend of chitosan, collagen and hyaluronic acid with the addition of nano-hydroxyapatite were prepared. SEM images for the composites were made and the structure was assessed. Mechanical properties were studied using a Zwick&Roell Testing Mashine. In addition, the porosity and density of composites were measured. The concentration of calcium ions released from the material was detected by the complexometric titration method. The results showed that in 3D porous sponge based on the blend of chitosan, collagen and hyaluronic acid, inorganic particles of nanohydroxyapatite can be incorporated, as well as that the properties of 3D composites depend on the material composition. Mechanical parameters and thermal stability of ternary biopolymeric blends were improved by the addition of hydroxyapatite. Moreover, the porosity of ternary materials was higher than in materials based on pure chitosan or collagen. All composites were characterized by a porous structure with interconnected pores. Calcium ions can be released from the composite during its degradation in water. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis of calcium hydrogen phosphate and hydroxyapatite coating on SS316 substrate through pulsed electrodeposition.

PubMed

Chakraborty, Rajib; Sengupta, Srijan; Saha, Partha; Das, Karabi; Das, Siddhartha

2016-12-01

The orthopaedic implants for human body are generally made of different biomaterials like stainless steels or Ti based alloys. However, it has been found that from surface properties point of view, none of these materials is attractive for fast tissue or cell growth on the surface of implant. This is one of the most important criteria to assure quick bonding between implant and body tissues vis-à-vis minimum recovery time for the patient. Keeping in view of the above facts, this work involves the pulsed electro-deposition coating of biocompatible hydroxyapatite and its group compounds from a diluted bath of calcium and phosphate salt at various current densities over the biomaterial sheet of SS316. SEM study confirms different morphologies of the coatings at different current densities. Characterization techniques like X-ray diffraction, SEM with EDX and FTIR have been used to confirm the phase and percentage quantity of hydroxyapatite compound in the depositions. This coating can serve as a medium for faster tissue growth over the metallic implants. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation, Physical-Chemical Characterization, and Cytocompatibility of Polymeric Calcium Phosphate Cements

PubMed Central

Khashaba, Rania M.; Moussa, Mervet; Koch, Christopher; Jurgensen, Arthur R.; Missimer, David M.; Rutherford, Ronny L.; Chutkan, Norman B.; Borke, James L.

2011-01-01

Aim. Physicochemical mechanical and in vitro biological properties of novel formulations of polymeric calcium phosphate cements (CPCs) were investigated. Methods. Monocalcium phosphate, calcium oxide, and synthetic hydroxyapatite were combined with either modified polyacrylic acid, light activated polyalkenoic acid, or polymethyl vinyl ether maleic acid to obtain Types I, II, and III CPCs. Setting time, compressive and diametral strength of CPCs was compared with zinc polycarboxylate cement (control). Specimens were characterized using X-ray diffraction, scanning electron microscopy, and infrared spectroscopy. In vitro cytotoxicity of CPCs and control was assessed. Results. X-ray diffraction analysis showed hydroxyapatite, monetite, and brushite. Acid-base reaction was confirmed by the appearance of stretching peaks in IR spectra of set cements. SEM revealed rod-like crystals and platy crystals. Setting time of cements was 5–12 min. Type III showed significantly higher strength values compared to control. Type III yielded high biocompatibility. Conclusions. Type III CPCs show promise for dental applications. PMID:21941551

Influence of Fe3O4 Nanoparticles in Hydroxyapatite Scaffolds on Proliferation of Primary Human Fibroblast Cells

NASA Astrophysics Data System (ADS)

Maleki-Ghaleh, H.; Aghaie, E.; Nadernezhad, A.; Zargarzadeh, M.; Khakzad, A.; Shakeri, M. S.; Beygi Khosrowshahi, Y.; Siadati, M. H.

2016-06-01

Modern techniques for expanding stem cells play a substantial role in tissue engineering: the raw material that facilitates regeneration of damaged tissues and treats diseases. The environmental conditions and bioprocessing methods are the primary determinants of the rate of cultured stem cell proliferation. Bioceramic scaffolds made of calcium phosphate are effective substrates for optimal cell proliferation. The present study investigates the effects of two bioceramic scaffolds on proliferating cells in culture media. One scaffold was made of hydroxyapatite and the other was a mixture of hydroxyapatite and ferromagnetic material (Fe3O4 nanoparticles). Disk-shaped (10 mm × 2 mm) samples of the two scaffolds were prepared. Primary human fibroblast proliferation was 1.8- and 2.5-fold faster, respectively, when cultured in the presence of hydroxyapatite or ferrous nanoparticle/hydroxyapatite mixtures. Optical microscopy images revealed that the increased proliferation was due to enhanced cell-cell contact. The presence of magnetic Fe3O4 nanoparticles in the ceramic scaffolds significantly increased cell proliferation compared to hydroxyapatite scaffolds and tissue culture polystyrene.

Advantages of TOF-SIMS analysis of hydroxyapatite and fluorapatite in comparison with XRD, HR-TEM and FT-IR.

PubMed

Okazaki, Masayuki; Hirata, Isao; Matsumoto, Takuya; Takahashi, Junzo

2005-12-01

The chemical analysis of hydroxyapatite and fluorapatite was carried out using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Hydroxyapatite and fluorapatite were synthesized at 80 +/- 1 degrees C and pH 7.4 +/- 0.2. Fluorapatite was better crystallized, with its (300) reflection shifted to a slightly higher angle. High-resolution transmission electron microscopy clearly revealed a typical, regular hexagonal cross section perpendicular to the c-axis for fluorapatite and a flattened hexagonal cross section for hydroxyapatite. FT-IR spectra of fluorapatite confirmed the absence of OH absorption peak--which was seen in hydroxyapatite at about 3570 cm(-1). TOF-SIMS mass spectra showed a peak at 40 amu due to calcium. In addition, a peak at 19 amu due to fluorine could be clearly seen, although the intensities of PO, PO2, and PO3 were very low. It was confirmed that TOF-SIMS clearly showed the differences between positive and negative mass spectra of hydroxyapatite and fluorapatite, especially for F-. We concluded that TOF-SIMS exhibited distinct advantages compared with other methods of analysis.

The nature of the hydroxyapatite-binding site in salivary acidic proline-rich proteins.

PubMed

Bennick, A; Cannon, M; Madapallimattam, G

1979-10-01

Protein A and C, which are major components of the acidic proline-rich proteins in human saliva, were digested, before or after adsorption to hydroxyapatite, with alkaline phosphatase, trypsin, thermolysin and a proteinase preparation from salivary sediment. The results demonstrate that the binding site is located in the proline-poor N-terminal part of the protein, possibly between residues 3 and 25. Phosphoserine is necessary for maximal adsorption of the proteins to hydroxyapatite. When proteins A and C are adsorbed to hydroxyapatite before proteolytic digestion there is a protection of some of the susceptible bonds in the N-terminal part of the proteins and a gradual removal of the proline-rich C-terminal part. Thermolysin can cleave susceptible bonds in the part of the protein that remains bound to hydroxyapatite, but at least some of the resulting peptides are retained on the mineral. Since the ability of the proteins to inhibit hydroxyapatite formation and to bind calcium is located in the N-terminal proline-poor part, it is possible that these activities are retained after proteolytic digestion of the adsorbed proteins.

Novel synthesis strategy for composite hydrogel of collagen/hydroxyapatite-microsphere originating from conversion of CaCO3 templates.

PubMed

Wei, Qingrong; Lu, Jian; Wang, Qiaoying; Fan, Hongsong; Zhang, Xingdong

2015-03-20

Inspired by coralline-derived hydroxyapatite, we designed a methodological route to synthesize carbonated-hydroxyapatite microspheres from the conversion of CaCO3 spherulite templates within a collagen matrix under mild conditions and thus constructed the composite hydrogel of collagen/hydroxyapatite-microspheres. Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) were employed to confirm the successful generation of the carbonated hydroxyapatite phase originating from CaCO3, and the ratios of calcium to phosphate were tracked over time. Variations in the weight portion of the components in the hybrid gels before and after the phase transformation of the CaCO3 templates were identified via thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) shows these composite hydrogels have a unique multiscale microstructure consisting of a collagen nanofibril network and hydroxyapatite microspheres. The relationship between the hydroxyapatite nanocrystals and the collagen fibrils was revealed by transmission electron microscopy (TEM) in detail, and the selected area electron diffraction (SAED) pattern further confirmed the results of the XRD analyses which show the typical low crystallinity of the generated hydroxyapatite. This smart synthesis strategy achieved the simultaneous construction of microscale hydroxyapatite particles and collagen fibrillar hydrogel, and appears to provide a novel route to explore an advanced functional hydrogel materials with promising potentials for applications in bone tissue engineering and reconstruction medicine.

Evolution of the magnesium incorporated amorphous calcium phosphate to nano-crystallized hydroxyapatite in alkaline solution

NASA Astrophysics Data System (ADS)

Zhang, Xiao-Juan; Lin, Dong-Yang; Yan, Xiao-Hui; Wang, Xiao-Xiang

2011-12-01

A homogeneous amorphous calcium phosphate (ACP) coating containing magnesium was achieved on titanium substrates by electrochemical deposition (ECD). Its amorphous structure is confirmed by transmission electron microscope (TEM) together with grazing reflection absorption infrared spectroscopy (IR) spectrometer. In the images of high-resolution transmission electron microscope (HRTEM), the ACP spheres are assembled by nano-particles with the diameter of 5-10 nm. In the alkaline environment, nucleation of hydroxyapatite (HAP) occurs on the surfaces of ACP spheres. By consuming the Ca and PO 4 ions inside the ACP spheres, the HAP nuclei grow outward. Confirmed by TEM, the ACP spheres converse to hollow HAP spheres composed of HAP nano-needles. The coating is finally constructed by the HAP nano-needles, which are themselves aggregated by numerous nano-particles.

In vitro degradation of multisubstituted hydroxyapatite and fluorapatite in the physiological condition

NASA Astrophysics Data System (ADS)

Sumathi, Shanmugam; Gopal, Buvaneswari

2015-07-01

Structure of hydroxyapatite (HAP) is more flexible towards ionic substitutions. Properties such as solubility, antimicrobial property can be tailored by substitutions. Substituted hydroxyapatite and fluorapatite of formulae BiNaCa3(PO4)3OH, Bi0.5M0.5Ca4(PO4)3OH (M=K, Ag), Ca10-xCux(PO4)6(OH/F)2 d(x=0.05-0.25) and Bi0.5Na0.5Ca4(PO4)3F were synthesized and characterized by powder XRD, FT-IR, SEM-EDAX and TGA. In vitro solubility of the synthesized compounds was studied in the phosphate buffered medium of pH 7.4 at 37 °C. Based on the release of calcium and phosphorus ion concentration and pH, the solubility of these compounds is discussed. Bismuth and sodium co-substituted hydroxyapatite are found to be more soluble compared with other substituted apatite compounds and unsubstituted hydroxyapatite.

Development of a Calcifiable Matrix for Bone Formation.

DTIC Science & Technology

1987-09-01

Previous editions are obsolete. SECURITY CLASSIFICATION OF THIS PAGE 4 ! Ir .€ w)N "," f " f " W"€ r ,. . , a v " -.-. ,. . P "w...process is hydroxyapatite *o(15). It was the purpose of our study to determine if three different doses of -.ofour variations of the polypentapeptide...phosphate would bind until a cascading series of events led to calcium phosphate deposition and its conversion to hydroxyapatite . The validity of this

Characterisation of Sol-Gel Synthesis of Phase Pure CaTiO3 Nano Powders after Drying

NASA Astrophysics Data System (ADS)

Mallik, P. K.; Biswal, G.; Patnaik, S. C.; Senapati, S. K.

2015-02-01

According to a few recent studies, calcium titanate (CT) is a material that is similar to hydroxyapatite in biological properties. However, calcium titanate is not currently being used in the biomedical applications as to hydroxyapatite. The objective is to prepare nano calcium titanate powders from the equimolar solution of calcium oxide, ethanol and Titanium (IV) isopropoxide via sol-gel synthesis. The phase analysis and morphology of powder particles were studied by X-ray diffraction (XRD), while the composition and size of powder particles were determined by Transmission electron microscope (TEM) attached with energy dispersive x-ray spectrometer (EDS). As results, XRD confirm the presence of phase pure crystalline CaTiO3 after drying at 100°C for 24 hours, while TEM analysis confirms about 13 nm sizes of CaTiO3 particles and some agglomerated particle of 20-30 nm. Moreover, EDS analysis indicates that the approximately stoichiometric Ca/Ti ratio 1:1 was obtained in the CaTiO3 powders. Finally, it can be concluded that described sol-gel synthesis could be novel method for the production of nano CaTiO3 particles at lower temperature compared to any other methods of production.

Study of mixed Ca-Zn hydroxyapatite surface modified by lactic acid

NASA Astrophysics Data System (ADS)

Turki, Thouraya; Aissa, Abdallah; Bac, Christophe Goze; Rachdi, Férid; Debbabi, Mongi

2012-07-01

The new hybrid inorganic-organic composites, Ca(10-x)Znx(PO4)6(OH)2-lactic acid, at different amounts of zinc and lactic acid were prepared by dissolution of the organic compound in an hydroxyapatite suspension. They were characterized by XRD, IR, MAS NMR (13C and 1H) and chemical analysis. The crystallinity was slightly affected by the presence of organic fragments. IR and (13C and 1H) MAS NMR measurements indicate that the carboxylic groups of the acid interact with calcium and zinc ions of hydroxyapatite surface. Chemical analysis displays that zinc promotes the acid grafting. A mechanism of surface modification is proposed based on the obtained results.

Synthesis and application of hydroxyapatite and fluoroapatite to scorodite encapsulation

NASA Astrophysics Data System (ADS)

Katsarou, Lydia

Recent research has investigated the precipitation of crystalline scorodite (FeAsO4˙2H2O) as a method to stabilise arsenic for disposal due to its good stability performance according to EPA's TCLP test. It has been determined, however, that scorodite releases arsenic in significant concentrations under alkaline pH or under anoxic conditions. With the objective of enhancing the stability of scorodite, its encapsulation with minerals inert to pH and redox potential variations is considered in this work. Such encapsulation materials are hydroxyapatite (HAP-Ca5(PO4)3OH) and fluoroapatite (FAP-Ca5(PO4)3F), the two most stable of the calcium phosphates. The work described in this thesis includes: 1) the preparation of hydroxyapatite and fluoroapatite powders and their characterisation, 2) the synthesis of crystalline scorodite under atmospheric conditions and its characterisation, 3) the encapsulation of scorodite with hydroxyapatite and fluoroapatite, and 4) the long term stability testing of the encapsulated solids. Hydroxyapatite and fluoroapatite were prepared first by homogeneous precipitation from a metastable solution, to which "Ca" and "PO4" source reagents of different concentrations were added at variable rates. The crystallinity of the produced materials was found to increase with temperature. Crystalline scorodite was produced by seeded crystallisation in ambient pressure. For the encapsulation of the scorodite particles various methods of direct precipitation by controlled supersaturation were attempted, by adjusting the pH and adding/mixing feed solutions of individual calcium and phosphate source reagents. Heterogeneous deposition of HAP on scorodite proved rather difficult. Optimum results were obtained via prior conditioning of the scorodite substrate in a calcium solution and employment of low agitation regime and high (37 °C rather than 22°C) temperature. The stability tests were done in oxic and anoxic environments and their results demonstrated that the encapsulated solids had enhanced stability, since the release of arsenic was lower than it was for naked scorodite. The presence of gypsum was found to help reduce the release of arsenic further as well as phosphorus under oxic, but not anoxic conditions due to possible interaction with the sulphite ions used as reducing agent.

Application of Calcium Phosphate Materials in Dentistry

PubMed Central

Al-Sanabani, Jabr S.; Al-Sanabani, Fadhel A.

2013-01-01

Calcium phosphate materials are similar to bone in composition and in having bioactive and osteoconductive properties. Calcium phosphate materials in different forms, as cements, composites, and coatings, are used in many medical and dental applications. This paper reviews the applications of these materials in dentistry. It presents a brief history, dental applications, and methods for improving their mechanical properties. Notable research is highlighted regarding (1) application of calcium phosphate into various fields in dentistry; (2) improving mechanical properties of calcium phosphate; (3) biomimetic process and functionally graded materials. This paper deals with most common types of the calcium phosphate materials such as hydroxyapatite and tricalcium phosphate which are currently used in dental and medical fields. PMID:23878541

Characterization of Nano-Hydroxyapatite Synthesized from Sea Shells Through Wet Chemical Method

NASA Astrophysics Data System (ADS)

Santhosh, S.; Prabu, S. Balasivanandha

2012-10-01

Nano-hydroxyapatite (HA) was synthesized by a wet chemical reaction using powdered sea shells (CaO) as starting material which was converted to calcium hydroxide (Ca(OH)2) and subsequently reacted with phosphoric acid (H3PO4). Initially raw sea shells (CaCO3) were thermally converted to amorphous calcium oxide by heat treatment. Two sets of experiments were done; in the first experiment, HA powder was dried in an electric furnace and in the second experiment, the reactants were irradiated in a domestic microwave oven followed by microwave drying. In each set of experiments, the concentrations of the reactants were decreased gradually. HA was synthesized by slow addition of phosphoric acid (H3PO4) in to calcium hydroxide (Ca(OH)2) maintaining the pH of the solution at 10 to avoid the formation of calcium deficient apatites. In both the experiments, Ca:P ratio of 1.67 was maintained for the reagents. The synthesized samples showed X-ray diffraction (XRD) patterns corresponding to hydroxyapatite. The wet chemical process with furnace drying resulted in HA particles of size 7-34 nm, whereas microwave irradiated process yielded HA particles of size 34-102 nm as evidenced from XRD analyses. The above experimental work done by wet chemical synthesis to produce HA powder from sea shells is a simple processing method at room temperature. Microwave irradiation leads to uniform crystallite sizes as evident from this study, at differing concentrations of the reactants and is a comparatively easy method to synthesize HA. The high resolution scanning electron microscopy (HRSEM)/transmission electron microscopic (TEM) analyses revealed the characteristic rod-shaped nanoparticles of HA for the present study.

Coronary artery calcium: a multi-institutional, multimanufacturer international standard for quantification at cardiac CT.

PubMed

McCollough, Cynthia H; Ulzheimer, Stefan; Halliburton, Sandra S; Shanneik, Kaiss; White, Richard D; Kalender, Willi A

2007-05-01

To develop a consensus standard for quantification of coronary artery calcium (CAC). A standard for CAC quantification was developed by a multi-institutional, multimanufacturer international consortium of cardiac radiologists, medical physicists, and industry representatives. This report specifically describes the standardization of scan acquisition and reconstruction parameters, the use of patient size-specific tube current values to achieve a prescribed image noise, and the use of the calcium mass score to eliminate scanner- and patient size-based variations. An anthropomorphic phantom containing calibration inserts and additional phantom rings were used to simulate small, medium-size, and large patients. The three phantoms were scanned by using the recommended protocols for various computed tomography (CT) systems to determine the calibration factors that relate measured CT numbers to calcium hydroxyapatite density and to determine the tube current values that yield comparable noise values. Calculation of the calcium mass score was standardized, and the variance in Agatston, volume, and mass scores was compared among CT systems. Use of the recommended scanning parameters resulted in similar noise for small, medium-size, and large phantoms with all multi-detector row CT scanners. Volume scores had greater interscanner variance than did Agatston and calcium mass scores. Use of a fixed calcium hydroxyapatite density threshold (100 mg/cm(3)), as compared with use of a fixed CT number threshold (130 HU), reduced interscanner variability in Agatston and calcium mass scores. With use of a density segmentation threshold, the calcium mass score had the smallest variance as a function of patient size. Standardized quantification of CAC yielded comparable image noise, spatial resolution, and mass scores among different patient sizes and different CT systems and facilitated reduced radiation dose for small and medium-size patients.

Rapid Mix Preparation of Bioinspired Nanoscale Hydroxyapatite for Biomedical Applications

PubMed Central

Wilcock, Caroline J.; Gentile, Piergiorgio; Hatton, Paul V.; Miller, Cheryl A.

2017-01-01

Hydroxyapatite (HA) has been widely used as a medical ceramic due to its good biocompatibility and osteoconductivity. Recently there has been interest regarding the use of bioinspired nanoscale hydroxyapatite (nHA). However, biological apatite is known to be calcium-deficient and carbonate-substituted with a nanoscale platelet-like morphology. Bioinspired nHA has the potential to stimulate optimal bone tissue regeneration due to its similarity to bone and tooth enamel mineral. Many of the methods currently used to fabricate nHA both in the laboratory and commercially, involve lengthy processes and complex equipment. Therefore, the aim of this study was to develop a rapid and reliable method to prepare high quality bioinspired nHA. The rapid mixing method developed was based upon an acid-base reaction involving calcium hydroxide and phosphoric acid. Briefly, a phosphoric acid solution was poured into a calcium hydroxide solution followed by stirring, washing and drying stages. Part of the batch was sintered at 1,000 °C for 2 h in order to investigate the products' high temperature stability. X-ray diffraction analysis showed the successful formation of HA, which showed thermal decomposition to β-tricalcium phosphate after high temperature processing, which is typical for calcium-deficient HA. Fourier transform infrared spectroscopy showed the presence of carbonate groups in the precipitated product. The nHA particles had a low aspect ratio with approximate dimensions of 50 x 30 nm, close to the dimensions of biological apatite. The material was also calcium deficient with a Ca:P molar ratio of 1.63, which like biological apatite is lower than the stoichiometric HA ratio of 1.67. This new method is therefore a reliable and far more convenient process for the manufacture of bioinspired nHA, overcoming the need for lengthy titrations and complex equipment. The resulting bioinspired HA product is suitable for use in a wide variety of medical and consumer health applications. PMID:28287572

Rapid Mix Preparation of Bioinspired Nanoscale Hydroxyapatite for Biomedical Applications.

PubMed

Wilcock, Caroline J; Gentile, Piergiorgio; Hatton, Paul V; Miller, Cheryl A

2017-02-23

Hydroxyapatite (HA) has been widely used as a medical ceramic due to its good biocompatibility and osteoconductivity. Recently there has been interest regarding the use of bioinspired nanoscale hydroxyapatite (nHA). However, biological apatite is known to be calcium-deficient and carbonate-substituted with a nanoscale platelet-like morphology. Bioinspired nHA has the potential to stimulate optimal bone tissue regeneration due to its similarity to bone and tooth enamel mineral. Many of the methods currently used to fabricate nHA both in the laboratory and commercially, involve lengthy processes and complex equipment. Therefore, the aim of this study was to develop a rapid and reliable method to prepare high quality bioinspired nHA. The rapid mixing method developed was based upon an acid-base reaction involving calcium hydroxide and phosphoric acid. Briefly, a phosphoric acid solution was poured into a calcium hydroxide solution followed by stirring, washing and drying stages. Part of the batch was sintered at 1,000 °C for 2 h in order to investigate the products' high temperature stability. X-ray diffraction analysis showed the successful formation of HA, which showed thermal decomposition to β-tricalcium phosphate after high temperature processing, which is typical for calcium-deficient HA. Fourier transform infrared spectroscopy showed the presence of carbonate groups in the precipitated product. The nHA particles had a low aspect ratio with approximate dimensions of 50 x 30 nm, close to the dimensions of biological apatite. The material was also calcium deficient with a Ca:P molar ratio of 1.63, which like biological apatite is lower than the stoichiometric HA ratio of 1.67. This new method is therefore a reliable and far more convenient process for the manufacture of bioinspired nHA, overcoming the need for lengthy titrations and complex equipment. The resulting bioinspired HA product is suitable for use in a wide variety of medical and consumer health applications.

Confocal Raman and electronic microscopy studies on the topotactic conversion of calcium carbonate from Pomacea lineate shells into hydroxyapatite bioceramic materials in phosphate media.

PubMed

dePaula, S M; Huila, M F G; Araki, K; Toma, H E

2010-12-01

Conversion of Pomacea lineate shells into hydroxyapatite (HA) bioceramic materials was investigated by their in vitro treatment with phosphate solutions, at room temperature. Confocal Raman microscopy revealed that the conversion proceeds at distinct rates through the nacreous or periostracum sides of the shell. The conversion can be accelerated using powdered samples, yielding biocompatible materials of great interest in biomedicine. Copyright © 2010 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Xin-Yu; Zhu, Ying-Jie, E-mail: y.j.zhu@mail.sic.ac.cn; Lu, Bing-Qiang

Graphical abstract: Hydroxyapatite nanorods are synthesized using biocompatible biomolecule pyridoxal-5′-phosphate as a new organic phosphorus source by the hydrothermal method. - Highlights: • Hydrothermal synthesis of hydroxyapatite nanorods is reported. • Biocompatible pyridoxal-5′-phosphate is used as an organic phosphorus source. • This method is simple, surfactant-free and environmentally friendly. - Abstract: Hydroxyapatite nanorods are synthesized by the hydrothermal method using biocompatible biomolecule pyridoxal-5′-phosphate (PLP) as a new organic phosphorus source. In this method, PLP biomolecules are hydrolyzed to produce phosphate ions under hydrothermal conditions, and these phosphate ions react with pre-existing calcium ions to form hydroxyapatite nanorods. The effects ofmore » experimental conditions including hydrothermal temperature and time on the morphology and crystal phase of the products are investigated. This method is simple, surfactant-free and environmentally friendly. The products are characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric (TG) analysis.« less

Fabrication, Properties and Applications of Dense Hydroxyapatite: A Review

PubMed Central

Prakasam, Mythili; Locs, Janis; Salma-Ancane, Kristine; Loca, Dagnija; Largeteau, Alain; Berzina-Cimdina, Liga

2015-01-01

In the last five decades, there have been vast advances in the field of biomaterials, including ceramics, glasses, glass-ceramics and metal alloys. Dense and porous ceramics have been widely used for various biomedical applications. Current applications of bioceramics include bone grafts, spinal fusion, bone repairs, bone fillers, maxillofacial reconstruction, etc. Amongst the various calcium phosphate compositions, hydroxyapatite, which has a composition similar to human bone, has attracted wide interest. Much emphasis is given to tissue engineering, both in porous and dense ceramic forms. The current review focusses on the various applications of dense hydroxyapatite and other dense biomaterials on the aspects of transparency and the mechanical and electrical behavior. Prospective future applications, established along the aforesaid applications of hydroxyapatite, appear to be promising regarding bone bonding, advanced medical treatment methods, improvement of the mechanical strength of artificial bone grafts and better in vitro/in vivo methodologies to afford more particular outcomes. PMID:26703750

Facial skeletal augmentation using hydroxyapatite cement.

PubMed

Shindo, M L; Costantino, P D; Friedman, C D; Chow, L C

1993-02-01

This study investigates the use of a new calcium phosphate cement, which sets to solid, microporous hydroxyapatite, for facial bone augmentation. In six dogs, the supraorbital ridges were augmented bilaterally with this hydroxyapatite cement. On one side, the hydroxyapatite cement was placed directly onto the bone within a subperiosteal pocket. On the opposite side, the cement was contained within a collagen membrane tubule and then inserted into a subperiosteal pocket. The use of collagen tubules facilitated easy, precise placement of the cement. All implants maintained their original augmented height throughout the duration of the study. They were well tolerated without extrusion or migration, and there was no significant sustained inflammatory response. Histologic studies, performed at 3, 6, and 9 months revealed that when the cement was placed directly onto bone, progressive replacement of the implant by bone (osseointegration of the hydroxyapatite with the underlying bone) without a loss of volume was observed. In contrast, when the cement-collagen tubule combination was inserted, primarily a fibrous union was noted. Despite such fibrous union, the hydroxyapatite-collagen implant solidly bonded to the underlying bone, and no implant resorption was observed. Hydroxyapatite cement can be used successfully for the experimental augmentation of the craniofacial skeleton and may be applicable for such uses in humans.

Polymer-Ceramic Composite Scaffolds: The Effect of Hydroxyapatite and β-tri-Calcium Phosphate

PubMed Central

Caetano, Guilherme; Vyas, Cian; Diver, Carl; Bártolo, Paulo

2018-01-01

The design of bioactive scaffolds with improved mechanical and biological properties is an important topic of research. This paper investigates the use of polymer-ceramic composite scaffolds for bone tissue engineering. Different ceramic materials (hydroxyapatite (HA) and β-tri-calcium phosphate (TCP)) were mixed with poly-ε-caprolactone (PCL). Scaffolds with different material compositions were produced using an extrusion-based additive manufacturing system. The produced scaffolds were physically and chemically assessed, considering mechanical, wettability, scanning electron microscopy and thermal gravimetric tests. Cell viability, attachment and proliferation tests were performed using human adipose derived stem cells (hADSCs). Results show that scaffolds containing HA present better biological properties and TCP scaffolds present improved mechanical properties. It was also possible to observe that the addition of ceramic particles had no effect on the wettability of the scaffolds. PMID:29342890

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yasukawa, Akemi, E-mail: yasukawa@cc.hirosaki-u.ac.jp; Kandori, Kazuhiko; Tanaka, Hidekazu

Highlights: Black-Right-Pointing-Pointer LnCaHap solid solution particles were prepared using five types of heavy rare earth ions by a precipitation method. Black-Right-Pointing-Pointer The length and the crystallinity of the LnCaHap particles first increased and then decreased with increasing Ln{sup 3+} contents. Black-Right-Pointing-Pointer A series of YCaHap solid solution particles formed with Y/(Y + Ca) = 0-0.10 were investigated using various methods in detail. -- Abstract: Calcium hydroxyapatite (CaHap) particles substituted five types of heavy rare earth ions (Ln: Y{sup 3+}, Gd{sup 3+}, Dy{sup 3+}, Er{sup 3+} and Yb{sup 3+}) were synthesized using a precipitation method and characterized using various means. Thesemore » Ln ions strongly affected the crystal phases and the structures of the products. With increasing Ln/(Ln + Ca) in the starting solution ([X{sub Ln}]), the length and the crystallinity of the particles first increased and then decreased. The rare earth metal-calcium hydroxyapatite (LnCaHap) solid solution particles were obtained at [X{sub Y}] {<=} 0.10 for substituting Y system and at [X{sub Ln}] {<=} 0.01-0.03 for substituting the other Ln systems. LnPO{sub 4} was mixed with LnCaHap at higher [X{sub Ln}] for all Ln systems. A series of yttrium-calcium hydroxyapatite (YCaHap) solid solutions with [X{sub Y}] = 0-0.10 were investigated using XRD, TEM, ICP-AES, IR and TG-DTA in detail.« less

Using MRI to detect and differentiate calcium oxalate and calcium hydroxyapatite crystals in air-bubble-free phantom

PubMed Central

Mustafi, Devkumar; Fan, Xiaobing; Peng, Bo; Foxley, Sean; Palgen, Jeremy; Newstead, Gillian M.

2015-01-01

Calcium oxalate (CaOX) crystals and calcium hydroxyapatite (CaHA) crystals were commonly associated with breast benign and malignant lesions, respectively. In this research, CaOX (n = 6) and CaHA (n = 6) crystals in air-bubble-free agarose phantom were studied and characterized by using MRI at 9.4 Tesla scanner. Calcium micro-crystals sizes ranged from 200 – 500 microns were made with either 99% pure CaOX or CaHA powder and embedded in agar to mimic the dimensions and calcium content of breast microcalcifications in vivo. MRI data were acquired with high spatial resolution T2-weighted (T2W) images and gradient echo images with five different echo times (TEs). The crystals areas were determined by setting the threshold relative to agarose signal. The ratio of crystals areas were calculated by the measurements from gradient echo images divided by T2W images. Then the ratios as a function of TE were fitted with the radical function. The results showed that the blooming artifacts due to magnetic susceptibility between agar and CaHA crystals were more than twice as large as the susceptibility in CaOX crystals (p < 0.05). In addition, larger bright rings were observed on gradient echo images around CaHA crystals compared to CaOX crystals. Our results suggest that MRI may provide useful information regarding breast microcalcifications by evaluating the apparent area of crystals ratios obtained between gradient echo and T2W images. PMID:26392170

Ceramic and non-ceramic hydroxyapatite as a bone graft material: a brief review.

PubMed

Dutta, S R; Passi, D; Singh, P; Bhuibhar, A

2015-03-01

Treatment of dental, craniofacial and orthopedic defects with bone graft substitutes has shown promising result achieving almost complete bone regeneration depending on product resorption similar to human bone's physicochemical and crystallographic characteristics. Among these, non-ceramic and ceramic hydroxyapatite being the main inorganic salt of bone is the most studied calcium phosphate material in clinical practices ever since 1970s and non-ceramic since 1985. Its "chemical similarity" with the mineralized phase of biologic bone makes it unique. Hydroxyapatite as an excellent carrier of osteoinductive growth factors and osteogenic cell populations is also useful as drug delivery vehicle regardless of its density. Porous ceramic and non-ceramic hydroxyapatite is osteoconductive, biocompatible and very inert. The need for bone graft material keeps on increasing with increased age of the population and the increased conditions of trauma. Recent advances in genetic engineering and doping techniques have made it possible to use non-ceramic hydroxyapatite in larger non-ceramic crystals and cluster forms as a successful bone graft substitute to treat various types of bone defects. In this paper we have mentioned some recently studied properties of hydroxyapatite and its various uses through a brief review of the literatures available to date.

Activity of plasma sprayed yttria stabilized zirconia reinforced hydroxyapatite/Ti-6Al-4V composite coatings in simulated body fluid.

PubMed

Gu, Y W; Khor, K A; Pan, D; Cheang, P

2004-07-01

Hydroxyapatite (HA)/yttria stabilized zirconia/Ti-6Al-4V bio-composite coatings deposited onto Ti-6Al-4V substrate through a plasma spray technique were immersed in simulated body fluid (SBF) to investigate their behavior in vitro. Surface morphologies and structural changes in the coatings were analyzed by scanning electron microscopy, thin-film X-ray diffractometer, and X-ray photoelectron spectroscopy. The tensile bond strength of the coatings after immersion was also conducted through the ASTM C-633 standard for thermal sprayed coatings. Results showed that carbonate-containing hydroxyapatite (CHA) layer formed on the surface of composite coatings after 4 weeks immersion in SBF solution, indicating the composite coating possessed excellent bioactivity. The mechanical properties were found to decrease with immersion duration of maximum 56 days. However, minimal variation in mechanical properties was found subsequent to achieving supersaturation of the calcium ions, which was attained with the precipitation of the calcium phosphate layers. The mechanical properties of the composite coating were found to be significantly higher than those of pure HA coatings even after immersion in the SBF solution, indicating the enhanced mechanical properties of the composite coatings.

Phosphate Recovery from Human Waste via the Formation of Hydroxyapatite during Electrochemical Wastewater Treatment

PubMed Central

2018-01-01

Electrolysis of toilet wastewater with TiO2-coated semiconductor anodes and stainless steel cathodes is a potentially viable onsite sanitation solution in parts of the world without infrastructure for centralized wastewater treatment. In addition to treating toilet wastewater, pilot-scale and bench-scale experiments demonstrated that electrolysis can remove phosphate by cathodic precipitation as hydroxyapatite at no additional energy cost. Phosphate removal could be predicted based on initial phosphate and calcium concentrations, and up to 80% total phosphate removal was achieved. While calcium was critical for phosphate removal, magnesium and bicarbonate had only minor impacts on phosphate removal rates at concentrations typical of toilet wastewater. Optimal conditions for phosphate removal were 3 to 4 h treatment at about 5 mA cm–2 (∼3.4 V), with greater than 20 m2 m–3 electrode surface area to reactor volume ratios. Pilot-scale systems are currently operated under similar conditions, suggesting that phosphate removal can be viewed as an ancillary benefit of electrochemical wastewater treatment, adding utility to the process without requiring additional energy inputs. Further value may be provided by designing reactors to recover precipitated hydroxyapatite for use as a low solubility phosphorus-rich fertilizer. PMID:29607266

Phosphate Recovery from Human Waste via the Formation of Hydroxyapatite during Electrochemical Wastewater Treatment.

PubMed

Cid, Clément A; Jasper, Justin T; Hoffmann, Michael R

2018-03-05

Electrolysis of toilet wastewater with TiO 2 -coated semiconductor anodes and stainless steel cathodes is a potentially viable onsite sanitation solution in parts of the world without infrastructure for centralized wastewater treatment. In addition to treating toilet wastewater, pilot-scale and bench-scale experiments demonstrated that electrolysis can remove phosphate by cathodic precipitation as hydroxyapatite at no additional energy cost. Phosphate removal could be predicted based on initial phosphate and calcium concentrations, and up to 80% total phosphate removal was achieved. While calcium was critical for phosphate removal, magnesium and bicarbonate had only minor impacts on phosphate removal rates at concentrations typical of toilet wastewater. Optimal conditions for phosphate removal were 3 to 4 h treatment at about 5 mA cm -2 (∼3.4 V), with greater than 20 m 2 m -3 electrode surface area to reactor volume ratios. Pilot-scale systems are currently operated under similar conditions, suggesting that phosphate removal can be viewed as an ancillary benefit of electrochemical wastewater treatment, adding utility to the process without requiring additional energy inputs. Further value may be provided by designing reactors to recover precipitated hydroxyapatite for use as a low solubility phosphorus-rich fertilizer.

Optimisation of nutritional requirements for dopamine synthesis by calcium alginate-entrapped mutant strain of Aspergillus oryzae EMS-6.

PubMed

Ali, Sikander; Nawaz, Wajeeha

2017-02-01

The optimisation of nutritional requirements for dopamine (DA) synthesis by calcium alginate-entrapped mutant variant of Aspergillus oryzae EMS-6 using submerged fermentation technique was investigated. A total of 13 strains were isolated from soil. Isolate I-2 was selected as a better producer of DA and improved by exposing with ethyl methylsulphonate (EMS). EMS-6 was selected as it exhibited 43 μg/mL DA activity. The mutant variable was further treated with low levels of l-cysteine HCl to make it resistant against diversion and environmental stress. The conidiospores of mutant variant were entrapped in calcium alginate beads for stable product formation. EMS-6 gave maximum DA activity (124 μg/mL) when supplemented with 0.1% peptone and 0.2% sucrose, under optimised parameters viz. pH 3, temperature of 55 °C and incubation time of 70 min. The study involves the high profile of DA activity and is needed, as DA is capable to control numerous neurogenic disorders.

In Vivo Osteogenic Potential of Biomimetic Hydroxyapatite/Collagen Microspheres: Comparison with Injectable Cement Pastes

PubMed Central

Manzanares, Maria-Cristina; Ginebra, Maria-Pau; Franch, Jordi

2015-01-01

The osteogenic capacity of biomimetic calcium deficient hydroxyapatite microspheres with and without collagen obtained by emulsification of a calcium phosphate cement paste has been evaluated in an in vivo model, and compared with an injectable calcium phosphate cement with the same composition. The materials were implanted into a 5 mm defect in the femur condyle of rabbits, and bone formation was assessed after 1 and 3 months. The histological analysis revealed that the cements presented cellular activity only in the margins of the material, whereas each one of the individual microspheres was covered with osteogenic cells. Consequently, bone ingrowth was enhanced by the microspheres, with a tenfold increase compared to the cement, which was associated to the higher accessibility for the cells provided by the macroporous network between the microspheres, and the larger surface area available for osteoconduction. No significant differences were found in terms of bone formation associated with the presence of collagen in the materials, although a more extensive erosion of the collagen-containing microspheres was observed. PMID:26132468

Development and Characterization of Biphasic Hydroxyapatite/β-TCP Cements.

PubMed

Gallinetti, Sara; Canal, Cristina; Ginebra, Maria-Pau; Ferreira, J

2014-04-01

Biphasic calcium phosphate bioceramics composed of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) have relevant properties as synthetic bone grafts, such as tunable resorption, bioactivity, and intrinsic osteoinduction. However, they have some limitations associated to their condition of high-temperature ceramics. In this work self-setting Biphasic Calcium Phosphate Cements (BCPCs) with different HA/β-TCP ratios were obtained from self-setting α-TCP/β-TCP pastes. The strategy used allowed synthesizing BCPCs with modulated composition, compressive strength, and specific surface area. Due to its higher solubility, α-TCP was fully hydrolyzed to a calcium-deficient HA (CDHA), whereas β-TCP remained unreacted and completely embedded in the CDHA matrix. Increasing amounts of the non-reacting β-TCP phase resulted in a linear decrease of the compressive strength, in association to the decreasing amount of precipitated HA crystals, which are responsible for the mechanical consolidation of apatitic cements. Ca 2+ release and degradation in acidic medium was similar in all the BCPCs within the timeframe studied, although differences might be expected in longer term studies once β-TCP, the more soluble phase was exposed to the surrounding media.

Comparative evaluation of Nano-Hydroxyapatite preparation and Calcium Sucrose Phosphate on microhardness of deciduous teeth after iron drop exposure - An in-vitro study.

PubMed

Rathi, Nilesh; Baid, Rutika; Baliga, Sudhindra; Thosar, Nilima

2017-04-01

To evaluate and compare the microhardness of deciduous teeth treated with nano-hydroxyapatite and calcium sucrose phosphate after iron drop exposure. Twenty healthy anterior deciduous teeth were collected and stored in 0.9% saline solution at room temperature. All the teeth were immersed in artificial saliva in an incubator shaker at 37° for an hour and then subjected to Vickers microhardness test at 100g load for 5 seconds. The teeth were then immersed in iron drop for 5 minutes, twice daily, rinsed with distilled water and kept in artificial saliva. This procedure was repeated for 7 days and teeth were subjected to microhardness testing. Further, the teeth were divided in two groups, each group containing 10 teeth. In group I, nanohydroxyapatite preparation and in group II, calcium sucrose phosphate were applied for 10 minutes, twice daily for 7 days and subjected again to microhardness testing again. Vickers microhardness analysis revealed that iron drop exposure to teeth caused significant decrease in microhardness ( p <0.05). Application of nanohydroxyapatite preparation in Group I showed significantly increased enamel microhardness (206.90) than that after iron drop exposure. Similarly, application of calcium sucrose phosphate in Group II showed significantly increased enamel microhardness (200.89) than that after iron drop exposure. Statistical difference was seen between the two groups, with nanohydroxyapatite preparation showing increased microhardness than calcium sucrose phosphate. Nanohydroxyapatite preparation and calcium sucrose phosphate have remineralizing effect over teeth affected by acid challenge of iron drops, nanohydroxyapatite preparation showing better results than calcium sucrose phosphate. Key words: Iron drops, Nanohydroxyapaptite, calcium sucrose phosphate, anticay.

Inhibition of hydroxyapatite growth by casein, a potential salivary phosphoprotein homologue.

PubMed

Romero, Maria J R H; Nakashima, Syozi; Nikaido, Toru; Ichinose, Shizuko; Sadr, Alireza; Tagami, Junji

2015-08-01

Salivary phosphoproteins are essential in tooth mineral regulation but are often overlooked in vitro. This study aimed to evaluate the effect of casein, as a salivary phosphoprotein homologue, on the deposition and growth of hydroxyapatite (HA) on tooth surfaces. Hydroxyapatite growth was quantified using seeded crystal systems. Artificial saliva (AS) containing HA powder and 0, 10, 20, 50, or 100 μg ml(-1) of casein, or 100 μg ml(-1) of dephosphorylated casein (Dcasein), was incubated for 0-8 h at 37°C, pH 7.2. Calcium concentrations were measured using atomic absorption spectroscopy (AAS). Surface precipitation of HA on bovine enamel and dentine blocks, incubated in similar conditions for 7 d, was examined using field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) with selected area electron diffraction (SAED). Casein adsorption was assessed using modified Lowry assays and zeta-potential measurements. The AAS results revealed a concentration-dependent inhibition of calcium consumption. Hydroxyapatite precipitation occurred when no casein was present, whereas precipitation of HA was apparently completely inhibited in casein-containing groups. Adsorption data demonstrated increasingly negative zeta-potential with increased casein concentration and an affinity constant similar to proline-rich proteins with Langmuir modelling. Casein inhibited the deposition and growth of HA primarily through the binding of esterized phosphate to HA active sites, indicating its potential as a mineral-regulating salivary phosphoprotein homologue in vitro. © 2015 Eur J Oral Sci.

Electric field-assisted formation of organically modified hydroxyapatite (ormoHAP) spheres in carboxymethylated gelatin gels.

PubMed

Heinemann, C; Heinemann, S; Kruppke, B; Worch, H; Thomas, J; Wiesmann, H P; Hanke, T

2016-10-15

A biomimetic strategy was developed in order to prepare organically modified hydroxyapatite (ormoHAP) with spherical shape. The technical approach is based on electric field-assisted migration of calcium ions and phosphate ions into a hydrogel composed of carboxymethylated gelatin. The electric field as well as the carboxymethylation using glucuronic acid (GlcA) significantly accelerates the mineralization process, which makes the process feasible for lab scale production of ormoHAP spheres and probably beyond. A further process was developed for gentle separation of the ormoHAP spheres from the gelatin gel without compromising the morphology of the mineral. The term ormoHAP was chosen since morphological analyses using electron microscopy (SEM, TEM) and element analysis (EDX, FT-IR, XRD) confirmed that carboxymethylated gelatin molecules use to act as organic templates for the formation of nanocrystalline HAP. The hydroxyapatite (HAP) crystals self-organize to form hollow spheres with diameters ranging from 100 to 500nm. The combination of the biocompatible chemical composition and the unique structure of the nanocomposites is considered to be a useful basis for future applications in functionalized degradable biomaterials. A novel bioinspired mineralization process was developed based on electric field-assisted migration of calcium and phosphate ions into biochemically carboxymethylated gelatin acting as organic template. Advantages over conventional hydroxyapatite include particle size distribution and homogeneity as well as achievable mechanical properties of relevant composites. Moreover, specifically developed calcium ion or phosphate ion release during degradation can be useful to adjust the fate of bone cells in order to manipulate remodeling processes. The hollow structure of the spheres can be useful for embedding drugs in the core, encapsulated by the highly mineralized outer shell. In this way, controlled drug release could be achieved, which enables advanced strategies for threating bone-related diseases, e.g. osteoporosis and multiple myeloma. Copyright © 2016. Published by Elsevier Ltd.

Preparation and Characterization of Hydroxyapatite-Silica Composite Nanopowders

NASA Astrophysics Data System (ADS)

Latifi, S. M.; Fathi, M. H.; Golozar, M. A.

One of the most important objectives in the field of biomaterials science and engineering is development of new materials as bone substitutes. Silica (SiO2) has an important role in the biomineralization and biological responses. The aim of this research was to prepare and characterize hydroxyapatite-silica (HA-SiO2) composite nanopowder with different content of silica. Hydroxyapatite-silica composite nanopowders with 20 and 40 wt% silica were prepared using a sol-gel method at 600°C with phosphoric pentoxide and calcium nitrate tetrahydrate as a source of hydroxyapatite; also, tetraethylorthosilicate and methyltriethoxisilane as a source of silica. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) techniques were used for characterization and evaluation of the products. The results indicated the presence of nanocrystalline hydroxyapatite phase beside amorphous silica phase in prepared composite nanopowders. Moreover, by increasing the content of silica in composite nanopowders, the crystallinity will be decreased,and the ability of the product as a bone substitute material might be controlled by changing the content of the ingredients and subsequently its structure.

Minerals and aligned collagen fibrils in tilapia fish scales: structural analysis using dark-field and energy-filtered transmission electron microscopy and electron tomography.

PubMed

Okuda, Mitsuhiro; Ogawa, Nobuhiro; Takeguchi, Masaki; Hashimoto, Ayako; Tagaya, Motohiro; Chen, Song; Hanagata, Nobutaka; Ikoma, Toshiyuki

2011-10-01

The mineralized structure of aligned collagen fibrils in a tilapia fish scale was investigated using transmission electron microscopy (TEM) techniques after a thin sample was prepared using aqueous techniques. Electron diffraction and electron energy loss spectroscopy data indicated that a mineralized internal layer consisting of aligned collagen fibrils contains hydroxyapatite crystals. Bright-field imaging, dark-field imaging, and energy-filtered TEM showed that the hydroxyapatite was mainly distributed in the hole zones of the aligned collagen fibrils structure, while needle-like materials composed of calcium compounds including hydroxyapatite existed in the mineralized internal layer. Dark-field imaging and three-dimensional observation using electron tomography revealed that hydroxyapatite and needle-like materials were mainly found in the matrix between the collagen fibrils. It was observed that hydroxyapatite and needle-like materials were preferentially distributed on the surface of the hole zones in the aligned collagen fibrils structure and in the matrix between the collagen fibrils in the mineralized internal layer of the scale.

Precipitation of hydroxyapatite on electrospun polycaprolactone/aloe vera/silk fibroin nanofibrous scaffolds for bone tissue engineering.

PubMed

Shanmugavel, Suganya; Reddy, Venugopal Jayarama; Ramakrishna, Seeram; Lakshmi, B S; Dev, Vr Giri

2014-07-01

Advances in electrospun nanofibres with bioactive materials have enhanced the scope of fabricating biomimetic scaffolds for tissue engineering. The present research focuses on fabrication of polycaprolactone/aloe vera/silk fibroin nanofibrous scaffolds by electrospinning followed by hydroxyapatite deposition by calcium-phosphate dipping method for bone tissue engineering. Morphology, composition, hydrophilicity and mechanical properties of polycaprolactone/aloe vera/silk fibroin-hydroxyapatite nanofibrous scaffolds along with controls polycaprolactone and polycaprolactone/aloe vera/silk fibroin nanofibrous scaffolds were examined by field emission scanning electron microscopy, Fourier transform infrared spectroscopy, contact angle and tensile tests, respectively. Adipose-derived stem cells cultured on polycaprolactone/aloe vera/silk fibroin-hydroxyapatite nanofibrous scaffolds displayed highest cell proliferation, increased osteogenic markers expression (alkaline phosphatase and osteocalcin), osteogenic differentiation and increased mineralization in comparison with polycaprolactone control. The obtained results indicate that polycaprolactone/aloe vera/silk fibroin-hydroxyapatite nanofibrous scaffolds have appropriate physico-chemical and biological properties to be used as biomimetic scaffolds for bone tissue regeneration. © The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Heat treatment's effects on hydroxyapatite powders in water vapor and air atmosphere

NASA Astrophysics Data System (ADS)

Karabulut, A.; Baştan, F. E.; Erdoǧan, G.; Üstel, F.

2015-03-01

Hydroxyapatite (HA; Ca10(PO4)6(OH)2) is the main chemical constituent of bone tissue (~70%) as well as HA which is a calcium phosphate based ceramic material forms inorganic tissue of bone and tooth as hard tissues is used in production of prosthesis for synthetic bone, fractured and broken bone restoration, coating of metallic biomaterials and dental applications because of its bio compatibility. It is known that Hydroxyapatite decomposes with high heat energy after heat treatment. Therefore hydroxyapatite powders that heated in water vapor will less decomposed phases and lower amorphous phase content than in air atmosphere. In this study high purity hydroxyapatite powders were heat treated with open atmosphere furnace and water vapor atmosphere with 900, 1000, 1200 °C. Morphology of same powder size used in this process by SEM analyzed. Chemical structures of synthesized coatings have been examined by XRD. The determination of particle size and morphological structure of has been characterized by Particle Sizer, and SEM analysis, respectively. Weight change of sample was recorded by thermogravimetric analysis (TGA) during heating and cooling.

In vitro degradation of calcium phosphates: Effect of multiscale porosity, textural properties and composition.

PubMed

Diez-Escudero, A; Espanol, M; Beats, S; Ginebra, M-P

2017-09-15

The capacity of calcium phosphates to be replaced by bone is tightly linked to their resorbability. However, the relative importance of some textural parameters on their degradation behavior is still unclear. The present study aims to quantify the effect of composition, specific surface area (SSA), and porosity at various length scales (nano-, micro- and macroporosity) on the in vitro degradation of different calcium phosphates. Degradation studies were performed in an acidic medium to mimic the osteoclastic environment. Small degradations were found in samples with interconnected nano- and micropores with sizes below 3µm although they were highly porous (35-65%), with maximum weight loss of 8wt%. Biomimetic calcium deficient hydroxyapatite, with high SSA and low crystallinity, presented the highest degradation rates exceeding even the more soluble β-TCP. A dependence of degradation on SSA was indisputable when porosity and pore sizes were increased. The introduction of additional macroporosity with pore interconnections above 20µm significantly impacted degradation, more markedly in the substrates with high SSA (>15m 2 /g), whereas in sintered substrates with low SSA (<1m 2 /g) it resulted just in a linear increase of degradation. Up to 30 % of degradation was registered in biomimetic substrates, compared to 15 % in β-TCP or 8 % in sintered hydroxyapatite. The incorporation of carbonate in calcium deficient hydroxyapatite did not increase its degradation rate. Overall, the study highlights the importance of textural properties, which can modulate or even outweigh the effect of other features such as the solubility of the compounds. The physicochemical features of calcium phosphates are crucial to tune biological events like resorption during bone remodeling. Understanding in vitro resorption can help to predict the in vivo behavior. Besides chemical composition, other parameters such as porosity and specific surface area have a strong influence on resorption. The complexity of isolating the contribution of each parameter lies in the close interrelation between them. In this work, a multiscale study was proposed to discern the extent to which each parameter influences degradation in a variety of calcium phosphates, using an acidic medium to resemble the osteoclastic environment. The results emphasize the importance of textural properties, which can modulate or even outweigh the effect of the intrinsic solubility of the compounds. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Equilibrium and kinetic studies of sorption of 2.4-dichlorophenol onto 2 mixtures: bamboo biochar plus calcium sulphate (BC) and hydroxyapatite plus bamboo biochar plus calcium sulphate (HBC), in a fluidized bed circulation column

DOE PAGES

Alamin, Ahmed Hassan; Kaewsichan, Lupong

2016-06-30

Sorption studies were carried out to investigate removal of 2.4-dichlorophenol (2.4-DCP) from aqueous solution in a fluidized bed by two types of adsorbent mixtures: BC (Bamboo char plus Calcium sulphate), and HBC (Hydroxyapatite plus Bamboo char plus Calcium sulphate); both manufactured in ball shape. The main material bamboo char was characterized by FTIR, DTA and SEM. The adsorption experiments were conducted in a fluidized bed circulation column. Adsorption, isotherms and kinetic studies were established under 180 min operating process time, at different initial 2.4-DCP solution concentrations ranging from 5–10 mg/L, and at different flow rates ranging from 0.25–0.75 L/min. Themore » data obtained fitted well for both the Langmuir and Freundlich isotherm models; indicating favorable condition of monolayer adsorption. The kinetics of both adsorbents complies with the pseudo second-order kinetic model. BC was proven a new effective composite and low cost adsorbent which can be applied in the field of wastewater treatment, and it can also play an important role in industry water treatment« less

Equilibrium and kinetic studies of sorption of 2.4-dichlorophenol onto 2 mixtures: bamboo biochar plus calcium sulphate (BC) and hydroxyapatite plus bamboo biochar plus calcium sulphate (HBC), in a fluidized bed circulation column

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alamin, Ahmed Hassan; Kaewsichan, Lupong

Sorption studies were carried out to investigate removal of 2.4-dichlorophenol (2.4-DCP) from aqueous solution in a fluidized bed by two types of adsorbent mixtures: BC (Bamboo char plus Calcium sulphate), and HBC (Hydroxyapatite plus Bamboo char plus Calcium sulphate); both manufactured in ball shape. The main material bamboo char was characterized by FTIR, DTA and SEM. The adsorption experiments were conducted in a fluidized bed circulation column. Adsorption, isotherms and kinetic studies were established under 180 min operating process time, at different initial 2.4-DCP solution concentrations ranging from 5–10 mg/L, and at different flow rates ranging from 0.25–0.75 L/min. Themore » data obtained fitted well for both the Langmuir and Freundlich isotherm models; indicating favorable condition of monolayer adsorption. The kinetics of both adsorbents complies with the pseudo second-order kinetic model. BC was proven a new effective composite and low cost adsorbent which can be applied in the field of wastewater treatment, and it can also play an important role in industry water treatment« less

Effect of reaction solvent on hydroxyapatite synthesis in sol-gel process

NASA Astrophysics Data System (ADS)

Nazeer, Muhammad Anwaar; Yilgor, Emel; Yagci, Mustafa Baris; Unal, Ugur; Yilgor, Iskender

2017-12-01

Synthesis of hydroxyapatite (HA) through sol-gel process in different solvent systems is reported. Calcium nitrate tetrahydrate (CNTH) and diammonium hydrogen phosphate (DAHP) were used as calcium and phosphorus precursors, respectively. Three different synthesis reactions were carried out by changing the solvent media, while keeping all other process parameters constant. A measure of 0.5 M aqueous DAHP solution was used in all reactions while CNTH was dissolved in distilled water, tetrahydrofuran (THF) and N,N-dimethylformamide (DMF) at a concentration of 0.5 M. Ammonia solution (28-30%) was used to maintain the pH of the reaction mixtures in the 10-12 range. All reactions were carried out at 40 ± 2°C for 4 h. Upon completion of the reactions, products were filtered, washed and calcined at 500°C for 2 h. It was clearly demonstrated through various techniques that the dielectric constant and polarity of the solvent mixture strongly influence the chemical structure and morphological properties of calcium phosphate synthesized. Water-based reaction medium, with highest dielectric constant, mainly produced β-calcium pyrophosphate (β-CPF) with a minor amount of HA. DMF/water system yielded HA as the major phase with a very minor amount of β-CPF. THF/water solvent system with the lowest dielectric constant resulted in the formation of pure HA.

21 CFR 74.2053 - D&C Black No. 3.

Code of Federal Regulations, 2010 CFR

2010-04-01

... may be avoided by current good manufacturing practices: (1) Calcium hydroxyapatite (CaO and P2O5), not...) Total polycyclic aromatic hydrocarbons (PAHs), not more than 5 mg/kg (5 ppm). (c) Uses and restrictions...

Raman spectroscopic sensing of carbonate intercalation in breast microcalcifications at stereotactic biopsy

PubMed Central

Sathyavathi, R.; Saha, Anushree; Soares, Jaqueline S.; Spegazzini, Nicolas; McGee, Sasha; Rao Dasari, Ramachandra; Fitzmaurice, Maryann; Barman, Ishan

2015-01-01

Microcalcifications are an early mammographic sign of breast cancer and frequent target for stereotactic biopsy. Despite their indisputable value, microcalcifications, particularly of the type II variety that are comprised of calcium hydroxyapatite deposits, remain one of the least understood disease markers. Here we employed Raman spectroscopy to elucidate the relationship between pathogenicity of breast lesions in fresh biopsy cores and composition of type II microcalcifications. Using a chemometric model of chemical-morphological constituents, acquired Raman spectra were translated to characterize chemical makeup of the lesions. We find that increase in carbonate intercalation in the hydroxyapatite lattice can be reliably employed to differentiate benign from malignant lesions, with algorithms based only on carbonate and cytoplasmic protein content exhibiting excellent negative predictive value (93–98%). Our findings highlight the importance of calcium carbonate, an underrated constituent of microcalcifications, as a spectroscopic marker in breast pathology evaluation and pave the way for improved biopsy guidance. PMID:25927331

Raman spectroscopic sensing of carbonate intercalation in breast microcalcifications at stereotactic biopsy

NASA Astrophysics Data System (ADS)

Sathyavathi, R.; Saha, Anushree; Soares, Jaqueline S.; Spegazzini, Nicolas; McGee, Sasha; Rao Dasari, Ramachandra; Fitzmaurice, Maryann; Barman, Ishan

2015-04-01

Microcalcifications are an early mammographic sign of breast cancer and frequent target for stereotactic biopsy. Despite their indisputable value, microcalcifications, particularly of the type II variety that are comprised of calcium hydroxyapatite deposits, remain one of the least understood disease markers. Here we employed Raman spectroscopy to elucidate the relationship between pathogenicity of breast lesions in fresh biopsy cores and composition of type II microcalcifications. Using a chemometric model of chemical-morphological constituents, acquired Raman spectra were translated to characterize chemical makeup of the lesions. We find that increase in carbonate intercalation in the hydroxyapatite lattice can be reliably employed to differentiate benign from malignant lesions, with algorithms based only on carbonate and cytoplasmic protein content exhibiting excellent negative predictive value (93-98%). Our findings highlight the importance of calcium carbonate, an underrated constituent of microcalcifications, as a spectroscopic marker in breast pathology evaluation and pave the way for improved biopsy guidance.

Identification of monoclinic calcium pyrophosphate dihydrate and hydroxyapatite in human sclera using Raman microspectroscopy.

PubMed

Chen, Ko-Hua; Li, Mei-Jane; Cheng, Wen-Ting; Balic-Zunic, Tonci; Lin, Shan-Yang

2009-02-01

Raman microspectroscopy was first used to determine the composition of a calcified plaque located at the pterygium-excision site of a 51-year-old female patient's left nasal sclera after surgery. It was unexpectedly found that the Raman spectrum of the calcified sample at 1149, 1108, 1049, 756, 517, 376 and 352/cm was similar to the Raman spectrum of monoclinic form of calcium pyrophosphate dihydrate (CPPD) crystal, but differed from the Raman spectrum of triclinic form of CPPD. An additional peak at 958/cm was also observed in the Raman spectrum of the calcified plaque, which was identical to the characteristic peak at 958/cm of hydroxyapatite (HA). This is the first study to report the spectral biodiagnosis of both monoclinic CPPD and HA co-deposited in the calcified plaque of a patient with sclera dystrophic calcification using Raman microspectroscopy.

Identification of monoclinic calcium pyrophosphate dihydrate and hydroxyapatite in human sclera using Raman microspectroscopy

PubMed Central

Chen, Ko-Hua; Li, Mei-Jane; Cheng, Wen-Ting; Balic-Zunic, Tonci; Lin, Shan-Yang

2009-01-01

Raman microspectroscopy was first used to determine the composition of a calcified plaque located at the pterygium-excision site of a 51-year-old female patient's left nasal sclera after surgery. It was unexpectedly found that the Raman spectrum of the calcified sample at 1149, 1108, 1049, 756, 517, 376 and 352/cm was similar to the Raman spectrum of monoclinic form of calcium pyrophosphate dihydrate (CPPD) crystal, but differed from the Raman spectrum of triclinic form of CPPD. An additional peak at 958/cm was also observed in the Raman spectrum of the calcified plaque, which was identical to the characteristic peak at 958/cm of hydroxyapatite (HA). This is the first study to report the spectral biodiagnosis of both monoclinic CPPD and HA co-deposited in the calcified plaque of a patient with sclera dystrophic calcification using Raman microspectroscopy. PMID:19200254

Raman spectroscopic sensing of carbonate intercalation in breast microcalcifications at stereotactic biopsy.

PubMed

Sathyavathi, R; Saha, Anushree; Soares, Jaqueline S; Spegazzini, Nicolas; McGee, Sasha; Rao Dasari, Ramachandra; Fitzmaurice, Maryann; Barman, Ishan

2015-04-30

Microcalcifications are an early mammographic sign of breast cancer and frequent target for stereotactic biopsy. Despite their indisputable value, microcalcifications, particularly of the type II variety that are comprised of calcium hydroxyapatite deposits, remain one of the least understood disease markers. Here we employed Raman spectroscopy to elucidate the relationship between pathogenicity of breast lesions in fresh biopsy cores and composition of type II microcalcifications. Using a chemometric model of chemical-morphological constituents, acquired Raman spectra were translated to characterize chemical makeup of the lesions. We find that increase in carbonate intercalation in the hydroxyapatite lattice can be reliably employed to differentiate benign from malignant lesions, with algorithms based only on carbonate and cytoplasmic protein content exhibiting excellent negative predictive value (93-98%). Our findings highlight the importance of calcium carbonate, an underrated constituent of microcalcifications, as a spectroscopic marker in breast pathology evaluation and pave the way for improved biopsy guidance.

Size controlled hydroxyapatite and calcium carbonate particles: synthesis and their application as templates for SERS platform.

PubMed

Parakhonskiy, B V; Svenskaya, Yu I; Yashchenok, A М; Fattah, H A; Inozemtseva, O A; Tessarolo, F; Antolini, R; Gorin, D A

2014-06-01

An elegant route for hydroxyapatite (HA) particle synthesis via ionic exchange reaction is reported. Calcium carbonate particles (CaCO3) were recrystallized into HA beads in water solution with phosphate ions. The size of initial CaCO3 particles was controlled upon the synthesis by varying the amount of ethylene glycol (EG) in aqueous solution. The average size of HA beads ranged from 0.6±0.1 to 4.3±1.1μm. Silver nanoparticles were deposited on the surface of HA and CaCO3 particles via silver mirror reaction. Surface enhanced Raman scattering of silver functionalized beads was demonstrated by detecting Rhodamine B. CaCO3 and HA particles have a great potential for design of carrier which can provide diagnostic and therapeutic functions. Copyright © 2014 Elsevier B.V. All rights reserved.

Three-dimensional printed bone scaffolds: The role of nano/micro-hydroxyapatite particles on the adhesion and differentiation of human mesenchymal stem cells.

PubMed

Domingos, Marco; Gloria, Antonio; Coelho, Jorge; Bartolo, Paulo; Ciurana, Joaquim

2017-06-01

Bone tissue engineering is strongly dependent on the use of three-dimensional scaffolds that can act as templates to accommodate cells and support tissue ingrowth. Despite its wide application in tissue engineering research, polycaprolactone presents a very limited ability to induce adhesion, proliferation and osteogenic cell differentiation. To overcome some of these limitations, different calcium phosphates, such as hydroxyapatite and tricalcium phosphate, have been employed with relative success. This work investigates the influence of nano-hydroxyapatite and micro-hydroxyapatite (nHA and mHA, respectively) particles on the in vitro biomechanical performance of polycaprolactone/hydroxyapatite scaffolds. Morphological analysis performed with scanning electron microscopy allowed us to confirm the production of polycaprolactone/hydroxyapatite constructs with square interconnected pores of approximately 350 µm and to assess the distribution of hydroxyapatite particles within the polymer matrix. Compression mechanical tests showed an increase in polycaprolactone compressive modulus ( E) from 105.5 ± 11.2 to 138.8 ± 12.9 MPa (PCL_nHA) and 217.2 ± 21.8 MPa (PCL_mHA). In comparison to PCL_mHA scaffolds, the addition of nano-hydroxyapatite enhanced the adhesion and viability of human mesenchymal stem cells as confirmed by Alamar Blue assay. In addition, after 14 days of incubation, PCL_nHA scaffolds showed higher levels of alkaline phosphatase activity compared to polycaprolactone or PCL_mHA structures.

Novel silk fibroin films prepared by formic acid/hydroxyapatite dissolution method.

PubMed

Ming, Jinfa; Liu, Zhi; Bie, Shiyu; Zhang, Feng; Zuo, Baoqi

2014-04-01

Bombyx mori silk fibroin from the silkworm was firstly found to be soluble in formic acid/hydroxyapatite system. The rheological behavior of silk fibroin solution was significantly influenced by HAp contents in dissolved solution. At the same time, silk fibroin nanofibers were observed in dissolved solution with 103.6±20.4nm in diameter. Moreover, the structure behavior of SF films prepared by formic acid/hydroxyapatite dissolution method was examined. The secondary structure of silk fibroin films was attributed to silk II structure (β-sheet), indicating that the hydroxyapatite contents in dissolved solution were not significantly affected by the structure of silk fibroin. The X-ray diffraction results exhibited obviously hydroxyapatite crystalline nature existing in silk fibroin films; however, when the hydroxyapatite content was 5.0wt.% in dissolved solution, some hydroxyapatite crystals were converted to calcium hydrogen phosphate dehydrate in silk fibroin dissolution process. This result was also confirmed by Fourier transform infrared analysis and DSC measurement. In addition, silk fibroin films prepared by this dissolution method had higher breaking strength and extension at break. Based on these analyses, an understanding of novel SF dissolution method may provide an additional tool for designing and synthesizing advanced materials with more complex structures, which should be helpful in different fields, including biomaterial applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Adsorption and bioactivity studies of albumin onto hydroxyapatite surface.

PubMed

Mavropoulos, Elena; Costa, Andréa M; Costa, Lilian T; Achete, Carlos A; Mello, Alexandre; Granjeiro, José M; Rossi, Alexandre M

2011-03-01

Bovine serum albumin (BSA) may have an inhibitory or promoter effect on hydroxyapatite (HA) nucleation when apatite is precipitated in a medium containing the protein. In this study we evaluated the influence of BSA on the precipitation of calcium phosphate phases (CP) from simulated body fluid (SBF) when the protein was previously bounded to HA surface. The kinetics of BSA immobilization onto hydroxyapatite surface was performed in different buffers and protein concentrations in order to adjust experimental conditions in which BSA was tightly linked to HA surface for long periods in SBF solution. It was shown that for BSA concentration higher than 0.1mg/mL the adsorption to HA surface followed Langmuir-Freundlich mechanisms, which confirmed the existence of cooperative protein-protein interactions on HA surface. Fourier Transformed Infrared Attenuated Total Reflectance Microscopy (FTIRM-ATR) evidenced changes in BSA conformational state in favor of less-ordered structure. Analyses from high resolution grazing incident X-ray diffraction using synchrotron radiation (GIXRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) showed that a poorly crystalline calcium phosphate was precipitated on the surface of HA discs coated with BSA, after the immersion in SBF for 4 days. The new bioactive layer had morphological characteristics similar to the one formed on the HA surface without protein. It was identified as a carbonated apatite with preferential crystal growth along apatite 002 direction. The GIXRD results also revealed that BSA layer bound to the surface inhibited the HA dissolution leading to a reduction on the formation of new calcium phosphate phase. 2010 Elsevier B.V. All rights reserved.

Patterns of calcium oxalate monohydrate crystallization in complex biological systems

NASA Astrophysics Data System (ADS)

Golovanova, O. A.; Korol'kov, V. V.; Kuimova, M. V.

2017-01-01

The paper presents the features of calcium oxalate crystallization in the presence of additives revealed through experimental modeling. The patterns of phase formation are shown for the Ca2+ - C2O4 2- - H2O and Ca2+ - C2O4 2- - PO4 3- - H2O systems with the components and pH of the saline varying over a wide concentrations range. The effect of additives on crystallization of calcium oxalate monohydrate was investigated. It was found that the ionic strength and magnesium ions are inhibitors, and calcium oxalate and hydroxyapatite crystals are catalysts of calcium oxalate monohydrate crystallization. The basic calcium phosphate (apatite) was found to be most thermodynamically stable, which indicates its special role in kidney stone formation since it is found in virtually all stones.

Preparation and characterization of selenite substituted hydroxyapatite.

PubMed

Ma, Jun; Wang, Yanhua; Zhou, Lei; Zhang, Shengmin

2013-01-01

Selenite-substituted hydroxyapatite (Se-HA) with different Se/P ratios was synthesized by a co-precipitation method, using sodium selenite (Na2SeO3) as a Se source. Selenium has been incorporated into the hydroxyapatite lattice by partially replacing phosphate (PO4(3-)) groups with selenite (SeO3(2-)) groups. X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) techniques reveal that substitutions of phosphate groups by selenite groups cause lower carbonate groups occupying at phosphate sites and change the lattice parameters of hydroxyapatite. The powders obtained are nano-crystalline hydroxyapatite when the Se/P ratios are not more than 0.1. The particle shape of Se-HA has not been altered compared with selenite-free hydroxyapatite but Se-incorporation reduces the crystallite size. The crystallinity was reduced as the Se/P ratios increased until amorphous phase (Se/P=0.3) appeared in the Se-HA powder obtained, and then another crystal phase presented as calcium selenite hydrate (Se/P=10). In addition, the sintering tests show that the Se-HA powders with the Se/P ratio of 0.1 have thermal stability at 900 °C for 2 h; hence they have great potential in the fabrication of bone repair scaffolds. Copyright © 2012 Elsevier B.V. All rights reserved.

Recent advances in synthesis, characterization of hydroxyapatite/polyurethane composites and study of their biocompatible properties.

PubMed

Popescu, L M; Piticescu, R M; Antonelli, A; Rusti, C F; Carboni, E; Sfara, C; Magnani, M; Badilita, V; Vasile, E; Trusca, R; Buruiana, T

2013-11-01

The development of engineered biomaterials that mimic bone tissues is a promising research area that benefits from a growing interest. Polymers and polymer-ceramic composites are the principle materials investigated for the development of synthetic bone scaffolds thanks to their proven biocompatibility and biostability. Several polymers have been combined with calcium phosphates (mainly hydroxyapatite) to prepare nanocomposites with improved biocompatible and mechanical properties. Here, we report the hydrothermal synthesis in high pressure conditions of nanostructured composites based on hydroxyapatite and polyurethane functionalized with carboxyl and thiol groups. Cell-material interactions were investigated for potential applications of these new types of composites as coating for orthopedic implants. Physical-chemical and morphological characteristics of hydroxyapatite/polyurethane composites were evaluated for different compositions, showing their dependence on synthesis parameters (pressure, temperature). In vitro experiments, performed to verify if these composites are biocompatible cell culture substrates, showed that they are not toxic and do not affect cell viability.

Advanced Microstructural Study of Suspension Plasma Sprayed Hydroxyapatite Coatings

NASA Astrophysics Data System (ADS)

Podlesak, Harry; Pawlowski, Lech; D'Haese, Romain; Laureyns, Jacky; Lampke, Thomas; Bellayer, Severine

2010-03-01

Fine, home-synthesized, hydroxyapatite powder was formulated with water and alcohol to obtain a suspension used to plasma spray coatings onto a titanium substrate. The deposition process was optimized using statistical design of 2 n experiments with two variables: spray distance and electric power input to plasma. X-ray diffraction (XRD) was used to determine quantitatively the phase composition of obtained deposits. Raman microscopy and electron probe microanalysis (EPMA) enabled localization of the phases in different positions of the coating cross sections. Transmission electron microscopic (TEM) study associated with energy-dispersive x-ray spectroscopy (EDS) enabled visualization and analysis of a two-zone microstructure. One zone contained crystals of hydroxyapatite, tetracalcium phosphate, and a phase rich in calcium oxide. This zone included lamellas, usually observed in thermally sprayed coatings. The other zone contained fine hydroxyapatite grains that correspond to nanometric and submicrometric solids from the suspension that were agglomerated and sintered in the cold regions of plasma jet and on the substrate.

Characterization of a silver-incorporated calcium phosphate film by RBS and its antimicrobial effects

NASA Astrophysics Data System (ADS)

Han, I.-H.; Lee, I.-S.; Song, J.-H.; Lee, M.-H.; Park, J.-C.; Lee, G.-H.; Sun, X.-D.; Chung, S.-M.

2007-09-01

A thin calcium phosphate film was synthesized on both commercially pure Ti and Si wafers by electron beam evaporation of hydroxyapatite as an evaporant with simultaneous Ar ion beam bombardments. Silver was introduced into an ion-beam-assisted deposition of a calcium phosphate thin film for antimicrobial effect. The amount of incorporated silver ions was controlled by immersing calcium-phosphate-coated samples in different AgNO3 concentrations, and Rutherford backscattering spectrometry (RBS) was employed to measure the amounts of substituted silver. The higher concentration of silver in the calcium phosphate film was more effective in reducing the bacteria of Escherichia coli ATCC 8739 and Streptococcus mutans OMZ 65 on contact with respect to controls.

Characterization of a silver-incorporated calcium phosphate film by RBS and its antimicrobial effects.

PubMed

Han, I-H; Lee, I-S; Song, J-H; Lee, M-H; Park, J-C; Lee, G-H; Sun, X-D; Chung, S-M

2007-09-01

A thin calcium phosphate film was synthesized on both commercially pure Ti and Si wafers by electron beam evaporation of hydroxyapatite as an evaporant with simultaneous Ar ion beam bombardments. Silver was introduced into an ion-beam-assisted deposition of a calcium phosphate thin film for antimicrobial effect. The amount of incorporated silver ions was controlled by immersing calcium-phosphate-coated samples in different AgNO(3) concentrations, and Rutherford backscattering spectrometry (RBS) was employed to measure the amounts of substituted silver. The higher concentration of silver in the calcium phosphate film was more effective in reducing the bacteria of Escherichia coli ATCC 8739 and Streptococcus mutans OMZ 65 on contact with respect to controls.

[May renal lithiasis be really prevented? New trends and therapeutic tools.

PubMed

Grases, Félix; Costa-Bauzá, Antonia; Prieto, Rafael M

2017-01-01

Renal calculi are generally formed as a result of the combination of certain factors, some related to urine composition (concentration of lithogenic substances, deficiency of crystallization inhibitors, presence of heterogeneous nucleants) and others with renal morphology and anatomy (urinary tract stasis, low urodynamic efficiency cavities, morpho-anatomic deformations, renal papillary tissue lesions). In fact, the composition, macrostructure and microstructure of the calculus will clearly depend on the factors that have induced it. For this reason, the appropriate study and classification of the renal calculi simplifies the diagnosis and allows a more effective therapeutic approach since it can be oriented to directly correct the etiological factors responsible for stone formation. In this article, we review the main etiological factors involved in the formation of each type of calculus and the prophylactic measures that can be adopted for proper correction. The most frequent kidney stones have been classified into the following types: calcium oxalate monohydrate papillary calculi, calcium oxalate monohydrate non-papillary calculi, calcium oxalate dihydrate calculi, mixed hydroxyapatite/ calcium oxalate calculi, carboxyapatite/hydroxyapatite calculi, brushite calculi, struvite/carboxyapatite calculi, uric acid calculi, uric acid/calcium oxalate monohydrate calculi, and cystine calculi. Occasionally, however, the calculus is not available for study, in which case the only way forward is to use all available information (clinical history, life habits, radiological data), together with basic biochemical information, to identify and correct all etiological factors related to renal lithiasis that have been identified.

Dentin abrasivity of various desensitizing toothpastes.

PubMed

Arnold, W H; Gröger, Ch; Bizhang, M; Naumova, E A

2016-04-02

The aim of this study was to compare the abrasivity of various commercially available toothpastes that claim to reduce dentin hypersensitivity. Dentin discs were prepared from 70 human extracted molars. The discs were etched with lemon juice for 5 min, and one half of the discs were covered with aluminum tape. Following this, they were brushed with 6 different toothpastes, simulating a total brushing time of 6 months. As a negative control, discs were brushed with tap water only. The toothpastes contained pro-arginine and calcium carbonate, strontium acetate, stannous fluoride, zinc carbonate and hydroxyapatite, new silica, or tetrapotassium pyrophosphate and hydroxyapatite. After brushing, the height differences between the control halves and the brushed halves were determined with a profilometer and statistically compared using a Mann-Whitney U test for independent variables. A significant difference (p < 0.001) in height difference between the controls and the toothpaste-treated samples was found in all cases, except for the stannous fluoride-containing toothpaste (p = 0.583). The highest abrasion was found in the toothpaste containing zinc carbonate and hydroxyapatite, and the lowest was found in the toothpaste containing pro-arginine and calcium carbonate. Desensitizing toothpastes with different desensitizing ingredients have different levels of abrasivity, which may have a negative effect on their desensitizing abilities over a long period of time.

Assessment of a Hydroxyapatite Permeable Reactive Barrier to Remediate Uranium at the Old Rifle Site Colorado.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, Robert C.; Szecsody, James; Rigali, Mark J.

We have performed an initial evaluation and testing program to assess the effectiveness of a hydroxyapatite (Ca10(PO4)6(OH)2) permeable reactive barrier and source area treatment to decrease uranium mobility at the Department of Energy (DOE) former Old Rifle uranium mill processing site in Rifle, western Colorado. Uranium ore was processed at the site from the 1940s to the 1970s. The mill facilities at the site as well as the uranium mill tailings previously stored there have all been removed. Groundwater in the alluvial aquifer beneath the site still contains elevated concentrations of uranium, and is currently used for field tests tomore » study uranium behavior in groundwater and investigate potential uranium remediation technologies. The technology investigated in this work is based on in situ formation of apatite in sediment to create a subsurface apatite PRB and also for source area treatment. The process is based on injecting a solution containing calcium citrate and sodium into the subsurface for constructing the PRB within the uranium plume. As the indigenous sediment micro-organisms biodegrade the injected citrate, the calcium is released and reacts with the phosphate to form hydroxyapatite (precipitate). This paper reports on proof-of-principle column tests with Old Rifle sediment and synthetic groundwater.« less

Controlled, sustained release of proteins via an injectable, mineral-coated microsphere delivery vehicle

NASA Astrophysics Data System (ADS)

Franklin-Ford, Travelle

Hydroxyapatite interfaces have demonstrated strong protein binding and protein selection from a passing solution and can serve as a biocompatible carrier for controlled protein delivery. Hydroxyapatite is a major component of long bones and tooth enamel and is the most stable of all calcium phosphate isoforms in aqueous solutions at physiologic pH, providing a sensitive chromatographic mechanism for separating proteins. Here we describe an approach to create a synthetic hydroxyapatite coating through a biomimetic, heterogeneous nucleation from a modified simulated body fluid--supersaturated with calcium and phosphate ions on the surface of injectable polymer microspheres. We are able to bind and release bioactive growth factors into a variety of in vitro and in vivo conditions, demonstrating the functionality and advantage of the biomaterial. Creating a hydroxyapatite layer on the Poly(D,L-lactide-co-glycolide) (PLG) microsphere surface, avails the microsphere interior for another application that will not compete with protein binding and release. Encapsulating an imaging agent within the aqueous phase of the emulsion provides a visual reference for the injectable therapy upon microsphere fabrication. Another advantage of this system is that the mineral coating and subsequent protein binding is not compromised by the encapsulated imaging agent. This dual function delivery vehicle is not only advantageous for spatial tracking therapeutic applications, but also determining the longevity of the delivery vehicle once injected. In the broader sense, providing a mechanism to image and track our temporally controlled, sustained delivery system gives more evidence to support the effects of released protein on in vivo responses (bioactivity) and locate microspheres within different biological systems.

In vivo response of bioactive PMMA-based bone cement modified with alkoxysilane and calcium acetate.

PubMed

Sugino, Atsushi; Ohtsuki, Chikara; Miyazaki, Toshiki

2008-11-01

The use of polymethylmethacrylate (PMMA)-based bone cement is popular in orthopedics for the fixation of artificial joints with bone. However, it has a major problem with prostheses loosening because of coverage by fibrous tissue after long-term implantation. Recently, a bioactive bone cement has been developed that shows direct bonding to living bone through modification of PMMA resin with gamma-methacryloxypropyltrimethoxysilane (MPS) and calcium acetate. The cement is designed to exhibit bioactivity, through incorporation of silanol groups and calcium ions. Thus, it has the potential to form a layer of bone-like hydroxyapatite, which is essential for achieving direct bonding to living bone. This type of modification allows the cement to show spontaneous hydroxyapatite formation on its surface in a simulated body fluid after one day, and there is evidence of osteoconduction of the cement in rabbit tibia for periods of more than three weeks. However, the influence of the dissolved ions from the modified cement has not yet been clarified. Thus, the authors focused on the dissolution of the modified PMMA-based bone cement and its tissue response in muscle and bone by comparison with the behavior of non-modified PMMA-based bone cement. One week after implantation in the latissimus dorsi of a rabbit, the modified PMMA-based bone cement showed more inflammatory width than the commercial cement. However, four weeks after implantation, the inflammatory width of both cements was essentially the same. The osteoconductivity around the modified cement was higher than that for the conventional cement after four weeks implantation. These results indicate that the initial dissolution of calcium acetate from the modified cement to form the hydroxyapatite induced the acute inflammation around tissue, but also developed the osteoconductivity. It is suggested that the initial inflammation can be effective for inducing osteoconduction through a bone healing reaction when the material provides an environment that promotes bone formation.

Cytotoxic evaluation of hydroxyapatite-filled and silica/hydroxyapatite-filled acrylate-based restorative composite resins: An in vitro study.

PubMed

Chadda, Harshita; Naveen, Sangeetha Vasudevaraj; Mohan, Saktiswaren; Satapathy, Bhabani K; Ray, Alok R; Kamarul, Tunku

2016-07-01

Although the physical and mechanical properties of hydroxyapatite-filled dental restorative composite resins have been examined, the biocompatibility of these materials has not been studied in detail. The purpose of this in vitro study was to analyze the toxicity of acrylate-based restorative composite resins filled with hydroxyapatite and a silica/hydroxyapatite combination. Five different restorative materials based on bisphenol A-glycidyl methacrylate (bis-GMA) and tri-ethylene glycol dimethacrylate (TEGDMA) were developed: unfilled (H0), hydroxyapatite-filled (H30, H50), and silica/hydroxyapatite-filled (SH30, SH50) composite resins. These were tested for in vitro cytotoxicity by using human bone marrow mesenchymal stromal cells. Surface morphology, elemental composition, and functional groups were determined by scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), and Fourier-transformed infrared spectroscopy (FTIR). The spectra normalization, baseline corrections, and peak integration were carried out by OPUS v4.0 software. Both in vitro cytotoxicity results and SEM analysis indicated that the composite resins developed were nontoxic and supported cell adherence. Elemental analysis with EDX revealed the presence of carbon, oxygen, calcium, silicon, and gold, while the presence of methacrylate, hydroxyl, and methylene functional groups was confirmed through FTIR analysis. The characterization and compatibility studies showed that these hydroxyapatite-filled and silica/hydroxyapatite-filled bis-GMA/TEGDMA-based restorative composite resins are nontoxic to human bone marrow mesenchymal stromal cells and show a favorable biologic response, making them potential biomaterials. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Prostaglandin PGE2: a possible mechanism for bone destruction in calcinosis circumscripta.

PubMed

Caniggia, A; Gennari, C; Vattimo, A; Runci, F; Bombardieri, S

1978-02-28

A patient showed evident osteolysis in phalanges and heavy periarticular calcium deposits of the fingers, wrists and toes which avidly took up 47Ca. The dense, white, tooth-paste like fluid contained in the periarticular calcium deposits has been studied by two different X-ray diffraction methods, by Ubatuba's bioassay for prostaglandin, by thin layer chromatography and by mass spectrometry. The calcium deposits were hydroxyapatite and prostaglandin PGE2 was detected in them. The bone resorption stimulating activity of PGE2 would be expected to result in increased bone destruction with release of calcium salts and this could be a working hypothesis of the pathogenesis of calcinosis circumscripta.

Influence of polarized PZT on the crystal growth of calcium phosphate

NASA Astrophysics Data System (ADS)

Sun, Xiaodan; Ma, Chunlai; Wang, Yude; Li, Hengde

2002-01-01

The effects of polarization on the crystallization of calcium phosphate are studied in this work. Crystals of calcium phosphate from saturated solution of hydroxyapatite (HA, Ca 10(PO 4) 6(OH) 2) were deposited on the surfaces of ferroelectric ceramics lead zirconate titanium (Pb(Ti,Zr)O 3, PZT). The results of the experiment demonstrated the acceleration effects of polarized PZT on the crystal growth of calcium phosphate. Furthermore, it is indicated that polarization also influenced the orientation of the deposited crystals due to the growth of a layer of (0 0 2) oriented octacalcium phosphate (OCP, Ca 8H 2(PO 4) 6·5H 2O) on the negatively charged surfaces of PZT.

Development and Characterization of Biphasic Hydroxyapatite/β-TCP Cements

PubMed Central

Gallinetti, Sara; Canal, Cristina; Ginebra, Maria-Pau; Ferreira, J

2014-01-01

Biphasic calcium phosphate bioceramics composed of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) have relevant properties as synthetic bone grafts, such as tunable resorption, bioactivity, and intrinsic osteoinduction. However, they have some limitations associated to their condition of high-temperature ceramics. In this work self-setting Biphasic Calcium Phosphate Cements (BCPCs) with different HA/β-TCP ratios were obtained from self-setting α-TCP/β-TCP pastes. The strategy used allowed synthesizing BCPCs with modulated composition, compressive strength, and specific surface area. Due to its higher solubility, α-TCP was fully hydrolyzed to a calcium-deficient HA (CDHA), whereas β-TCP remained unreacted and completely embedded in the CDHA matrix. Increasing amounts of the non-reacting β-TCP phase resulted in a linear decrease of the compressive strength, in association to the decreasing amount of precipitated HA crystals, which are responsible for the mechanical consolidation of apatitic cements. Ca2+ release and degradation in acidic medium was similar in all the BCPCs within the timeframe studied, although differences might be expected in longer term studies once β-TCP, the more soluble phase was exposed to the surrounding media. PMID:25866411

Influence of the modulated two-step synthesis of biogenic hydroxyapatite on biomimetic products' surface

NASA Astrophysics Data System (ADS)

Miculescu, Florin; Mocanu, Aura Cătălina; Stan, George E.; Miculescu, Marian; Maidaniuc, Andreea; Cîmpean, Anisoara; Mitran, Valentina; Voicu, Stefan Ioan; Machedon-Pisu, Teodor; Ciocan, Lucian Toma

2018-04-01

Processing calcium-rich natural resources, such as marble and mussel seashells, into biomimetic products could constitute an environmentally-friendly and economically sustainable alternative given their geographical widespread. Hitherto, their value for biomedicine was demonstrated only for seashells, with the technological exploitation approaches still facing challenges with respect to the identification of generic synthesis parameters capable to allow the reproducible and designed synthesis of calcium phosphate at an industrial-ready level. In this study was targeted the optimization of Rathje synthesis method for the fabrication of biogenic calcium phosphates, by conveniently adjusting the chemical composition of employed reagents. It was shown that post-synthesis heat-treatment of compacted powders is the key step for inducing structural transformations suitable to attain biomimetic products for reconstructive orthopedic applications. The sintered materials have been multi-parametricallyevaluated from morpho-compositional, structural, wettability, mechanical and cytocompatibility points of view and the results have been cross-examined and discussed. Convenient and efficient preparation routes to produce biogenic hydroxyapatite have been identified. The functional performances of the as-prepared biogenic ceramics endorse their use as a solid and inexpensive alternative source material for the fabrication of various bone regenerative products and implant coatings.

Impact of annealing on features of BCP coating on NiTi shape memory alloy: Preparation and physicochemical characterization

NASA Astrophysics Data System (ADS)

Dulski, Mateusz; Dudek, Karolina; Grelowski, Michał; Kubacki, Jerzy; Hertlein, Justyna; Wojtyniak, Marcin; Goryczka, Tomasz

2018-04-01

A multifunctional composite structure consisting of resorbable tricalcium phosphate with non-resorbable hydroxyapatite and NiTi shape memory alloy (SMA) has been manufactured to develop a biocompatible system for long-term implant applications. The hybrid system has been vacuum sintered to consolidate and form chemical binding between phosphate biomaterials and NiTi SMA. In this context, the impact of sintering on biomaterial's features in relation to initial material has been analyzed using a combination of structural and surface sensitive approaches. Moreover, a partial decomposition of the NiTi parent phase to the equilibrium Ti2Ni with cubic structure, and non-equilibrium Ti3Ni4 with hexagonal structure has been detected. Moreover, a sintering has provided a reconstruction of the orthophosphate surface through the disintegration of calcium phosphate material and increase of hydroxyapatite with smaller particles in volume. The biomaterial surface has become more enriched in calcium in relation to the initial composition, with a simultaneous decline of the roughness parameters due to the gradual consolidation of orthophosphates. Finally, surface modification accompanied with heat treatment has led to an increase of surface Young's modulus as an effect of partial recrystallization of calcium phosphates.

MAO-derived hydroxyapatite/TiO2 nanostructured multi-layer coatings on titanium substrate

NASA Astrophysics Data System (ADS)

Abbasi, S.; Golestani-Fard, F.; Rezaie, H. R.; Mirhosseini, S. M. M.

2012-11-01

In this study, titanium substrates which previously oxidized through Micro arc oxidation method, was coated by Hydroxyapatite (HAp) coating once more by means of the same method. Morphology, topography and chemical properties as well as phase composition and thickness of layers were studied to reveal the effect of the electrolyte concentration on coating features. According to results, the obtained coatings are consisted of HAp and titania as the major phases along with minor amounts of calcium titanate and α-tri calcium phosphate. Ca and P are present on surface of obtained layers as well as predictable Ti and O based on the XPS results. Thickness profile of coatings figured out that by increasing the electrolyte concentration, especially by addition of more Calcium Acetate (CA) to electrolyte, the thickness of HAp layer would rise, consequently. However, the influence of coating time on thickness of obtained coatings would be more considerable than electrolyte concentration. High specific area coatings with nest morphology were obtained in Electrolyte containing 5 g/L β-Glycero Phosphate (β-GP) and 5 g/L CA. Increasing coating duration time in this kind of coatings would cause deduction of the nesting in their structure.

Composition of chitosan-hydroxyapatite-collagen composite scaffold evaluation after simulated body fluid immersion as reconstruction material

NASA Astrophysics Data System (ADS)

Verisqa, F.; Triaminingsih, S.; Corputty, J. E. M.

2017-08-01

Hydroxyapatite (HA) formation is one of the most important aspects of bone regeneration. Because domestically made chitosan-hydroxyapatite-collagen composite scaffolding from crab shell and bovine bone and tendon has potential as a maxillofacial reconstruction material, the material’s HA-forming ability requires evaluation. The aim of this research is to investigate chitosan-hydroxyapatite-collagen composite scaffold’s potential as a maxillofacial reconstruction material by observing the scaffold’s compositional changes. Scaffold specimens were immersed in 37°C simulated body fluid (SBF) for periods of 2, 4, 6, and 8 days. Scaffold composition was then evaluated by using energy dispersive spectroscopy (EDS). The calcium (Ca) and phosphorus (P) percentages of the scaffold were found to increase following SBF immersion. The high Ca/P ratio (3.82) on the scaffold indicated HA formation. Ion exchange played a significant role in the increased percentages of Ca and P, which led to new HA layer formation. The scaffold’s HA acted as a nucleation site of Ca and P from the SBF, with collagen and chitosan as the scaffold’s matrix. Chitosan-hydroxyapatite-collagen composite scaffold shows potential as a maxillofacial reconstruction material, since its composition favors HA formation.

Synthesis and characterization of hydroxyapatite nanoparticles by chemical precipitation method for potential application in water treatment

NASA Astrophysics Data System (ADS)

Joshi, Parth; Patel, Chirag; Vyas, Meet

2018-05-01

Hydroxyapatite (HA) is a unique material having high adsorption capacity of heavy metals, high ion exchange capacity, high biological compatibility, low water solubility, high stability under reducing and oxidizing conditions, availability and low cost. As the starting reagents, analytical grade Ca(NO3)2.4H2O, (NH4)2HPO4 and NaOH were used. In order to study the factors that have an important influence on the chemical precipitation process a experimental platform has been designed for hydroxyapatite synthesis. The addition of Phosphorus pentaoxide to Calcium hydroxide was carried out slowly with simultaneous stirring. After addition, solution was aged for maturation. The precipitate was dried at 80°C overnight and further heat treated at 600°C for 2 hours. The dried and calcined particles were characterized by Fourier transform infra-red spectroscopy and Thermo gravimetric analysis. The particle size and morphology were studied using transmission electron microscopy. TEM examination of the treated powders displayed particles of polygon morphology with dimensions 30-70 nm in length. The FT-IR spectra for sample confirmed the formation of hydroxyapatite. Purity of the prepared Hydroxyapatite has been confirmed by XRD analysis.

Biomorphous porous hydroxyapatite-ceramics from rattan (Calamus Rotang).

PubMed

Eichenseer, Christiane; Will, Julia; Rampf, Markus; Wend, Süsen; Greil, Peter

2010-01-01

The three-dimensional, highly oriented pore channel anatomy of native rattan (Calamus rotang) was used as a template to fabricate biomorphous hydroxyapatite (Ca(5)(PO(4))(3)OH) ceramics designed for bone regeneration scaffolds. A low viscous hydroxyapatite-sol was prepared from triethyl phosphite and calcium nitrate tetrahydrate and repeatedly vacuum infiltrated into the native template. The template was subsequently pyrolysed at 800 degrees C to form a biocarbon replica of the native tissue. Heat treatment at 1,300 degrees C in air atmosphere caused oxidation of the carbon skeleton and sintering of the hydroxyapatite. SEM analysis confirmed detailed replication of rattan anatomy. Porosity of the samples measured by mercury porosimetry showed a multimodal pore size distribution in the range of 300 nm to 300 microm. Phase composition was determined by XRD and FT-IR revealing hydroxyapatite as the dominant phase with minimum fractions of CaO and Ca(3)(PO(4))(2). The biomorphous scaffolds with a total porosity of 70-80% obtained a compressive strength of 3-5 MPa in axial direction and 1-2 MPa in radial direction of the pore channel orientation. Bending strength was determined in a coaxial double ring test resulting in a maximum bending strength of approximately 2 MPa.

Topography, wetting, and corrosion responses of electrodeposited hydroxyapatite and fluoridated hydroxyapatite on magnesium.

PubMed

Assadian, Mahtab; Jafari, Hassan; Ghaffari Shahri, Seyed Morteza; Idris, Mohd Hasbullah; Almasi, Davood

2016-08-12

In this study, different types of calcium-phosphate phases were coated on NaOH pre-treated pure magnesium. The coating was applied by electrodeposition method in order to provide higher corrosion resistance and improve biocompatibility for magnesium. Thickness, surface morphology and topography of the coatings were analyzed using optical, scanning electron and atomic-force microscopies, respectively. Composition and chemical bonding, crystalline structures and wettability of the coatings were characterized using energy-dispersive and attenuated total reflectance-Fourier transform infrared spectroscopies, grazing incidence X-ray diffraction and contact angle measurement, respectively. Degradation behavior of the coated specimens was also investigated by potentiodynamic polarization and immersion tests. The experiments proved the presence of a porous coating dominated by dicalcium-phosphate dehydrate on the specimens. It was also verified that the developed hydroxyapatite was crystallized by alkali post-treatment. Addition of supplemental fluoride to the coating electrolyte resulted in stable and highly crystallized structures of fluoridated hydroxyapatite. The coatings were found effective to improve biocompatibility combined with corrosion resistance of the specimens. Noticeably, the fluoride supplemented layer was efficient in lowering corrosion rate and increasing surface roughness of the specimens compared to hydroxyapatite and dicalcium-phosphate dehydrates layers.

Application of electron probe X-ray microanalysis to calcification studies of bone and cartilage.

PubMed

Landis, W J

1979-01-01

The use of electron probe x-ray microanalysis in previous studies of bone and cartilage has been reviewed with emphasis on the results which have contributed to some of the current concepts of the mechanism of mineralization in these tissues. A number of investigations continuing in the author's laboratory utilizing high spatial resolution x-ray microanalysis and anhydrous methods of specimen preparation are described, including aspects concerning the derivation of calibration curves from synthetic calcium phosphate solids, qualitative and quantitative analyses of calcium and phosphorus in bone from embryonic chicks and in growth plate cartilage from rats, and the role of organically-bound phosphorus in mineralizing tissues. The data obtained have helped identify brushite, CaHPO4-2H2O, as the major crystalline solid phase of calcium phosphate in the earliest mineral deposits of bone tissue, brushite and poorly crystalline hydroxyapatite in bone mineral of increasing age, and poorly crystalline hydroxyapatite in the most mature mineral portions of the tissue. Growth plate cartilage examination has revealed calcium and phosphorus in single mitochondrial granules within chondrocytes and in certain extracellular particles distinct from matrix vesicles. These results have provided important information about the possible roles of cells, extracellular components, and the organic matrix in the regulation of mineralization and about the composition, structure, and organization of the mineral phase as a function of progressively increasing age and maturation of the tissues studied.

Quantification In Situ of Crystalline Cholesterol and Calcium Phosphate Hydroxyapatite in Human Atherosclerotic Plaques by Solid-State Magic Angle Spinning NMR

PubMed Central

Guo, Wen; Morrisett, Joel D.; DeBakey, Michael E.; Lawrie, Gerald M.; Hamilton, James A.

2010-01-01

Because of renewed interest in the progression, stabilization, and regression of atherosclerotic plaques, it has become important to develop methods for characterizing structural features of plaques in situ and noninvasively. We present a nondestructive method for ex vivo quantification of 2 solid-phase components of plaques: crystalline cholesterol and calcium phosphate salts. Magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra of human carotid endarterectomy plaques revealed 13C resonances of crystalline cholesterol monohydrate and a 31P resonance of calcium phosphate hydroxyapatite (CPH). The spectra were obtained under conditions in which there was little or no interference from other chemical components and were suitable for quantification in situ of the crystalline cholesterol and CPH. Carotid atherosclerotic plaques showed a wide variation in their crystalline cholesterol content. The calculated molar ratio of liquid-crystalline cholesterol to phospholipid ranged from 1.1 to 1.7, demonstrating different capabilities of the phospholipids to reduce crystallization of cholesterol. The spectral properties of the phosphate groups in CPH in carotid plaques were identical to those of CPH in bone. 31P MAS NMR is a simple, rapid method for quantification of calcium phosphate salts in tissue without extraction and time-consuming chemical analysis. Crystalline phases in intact atherosclerotic plaques (ex vivo) can be quantified accurately by solid-state 13C and 31PMAS NMR spectroscopy. PMID:10845882

In Vitro Evaluation of Nanoscale Hydroxyapatite-Based Bone Reconstructive Materials with Antimicrobial Properties.

PubMed

Ajduković, Zorica R; Mihajilov-Krstev, Tatjana M; Ignjatović, Nenad L; Stojanović, Zoran; Mladenović-Antić, Snezana B; Kocić, Branislava D; Najman, Stevo; Petrović, Nenad D; Uskoković, Dragan P

2016-02-01

In the field of oral implantology the loss of bone tissue prevents adequate patient care, and calls for the use of synthetic biomaterials with properties that resemble natural bone. Special attention is paid to the risk of infection after the implantation of these materials. Studies have suggested that some nanocontructs containing metal ions have antimicrobial properties. The aim of this study was to examine the antimicrobial and hemolytic activity of cobalt-substituted hydroxyapatite nanoparticles, compared to hydroxyapatite and hydroxyapatite/poly-lactide-co-glycolide. The antibacterial effects of these powders were tested against two pathogenic bacterial strains: Escherichia coi (ATCC 25922) and Staphylococcus aureus (ATCC 25923), using the disc diffusion method and the quantitative antimicrobial test in a liquid medium. The quantitative antimicrobial test showed that all of the tested biomaterials have some antibacterial properties. The effects of both tests were more prominent in case of S. aureus than in E coli. A higher percentage of cobalt in the crystal structure of cobalt-substituted hydroxyapatite nanoparticles led to an increased antimicrobial activity. All of the presented biomaterial samples were found to be non-hemolytic. Having in mind that the tested of cobalt-substituted hydroxyapatite (Ca/Co-HAp) material in given concentrations shows good hemocompatibility and antimicrobial effects, along with its previously studied biological properties, the conclusion can be reached that it is a potential candidate that could substitute calcium hydroxyapatite as the material of choice for use in bone tissue engineering and clinical practices in orthopedic, oral and maxillofacial surgery.

Detection of hydroxyapatite in calcified cardiovascular tissues.

PubMed

Lee, Jae Sam; Morrisett, Joel D; Tung, Ching-Hsuan

2012-10-01

The objective of this study is to develop a method for selective detection of the calcific (hydroxyapatite) component in human aortic smooth muscle cells in vitro and in calcified cardiovascular tissues ex vivo. This method uses a novel optical molecular imaging contrast dye, Cy-HABP-19, to target calcified cells and tissues. A peptide that mimics the binding affinity of osteocalcin was used to label hydroxyapatite in vitro and ex vivo. Morphological changes in vascular smooth muscle cells were evaluated at an early stage of the mineralization process induced by extrinsic stimuli, osteogenic factors and a magnetic suspension cell culture. Hydroxyapatite components were detected in monolayers of these cells in the presence of osteogenic factors and a magnetic suspension environment. Atherosclerotic plaque contains multiple components including lipidic, fibrotic, thrombotic, and calcific materials. Using optical imaging and the Cy-HABP-19 molecular imaging probe, we demonstrated that hydroxyapatite components could be selectively distinguished from various calcium salts in human aortic smooth muscle cells in vitro and in calcified cardiovascular tissues, carotid endarterectomy samples and aortic valves, ex vivo. Hydroxyapatite deposits in cardiovascular tissues were selectively detected in the early stage of the calcification process using our Cy-HABP-19 probe. This new probe makes it possible to study the earliest events associated with vascular hydroxyapatite deposition at the cellular and molecular levels. This target-selective molecular imaging probe approach holds high potential for revealing early pathophysiological changes, leading to progression, regression, or stabilization of cardiovascular diseases. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Detection of Hydroxyapatite in Calcified Cardiovascular Tissues

PubMed Central

Lee, Jae Sam; Morrisett, Joel D.; Tung, Ching-Hsuan

2012-01-01

Objective The objective of this study is to develop a method for selective detection of the calcific (hydroxyapatite) component in human aortic smooth muscle cells in vitro and in calcified cardiovascular tissues ex vivo. This method uses a novel optical molecular imaging contrast dye, Cy-HABP-19, to target calcified cells and tissues. Methods A peptide that mimics the binding affinity of osteocalcin was used to label hydroxyapatite in vitro and ex vivo. Morphological changes in vascular smooth muscle cells were evaluated at an early stage of the mineralization process induced by extrinsic stimuli, osteogenic factors and a magnetic suspension cell culture. Hydroxyapatite components were detected in monolayers of these cells in the presence of osteogenic factors and a magnetic suspension environment. Results Atherosclerotic plaque contains multiple components including lipidic, fibrotic, thrombotic, and calcific materials. Using optical imaging and the Cy-HABP-19 molecular imaging probe, we demonstrated that hydroxyapatite components could be selectively distinguished from various calcium salts in human aortic smooth muscle cells in vitro and in calcified cardiovascular tissues, carotid endarterectomy samples and aortic valves, ex vivo. Conclusion Hydroxyapatite deposits in cardiovascular tissues were selectively detected in the early stage of the calcification process using our Cy-HABP-19 probe. This new probe makes it possible to study the earliest events associated with vascular hydroxyapatite deposition at the cellular and molecular levels. This target-selective molecular imaging probe approach holds high potential for revealing early pathophysiological changes, leading to progression, regression, or stabilization of cardiovascular diseases. PMID:22877867

Electrophoretic Deposition of Hydroxyapatite Film Containing Re-Doped MoS₂ Nanoparticles.

PubMed

Shalom, Hila; Feldman, Yishay; Rosentsveig, Rita; Pinkas, Iddo; Kaplan-Ashiri, Ifat; Moshkovich, Alexey; Perfilyev, Vladislav; Rapoport, Lev; Tenne, Reshef

2018-02-26

Films combining hydroxyapatite (HA) with minute amounts (ca. 1 weight %) of (rhenium doped) fullerene-like MoS₂ (IF) nanoparticles were deposited onto porous titanium substrate through electrophoretic process (EPD). The films were analyzed by scanning electron microscopy (SEM), X-ray diffraction and Raman spectroscopy. The SEM analysis showed relatively uniform coatings of the HA + IF on the titanium substrate. Chemical composition analysis using energy dispersive X-ray spectroscopy (EDS) of the coatings revealed the presence of calcium phosphate minerals like hydroxyapatite, as a majority phase. Tribological tests were undertaken showing that the IF nanoparticles endow the HA film very low friction and wear characteristics. Such films could be of interest for various medical technologies. Means for improving the adhesion of the film to the underlying substrate and its fracture toughness, without compromising its biocompatibility are discussed at the end.

Multi-Functions of Carbonated Calcium Deficient Hydroxyapatite (CDHA)

NASA Astrophysics Data System (ADS)

Zhou, Huan

Natural bone is a complex composite mainly constituted of inorganic minerals and organic collagen molecules. Calcium phosphate (CaP) based materials have been proposed as the predominant bone substitute for bone tissue engineering applications due to their chemical similarity to bone mineral. Amorphous carbonated calcium deficient hydroxyapatite (CDHA) is an important compound among CaP materials because of the amorphous crystallite structure. The presence of extra ions in its lattice structure not only influences cell attachment and proliferation of osteoblasts, but also helps in bone metabolism. Biomimetic coating approach is the most widely used approach to produce CDHA coatings to implant. It is a process using simulated body fluid (SBF) to deposit bone-like CDHA coating to various material surfaces. The CDHA formation mechanism, SBF compositions and reacting conditions of biomimetic coating have already been sufficiently studied and compared in the past 20 years. It is an attempt in this thesis to explore new applications of SBF in biomedical research, focusing on different biomaterial applications: 1) based on the low temperature reaction condition of SBF, bisphosphonate incorporated CDHA coatings were deposited onto Ti6Al4V surface for the treatment of osteoporosis; 2) amorphous calcium phosphate nanospheres with extra elements in the lattice structure were prepared by a novel microwave assisted approach, providing a new potential of CaP materials production; 3) CDHA particles formed in SBF can be used as great fillers with biopolymers for preparing biocomposites for biomedical applications; 4) based on the high activity of CDHA amorphous structure and the stabilization ability of ethanol, yttrium and europium doped calcium phosphates were prepared using CDHA as a sacrificing template. In the end, future work based on these observations in the thesis is addressed, including areas of drug delivery, biocomposite fabrication and preparation of functionalized calcium phosphate materials.

Reaction of sodium calcium borate glasses to form hydroxyapatite.

PubMed

Han, Xue; Day, Delbert E

2007-09-01

This study investigated the transformation of two sodium calcium borate glasses to hydroxyapatite (HA). The chemical reaction was between either 1CaO . 2Na(2)O . 6B(2)O(3) or 2CaO . 2Na(2)O . 6B(2)O(3) glass and a 0.25 M phosphate (K(2)HPO(4)) solution at 37, 75 and 200 degrees C. Glass samples in the form of irregular particles (125-180 microm) and microspheres (45-90 and 125-180 microm) were used in order to understand the reaction mechanism. The effect of glass composition (calcium content) on the weight loss rate and reaction temperature on crystal size, crystallinity and grain shape of the reaction products were studied. Carbonated HA was made by dissolving an appropriate amount of carbonate (K(2)CO(3)) in the 0.25 M phosphate solution. X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy were used to characterize the reaction products. The results show that sodium calcium borate glasses can be transformed to HA by reacting with a phosphate solution. It is essentially a process of dissolution of glass and precipitation of HA. The transformation begins from an amorphous state to calcium-deficient HA without changing the size and shape of the original glass sample. Glass with a lower calcium content (1CaO . 2Na(2)O . 6B(2)O(3)), or reacted at an elevated temperature (75 degrees C), has a higher reaction rate. The HA crystal size increases and grain shape changes from spheroidal to cylindrical as temperature increases from 37 to 200 degrees C. Increase in carbonate concentration can also decrease the crystal size and yield a more needle-like grain shape.

Kidney stones during pregnancy: an investigation into stone composition.

PubMed

Ross, Ashley E; Handa, Shelly; Lingeman, James E; Matlaga, Brian R

2008-05-01

Kidney stones can be a source of considerable morbidity for pregnant women. Although there is a body of literature confirming that different stone compositions predominate for different age and sex cohorts, there have been no similar reports characterizing the nature of stone disease during pregnancy. We performed a multi-institutional study to define the composition of renal calculi diagnosed during pregnancy. We retrospectively reviewed the records from two stone referral centers of all patients diagnosed with a de novo kidney stone during pregnancy who underwent a procedure for the purpose of stone removal from June 2001 through September 2007. A total of 27 patients were identified, with a mean age of 26.8 years (range, 21-34). Twenty patients (74%) had no history of prior stone formation. Seven patients (26%) had previously formed stones, although none of these patients had a known kidney stone at the time they became pregnant. Stones were removed in the first, second, third trimester and immediately post-partum in 4, 52, 22, and 22% respectively. Stone removal was performed without complication in all cases. Analysis found that in 74% of all cases (20 patients) stones were composed predominantly of calcium phosphate (hydroxyapatite). In 26% of cases, (7 patients) the stones were composed predominantly of calcium oxalate. Of the seven patients with prior stone history, three patients had previously formed calcium phosphate stones and four patients had previously formed calcium oxalate stones. Calcium oxalate calculi are the most common stone in non-pregnant women of a comparable age as our subjects. However, our present data suggest that stones detected during pregnancy are most commonly composed of calcium phosphate (hydroxyapatite). Indeed, it is the minority of stones that are composed of calcium oxalate. Although the reason for this unusual preponderance of calcium phosphate calculi is unclear, physiologic alterations that occur during pregnancy may be influential.

Synthesis and characterization of amino acid-functionalized calcium phosphate nanoparticles for siRNA delivery.

PubMed

Bakan, Feray; Kara, Goknur; Cokol Cakmak, Melike; Cokol, Murat; Denkbas, Emir Baki

2017-10-01

Small interfering RNAs (siRNA) are short nucleic acid fragments of about 20-27 nucleotides, which can inhibit the expression of specific genes. siRNA based RNAi technology has emerged as a promising method for the treatment of a variety of diseases. However, a major limitation in the therapeutic use of siRNA is its rapid degradation in plasma and cellular cytoplasm, resulting in short half-life. In addition, as siRNA molecules cannot penetrate into the cell efficiently, it is required to use a carrier system for its delivery. In this work, chemically and morphologically different calcium phosphate (CaP) nanoparticles, including spherical-like hydroxyapatite (HA-s), needle-like hydroxyapatite (HA-n) and calcium deficient hydroxyapatite (CDHA) nanoparticles were synthesized by the sol-gel technique and the effects of particle characteristics on the binding capacity of siRNA were investigated. In order to enhance the gene loading efficiency, the nanoparticles were functionalized with arginine and the morphological and their structural characteristics were analyzed. The addition of arginine did not significantly change the particle sizes; however, it provided a significantly increased binding of siRNA for all types of CaP nanoparticles, as revealed by spectrophotometric measurements analysis. Arginine functionalized HA-n nanoparticles showed the best binding behavior with siRNA among the other nanoparticles due to its high, positive zeta potential (+18.8mV) and high surface area of Ca ++ rich "c" plane. MTT cytotoxicity assays demonstrated that all the nanoparticles tested herein were biocompatible. Our results suggest that high siRNA entrapment in each of the three modified non-toxic CaP nanoparticles make them promising candidates as a non-viral vector for delivering therapeutic siRNA molecules to treat cancer. Copyright © 2017 Elsevier B.V. All rights reserved.

Luminescence variations in hydroxyapatites doped with Eu2+ and Eu3+ ions.

PubMed

Graeve, Olivia A; Kanakala, Raghunath; Madadi, Abhiram; Williams, Brandon C; Glass, Katelyn C

2010-05-01

We present a detailed analysis of the luminescence behavior of europium-doped hydroxyapatite (HAp) and calcium-deficient hydroxyapatite (Ca-D HAp) nanopowders. The results show that, while both powders are similar in crystallite size, particle size, and morphology, the luminescence behavior differs significantly. For the HAp:Eu powders, the emission is clearly from Eu(3+) ions and corresponds to typical (5)D(0) --> (7)F(J) emissions, whereas for the Ca-D HAp:Eu powders, we also see a broad emission with two peaks at 420 and 445 nm, corresponding to the 4f(6)5d(1) --> 4f(7) ((8)S(7/2)) transition of Eu(2+). The powders are weakly luminescent in the as-synthesized state, as expected for combustion-synthesized materials and have higher emission intensities as the heat treatment temperature is increased. Luminescence spectra obtained using an excitation wavelength of 254 nm are weak for all samples. Excitation wavelengths of 305, 337, and 359 nm, are better at promoting the Eu(3+) and Eu(2+) emissions in hydroxyapatites. We propose that fluorescence measurements are an excellent way of qualitatively determining the phase composition of europium-doped hydroxyapatite powders, since powders that exhibit a blue emission contain substantial amounts of Ca-D HAp, allowing the determination of the presence of this phase in mixed-phase hydroxyapatites. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Lanthanum-silicon-substituted hydroxyapatite: Mechanochemical synthesis and prospects for medical applications

NASA Astrophysics Data System (ADS)

Chaikina, M. V.; Komarova, E. G.; Sharkeev, Yu. P.; Bulina, N. V.; Prosanov, I. Yu.

2016-08-01

The paper presents the results of mechanochemical synthesis of hydroxyapatite (HAP) with simultaneous substitutions of lanthanum (La3+) for calcium ions and silicate ((SiO4)4--group) for the phosphate group with the substituent concentrations in the range 0.2-2.0 mol per HAP mol. The use of Si-substituted HAP as a coating material promotes accelerated osteosynthesis and osteointegration of implants into the bone tissue. The replacement of calcium ions by La3+ in the HAP structure plays an antimicrobial role preventing inflammatory processes. Annealing-induced variations in the lattice parameters of synthesized samples indicate the substituent incorporation into the HAP structure. It is known that complex compounds with lanthanides are used for cancer chemotherapy. In particular, La plays a key role in the course of treatment of injured defects of bone tissue. In addition, La-substituted HAP can be used for filling bone defects and coating implants in postoperational areas affected by bone cancer.

[Apatite-forming ability of pure titanium implant after micro-arc oxidation treatment].

PubMed

Tian, Zhihui; Zhang, Yu; Wang, Lichao; Nan, Kaihui

2013-10-01

To investigate the apatite forming ability of pure titanium implant after micro-arc oxidation treatment in simulated body fluid (SBF) and obtain implants with calcium phosphate (Ca-P) layers. The implants were immersed in (SBF) after micro-arc oxidation treatment for different time lengths, and their apatite forming ability and the morphology and constituents of the Ca-P layers formed on the sample surface were analyzed using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and energy dispersive electron probe. After immersion in SBF, large quantities of Ca-P layers were induced on the surface of the samples. The Ca-P layers were composed of octacalcium phosphate and carbonated hydroxyapatite, and the crystals showed a plate-like morphology with an oriented growth. The implants with micro-arc oxidation treatment show good apatite forming ability on the surface with rich calcium and phosphorus elements. The formed layers are composed of bone-like apatite including octacalcium phosphate and carbonated hydroxyapatite.

Development of dental composites with reactive fillers that promote precipitation of antibacterial-hydroxyapatite layers.

PubMed

Aljabo, Anas; Abou Neel, Ensanya A; Knowles, Jonathan C; Young, Anne M

2016-03-01

The study aim was to develop light-curable, high strength dental composites that would release calcium phosphate and chlorhexidine (CHX) but additionally promote surface hydroxyapatite/CHX co-precipitation in simulated body fluid (SBF). 80 wt.% urethane dimethacrylate based liquid was mixed with glass fillers containing 10 wt.% CHX and 0, 10, 20 or 40 wt.% reactive mono- and tricalcium phosphate (CaP). Surface hydroxyapatite layer thickness/coverage from SEM images, Ca/Si ratio from EDX and hydroxyapatite Raman peak intensities were all proportional to both time in SBF and CaP wt.% in the filler. Hydroxyapatite was, however, difficult to detect by XRD until 4 weeks. XRD peak width and SEM images suggested this was due to the very small size (~10 nm) of the hydroxyapatite crystallites. Precipitate mass at 12 weeks was 22 wt.% of the sample CaP total mass irrespective of CaP wt.% and up to 7 wt.% of the specimen. Early diffusion controlled CHX release, assessed by UV spectrometry, was proportional to CaP and twice as fast in water compared with SBF. After 1 week, CHX continued to diffuse into water but in SBF, became entrapped within the precipitating hydroxyapatite layer. At 12 weeks CHX formed 5 to 15% of the HA layer with 10 to 40 wt.% CaP respectively. Despite linear decline of strength and modulus in 4 weeks from 160 to 101 MPa and 4 to 2.4 GPa, respectively, upon raising CaP content, all values were still within the range expected for commercial composites. The high strength, hydroxyapatite precipitation and surface antibacterial accumulation should reduce tooth restoration failure due to fracture, aid demineralised dentine repair and prevent subsurface carious disease respectively. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

In vitro study of electrodeposited fluoridated hydroxyapatite coating on G-II titanium with a nanostructured TiO2 interlayer.

PubMed

Lin, Jin-Shyong; Tsai, Tzung-Bau; Say, Wen-Ching; Chiu, Chun; Chen, Shih-Hsun

2017-04-04

Titanium and its alloys have been widely used as orthopedic and dental implants for several decades due to their superior mechanical properties, corrosion resistance and biocompatibility. Recently, many researches revealed that the hydroxyapatite coatings on biomedical materials can further improve their biocompatibility and bioactivity. However, hydroxyapatite coatings are easily decomposed, weakening the bonding between implants and bone tissues and resulting in a high dissolution rate in the biological environment. Prolonging the lifetime of hydroxyapatite in implants is valuable for improving postoperative quality. Hydroxyapatite is the primary inorganic component of bones and teeth. A suitable amount of fluoride ions would be beneficial for the formation of fluoridated hydroxyapatite, which can enhance bone-cell response and the acid resistance of enamel. In this study, G-II titanium substrate was anodized to form a TiO 2 interlayer with a nanotube structure. An electrolyte composed of fluoride, calcium and phosphorus ions was prepared for electroplating fluoridated hydroxyapatite (FHA) coatings onto anodized G-II titanium substrates at a constant voltage. The obtained coatings were examined for their microstructure, mechanical properties; moreover, the changes of apatite structure, surface morphology and corrosion resistance were further investigated after immersion in simulated body fluid (SBF) for a number of weeks. The results show that FHA coatings have a higher surface roughness and hardness than plain hydroxyapatite. After immersion in SBF, the FHA coatings induced the nucleation and growth of apatite on the surface and increased their crystallinity. In a potentiodynamic polarization test, FHA coatings exhibited a better anti-corrosion ability than bare G-II titanium substrate in SBF. Additionally, the anodized TiO 2 nanotube improved the adhesion and corrosion resistance of FHA as well.

Isolation and purification of recombinant proteins, antibodies and plasmid DNA with hydroxyapatite chromatography.

PubMed

Hilbrig, Frank; Freitag, Ruth

2012-01-01

Hydroxyapatite and related stationary phases increasingly play a role in the downstream processing of high-value biological materials, such as recombinant proteins, therapeutic antibodies and pharmaceutical-grade plasmid DNA. Chromatographic hydroxyapatite is an inorganic, ceramic material identical in composition, if not in structure, to calcium phosphate found in human bones and teeth. The interaction of hydroxyapatite with biomacromolecules is complex and highly dynamic, which can make predicting performance difficult, but also allows the design of very selective isolation processes. This review discusses the currently commercially available chromatographic materials, different retention mechanisms supported by these materials and differential exploitation for the design of highly specific isolation procedures. The state of the art of antibody purification by hydroxy- and fluoroapatite is reviewed together with tested routines for method development and implementation. Finally, the isolation of plasmid DNA is discussed, since the purification of DNA therapeutics at a sufficiently large scale is an emerging need in bioprocess development and perhaps the area in bioseparation where apatite chromatography can make its most important contribution to date. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrasonic synthesis of hydroxyapatite in non-cavitation and cavitation modes.

PubMed

Nikolaev, A L; Gopin, A V; Severin, A V; Rudin, V N; Mironov, M A; Dezhkunov, N V

2018-06-01

The size control of materials is of great importance in research and technology because materials of different size and shape have different properties and applications. This paper focuses on the synthesis of hydroxyapatite in ultrasound fields of different frequencies and intensities with the aim to find the conditions which allow control of the particles size. The results are evaluated by X-ray diffraction, Transmission Electron Microscopy, morphological and sedimentation analyses. It is shown that the hydroxyapatite particles synthesized at low intensity non-cavitation regime of ultrasound have smaller size than those prepared at high intensity cavitation regime. The explanation of observed results is based on the idea of formation of vortices at the interface between phosphoric acid and calcium hydroxide solution where the nucleation of hydroxyapatite particles is taken place. Smaller vortices formed at high frequency non-cavitation ultrasound regime provide smaller nucleation sites and smaller resulting particles, compared to vortices and particles obtained without ultrasound. Discovered method has a potential of industrial application of ultrasound for the controlled synthesis of nanoparticles. Copyright © 2018 Elsevier B.V. All rights reserved.

Putty-like bone fillers based on CaP ceramics or Biosilicate® combined with carboxymethylcellulose: Characterization, optimization, and evaluation.

PubMed

Gabbai-Armelin, Paulo R; Renno, Ana Cm; Crovace, Murilo C; Magri, Angela Mp; Zanotto, Edgar D; Peitl, Oscar; Leeuwenburgh, Sander Cg; Jansen, John A; van den Beucken, Jeroen Jjp

2017-08-01

Calcium phosphates and bioactive glass ceramics have been considered promising biomaterials for use in surgeries. However, their moldability should be further enhanced. We here thereby report the handling, physicochemical features, and morphological characteristics of formulations consisting of carboxymethylcellulose-glycerol and hydroxyapatite-tricalcium phosphate or Biosilicate® particles. We hypothesized that combining either material with carboxymethylcellulose-glycerol would improve handling properties, retaining their bioactivity. In addition to scanning electron microscopy, cohesion, mineralization, pH, and viscoelastic properties of the novel formulations, cell culture experiments were performed to evaluate the cytotoxicity and cell proliferation. Putty-like formulations were obtained with improved cohesion and moldability. Remarkably, mineralization in simulated body fluid of hydroxyapatite-tricalcium phosphate/carboxymethylcellulose-glycerol formulations was enhanced compared to pure hydroxyapatite-tricalcium phosphate. Cell experiments showed that all formulations were noncytotoxic and that HA-TCP60 and BGC50 extracts led to an increased cell proliferation. We conclude that combining carboxymethylcellulose-glycerol with either hydroxyapatite-tricalcium phosphate or Biosilicate® allows for the generation of moldable putties, improves handling properties, and retains the ceramic bioactivity.

Intercalated chitosan/hydroxyapatite nanocomposites: Promising materials for bone tissue engineering applications.

PubMed

Nazeer, Muhammad Anwaar; Yilgör, Emel; Yilgör, Iskender

2017-11-01

Preparation and characterization of chitosan/hydroxyapatite (CS/HA) nanocomposites displaying an intercalated structure is reported. Hydroxyapatite was synthesized through sol-gel process. Formic acid was introduced as a new solvent to obtain stable dispersions of nano-sized HA particles in polymer solution. CS/HA dispersions with HA contents of 5, 10 and 20% by weight were prepared. Self-assembling of HA nanoparticles during the drying of the solvent cast films led to the formation of homogeneous CS/HA nanocomposites. Composite films were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-rays (EDX) analysis, Fourier transform infrared (FTIR) spectroscopy, X-rays diffraction (XRD) analysis and thermogravimetric analysis (TGA). SEM and AFM confirmed the presence of uniformly distributed HA nanoparticles on the chitosan matrix surface. XRD patterns and cross-sectional SEM images showed the formation of layered nanocomposites. Complete degradation of chitosan matrix in TGA experiments, led to the formation of nanoporous 3D scaffolds containing hydroxyapatite, β-tricalcium phosphate and calcium pyrophosphate. CS/HA composites can be considered as promising materials for bone tissue engineering applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Microwave assisted synthesis and characterization of magnesium substituted calcium phosphate bioceramics.

PubMed

Khan, Nida Iqbal; Ijaz, Kashif; Zahid, Muniza; Khan, Abdul S; Abdul Kadir, Mohammed Rafiq; Hussain, Rafaqat; Anis-Ur-Rehman; Darr, Jawwad A; Ihtesham-Ur-Rehman; Chaudhry, Aqif A

2015-11-01

Hydroxyapatite is used extensively in hard tissue repair due to its biocompatibility and similarity to biological apatite, the mineral component of bone. It differs subtly in composition from biological apatite which contains other ions such as magnesium, zinc, carbonate and silicon (believed to play biological roles). Traditional methods of hydroxyapatite synthesis are time consuming and require strict reaction parameter control. This paper outlines synthesis of magnesium substituted hydroxyapatite using simple microwave irradiation of precipitated suspensions. Microwave irradiation resulted in a drastic decrease in ageing times of amorphous apatitic phases. Time taken to synthesize hydroxyapatite (which remained stable upon heat treatment at 900°C for 1h) reduced twelve folds (to 2h) as compared to traditionally required times. The effects of increasing magnesium concentration in the precursors on particle size, surface area, phase-purity, agglomeration and thermal stability, were observed using scanning electron microscopy, BET surface area analysis, X-ray diffraction and photo acoustic Fourier transform infra-red spectroscopy. Porous agglomerates were obtained after a brief heat-treatment (1h) at 900°C. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of phosphorus fertilizer soil reactions by Raman and synchrotron infrared microspectroscopy.

PubMed

Vogel, Christian; Adam, Christian; Sekine, Ryo; Schiller, Tara; Lipiec, Ewelina; McNaughton, Don

2013-10-01

The reaction mechanisms of phosphate-bearing mineral phases from sewage sludge ash-based fertilizers in soil were determined by Raman and synchrotron infrared microspectroscopy. Different reaction mechanisms in wet soil were found for calcium and magnesium (pyro-) phosphates. Calcium orthophosphates were converted over time to hydroxyapatite. Conversely, different magnesium phosphates were transformed to trimagnesium phosphate. Since the magnesium phosphates are unable to form an apatite structure, the plant-available phosphorus remains in the soil, leading to better growth results observed in agricultural pot experiments. The pyrophosphates also reacted very differently. Calcium pyrophosphate is unreactive in soil. In contrast, magnesium pyrophosphate quickly formed plant-available dimagnesium phosphate.

Phosphate Adsorption from Membrane Bioreactor Effluent Using Dowex 21K XLT and Recovery as Struvite and Hydroxyapatite

PubMed Central

Nur, Tanjina; Loganathan, Paripurnanda; Kandasamy, Jaya; Vigneswaran, Saravanamuthu

2016-01-01

Discharging phosphate through wastewaters into waterways poses a danger to the natural environment due to the serious risks of eutrophication and health of aquatic organisms. However, this phosphate, if economically recovered, can partly overcome the anticipated future scarcity of phosphorus (P) resulting from exhaustion of natural phosphate rock reserves. An experiment was conducted to determine the efficiency of removing phosphate from a membrane bioreactor effluent (pH 7.0–7.5, 20, 35 mg phosphate/L) produced in a water reclamation plant by adsorption onto Dowex 21K XLT ion exchange resin and recover the phosphate as fertilisers. The data satisfactorily fitted to Langmuir adsorption isotherm with a maximum adsorption capacity of 38.6 mg·P/g. The adsorbed phosphate was quantitatively desorbed by leaching the column with 0.1 M NaCl solution. The desorbed phosphate was recovered as struvite when ammonium and magnesium were added at the molar ratio of phosphate, ammonium and magnesium of 1:1:1 at pH 9.5. Phosphate was also recovered from the desorbed solution as hydroxyapatite precipitate by adding calcium hydroxide to the solution at a phosphate to calcium molar ratio of 1:2 at pH 7.0. The P contents of struvite and hydroxyapatite produced were close to those of the respective commercial phosphate fertilisers. PMID:26950136

Modifications of a calcium phosphate cement with biomolecules--influence on nanostructure, material, and biological properties.

PubMed

Vater, Corina; Lode, Anja; Bernhardt, Anne; Reinstorf, Antje; Nies, Berthold; Gelinsky, Michael

2010-12-01

Calcium phosphate cements (CPC), forming hydroxyapatite during the setting reaction, are characterized by good biocompatibility and osteoconductivity, however, their remodeling into native bone tissue is slow. One strategy to improve remodeling and bone regeneration is the directed modification of their nanostructure. In this study, a CPC was set in the presence of cocarboxylase, glucuronic acid, tartaric acid, α-glucose-1-phosphate, L-arginine, L-aspartic acid, and L-lysine, respectively, with the aim to influence formation and growth of hydroxyapatite crystals through the functional groups of these biomolecules. Except for glucuronic acid, all these modifications resulted in the formation of smaller and more agglomerated hydroxyapatite particles which had a positive impact on the biological performance indicated by first experiments with the human osteoblast cell line hFOB 1.19. Moreover, adhesion, proliferation, and osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSC) as well as binding of the growth factors BMP-2 and VEGF was investigated on CPC modified with cocarboxylase, arginine, and aspartic acid. Initial adhesion of hBMSC was improved on these three modifications and proliferation was enhanced on CPC modified with cocarboxylase and arginine whereas osteogenic differentiation remained unaffected. Modification of the CPC with arginine and aspartic acid, but not with cocarboxylase, led to a higher BMP-2 binding. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.

Impact of non-thermal plasma surface modification on porous calcium hydroxyapatite ceramics for bone regeneration

PubMed Central

Moriguchi, Yu; Lee, Dae-Sung; Thamina, Khair; Masuda, Kazuto; Itsuki, Dai; Yoshikawa, Hideki; Hamaguchi, Satoshi; Myoui, Akira

2018-01-01

In the physiochemical sciences, plasma is used to describe an ionized gas. Previous studies have implicated plasma surface treatment in the enhancement of hydrophilicity of implanted musculoskeletal reconstructive materials. Hydroxyapatite (HA) ceramics, widely used in bone tissue regeneration, have made great advancements to skeletal surgery. In the present study, we investigate the impact of low-pressure plasma on the interconnected porous calcium hydroxyapatite (IP-CHA) both in vitro and in vivo. Our results indicate that dielectric barrier discharge (DBD) plasma, when used with oxygen, can augment the hydrophilicity of non-porous HA surfaces and the osteoconductivity of the IP-CHA disc via increased water penetration of inner porous structures, as demonstrated through microfocus computed tomography (μCT) assay. In vivo implantation of plasma-treated IP-CHA displayed superior bone ingrowth than untreated IP-CHA. Though plasma-treated IP-CHA did not alter osteoblast cell proliferation, it accelerated osteogenic differentiation of seeded marrow mesenchymal stem cells. In vitro X-ray photoelectron spectroscopy (XPS) revealed that this plasma treatment increases levels of oxygen, rather than nitrogen, on the plasma-treated IP-CHA surface. These findings suggest that plasma treatment, an easy and simple processing, can significantly improve the osteoconductive potential of commonly used artificial bones such as IP-CHA. Further optimization of plasma treatment and longer-term follow-up of in vivo application are required toward its clinical application. PMID:29538457

Cementless Hydroxyapatite Coated Hip Prostheses

PubMed Central

Herrera, Antonio; Mateo, Jesús; Gil-Albarova, Jorge; Lobo-Escolar, Antonio; Ibarz, Elena; Gabarre, Sergio; Más, Yolanda

2015-01-01

More than twenty years ago, hydroxyapatite (HA), calcium phosphate ceramics, was introduced as a coating for cementless hip prostheses. The choice of this ceramic is due to its composition being similar to organic apatite bone crystals. This ceramic is biocompatible, bioactive, and osteoconductive. These qualities facilitate the primary stability and osseointegration of implants. Our surgical experience includes the implantation of more than 4,000 cementless hydroxyapatite coated hip prostheses since 1990. The models implanted are coated with HA in the acetabulum and in the metaphyseal area of the stem. The results corresponding to survival and stability of implants were very satisfactory in the long-term. From our experience, HA-coated hip implants are a reliable alternative which can achieve long term survival, provided that certain requirements are met: good design selection, sound choice of bearing surfaces based on patient life expectancy, meticulous surgical technique, and indications based on adequate bone quality. PMID:25802848

Electrophoretic Deposition of Hydroxyapatite Film Containing Re-Doped MoS2 Nanoparticles

PubMed Central

Shalom, Hila; Feldman, Yishay; Rosentsveig, Rita; Pinkas, Iddo; Kaplan-Ashiri, Ifat; Moshkovich, Alexey; Perfilyev, Vladislav; Rapoport, Lev

2018-01-01

Films combining hydroxyapatite (HA) with minute amounts (ca. 1 weight %) of (rhenium doped) fullerene-like MoS2 (IF) nanoparticles were deposited onto porous titanium substrate through electrophoretic process (EPD). The films were analyzed by scanning electron microscopy (SEM), X-ray diffraction and Raman spectroscopy. The SEM analysis showed relatively uniform coatings of the HA + IF on the titanium substrate. Chemical composition analysis using energy dispersive X-ray spectroscopy (EDS) of the coatings revealed the presence of calcium phosphate minerals like hydroxyapatite, as a majority phase. Tribological tests were undertaken showing that the IF nanoparticles endow the HA film very low friction and wear characteristics. Such films could be of interest for various medical technologies. Means for improving the adhesion of the film to the underlying substrate and its fracture toughness, without compromising its biocompatibility are discussed at the end. PMID:29495394

Selenium-substituted hydroxyapatite nanoparticles and their in vivo antitumor effect on hepatocellular carcinoma.

PubMed

Yanhua, Wang; Hao, Hang; Li, Yan; Zhang, Shengmin

2016-04-01

Absence of curative treatment creates urgent need for new strategies for unresectable hepatoma. Novel selenium-substituted hydroxyapatite nanoparticles (SeHAN) were designed to serve as anticancer agent. The authors examined the nanoparticles by physicochemical techniques. The in vivo efficacy and toxicity of these nanoparticles were also investigated on a nude mice model of human hepatocellular carcinoma. The results showed that the selenite ions can be incorporated into the hydroxyapatite lattice facilely. They exhibited bundles of needles shape with a size of 160-200 nm. In the in vivo study, they showed better survival advantage. The overall survival rate of nude mice in the control, pure hydroxyapatite and SeHAN group were 50.00%, 76.92%, and 100.00% respectively. Blood biochemical studies showed that SeHAN group had significantly lower toxicities on the liver and kidney functions. Histopathological studies confirmed that massive tumor necrosis and calcium deposition were evident after SeHAN treatment. Moreover, immunohistochemistry and Western blot assay showed significantly reduced expression of the Ki-67, VEGF and MMP-9 protein in the SeHAN group. Taken together, these results suggest that the selenium-substituted hydroxyapatite nanoparticles could be a new type of promising anticancer agent to provide both survival advantage and lower toxicity. Copyright © 2016 Elsevier B.V. All rights reserved.

Adsorption of benzoxaboroles on hydroxyapatite phases.

PubMed

Pizzoccaro, Marie-Alix; Nikel, Ondrej; Sene, Saad; Philippe, Coralie; Mutin, P Hubert; Bégu, Sylvie; Vashishth, Deepak; Laurencin, Danielle

2016-09-01

Benzoxaboroles are a family of molecules that are finding an increasing number of applications in the biomedical field, particularly as a "privileged scaffold" for the design of new drugs. Here, for the first time, we determine the interaction of these molecules with hydroxyapatites, in view of establishing (i) how benzoxaborole drugs may adsorb onto biological apatites, as this could impact on their bioavailability, and (ii) how apatite-based materials can be used for their formulation. Studies on the adsorption of the benzoxaborole motif (C7H7BO2, referred to as BBzx) on two different apatite phases were thus performed, using a ceramic hydroxyapatite (HAceram) and a nanocrystalline hydroxyapatite (HAnano), the latter having a structure and composition more similar to the one found in bone mineral. In both cases, the grafting kinetics and mechanism were studied, and demonstration of the surface attachment of the benzoxaborole under the form of a tetrahedral benzoxaborolate anion was established using (11)B solid state NMR (including (11)B-(31)P correlation experiments). Irrespective of the apatite used, the grafting density of the benzoxaborolates was found to be low, and more generally, these anions demonstrated a poor affinity for apatite surfaces, notably in comparison with other anions commonly found in biological media, such as carboxylates and (organo)phosphates. The study was then extended to the adsorption of a molecule with antimicrobial and antifungal properties (3-piperazine-bis(benzoxaborole)), showing, on a more general perspective, how hydroxyapatites can be used for the development of novel formulations of benzoxaborole drugs. Benzoxaboroles are an emerging family of molecules which have attracted much attention in the biomedical field, notably for the design of new drugs. However, the way in which these molecules, once introduced in the body, may interact with bone mineral is still unknown, and the possibility of associating benzoxaboroles to calcium phosphates for drug-formulation purposes has not been looked into. Here, we describe the first study of the adsorption of benzoxaboroles on hydroxyapatite, which is the main mineral phase present in bone. We describe the mode of grafting of benzoxaboroles on this material, and show that they only weakly bind to its surface, especially in comparison to other ionic species commonly found in physiological media, such as phosphates and carboxylates. This demonstrates that administered benzoxaborole drugs are unlikely to remain adsorbed on hydroxyapatite surfaces for long periods of time, which means that their biodistribution will not be affected by such phenomena. Moreover, this work shows that the formulation of benzoxaborole drugs by association to calcium phosphates like hydroxyapatite will lead to a rapid release of the molecules. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Microstructures of plasma-sprayed hydroxyapatite-coated Ti-6Al-4V dental implants.

PubMed

Tufekci, E; Brantley, W A; Mitchell, J C; McGlumphy, E A

1997-01-01

The purpose of this study was to investigate the microstructure of plasma-sprayed hydroxyapatite coatings and the elemental composition near the coating-substrate interface for two commercial implants, using the scanning electron microscope. Both coating surfaces and cross-sectioned specimens were examined. The results indicated that while the surface microstructures of both implants were consistent with the plasma-spraying process, the scale of the constituents was much finer for one product. In cross-section, both coatings exhibited minimal porosity and intimate contact with the titanium alloy substrate. It was found that limited interdiffusion of titanium and calcium occurred near the interface.

Solvothermal transformation of a calcium oleate precursor into large-sized highly ordered arrays of ultralong hydroxyapatite microtubes.

PubMed

Lu, Bing-Qiang; Zhu, Ying-Jie; Chen, Feng; Qi, Chao; Zhao, Xin-Yu; Zhao, Jing

2014-06-02

Hydroxyapatite (HAP), a well-known member of the calcium phosphate family, is the major inorganic component of bones and teeth in vertebrates. The highly ordered arrays of HAP structures are of great significance for hard tissue repair and for understanding the formation mechanisms of bones and teeth. However, the synthesis of highly ordered HAP structure arrays remains a great challenge. In this work, inspired by the ordered structure of tooth enamel, we have successfully synthesized three-dimensional bulk materials with large sizes (millimeter scale) that are made of highly ordered arrays of ultralong HAP microtubes (HOAUHMs) by solvothermal transformation of calcium oleate precursor. The core-shell-structured oblate sphere consists of a core that is composed of HAP nanorods and a shell that consists of highly ordered HAP microtube arrays. The prepared HOAUHMs are large: 6.0 mm in diameter and up to 1.4 mm in thickness. With increasing solvothermal reaction time, the HOAUHMs grow larger; the microtubes become more uniform and more ordered. This work provides a new synthetic method for synthesizing highly ordered arrays of uniform HAP ultralong microtubes that are promising for biomedical applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

RF magnetron sputtering of a hydroxyapatite target: A comparison study on polytetrafluorethylene and titanium substrates

NASA Astrophysics Data System (ADS)

Surmenev, Roman A.; Surmeneva, Maria A.; Grubova, Irina Yu.; Chernozem, Roman V.; Krause, Bärbel; Baumbach, Tilo; Loza, Kateryna; Epple, Matthias

2017-08-01

A pure hydroxyapatite (HA) target was used to prepare the biocompatible coating of HA on the surface of a polytetrafluorethylene (PTFE) substrate, which was placed on the same substrate holder with technically pure titanium (Ti) in the single deposition runs by radio-frequency (RF) magnetron sputtering. The XPS, XRD and FTIR analyses of the obtained surfaces showed that for all substrates, instead of the HA coating deposition, the coating of a mixture of calcium carbonate and calcium fluoride was grown. According to SEM investigations, the surface of PTFE was etched, and the surface topography of uncoated Ti was preserved after the depositions. The FTIR results reveal no phosphate bonds; only calcium tracks were observed in the EDX-spectra on the surface of the coated PTFE substrates. Phosphate oxide (V), which originated from the target, could be removed using a vacuum pump system, or no phosphate-containing bonds could be formed on the substrate surface because of the severe substrate bombardment process, which prevented the HA coating deposition. The observed results may be connected with the surface re-sputtering effect of the growing film by high-energy negatively charged ions (most probably oxygen or fluorine), which are accelerated in the cathode dark sheath.

Development of calcium phosphate cement using chitosan and citric acid for bone substitute materials.

PubMed

Yokoyama, Atsuro; Yamamoto, Satoru; Kawasaki, Takao; Kohgo, Takao; Nakasu, Masanori

2002-02-01

We developed a calcium phosphate cement that could be molded into any desired shape due to its chewing-gum-like consistency after mixing. The powder component of the cement consists of alpha-tricalcium phosphate and tetracalcium phosphate, which were made by decomposition of hydroxyapatite ceramic blocks. The liquid component consists of citric acid, chitosan and glucose solution. In this study, we used 20% citric acid (group 20) and 45% citric acid (group 45). The mechanical properties and biocompatibility of this new cement were investigated. The setting times of cements were 5.5 min, in group 20 and 6.4 min, in group 45. When incubated in physiological saline, the cements were transformed to hydroxyapatite at 3, and 6 weeks, the compressive strengths were 15.6 and 20.7 MPa, in group 45 and group 20, respectively. The inflammatory response around the cement implanted on the bone and in the subcutaneous tissue in rats was more prominent in group 45 than in group 20 at 1 week after surgery. After 4 weeks, the inflammation disappeared and the cement had bound to bone in both groups. These results indicate that this new calcium phosphate cement is a suitable bone substitute material and that the concentration of citric acid in the liquid component affects its mechanical properties and biocompatibility.

Assessing Anticalcification Treatments in Bioprosthetic Tissue by Using the New Zealand Rabbit Intramuscular Model

PubMed Central

Wright, Gregory A; Faught, Joelle M; Olin, Jane M

2009-01-01

The objective of this work was to demonstrate that the New Zealand White (NZW) rabbit intramuscular model can be used for detecting calcification in bioprosthetic tissue and to compare the calcification in the rabbit to that of native human valves. The rabbit model was compared with the commonly used Sprague–Dawley rat subcutaneous model. Eighteen rabbits and 18 rats were used to assess calcification in bioprosthetic tissue over time (7, 14, 30, and 90 d). The explanted rabbit and rat tissue discs were measured for calcium by using atomic absorption and Raman spectroscopy. Calcium deposits on the human valve explants were assessed by using Raman spectroscopy. The results showed that the NZW rabbit model is robust for detecting calcification in a shorter duration (14 d), with less infection complications, more space to implant tissue groups (thereby reducing animal use numbers), and a more metabolically and mechanically dynamic environment than the rat subcutaneous model . The human explanted valves and rabbit explanted tissue both showed Raman peaks at 960 cm−1 which is representative of hydroxyapatite. Hydroxyapatite is the final calcium and phosphate species in the calcification of bioprosthetic heart valves and rabbit intramuscular implants. The NZW rabbit intramuscular model is an effective model for assessing calcification in bioprosthetic tissue. PMID:19619417

Development and characterization of an injectable cement of nano calcium-deficient hydroxyapatite/multi(amino acid) copolymer/calcium sulfate hemihydrate for bone repair

PubMed Central

Qi, Xiaotong; Li, Hong; Qiao, Bo; Li, Weichao; Hao, Xinyan; Wu, Jun; Su, Bao; Jiang, Dianming

2013-01-01

A novel injectable bone cement was developed by integration of nano calcium-deficient hydroxyapatite/multi(amino acid) copolymer (n-CDHA/MAC) and calcium sulfate hemihydrate (CSH; CaSO4 · 1/2H2O). The structure, setting time, and compressive strength of the cement were investigated. The results showed that the cement with a liquid to powder ratio of 0.8 mL/g exhibited good injectability and appropriate setting time and mechanical properties. In vitro cell studies indicated that MC3T3-E1 cells cultured on the n-CDHA/MAC/CSH composite spread well and showed a good proliferation state. The alkaline phosphatase activity of the MC3T3-E1 cells cultured on the n-CDHA/MAC/CSH composite was significantly higher than that of the cells on pure CSH at 4 and 7 days of culture. The n-CDHA/MAC/CSH cement was implanted into critical size defects of the femoral condyle in rabbits to evaluate its biocompatibility and osteogenesis in vivo. Radiological and histological results indicated that introduction of the n-CDHA/MAC into CSH enhanced new bone formation, and the n-CDHA/MAC/CSH cement exhibited good biocompatibility and degradability. In conclusion, the injectable n-CDHA/MAC/CSH composite cement has a significant clinical advantage over pure CSH cement, and may be a promising bone graft substitute for the treatment of bone defects. PMID:24293996

Protein-adsorption and Ca-phosphate formation on chitosan-bioactive glass composite coatings

NASA Astrophysics Data System (ADS)

Wagener, V.; Boccaccini, A. R.; Virtanen, S.

2017-09-01

In the last years, chitosan-bioactive glass (BG) composites have been developed and investigated as bioactive coatings for orthopedic applications. The increase of bioactivity occurs due to the stimulation of calcium-phosphate/hydroxyapatite formation on the surface while the coating is degrading. In the present work, protein adsorption and its influence on calcium-phosphate precipitation was studied for the first time on such composite coatings. The experiments involved coating of 316L stainless steel substrates with chitosan (Ch) and chitosan-bioactive glass (Ch-BG) and immersion of the coated samples in two different bovine serum albumin (BSA) containing solutions, namely DI H2O (with pH adjusted to about 7.2 with diluted NaOH) and simulated body fluid (SBF). In order to investigate the influence of protein adsorption on calcium-phosphate precipitation, samples were also immersed in DI H2O and in SBF without BSA. Samples were analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Surface analysis revealed that adsorption of BSA takes place on all studied samples and that protein adsorption is influenced by the presence of Ca2+ and PO43- ions. Bioactivity in the form of hydroxyapatite pre-stage formation is significantly increased on Ch-BG composite coating as compared with bare stainless steel surface. However, calcium-phosphate precipitation in SBF is reduced by the presence of BSA.

Coating hydroxiapatite on stainless steel 316 L by using sago starch as binder with dip-coating method

NASA Astrophysics Data System (ADS)

Fadli, A.; Akbar, F.; Prabowo, A.; Hidayah, P. H.

2018-04-01

Hydroxyapatite (HA) is a mineral form of naturally occurring apatite calcium with Ca10(PO4)6(OH)2 formula. One of the major innovations in the field of bone reconstruction is to apply HA as a surface coating on a mechanically strong implant metal and to improve the stability of bone implants thereby increasing the lifetime of the metal implants. Pure hydroxyapatite has poor mechanical properties so it is necessary to add sago starch as a binder to combine the strength and hardness of metal surfaces with bioactive properties of hydroxyapatite by Dip Coating method. Stainless steel 316L is the most commonly used alloy as an implant for bones and teeth due to its excellent corrosion and oxidation resistance and is easily formed. In this study, hydroxyapatite coatings used fixed variables as hydroxyapatite mass (10 grams), aquades mass (20 grams), dipping time (20 seconds), and calcination conditions (800°C, 1 hour). The variables are sago starch mass (1, 1.25, 1.5 gram) and stirring time (16, 20, 24 hours). The shear strength value is higher in the addition of 1.25, 10, 20, and again in the binder ratio of 1.5; 10; 20. The addition of stirring time causes a decrease in shear strength. The highest shear strength value obtained was 3.07 MPa. The layer attached to the substrate is a hydroxyapatite with a composition of 99.4% as evidenced by the results of XRD analysis.

Hydroxyapatite promotes superior keratocyte adhesion and proliferation in comparison with current keratoprosthesis skirt materials.

PubMed

Mehta, J S; Futter, C E; Sandeman, S R; Faragher, R G A F; Hing, K A; Tanner, K E; Allan, B D S

2005-10-01

Published clinical series suggest the osteoodontokeratoprosthesis (OOKP) may have a lower extrusion rate than current synthetic keratoprostheses. The OOKP is anchored in the eye wall by autologous tooth. The authors' aim was to compare adhesion, proliferation, and morphology for telomerase transformed keratocytes seeded on calcium hydroxyapatite (the principal mineral constituent of tooth) and materials used in the anchoring elements of commercially available synthetic keratoprostheses. Test materials were hydroxyapatite, polytetrafluoroethylene (PTFE), polyhydroxyethyl methacrylate (HEMA), and glass (control). Cell adhesion and viability were quantified at 4 hours, 24 hours, and 1 week using a calcein-AM/EthD-1 viability/cytotoxicity assay. Focal contact expression and cytoskeletal organisation were studied at 24 hours by confocal microscopy with immunoflourescent labelling. Further studies of cell morphology were performed using light and scanning electron microscopy. Live cell counts were significantly greater on hydroxyapatite surfaces at each time point (p<0.04). Dead cell counts were significantly higher for PTFE at 7 days (p<0.002). ss(1) integrin expression was highest on hydroxyapatite. Adhesion structures were well expressed in flat, spread out keratocytes on both HA and glass. Keratocytes tended to be thinner and spindle shaped on PTFE. The relatively few keratocytes visible on HEMA test surfaces were rounded and poorly adherent. Keratocyte adhesion, spreading, and viability on hydroxyapatite test surfaces is superior to that seen on PTFE and HEMA. Improving the initial cell adhesion environment in the skirt element of keratoprostheses may enhance tissue integration and reduce device failure rates.

Interfacial Ca2+ environments in nanocrystalline apatites revealed by dynamic nuclear polarization enhanced 43Ca NMR spectroscopy

NASA Astrophysics Data System (ADS)

Lee, Daniel; Leroy, César; Crevant, Charlène; Bonhomme-Coury, Laure; Babonneau, Florence; Laurencin, Danielle; Bonhomme, Christian; de Paëpe, Gaël

2017-01-01

The interfaces within bones, teeth and other hybrid biomaterials are of paramount importance but remain particularly difficult to characterize at the molecular level because both sensitive and selective techniques are mandatory. Here, it is demonstrated that unprecedented insights into calcium environments, for example the differentiation of surface and core species of hydroxyapatite nanoparticles, can be obtained using solid-state NMR, when combined with dynamic nuclear polarization. Although calcium represents an ideal NMR target here (and de facto for a large variety of calcium-derived materials), its stable NMR-active isotope, calcium-43, is a highly unreceptive probe. Using the sensitivity gains from dynamic nuclear polarization, not only could calcium-43 NMR spectra be obtained easily, but natural isotopic abundance 2D correlation experiments could be recorded for calcium-43 in short experimental time. This opens perspectives for the detailed study of interfaces in nanostructured materials of the highest biological interest as well as calcium-based nanosystems in general.

Calcium phosphate nanocoatings and nanocomposites, part 2: thin films for slow drug delivery and osteomyelitis.

PubMed

Ben-Nissan, Besim; Macha, Innocent; Cazalbou, Sophie; Choi, Andy H

2016-01-01

During the last two decades although many calcium phosphate based nanomaterials have been proposed for both drug delivery, and bone regeneration, their coating applications have been somehow slow due to the problems related to their complicated synthesis methods. In order to control the efficiency of local drug delivery of a biomaterial the critical pore sizes as well as good control of the chemical composition is pertinent. A variety of calcium phosphate based nanocoated composite drug delivery systems are currently being investigated. This review aims to give an update into the advancements of calcium phosphate nanocoatings and thin film nanolaminates. In particular recent research on PLA/hydroxyapatite composite thin films and coatings into the slow drug delivery for the possible treatment of osteomyelitis is covered.

Synthesis, characterization and bioactivity of a calcium-phosphate glass-ceramics obtained by the sol-gel processing method.

PubMed

Jmal, Nouha; Bouaziz, Jamel

2017-02-01

In this work, a calcium-phosphate glass-ceramics was successfully obtained by heat treatment of a mixture of 26.52 in wt.% of fluorapatite (Fap) and 73.48 in wt.% of 77S (77 SiO 2 14 CaO9 P 2 O 5 in wt.%) gel. The calcium phosphate-glass-ceramics was prepared by sol-gel process with tetraethyl orthosilicate (TEOS), triethyl phosphate (TEP), calcium nitrate and fluorapatite. The synthesized powders were characterized by some commonly used tools such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), 31 P magic angle spinning nuclear magnetic resonance (MAS-NMR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and thin-film X-ray diffraction (TF-XRD). The obtained results seemed to confirm the nucleation and growth of hydroxyapatite (Hap) nano-phase in the glass. Moreover, an in-vitro evaluation of the glass-ceramic was performed. In addition, to assess its bioactive capacity, it was soaked in simulated body fluid (SBF) at different time intervals. The SEM, EDS and TF-XRD analyses showed the deposition of hydroxyapatite on the surface of the specimens after three days of immersion in SBF solution. The mechanical properties of the obtained material such as rupture strength, Vickers hardness and elastic modulus were measured. In addition, the friction coefficient of calcium phosphate-glass-ceramics was tested. The values of the composite of rupture strength (24MPa), Vickers hardness (214Hv), Young's modulus (52.3GPa), shear modulus (19GPa) and friction coefficient (0.327) were obtained. This glass-ceramics can have useful applications in dental prostheses. Indeed, this material may have promising applications for implants because of its content of fluorine, the effective protector against dental caries. Copyright © 2016 Elsevier B.V. All rights reserved.

In situ growth of hydroxyapatite within electrospun poly(DL-lactide) fibers.

PubMed

Cui, Wenguo; Li, Xiaohong; Zhou, Shaobing; Weng, Jie

2007-09-15

Development of nanocomposites of hydroxyapatite (HA) and polylactic acid (PLA) is attractive, as the advantageous properties of the two types of materials can be combined to suit better the mechanical and biological demands for biomedical uses. To solve the problematic issue of agglomeration of HA crystallites in the PLA matrix, a novel method is introduced in the present study to use electrospun nanofibers as the reaction confinement for composite fabrication. Poly(DL-lactide) ultrafine fibers with calcium nitrate entrapment were prepared by electrospinning and then incubated in phosphate solution to form in situ calcium phosphate on the polymer matrix. The formation of nonstoichiometric nanostructured HA and well dispersion of HA particles on the electrospun fibers were observed. Higher crystalline HA phase was indicated in samples after sintering at 1200 degrees C. The formation of the calcium-phosphate phase was dependent upon the precipitation conditions, and the effects of the incubation time, temperature, and the pH values of the incubation medium were investigated on the spontaneous precipitation and amorphous-crystalline transformation of HA in the current study. Considering the biodegradability of matrix polymer and the crystallinity and uniform dispersal of HA, optimal conditions for composite preparation were incubating calcium-containing ultrafine fibers at 37 degrees C in pH 7.4 or at 25 degrees C in pH 9.0 of diammonium hydrogen phosphate solutions for 7 days. Around 25%-34% of mineral contents can be synthesized in the resulting composites, which was higher than the theoretical value due to the nonstoichiometric HA formed in the composite, and the fiber degradation and partial calcium nitrate involved in the HA formation. Copyright 2007 Wiley Periodicals, Inc.

Idiopathic hypercalciuria and formation of calcium renal stones

PubMed Central

Coe, Fredric L.; Worcester, Elaine M.; Evan, Andrew P.

2018-01-01

The most common presentation of nephrolithiasis is idiopathic calcium stones in patients without systemic disease. Most stones are primarily composed of calcium oxalate and form on a base of interstitial apatite deposits, known as Randall’s plaque. By contrast some stones are composed largely of calcium phosphate, as either hydroxyapatite or brushite (calcium monohydrogen phosphate), and are usually accompanied by deposits of calcium phosphate in the Bellini ducts. These deposits result in local tissue damage and might serve as a site of mineral overgrowth. Stone formation is driven by supersaturation of urine with calcium oxalate and brushite. The level of supersaturation is related to fluid intake as well as to the levels of urinary citrate and calcium. Risk of stone formation is increased when urine citrate excretion is <400 mg per day, and treatment with potassium citrate has been used to prevent stones. Urine calcium levels >200 mg per day also increase stone risk and often result in negative calcium balance. Reduced renal calcium reabsorption has a role in idiopathic hypercalciuria. Low sodium diets and thiazide-type diuretics lower urine calcium levels and potentially reduce the risk of stone recurrence and bone diseas PMID:27452364

Sintering mechanism of the CaF2 on hydroxyapatite by a 10.6-l microm CO2 laser.

PubMed

Wu, Cheng-Chei; Roan, Rong-Tai; Chen, Jeng-Huey

2002-01-01

Laser has been reported as a heat source for melting and re-crystallization. Occurring at about 1100 degrees C, the melting of surface dental enamel along with re-crystallization might have an assistant role in the therapy of hypersensitive tooth, apical sealing of endodontic surgery in dentistry, preventive dentistry for pit and fissure sealing, and fluoridation. For laser to be accepted in clinical applications, it is desired that, studies must show the incorporation of CaF(2) into hydroxyapatite could reduce the sintering temperature for the sake of safety. In this study, the Sharplan 20XJ CO(2) laser with 10.6- microm wavelength was set under the following parameters: power, 5 W; repetitive mode, 0.1 second; beam, focused. Fluorite was added to hydroxyapatite as a synthetic compound to lower the sintering temperature. Human dental enamel without caries was used for in vitro sintering test. Scanning electron microscopy (SEM), X-ray diffractometer (XRD), Fourier transforming infrared spectroscopy (FTIR), and differential thermal analysis/thermogravimetric analysis (DAT/TGA) were used for the investigation of sintering mechanism of CaF(2). Fusion between hexagonal shape crystals and cubic shape crystals (CaF(2)) were observed under SEM study. Hexagonal shape crystals indicated the formation of fluorapatite under XRD analysis. Under FTIR study, we examined reductions of water (3445 cm(-1)) and hydroxyl bands (3567 and 627 cm(-1)) in irradiated compounds. From the DTA pattern of synthetic compound, it showed the endothermic reaction reaching its peak point around 1180 +/- 20 degrees C. It was attributed to the phase transformation and/or initial melting. In this study, we proposed the interrelationship of the eutectics between initiator (CaF(2)) and the reaction product (calcium hydroxide) that reduced the sintering temperature. It appeared that the co-eutectics interacted to reduce the sintering temperature of hydroxyapatite below 800 degrees C and that the key eutectic was calcium hydroxide. The clinical feasibility of the melting and re-crystallization of hydroxyapatite under 10.6-microm CO(2) laser would be therefore enhanced. Copyright 2002 Wiley-Liss, Inc.

Assessment of calcium scoring performance in cardiac computed tomography.

PubMed

Ulzheimer, Stefan; Kalender, Willi A

2003-03-01

Electron beam tomography (EBT) has been used for cardiac diagnosis and the quantitative assessment of coronary calcium since the late 1980s. The introduction of mechanical multi-slice spiral CT (MSCT) scanners with shorter rotation times opened new possibilities of cardiac imaging with conventional CT scanners. The purpose of this work was to qualitatively and quantitatively evaluate the performance for EBT and MSCT for the task of coronary artery calcium imaging as a function of acquisition protocol, heart rate, spiral reconstruction algorithm (where applicable) and calcium scoring method. A cardiac CT semi-anthropomorphic phantom was designed and manufactured for the investigation of all relevant image quality parameters in cardiac CT. This phantom includes various test objects, some of which can be moved within the anthropomorphic phantom in a manner that mimics realistic heart motion. These tools were used to qualitatively and quantitatively demonstrate the accuracy of coronary calcium imaging using typical protocols for an electron beam (Evolution C-150XP, Imatron, South San Francisco, Calif.) and a 0.5-s four-slice spiral CT scanner (Sensation 4, Siemens, Erlangen, Germany). A special focus was put on the method of quantifying coronary calcium, and three scoring systems were evaluated (Agatston, volume, and mass scoring). Good reproducibility in coronary calcium scoring is always the result of a combination of high temporal and spatial resolution; consequently, thin-slice protocols in combination with retrospective gating on MSCT scanners yielded the best results. The Agatston score was found to be the least reproducible scoring method. The hydroxyapatite mass, being better reproducible and comparable on different scanners and being a physical quantitative measure, appears to be the method of choice for future clinical studies. The hydroxyapatite mass is highly correlated to the Agatston score. The introduced phantoms can be used to quantitatively assess the performance characteristics of, for example, different scanners, reconstruction algorithms, and quantification methods in cardiac CT. This is especially important for quantitative tasks, such as the determination of the amount of calcium in the coronary arteries, to achieve high and constant quality in this field.

Structure, viability and bacterial kinetics of an in vitro biofilm model using six bacteria from the subgingival microbiota.

PubMed

Sánchez, M C; Llama-Palacios, A; Blanc, V; León, R; Herrera, D; Sanz, M

2011-04-01

There are few in vitro models available in the scientific literature for study of the structure, formation and development of the subgingival biofilm. The purpose of this study was to develop and validate an in vitro biofilm model, using representative selected bacteria from the subgingival microbiota. Six standard reference strains were used to develop biofilms over sterile ceramic calcium hydroxyapatite discs coated with saliva within the wells of presterilized polystyrene tissue culture plates. The selected species represent initial (Streptococcus oralis and Actinomyces naeslundii), early (Veillonella parvula), secondary (Fusobacterium nucleatum) and late colonizers (Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans). The structure of the biofilm obtained was studied using a vital fluorescence technique in conjunction with confocal laser scanning microscopy. The biofilm bacterial kinetics were studied by terminal restriction fragment length polymorphism analysis. After 12 h, initial and early colonizers were the first microorganisms detected adhering to the calcium hydroxyapatite discs. The intermediate colonizer F. nucleatum was not detected in the model until 24 h of incubation. Late colonizers A. actinomycetemcomitans and P. gingivalis could be measured inside the biofilm after 48 h. The biofilm reached its steady state between 72 and 96 h after inoculation, with bacterial vitality increasing from the hydroxyapatite surface to the central part of the biofilm. An in vitro biofilm model was developed and validated, demonstrating a pattern of bacterial colonization and maturation similar to the in vivo development of the subgingival biofilm. © 2011 John Wiley & Sons A/S.

Dynamic Light Scattering Study of Inhibition of Nucleation and Growth of Hydroxyapatite Crystals by Osteopontin

PubMed Central

de Bruyn, John R.; Goiko, Maria; Mozaffari, Maryam; Bator, Daniel; Dauphinee, Ron L.; Liao, Yinyin; Flemming, Roberta L.; Bramble, Michael S.; Hunter, Graeme K.; Goldberg, Harvey A.

2013-01-01

We study the effect of isoforms of osteopontin (OPN) on the nucleation and growth of crystals from a supersaturated solution of calcium and phosphate ions. Dynamic light scattering is used to monitor the size of the precipitating particles and to provide information about their concentration. At the ion concentrations studied, immediate precipitation was observed in control experiments with no osteopontin in the solution, and the size of the precipitating particles increased steadily with time. The precipitate was identified as hydroxyapatite by X-ray diffraction. Addition of native osteopontin (nOPN) extracted from rat bone caused a delay in the onset of precipitation and reduced the number of particles that formed, but the few particles that did form grew to a larger size than in the absence of the protein. Recombinant osteopontin (rOPN), which lacks phosphorylation, caused no delay in initial calcium phosphate precipitation but severely slowed crystal growth, suggesting that rOPN inhibits growth but not nucleation. rOPN treated with protein kinase CK2 to phosphorylate the molecule (p-rOPN) produced an effect similar to that of nOPN, but at higher protein concentrations and to a lesser extent. These results suggest that phosphorylations are critical to OPN’s ability to inhibit nucleation, whereas the growth of the hydroxyapatite crystals is effectively controlled by the highly acidic OPN polypeptide. This work also demonstrates that dynamic light scattering can be a powerful tool for delineating the mechanism of protein modulation of mineral formation. PMID:23457612

Characterizing Sintered Nano-Hydroxyapatite Sol-Gel Coating Deposited on a Biomedical Ti-Zr-Nb Alloy

NASA Astrophysics Data System (ADS)

Jafari, Hassan; Hessam, Hamid; Shahri, Seyed Morteza Ghaffari; Assadian, Mahtab; Shairazifard, Shahin Hamtaie Pour; Idris, Mohd Hasbullah

2016-03-01

In this study, sol-gel dip-coating method was used to coat nano-hydroxyapatite on specimens of Ti-14Zr-13Nb alloy for orthopedic applications. The coated specimens were sintered at three different temperatures and time spans to evaluate the impact of sintering process on microstructure, mechanical, bio-corrosion, and bioactivity properties of the coating. Field-emission scanning electron microscopy and x-ray diffraction were used to analyze the coating microstructure. Coating adhesion and mechanical performance were also investigated by scratch testing. Besides, electrochemical corrosion and immersion tests were performed in simulated body fluid to examine the sintering effect on corrosion performance and bioactivity of the coatings, respectively. The evaluations of coated specimens displayed that sintering at elevated temperatures leads to higher surface integrity and improves crystallinity of the nano-hydroxyapatite to approximately 89% which brings about distinctively enhanced mechanical properties. Similarly, it improved the corrosion rate for about 17 times through sintering at 700 °C. Immersion test proved that the coating increased the bioactivity resulted from the dissolution of calcium phosphates into the corresponding environment. It is noticeable that sintering the dip-coated specimens in the nano-hydroxyapatite improves corrosion performance and maintains bioactive behaviors as well.

Mechanochemical Synthesis of Hydroxyapatite and Its Modifications: Composition, Structure, and Properties

NASA Astrophysics Data System (ADS)

Chaikina, M. V.; Bulina, N. V.; Ishchenko, A. V.; Prosanov, I. Yu.

2014-02-01

The mechanochemical method is used to synthesize samples of hydroxyapatite (HA) with substitution of the phosphate ion by silicate and zirconate ions, and substitution of calcium ions by copper ions. In the process of mechanochemical synthesis, carbonate ions and water molecules are incorporated into the structure of HA due to interaction of components of the reaction mixture with air. Intrusion of carbonate into the structure of HA is a competing process with modification of apatite by silicate and zirconate anions; therefore, the composition of the product during synthesis differs from the prescribed one. After annealing of the samples, the composition of the anion-modified HA can be described by the formula Са10(РО4)6- х (АО4) х (ОН)2- х , where (АО4)4- is the modifying anion. Substitution of calcium by copper ions localized at the Са1 position has been detected. Silver ions are not incorporated into the structure of HA, but are distributed in the apatite matrix in the form of nanocrystals of metallic silver.

Synthesis and characterization of cadmium-calcium hydroxyapatite solid solutions

NASA Astrophysics Data System (ADS)

Zhao, Xin; Zhu, Yi-nian; Dai, Liu-qin

2014-06-01

A series of cadmium-calcium hydroxyapatite solid solutions was prepared by an aqueous precipitation method. By various means, the characterizations confirmed the formation of continuous solid solutions over all ranges of Cd/(Cd+Ca) atomic ratio. In the results, both lattice parameters a and c display slight deviations from Vegard's rule when the Cd/(Cd+Ca) atomic ratio is greater than 0.6. The particles change from smaller acicular to larger hexagonal columnar crystals as the Cd/(Cd+Ca) atomic ratio increases from 0-0.60 to 0.60-1.00. The area of the phosphate peak for symmetric P-O stretching decreases with the increase in Cd/(Cd+Ca) atomic ratio, and the peak disappears when the Cd/(Cd+Ca) atomic ratio is greater than 0.6; the two phosphate peaks of P-O stretching gradually merge together for the Cd/(Cd+Ca) atomic ratio near 0.60. These variations can be explained by a slight tendency of larger Cd ions to occupy M(2) sites and smaller Ca ions to prefer M(1) sites in the structure.

Synthesis, characterization and modelling of zinc and silicate co-substituted hydroxyapatite

PubMed Central

Friederichs, Robert J.; Chappell, Helen F.; Shepherd, David V.; Best, Serena M.

2015-01-01

Experimental chemistry and atomic modelling studies were performed here to investigate a novel ionic co-substitution in hydroxyapatite (HA). Zinc, silicate co-substituted HA (ZnSiHA) remained phase pure after heating to 1100°C with Zn and Si amounts of 0.6 wt% and 1.2 wt%, respectively. Unique lattice expansions in ZnSiHA, silicate Fourier transform infrared peaks and changes to the hydroxyl IR stretching region suggested Zn and silicate co-substitution in ZnSiHA. Zn and silicate insertion into HA was modelled using density functional theory (DFT). Different scenarios were considered where Zn substituted for different calcium sites or at a 2b site along the c-axis, which was suspected in singly substituted ZnHA. The most energetically favourable site in ZnSiHA was Zn positioned at a previously unreported interstitial site just off the c-axis near a silicate tetrahedron sitting on a phosphate site. A combination of experimental chemistry and DFT modelling provided insight into these complex co-substituted calcium phosphates that could find biomedical application as a synthetic bone mineral substitute. PMID:26040597

Apatite layer growth on glassy Zr48Cu36Al8Ag8 sputtered titanium for potential biomedical applications

NASA Astrophysics Data System (ADS)

Thanka Rajan, S.; Karthika, M.; Bendavid, Avi; Subramanian, B.

2016-04-01

The bioactivity of magnetron sputtered thin film metallic glasses (TFMGs) of Zr48Cu36Al8Ag8 (at.%) on titanium substrates was tested for bio implant applications. The structural and elemental compositions of TFMGs were analyzed by XRD, XPS and EDAX. X-ray diffraction analysis displayed a broad hump around the incident angle of 30-50°, suggesting that the coatings possess a glassy structure. An in situ crystal growth of hydroxyapatite was observed by soaking the sputtered specimen in simulated body fluid (SBF). The nucleation and growth of a calcium phosphate (Ca-P) bone-like hydroxyapatite on Zr48Cu36Al8Ag8 (at.%) TFMG from SBF was investigated by using XRD, AFM and SEM. The presence of calcium and phosphorus elements was confirmed by EDAX and XPS. In vitro electrochemical corrosion studies indicated that the Zr-based TFMG coating sustain in the stimulated body-fluid (SBF), exhibiting superior corrosion resistance with a lower corrosion penetration rate and electrochemical stability than the bare crystalline titanium substrate.

Crystal Analysis of Multi Phase Calcium Phosphate Nanoparticles Containing Different amount of Magnesium

NASA Astrophysics Data System (ADS)

Gozalian, Afsaneh; Behnamghader, Ali Asghar; Moshkforoush, Arash

In this study, Mg doped hydroxyapatite [(Ca, Mg)10(PO4)6(OH)2] and β-tricalcium phosphate nanoparticles were synthesized via sol gel method. Triethyl phosphite, calcium nitrate tetrahydrate and magnesium nitrate hexahydrate were used as P, Ca and Mg precursors. The ratio of (Ca+Mg)/P and the amount of magnesium (x) were kept constant at 1.67 and ranging x = 0 up to 3 in molecular formula of Ca10-xMgx (PO4)6(OH)2, respectively. Phase composition and chemical structure were performed using X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). Phase percentages, crystallite size, degree of crystallinity and lattice parameters were investigated. The presence of magnesium led to form the Mg doped tricalcium phosphate (β-TCMP) and Mg doped hydroxyapatite (Mg-HA). Based on the results of this study, lattice parameters, degree of crystallinity and crystallite size decreased with magnesium content. In addition, with increasing magnesium content, the amount of CaO phase decreased whereas the amount of MgO phase increased significantly. Obtained results can be used for new biomaterials design.

The usability of ark clam shell (Anadara granosa) as calcium precursor to produce hydroxyapatite nanoparticle via wet chemical precipitate method in various sintering temperature.

PubMed

Khiri, Mohammad Zulhasif Ahmad; Matori, Khamirul Amin; Zainuddin, Norhazlin; Abdullah, Che Azurahanim Che; Alassan, Zarifah Nadakkavil; Baharuddin, Nur Fadilah; Zaid, Mohd Hafiz Mohd

2016-01-01

This paper reported the uses of ark clam shell calcium precursor in order to form hydroxyapatite (HA) via the wet chemical precipitation method. The main objective of this research is to acquire better understanding regarding the effect of sintering temperature in the fabrication of HA. Throughout experiment, the ratio of Ca:P were constantly controlled, between 1.67 and 2.00. The formation of HA at these ratio was confirmed by means of energy-dispersive X-ray spectroscopy analysis. In addition, the effect of sintering temperature on the formation of HA was observed using X-ray diffraction analysis, while the structural and morphology was determined by means of field emission scanning electron microscopy. The formation of HA nanoparticle was recorded (~35-69 nm) in the form of as-synthesize HA powder. The bonding compound appeared in the formation of HA was carried out using Fourier transform infrared spectroscopy such as biomaterials that are expected to find potential applications in orthopedic and biomedical industries .

Preparation of micro-porous bioceramic containing silicon-substituted hydroxyapatite and beta-tricalcium phosphate.

PubMed

Fuh, Lih-Jyh; Huang, Ya-Jing; Chen, Wen-Cheng; Lin, Dan-Jae

2017-06-01

Dimensional instability caused by sintering shrinkage is an inevitable drawback for conventional processing of hydroxyapatite (HA). A new preparation method for biphasic calcium phosphates was developed to increase micro pores and biodegradation without significant dimensional change. Powder pressed HA discs, under 100MPa, were immersed in a colloidal mixture of tetraethoxysilane (TEOS) and ammonium hydroxide for 10min, followed by drying, and then were sintered at 900°C, 1050°C, and 1200°C, respectively. Comparing with pure HA discs, the newly prepared product sintered up to 1200°C contained silicon substituted HA, beta-tricalcium phosphate, and calcium silicate with better micro-porosity, high specific surface area, less sintering shrinkage and the strength maintained. The cytocompatibility test demonstrated a better viability for D1 mice stem cells cultured on TEOS treated HA for 14days compared to the pure HA. This simple TEOS sol-gel pretreatment has the potential to be applied to any existing manufacturing process of HA scaffold for better control of sintering shrinkage, create micropores, and increase biodegradation. Copyright © 2017 Elsevier B.V. All rights reserved.

Research on the preparation, biocompatibility and bioactivity of magnesium matrix hydroxyapatite composite material.

PubMed

Linsheng, Li; Guoxiang, Lin; Lihui, Li

2016-08-12

In this paper, magnesium matrix hydroxyapatite composite material was prepared by electrophoretic deposition method. The optimal process parameters of electrophoretic deposition were HA suspension concentration of 0.02 kg/L, aging time of 10 days and voltage of 60 V. Animal experiment and SBF immersion experiment were used to test the biocompatibility and bioactivity of this material respectively. The SD rats were divided into control group and implant group. The implant surrounding tissue was taken to do tissue biopsy, HE dyed and organizational analysis after a certain amount of time in the SD rat body. The biological composite material was soaked in SBF solution under homeothermic condition. After 40 days, the bioactivity of the biological composite material was evaluated by testing the growth ability of apatite on composite material. The experiment results showed that magnesium matrix hydroxyapatite biological composite material was successfully prepared by electrophoretic deposition method. Tissue hyperplasia, connective tissue and new blood vessels appeared in the implant surrounding soft tissue. No infiltration of inflammatory cells of lymphocytes and megakaryocytes around the implant was found. After soaked in SBF solution, a layer bone-like apatite was found on the surface of magnesium matrix hydroxyapatite biological composite material. The magnesium matrix hydroxyapatite biological composite material could promot calcium deposition and induce bone-like apatite formation with no cytotoxicity and good biocompatibility and bioactivity.

Selective effect of hydroxyapatite nanoparticles on osteoporotic and healthy bone formation correlates with intracellular calcium homeostasis regulation.

PubMed

Zhao, Rui; Xie, Pengfei; Zhang, Kun; Tang, Zhurong; Chen, Xuening; Zhu, Xiangdong; Fan, Yujiang; Yang, Xiao; Zhang, Xingdong

2017-09-01

Adequate bone substitutes osseointegration has been difficult to achieve in osteoporosis. Hydroxyapatite of the osteoporotic bone, secreted by pathologic osteoblasts, had a smaller crystal size and lower crystallinity than that of the normal. To date, little is known regarding the interaction of synthetic hydroxyapatite nanoparticles (HANPs) with osteoblasts born in bone rarefaction. The present study investigated the biological effects of HANPs on osteoblastic cells derived from osteoporotic rat bone (OVX-OB), in comparison with the healthy ones (SHM-OB). A selective effect of different concentrations of HANPs on the two cell lines was observed that the osteoporotic osteoblasts had a higher tolerance. Reductions in cell proliferation, ALP activity, collagen secretion and osteoblastic gene expressions were found in the SHM-OB when administered with HANPs concentration higher than 25µg/ml. In contrast, those of the OVX-OB suffered no depression but benefited from 25 to 250µg/ml HANPs in a dose-dependent manner. We demonstrated that the different effects of HANPs on osteoblasts were associated with the intracellular calcium influx into the endoplasmic reticulum. The in vivo bone defect model further confirmed that, with a critical HANPs concentration administration, the osteoporotic rats had more and mechanically matured new bone formation than the non-treated ones, whilst the sham rats healed no better than the natural healing control. Collectively, the observed epigenetic regulation of osteoblastic cell function by HANPs has significant implication on defining design parameters for a potential therapeutic use of nanomaterials. In this study, we investigated the biological effects of hydroxyapatite nanoparticles (HANPs) on osteoporotic rat bone and the derived osteoblast. Our findings revealed a previously unrecognized phenomenon that the osteoporotic individuals could benefit from higher concentrations of HANPs, as compared with the healthy individuals. The in vivo bone defect model confirmed that, with a critical HANPs concentration administration, the osteoporotic rats had more mechanically matured new bone formation than the non-treated ones, whilst the sham rats healed no better than the natural healing control. The selective effect of HANPs might be associated with the intracellular calcium influx into the endoplasmic reticulum. Collectively, the observed epigenetic regulation by HANPs has significant implication on defining design parameters for a potential therapeutic use of nanomaterials in a pathological condition. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Low temperature synthesis and characterization of carbonated hydroxyapatite nanocrystals

NASA Astrophysics Data System (ADS)

Anwar, Aneela; Asghar, Muhammad Nadeem; Kanwal, Qudsia; Kazmi, Mohsin; Sadiqa, Ayesha

2016-08-01

Carbonate substituted hydroxyapatite (CHA) nanorods were synthesized via coprecipitation method from aqueous solution of calcium nitrate tetrahydrate and diammonium hydrogen phosphate (with urea as carbonate ion source) in the presence of ammonium hydroxide solution at 70 °C at the conditions of pH 11. The obtained powders were physically characterized using transmission electron microscopy (TEM), X-ray powder diffraction analysis (XRD), and FTIR and Raman spectroscopy. The particle size was evaluated by Dynamic light scattering (DLS). The chemical structural analysis of as prepared sample was performed using X-ray photoelectron spectroscopy (XPS). After ageing for 12 h, and heat treatment at 1000 °C for 1 h, the product was obtained as highly crystalline nanorods of CHA.

Polarization-induced surface charges in hydroxyapatite ceramics

NASA Astrophysics Data System (ADS)

Horiuchi, N.; Nakaguki, S.; Wada, N.; Nozaki, K.; Nakamura, M.; Nagai, A.; Katayama, K.; Yamashita, K.

2014-07-01

Calcium hydroxyapatite (HAp; Ca10(PO4)6(OH)2) is a well-known biomaterial that is the main inorganic component of bones and teeth. Control over the surface charge on HAp would be a key advance in the development of the material for tissue engineering. We demonstrate here that surface charge can be induced by an electrical poling process using the Kelvin method. Positive and negative charges were induced on the HAp surface in response to the applied electric field in the poling process. The surface charging is attributed to dipole polarization that is homogeneously distributed in HAp. Additionally, the surface charging is considered to originate from the organization of OH- ions into a polar phase in the structure.

Dynamic Light Scattering and Zeta Potential of Colloidal Mixtures of Amelogenin and Hydroxyapatite in Calcium and Phosphate Rich Ionic Milieus

PubMed Central

Uskoković, Vuk; Odsinada, Roselyn; Djordjevic, Sonia; Habelitz, Stefan

2011-01-01

The concept of zeta-potential has been used for more than a century as a basic parameter in controlling the stability of colloidal suspensions, irrespective of the nature of their particulate ingredients – organic or inorganic. There are prospects that self-assembly of peptide species and the protein-mineral interactions related to biomineralization may be controlled using this fundamental physicochemical parameter. In this study, we have analyzed the particle size and zeta-potential of the full-length recombinant human amelogenin (rH174), the main protein of the developing enamel matrix, in the presence of calcium and phosphate ions and hydroxyapatite (HAP) particles. As calcium and phosphate salts are introduced to rH174 sols in increments, zeta-potential of the rH174 nanospheres is more affected by negatively charged ions, suggesting their tendency to locate within the double charge layer. Phosphate ions have a more pronounced effect on both the zeta-potential and aggregation propensity of rH174 nanospheres compared to calcium ions. The isoelectric point of amelogenin was independent on the ionic strength of the solution and the concentration of calcium and/or phosphate ions. Whereas rH174 shows a higher affinity for phosphate than for calcium, HAP attracts both of these ions to the shear plane of the double layer. The parallel size and zeta-potential analysis of HAP and rH174 colloidal mixtures indicated that at pH 7.4, despite both HAP and rH174 particles being negatively charged, rH174 adsorbs well onto HAP particles. The process is slower at pH 7.4 than at pH 4.5 when the HAP surface is negatively charged and the rH174 nanosphere carries an overall positive charge. The results presented hereby demonstrate that electrostatic interactions can affect the kinetics of the adsorption of rH174 onto HAP. PMID:21146151

Effect of phase composition of calcium silicate phosphate component on properties of brushite based composite cements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sopcak, T., E-mail: tsopcak@imr.saske.sk; Medvecky, L.; Giretova, M.

The composite cement mixtures were prepared by mixing brushite (B) with, the amorphous hydrated calcium silicate phosphate (CSPH) or annealed calcium silicate phosphate (CSP composed of Si-saturated hydroxyapatite, wollastonite and silica) phases and water as liquid component. The contents of the silicate-phosphate phase in composites were 10.30 and 50 wt%. The significant effect of both the Ca/P ratio and different solubility of calcium silicate phosphate component in starting cement systems on setting time and phase composition of the final composite cements was demonstrated. The compressive strength of the set cements increased with the filler addition and the highest value (~more » 48 MPa) exhibited the 50CSP/B cement composite. The final setting times of the composite cements decreased with the CSPH addition from about 25 to 17 min in 50CSHP/B and setting time of CSP/B composites was around 30 min. The higher content of silica in cements caused the precipitation of fine hydroxyapatite particles in the form of nanoneedles or thin plates perpendicularly oriented to sample surface. The analysis of in vitro cement cytotoxicity demonstrated the strong reduction in cytotoxicity of 10CSPH/B composite with time of cultivation (a low cytotoxicity after 9 days of culture) contrary to cements with higher calcium silicate-phosphate content. These results were attributed to the different surface topography of composite substrates and possible stimulation of cell proliferation by the slow continuously release of ions from 10CSPH/B cement. - Highlights: • Ca/P ratio and solubility of calcium silicate-phosphate components affect the self-setting properties of cements. • Strong relationship between the composite in vitro cytotoxicity and surface microtopography was demonstrated. • Plate-like morphology of coarser particles allowed cells to better adhere and proliferate as compared with nanoneedles.« less

Synthesis of spherical calcium phosphate particles for dental and orthopedic applications

PubMed Central

Bohner, Marc; Tadier, Solène; van Garderen, Noémie; de Gasparo, Alex; Döbelin, Nicola; Baroud, Gamal

2013-01-01

Calcium phosphate materials have been used increasingly in the past 40 years as bone graft substitutes in the dental and orthopedic fields. Accordingly, numerous fabrication methods have been proposed and used. However, the controlled production of spherical calcium phosphate particles remains a challenge. Since such particles are essential for the synthesis of pastes and cements delivered into the host bone by minimally-invasive approaches, the aim of the present document is to review their synthesis and applications. For that purpose, production methods were classified according to the used reagents (solutions, slurries, pastes, powders), dispersion media (gas, liquid, solid), dispersion tools (nozzle, propeller, sieve, mold), particle diameters of the end product (from 10 nm to 10 mm), and calcium phosphate phases. Low-temperature calcium phosphates such as monetite, brushite or octacalcium phosphate, as well as high-temperature calcium phosphates, such as hydroxyapatite, β-tricalcium phosphate or tetracalcium phosphate, were considered. More than a dozen production methods and over hundred scientific publications were discussed. PMID:23719177

Interaction of zinc with dental mineral.

PubMed

Ingram, G S; Horay, C P; Stead, W J

1992-01-01

As some currently available toothpastes contain zinc compounds, the reaction of zinc with dental mineral and its effect on crystal growth rates were studied using three synthetic calcium-deficient hydroxyapatites (HAP) as being representative of dental mineral. Zinc was readily acquired by all HAP samples in the absence of added calcium, the amount adsorbed being proportional to the HAP surface area; about 9 mumol Zn/m2 was adsorbed at high zinc concentrations. As zinc was acquired, calcium was released, consistent with 1:1 Ca:Zn exchange. Soluble calcium reduced zinc uptake and similarly, calcium post-treatment released zinc. Pretreatment of HAP with 0.5 mM zinc reduced its subsequent ability to undergo seeded crystal growth, as did extracts of a toothpaste containing 0.5% zinc citrate, even in the presence of saliva. The reverse reaction, i.e. displacement of adsorbed zinc by salivary levels of calcium, however, indicates the mechanism by which zinc can reduce calculus formation in vivo by inhibiting plaque mineralisation without adversely affecting the anti-caries effects of fluoride.

Effect of Hydroxyapatite on Bone Integration in a Rabbit Tibial Defect Model

PubMed Central

Sohn, Sung-Keun; Kim, Kyung-Taek; Kim, Chul-Hong; Ahn, Hee-Bae; Rho, Mee-Sook; Jeong, Min-Ho; Sun, Sang-Kyu

2010-01-01

Background The aim of the present study was to prepare hydroxyapatite (HA) and then characterize its effect on bone integration in a rabbit tibial defect model. The bone formation with different designs of HA was compared and the bony integration of several graft materials was investigated qualitatively by radiologic and histologic study. Methods Ten rabbits were included in this study; two holes were drilled bilaterally across the near cortex and the four holes in each rabbit were divided into four treatment groups (HAP, hydroxyapatite powder; HAC, hydroxyapatite cylinder; HA/TCP, hydroxyapatite/tri-calcium phosphate cylinder, and titanium cylinder). The volume of bone ingrowth and the change of bone mineral density were statistically calculated by computed tomography five times for each treatment group at 0, 2, 4, 6, and 8 weeks after grafting. Histologic analysis was performed at 8 weeks after grafting. Results The HAP group showed the most pronounced effect on the bone ingrowth surface area, which seen at 4, 6, and 8 weeks after graft (p < 0.05). On comparing the change of bone mineral density the bone ingrowth surface area among the 4 groups, there were no statistically significant differences among the groups found for any period (p > 0.05). On histological examination, the HAP group revealed well-recovered cortical bone, but the bone was irregularly thickened and haphazardly admixed with powder. The HAC group showed similar histological features to those of the HA/TCP group; the cortical surface of the newly developed bone was smooth and the bone matrix on the surface of the cylinder was regularly arranged. Conclusions We concluded that both the hydroxyapatite powder and cylinder models investigated in our study may be suitable as a bone substitute in the rabbit tibial defect model, but their characteristic properties are quite different. In contrast to hydroxyapatite powder, which showed better results for the bone ingrowth surface, the hydroxyapatite cylinder showed better results for the sustained morphology. PMID:20514266

Calcium ions and osteoclastogenesis initiate the induction of bone formation by coral-derived macroporous constructs

PubMed Central

Klar, Roland M; Duarte, Raquel; Dix-Peek, Therese; Dickens, Caroline; Ferretti, Carlo; Ripamonti, Ugo

2013-01-01

Coral-derived calcium carbonate/hydroxyapatite macroporous constructs of the genus Goniopora with limited hydrothermal conversion to hydroxyapatite (7% HA/CC) initiate the induction of bone formation. Which are the molecular signals that initiate pattern formation and the induction of bone formation? To evaluate the role of released calcium ions and osteoclastogenesis, 7% HA/CC was pre-loaded with either 500 μg of the calcium channel blocker, verapamil hydrochloride, or 240 μg of the osteoclast inhibitor, biphosphonate zoledronate, and implanted in the rectus abdominis muscle of six adult Chacma baboons Papio ursinus. Generated tissues on days 15, 60 and 90 were analysed by histomorphometry and qRT-PCR. On day 15, up-regulation of type IV collagen characterized all the implanted constructs correlating with vascular invasion. Zoledronate-treated specimens showed an important delay in tissue patterning and morphogenesis with limited bone formation. Osteoclastic inhibition yielded minimal, if any, bone formation by induction. 7% HA/CC pre-loaded with the Ca++ channel blocker verapamil hydrochloride strongly inhibited the induction of bone formation. Down-regulation of bone morphogenetic protein-2 (BMP-2) together with up-regulation of Noggin genes correlated with limited bone formation in 7% HA/CC pre-loaded with either verapamil or zoledronate, indicating that the induction of bone formation by coral-derived macroporous constructs is via the BMPs pathway. The spontaneous induction of bone formation is initiated by a local peak of Ca++ activating stem cell differentiation and the induction of bone formation. PMID:24106923

Site-specific equilibrium isotopic fractionation of oxygen, carbon and calcium in apatite

NASA Astrophysics Data System (ADS)

Aufort, Julie; Ségalen, Loïc; Gervais, Christel; Paulatto, Lorenzo; Blanchard, Marc; Balan, Etienne

2017-12-01

The stable isotope composition of biogenic apatite is an important geochemical marker that can record environmental parameters and is widely used to infer past climates, biomineralization processes, dietary preferences and habitat of vertebrates. In this study, theoretical equilibrium isotopic fractionation of oxygen, carbon and calcium in hydroxyapatite and carbonate-bearing hydroxyapatite is investigated using first-principles methods based on density-functional theory and compared to the theoretical isotopic fractionation properties of calcite, CO2 and H2O. Considering the variability of apatite crystal-chemistry, special attention is given to specific contributions of crystal sites to isotopic fractionation. Significant internal fractionation is calculated for oxygen and carbon isotopes in CO3 between the different structural sites occupied by carbonate groups in apatite (typically 7‰ for both 18O/16O and 13C/12C fractionation at 37 °C). Compared with calcite-water oxygen isotope fractionation, occurrence of A-type substitution in apatite structure, in addition to the main B-type substitution, could explain the larger temperature dependence of oxygen isotope fractionation measured at low temperature between carbonate in apatite and water. Theoretical internal fractionation of oxygen isotopes between carbonate and phosphate in B-type carbonated apatite (∼8‰ at 37 °C) is consistent with experimental values obtained from modern and well-preserved fossil bio-apatites. Concerning calcium, theoretical results suggest a small fractionation between apatite and calcite (-0.17‰ at 37 °C). Internal fractionation reaching 0.8‰ at 37 °C occurs between the two Ca sites in hydroxyapatite. Furthermore, the Ca isotopic fractionation properties of apatite are affected by the occurrence of carbonate groups, which could contribute to the variability observed on natural samples. Owing to the complexity of apatite crystal-chemistry and in light of the theoretical results, measurements of site-specific isotopic fractionation properties could improve our understanding and the interpretation of isotopic records in apatites.

Bioactive calcium phosphate-based glasses and ceramics and their biomedical applications: A review.

PubMed

Islam, Md Towhidul; Felfel, Reda M; Abou Neel, Ensanya A; Grant, David M; Ahmed, Ifty; Hossain, Kazi M Zakir

2017-01-01

An overview of the formation of calcium phosphate under in vitro environment on the surface of a range of bioactive materials (e.g. from silicate, borate, and phosphate glasses, glass-ceramics, bioceramics to metals) based on recent literature is presented in this review. The mechanism of bone-like calcium phosphate (i.e. hydroxyapatite) formation and the test protocols that are either already in use or currently being investigated for the evaluation of the bioactivity of biomaterials are discussed. This review also highlights the effect of chemical composition and surface charge of materials, types of medium (e.g. simulated body fluid, phosphate-buffered saline and cell culture medium) and test parameters on their bioactivity performance. Finally, a brief summary of the biomedical applications of these newly formed calcium phosphate (either in the form of amorphous or apatite) is presented.

The effects of excess calcium on the handling and mechanical properties of hydrothermal derived calcium phosphate bone cement

NASA Astrophysics Data System (ADS)

Razali, N. N.; Sukardi, M. A.; Sopyan, I.; Mel, M.; Salleh, H. M.; Rahman, M. M.

2018-01-01

The objective of this study is to determine the effects of excess calcium on the handling and mechanical properties of hydrothermal derived calcium phosphate cement (CPC) for bone filling applications. Hydroxyapatite powder was synthesized via hydrothermal method using calcium oxide, CaO and ammonium dihydrogen phosphate, NH4H2PO4 as the calcium and phosphorus precursors respectively. The effects of calcium excess were evaluated by varying the CaO content at 0, 5 and 15 mole %. The precursors were then refluxed in distilled water at 90-100°C and dried overnight until the calcium phosphate powder was formed. CPC was then produced by mixing the synthesized powder with distilled water at the powder-to-liquid (P/L) ratio of 1.5. The result from the morphological properties of CPC shows the increase in agglomeration and particles size with 5 mole % of calcium excess but decreased with 15 mole % of calcium excess in CPC. This result was in agreement with the compressive strength result where the CPC increased its strength with 5 mole % of calcium excess but reduced with 15 mole % of calcium excess. The excess in calcium precursor also significantly improved the setting time but reduced the injectability of CPC.

C-terminal Amidation of an Osteocalcin-derived Peptide Promotes Hydroxyapatite Crystallization*

PubMed Central

Hosseini, Samaneh; Naderi-Manesh, Hossein; Mountassif, Driss; Cerruti, Marta; Vali, Hojatollah; Faghihi, Shahab

2013-01-01

Genesis of natural biocomposite-based materials, such as bone, cartilage, and teeth, involves interactions between organic and inorganic systems. Natural biopolymers, such as peptide motif sequences, can be used as a template to direct the nucleation and crystallization of hydroxyapatite (HA). In this study, a natural motif sequence consisting of 13 amino acids present in the first helix of osteocalcin was selected based on its calcium binding ability and used as substrate for nucleation of HA crystals. The acidic (acidic osteocalcin-derived peptide (OSC)) and amidic (amidic osteocalcin-derived peptide (OSN)) forms of this sequence were synthesized to investigate the effects of different C termini on the process of biomineralization. Electron microscopy analyses show the formation of plate-like HA crystals with random size and shape in the presence of OSN. In contrast, spherical amorphous calcium phosphate is formed in the presence of OSC. Circular dichroism experiments indicate conformational changes of amidic peptide to an open and regular structure as a consequence of interaction with calcium and phosphate. There is no conformational change detectable in OSC. It is concluded that HA crystal formation, which only occurred in OSN, is attributable to C-terminal amidation of a natural peptide derived from osteocalcin. It is also proposed that natural peptides with the ability to promote biomineralization have the potential to be utilized in hard tissue regeneration. PMID:23362258

Crustacean derived calcium phosphate systems: Application in defluoridation of drinking water in East African rift valley.

PubMed

Wagutu, Agatha W; Machunda, Revocatus; Jande, Yusufu Abeid Chande

2018-04-05

Calcium phosphate adsorbents, derived from prawns and crabs shell biomass wastes have been developed using wet chemistry and low temperature treatment. The adsorbents were characterized by X-ray diffractometry and Fourier transform infrared spectroscopy. Batch adsorption test were carried out to investigate their effectiveness in adsorption of fluoride from ground and surface waters. Adsorption capacities were compared with bone char and synthetic hydroxyapatite (CCHA). Results indicate that prawns derived adsorbent (PHA) formed hexagonal structure with phases identifiable with hydroxyapatite while crabs based adsorbent (CHA) formed predominantly monoclinic structure with crystalline phase characteristic of brushite. Vibrational analysis and kinetic studies predicted defluoridation occurred mainly by ion exchange and ion adsorption mechanisms. Defluoridation capacity of the adsorbents was found to be superior compared to bone char and CCHA. CHA was the most effective with efficiencies above 92% and highest capacity of 13.6 mg/g in field water with fluoride concentration of 5-70 mg/L. PHA had highest capacity of 8.5 mg/g which was still better than 2.6 mg/g recorded by CCHA and bone char. Adsorption was best described by pseudo 2nd order kinetics. The findings indicate that crustacean derived calcium phosphate systems have better potential for defluoridation than traditional bone char and synthetic systems. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Properties of novel bone hemostat prepared using sugar-modified hydroxyapatite, phosphoryl oligosaccharides of calcium and thermoplastic resin

NASA Astrophysics Data System (ADS)

Mimira, Tokio; Umeda, Tomohiro; Musha, Yoshiro; Itatani, Kiyoshi

2013-12-01

A novel hemostatic agent was prepared using phosphoryl oligosaccharides of calcium (POs-Ca), hydroxyapatite (Ca10(PO4)6(OH)2; HAp) obtained by the hydrolysis of POs-Ca or sugar-containing HAp (s-HAp; 60.3 mass% calcium-deficient HAp and 39.5 mass% organic materials, Ca/P ratio = 1.56) and thermoplastic resin (the mixture of random copolymer of ethylene oxide/propylene oxide (EPO) and polyethylene oxide (EO); EPO : EO : water = 25 : 15 : 60 (mass ratio); 25EPO-15EO). The gel formed by mixing 25EPO-15EO with water (25EPO-15EO/water mass ratio: 0.20) was flash frozen at -80°C, freeze-dried at -50°C for 15 h and then ground using mixer. The consistency conditions of hemostats mixed with POs-Ca or s-HAp were optimized for the practical uses. The mean stanching times of hemostats were: s-HAp/25EPO-15EO (8.2 h; s-HAp/25EPO-15EO = 0.20) > 25EPO-15EO (5.3 h) > POs-Ca/25EPO-15EO (4.7 h; POs-Ca/25EPO-15EO = 0.20). The gentamicin, a typical antibiotic agent, loaded s-HAp/25EPO-15EO composite hemostat showed the steady state releasing in phosphate buffered saline till 10 h immersion at 37.0°C.

Sol gel derived hydroxyapatite coatings on titanium and its alloy Ti6Al4V

NASA Astrophysics Data System (ADS)

Stoch, A.; Jastrzebski, W.; Długoń, E.; Lejda, W.; Trybalska, B.; Stoch, G. J.; Adamczyk, A.

2005-06-01

Titanium has been used for many medical and dental applications; however, its joining to a living bone is not satisfactorily good or the implant integration with bone tissue takes several months.The aim of this work is to produce hydroxyapatite (HAP) coatings on titanium and its alloy for facilitating and shortening the processes towards osseointegration. HAP coatings were obtained by sol-gel method with sol solutions prepared from calcium nitrate tetrahydrate and triammonium phosphate trihydrate as the calcium and phosphorous sources. Two types of gelatine were added to the sol: agar-agar or animals gelatine. Both were found to enhance the formation and stability of amorphous HAP using soluble salts as the sources of calcium and phosphate. HAP coatings were deposited from HAP-GEL sol using dip-withdrawal technique, then the plates were dried and annealed at temperatures 460-750 °C. FTIR spectroscopy and XRD analysis were used to study the phase composition of phosphate coatings. Morphology and chemical analysis of HAP layers was performed using a scanning electron microscope equipped with an energy dispersive X-ray analyser (SEM+EDX). The biological activity of sol-gel phosphate coatings was observed during thermostatic held in simulated body fluid (SBF). It was found that chemical composition and structure of HAP coatings depends on pH and final thermal treatment of the layer.

Ionic liquid as a potential solvent for preparation of collagen-alginate-hydroxyapatite beads as bone filler.

PubMed

Iqbal, Bushra; Sarfaraz, Zenab; Muhammad, Nawshad; Ahmad, Pervaiz; Iqbal, Jibran; Khan, Zia Ul Haq; Gonfa, Girma; Iqbal, Farasat; Jamal, Arshad; Rahim, Abdur

2018-07-01

In this study, collagen/alginate/hydroxyapatite beads having different proportions were prepared as bone fillers for the restoration of osteological defects. Ionic liquid was used to dissolve the collagen and subsequently the solution was mixed with sodium alginate solution. Hydroxyapatite was added in different proportions, with the rationale to enhance mechanical as well as biological properties. The prepared solutions were given characteristic bead shapes by dropwise addition into calcium chloride solution. The prepared beads were characterized using FTIR, XRD, TGA and SEM analysis. Microhardness testing was used to evaluate the mechanical properties. The prepared beads were investigated for water adsorption behavior to ascertain its ability for body fluid uptake and adjusted accordingly to the bone cavity. Drug loading and subsequently the antibacterial activity was investigated for the prepared beads. The biocompatibility was assessed using the hemolysis testing and cell proliferation assay. The prepared collagen-alginate-HA beads, having biocompatibility and good mechanical properties, have showed an option of promising biologically active bone fillers for bone regeneration.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ji Shidong; Murakami, Setsuaki; Kamitakahara, Masanobu

The titania/hydroxyapatite composite granular photo-catalyst with novel microstructure was fabricated by the process based on the liquid immiscibility effect and followed by precalcination and hydrothermal treatment from commercially available powders of {alpha}-Tri-calcium phosphate and TiO{sub 2}. XRD, SEM, BET, optical microscopy and UV-vis spectrophotometer were applied to characterize the prepared photo-catalyst. Microstructure analysis indicated that the granule was weaved by rod-shaped hydroxyapatite crystals whose surface was covered by nano-sized TiO{sub 2}. In the composite granules, the active surface of anatase was retained effectively. With the hybridization of TiO{sub 2} and HAp, a 16-nm blue-shift of absorption edge could be observedmore » and the crystallinity of anatase could be enhanced by precalcination. The granules with the rod-shaped hydroxyapatite crystals performing as scaffold work as three-dimensional high porous, size-controllable small reactor. The phase and microstructure transformation of the granule before and after hydrothermal treatment was investigated and its decomposition ability was evaluated by using Methylene blue as a target pollutant compound.« less

Preparation of hydroxyapatite nanoparticles by sol-gel method with optimum processing parameters

NASA Astrophysics Data System (ADS)

Yusoff, Yusriha Mohd; Salimi, Midhat Nabil Ahmad; Anuar, Adilah

2015-05-01

Many studies have been carried out in order to prepare hydroxyapatite (HAp) by various methods. In this study, we focused on the preparation of HAp nanoparticles by using sol-gel technique in which few parameters are optimized which were stirring rate, aging time and sintering temperature. HAp nanoparticles were prepared by using precursors of calcium nitrate tetrahydrate, Ca(NO3)2.4H2O and phosphorous pentoxide, P2O5. Both precursors are mixed in ethanol respectively before they were mixed together in which it formed a stable sol. Fourier transform infrared (FTIR), X-ray diffraction (XRD) and Scanning electron microscopy (SEM) were used for its characterization in terms of functional group, phase composition, crystallite size and morphology of the nanoparticles produced. FTIR spectra showed that the functional groups that present in all five samples were corresponding to the formation of HAp. Besides, XRD shows that only one phase was formed which was hydroxyapatite. Meanwhile, SEM shows that the small particles combine together to form agglomeration.

Osteoblast and osteoclast responses to A/B type carbonate-substituted hydroxyapatite ceramics for bone regeneration.

PubMed

Germaini, Marie-Michèle; Detsch, Rainer; Grünewald, Alina; Magnaudeix, Amandine; Lalloue, Fabrice; Boccaccini, Aldo R; Champion, Eric

2017-06-06

The influence of carbonate substitution (4.4 wt%, mixed A/B type) in hydroxyapatite ceramics for bone remodeling scaffolds was investigated by separately analyzing the response of pre-osteoblasts and osteoclast-like cells. Carbonated hydroxyapatite (CHA) (Ca 9.5 (PO 4 ) 5.5 (CO 3 ) 0.5 (OH)(CO 3 ) 0.25 -CHA), mimicking the chemical composition of natural bone mineral, and pure hydroxyapatite (HA) (Ca 10 (PO 4 ) 6 (OH) 2 -HA) porous ceramics were processed to obtain a similar microstructure and surface physico-chemical properties (grain size, porosity ratio and pore size, surface roughness and zeta potential). The biological behavior was studied using MC3T3-E1 pre-osteoblastic and RAW 264.7 monocyte/macrophage cell lines. Chemical dissolution in the culture media and resorption lacunae produced by osteoclasts occur with both HA and CHA ceramics, but CHA exhibits much higher dissolution and greater bioresorption ability. CHA ceramics promoted a significantly higher level of pre-osteoblast proliferation. Osteoblastic differentiation, assessed by qRT-PCR of RUNX2 and COLIA2, and pre-osteoclastic proliferation and differentiation were not significantly different on CHA or HA ceramics but cell viability and metabolism were significantly greater on CHA ceramics. Thus, the activity of both osteoclast-like and osteoblastic cells was influenced by the carbonate substitution in the apatite structure. Furthermore, CHA showed a particularly interesting balance between biodegradation, by osteoclasts and chemical dissolution, and osteogenesis through osteoblasts' activity, to stimulate bone regeneration. It is hypothesized that this amount of 4.4 wt% carbonate substitution leads to an adapted concentration of calcium in the fluid surrounding the ceramic to stimulate the activity of cells. These results highlight the superior biological behavior of microporous 4.4 wt% A/B CHA ceramics that could beneficially replace the commonly used HA of biphasic calcium phosphates for future applications in bone tissue engineering.

Formulation and optimisation of raft-forming chewable tablets containing H2 antagonist

PubMed Central

Prajapati, Shailesh T; Mehta, Anant P; Modhia, Ishan P; Patel, Chhagan N

2012-01-01

Purpose: The purpose of this research work was to formulate raft-forming chewable tablets of H2 antagonist (Famotidine) using a raft-forming agent along with an antacid- and gas-generating agent. Materials and Methods: Tablets were prepared by wet granulation and evaluated for raft strength, acid neutralisation capacity, weight variation, % drug content, thickness, hardness, friability and in vitro drug release. Various raft-forming agents were used in preliminary screening. A 23 full-factorial design was used in the present study for optimisation. The amount of sodium alginate, amount of calcium carbonate and amount sodium bicarbonate were selected as independent variables. Raft strength, acid neutralisation capacity and drug release at 30 min were selected as responses. Results: Tablets containing sodium alginate were having maximum raft strength as compared with other raft-forming agents. Acid neutralisation capacity and in vitro drug release of all factorial batches were found to be satisfactory. The F5 batch was optimised based on maximum raft strength and good acid neutralisation capacity. Drug–excipient compatibility study showed no interaction between the drug and excipients. Stability study of the optimised formulation showed that the tablets were stable at accelerated environmental conditions. Conclusion: It was concluded that raft-forming chewable tablets prepared using an optimum amount of sodium alginate, calcium carbonate and sodium bicarbonate could be an efficient dosage form in the treatment of gastro oesophageal reflux disease. PMID:23580933

Formulation and optimisation of raft-forming chewable tablets containing H2 antagonist.

PubMed

Prajapati, Shailesh T; Mehta, Anant P; Modhia, Ishan P; Patel, Chhagan N

2012-10-01

The purpose of this research work was to formulate raft-forming chewable tablets of H2 antagonist (Famotidine) using a raft-forming agent along with an antacid- and gas-generating agent. Tablets were prepared by wet granulation and evaluated for raft strength, acid neutralisation capacity, weight variation, % drug content, thickness, hardness, friability and in vitro drug release. Various raft-forming agents were used in preliminary screening. A 2(3) full-factorial design was used in the present study for optimisation. The amount of sodium alginate, amount of calcium carbonate and amount sodium bicarbonate were selected as independent variables. Raft strength, acid neutralisation capacity and drug release at 30 min were selected as responses. Tablets containing sodium alginate were having maximum raft strength as compared with other raft-forming agents. Acid neutralisation capacity and in vitro drug release of all factorial batches were found to be satisfactory. The F5 batch was optimised based on maximum raft strength and good acid neutralisation capacity. Drug-excipient compatibility study showed no interaction between the drug and excipients. Stability study of the optimised formulation showed that the tablets were stable at accelerated environmental conditions. It was concluded that raft-forming chewable tablets prepared using an optimum amount of sodium alginate, calcium carbonate and sodium bicarbonate could be an efficient dosage form in the treatment of gastro oesophageal reflux disease.

[Quantitative mineralogical analyzes of kidney stones and diagnosing metabolic disorders in female patients with calcium oxalate urolithiasis].

PubMed

Kustov, A V; Moryganov, M A; Strel'nikov, A I; Zhuravleva, N I; Airapetyan, A O

2016-02-01

To conduct a complex examination of female patients with calcium oxalate urolithiasis to detect metabolic disorders, leading to stone formation. The study was carried out using complex physical and chemical methods, including quantitative X-ray phase analysis of urinary stones, pH measurement, volumetry, urine and blood spectrophotometry. Quantitative mineralogical composition of stones, daily urine pH profile, daily urinary excretion of ions of calcium, magnesium, oxalate, phosphate, citrate and uric acid were determined in 20 female patients with calcium oxalate stones. We have shown that most of the stones comprised calcium oxalate monohydrate or mixtures of calcium oxalate dihydrate and hydroxyapatite. Among the identified abnormalities, the most frequent were hypocitraturia and hypercalciuria - 90 and 45%, respectively. Our findings revealed that the daily secretion of citrate and oxalate in patients older than 50 years was significantly lower than in younger patients. In conclusion, daily urinary citrate excretion should be measured in female patients with calcium oxalate stones. This is necessary both to determine the causes of stone formation, and to monitor the effectiveness of citrate therapy.

21 CFR 74.2053 - D&C Black No. 3.

Code of Federal Regulations, 2011 CFR

2011-04-01

... may be avoided by current good manufacturing practices: (1) Calcium hydroxyapatite (CaO and P2O5), not... milligrams (mg)/kilogram (kg) (3 parts per million (ppm)); (6) Lead, not more than 10 mg/kg (10 ppm); and (7) Total polycyclic aromatic hydrocarbons (PAHs), not more than 5 mg/kg (5 ppm). (c) Uses and restrictions...

21 CFR 74.2053 - D&C Black No. 3.

Code of Federal Regulations, 2014 CFR

2014-04-01

... may be avoided by current good manufacturing practices: (1) Calcium hydroxyapatite (CaO and P2O5), not... milligrams (mg)/kilogram (kg) (3 parts per million (ppm)); (6) Lead, not more than 10 mg/kg (10 ppm); and (7) Total polycyclic aromatic hydrocarbons (PAHs), not more than 5 mg/kg (5 ppm). (c) Uses and restrictions...

21 CFR 74.2053 - D&C Black No. 3.

Code of Federal Regulations, 2013 CFR

2013-04-01

... may be avoided by current good manufacturing practices: (1) Calcium hydroxyapatite (CaO and P2O5), not... milligrams (mg)/kilogram (kg) (3 parts per million (ppm)); (6) Lead, not more than 10 mg/kg (10 ppm); and (7) Total polycyclic aromatic hydrocarbons (PAHs), not more than 5 mg/kg (5 ppm). (c) Uses and restrictions...

21 CFR 74.2053 - D&C Black No. 3.

Code of Federal Regulations, 2012 CFR

2012-04-01

... may be avoided by current good manufacturing practices: (1) Calcium hydroxyapatite (CaO and P2O5), not... milligrams (mg)/kilogram (kg) (3 parts per million (ppm)); (6) Lead, not more than 10 mg/kg (10 ppm); and (7) Total polycyclic aromatic hydrocarbons (PAHs), not more than 5 mg/kg (5 ppm). (c) Uses and restrictions...

Hybrid Calcium Phosphate Coatings for Titanium Implants

NASA Astrophysics Data System (ADS)

Kharapudchenko, E.; Ignatov, V.; Ivanov, V.; Tverdokhlebov, S.

2017-01-01

Hybrid multilayer coatings were obtained on titanium substrates by the combination of two methods: the micro-arc oxidation in phosphoric acid solution with the addition of calcium compounds to high supersaturated state and RF magnetron sputtering of the target made of synthetic hydroxyapatite. 16 different groups of coatings were formed on titanium substrates and in vitro studies were conducted in accordance with ISO 23317 in the solution simulating body fluid. The studies using SEM, XRD of the coatings of the samples before and after exposure to SBF were performed. The features of morphology, chemical and phase composition of the studied coatings are shown.

X-ray phase contrast imaging of the breast: Analysis of tissue simulating materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vedantham, Srinivasan; Karellas, Andrew

Purpose: Phase contrast imaging, particularly of the breast, is being actively investigated. The purpose of this work is to investigate the x-ray phase contrast properties of breast tissues and commonly used breast tissue substitutes or phantom materials with an aim of determining the phantom materials best representative of breast tissues. Methods: Elemental compositions of breast tissues including adipose, fibroglandular, and skin were used to determine the refractive index, n= 1 -{delta}+i {beta}. The real part of the refractive index, specifically the refractive index decrement ({delta}), over the energy range of 5-50 keV were determined using XOP software (version 2.3, Europeanmore » Synchrotron Radiation Facility, France). Calcium oxalate and calcium hydroxyapatite were considered to represent the material compositions of microcalcifications in vivo. Nineteen tissue substitutes were considered as possible candidates to represent adipose tissue, fibroglandular tissue and skin, and four phantom materials were considered as possible candidates to represent microcalcifications. For each material, either the molecular formula, if available, or the elemental composition based on weight fraction, was used to determine {delta}. At each x-ray photon energy, the absolute percent difference in {delta} between the breast tissue and the substitute material was determined, from which three candidates were selected. From these candidate tissue substitutes, the material that minimized the absolute percent difference in linear attenuation coefficient {mu}, and hence {beta}, was considered to be best representative of that breast tissue. Results: Over the energy range of 5-50 keV, while the {delta} of CB3 and fibroglandular tissue-equivalent material were within 1% of that of fibroglandular tissue, the {mu} of fibroglandular tissue-equivalent material better approximated the fibroglandular tissue. While the {delta} of BR10 and adipose tissue-equivalent material were within 1% of that of adipose tissue, the tissue-equivalent material better approximated the adipose tissue in terms of {mu}. Polymethyl methacrylate, a commonly used tissue substitute, exhibited {delta} greater than fibroglandular tissue by {approx}12%. The A-150 plastic closely approximated the skin. Several materials exhibited {delta} between that of adipose and fibroglandular tissue. However, there was an energy-dependent mismatch in terms of equivalent fibroglandular weight fraction between {delta} and {mu} for these materials. For microcalcifications, aluminum and calcium carbonate were observed to straddle the {delta} and {mu} of calcium oxalate and calcium hydroxyapatite. Aluminum oxide, commonly used to represent microcalcifications in the American College of Radiology recommended phantoms for accreditation exhibited {delta} greater than calcium hydroxyapatite by {approx}23%. Conclusions: A breast phantom comprising A-150 plastic to represent the skin, commercially available adipose and fibroglandular tissue-equivalent formulations to represent adipose and fibroglandular tissue, respectively, was found to be best suited for x-ray phase-sensitive imaging of the breast. Calcium carbonate or aluminum can be used to represent microcalcifications.« less

X-ray phase contrast imaging of the breast: Analysis of tissue simulating materials1

PubMed Central

Vedantham, Srinivasan; Karellas, Andrew

2013-01-01

Purpose: Phase contrast imaging, particularly of the breast, is being actively investigated. The purpose of this work is to investigate the x-ray phase contrast properties of breast tissues and commonly used breast tissue substitutes or phantom materials with an aim of determining the phantom materials best representative of breast tissues. Methods: Elemental compositions of breast tissues including adipose, fibroglandular, and skin were used to determine the refractive index, n = 1 − δ + i β. The real part of the refractive index, specifically the refractive index decrement (δ), over the energy range of 5–50 keV were determined using XOP software (version 2.3, European Synchrotron Radiation Facility, France). Calcium oxalate and calcium hydroxyapatite were considered to represent the material compositions of microcalcifications in vivo. Nineteen tissue substitutes were considered as possible candidates to represent adipose tissue, fibroglandular tissue and skin, and four phantom materials were considered as possible candidates to represent microcalcifications. For each material, either the molecular formula, if available, or the elemental composition based on weight fraction, was used to determine δ. At each x-ray photon energy, the absolute percent difference in δ between the breast tissue and the substitute material was determined, from which three candidates were selected. From these candidate tissue substitutes, the material that minimized the absolute percent difference in linear attenuation coefficient μ, and hence β, was considered to be best representative of that breast tissue. Results: Over the energy range of 5–50 keV, while the δ of CB3 and fibroglandular tissue-equivalent material were within 1% of that of fibroglandular tissue, the μ of fibroglandular tissue-equivalent material better approximated the fibroglandular tissue. While the δ of BR10 and adipose tissue-equivalent material were within 1% of that of adipose tissue, the tissue-equivalent material better approximated the adipose tissue in terms of μ. Polymethyl methacrylate, a commonly used tissue substitute, exhibited δ greater than fibroglandular tissue by ∼12%. The A-150 plastic closely approximated the skin. Several materials exhibited δ between that of adipose and fibroglandular tissue. However, there was an energy-dependent mismatch in terms of equivalent fibroglandular weight fraction between δ and μ for these materials. For microcalcifications, aluminum and calcium carbonate were observed to straddle the δ and μ of calcium oxalate and calcium hydroxyapatite. Aluminum oxide, commonly used to represent microcalcifications in the American College of Radiology recommended phantoms for accreditation exhibited δ greater than calcium hydroxyapatite by ∼23%. Conclusions: A breast phantom comprising A-150 plastic to represent the skin, commercially available adipose and fibroglandular tissue-equivalent formulations to represent adipose and fibroglandular tissue, respectively, was found to be best suited for x-ray phase-sensitive imaging of the breast. Calcium carbonate or aluminum can be used to represent microcalcifications. PMID:23556900

Synthesis and synchrotron characterisation of novel dual-template of hydroxyapatite scaffolds with controlled size porous distribution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lima, Thiago A. R. M.; Ilavsky, Jan; Hammons, Joshua

Hydroxyapatite (HAP) scaffolds with a hierarchical porous architecture were prepared by a new dual-template (corn starch and cetyltrimethylammonium bromide (CTAB) surfactant) used to cast HAP nanoparticles and development scaffolds with size hierarchical porous distribution. The Powder X-Ray diffraction (XRD) results showed that only the HAP crystalline phase is present in the samples after calcination; the Scanning Electron Microscopy (SEM) combined with Small Angle (SAXS) and Ultra-Small Angle X-ray Scattering (USAXS) techniques showed that the porous arrangement is promoted by needle-like HAP nanoparticles, and that the pore size distributions depend on the drip-order of the calcium and the phosphate solutions duringmore » the template preparation stage.« less

Synthesis, characterization, in vitro anti-proliferative and hemolytic activity of hydroxyapatite

NASA Astrophysics Data System (ADS)

Palanivelu, R.; Ruban Kumar, A.

2014-06-01

Hydroxyapatite (Ca10(PO4)6(OH)2, HAP) nanoparticles are widely used in several biomedical applications due to its compositional similarities to bone mineral, excellent biocompatibility and bioactivity, osteoconductivity. In this present investigation, HAP nanoparticles synthesized by precipitation technique using calcium nitrate and di-ammonium phosphate. The crystalline nature and the functional group analysis are confirmed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Fourier transform Raman spectroscopy (FT-Raman) respectively. The morphological observations are ascertained from field emission electron scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). In vitro anti-proliferative and hemolytic activities are carried out on the synthesized HAP samples and the studies reveals that HAP have mild activity against erythrocytes.

Structural and physical properties of antibacterial Ag-doped nano-hydroxyapatite synthesized at 100°C

PubMed Central

2011-01-01

Synthesis of nanosized particle of Ag-doped hydroxyapatite with antibacterial properties is in the great interest in the development of new biomedical applications. In this article, we propose a method for synthesized the Ag-doped nanocrystalline hydroxyapatite. A silver-doped nanocrystalline hydroxyapatite was synthesized at 100°C in deionized water. Other phase or impurities were not observed. Silver-doped hydroxyapatite nanoparticles (Ag:HAp) were performed by setting the atomic ratio of Ag/[Ag + Ca] at 20% and [Ca + Ag]/P as 1.67. The X-ray diffraction studies demonstrate that powders made by co-precipitation at 100°C exhibit the apatite characteristics with good crystal structure and no new phase or impurity is found. The scanning electron microscopy (SEM) observations suggest that these materials present a little different morphology, which reveals a homogeneous aspect of the synthesized particles for all samples. The presence of calcium (Ca), phosphor (P), oxygen (O), and silver (Ag) in the Ag:HAp is confirmed by energy dispersive X-ray (EDAX) analysis. FT-IR and FT-Raman spectroscopies revealed that the presence of the various vibrational modes corresponds to phosphates and hydroxyl groups. The strain of Staphylococcus aureus was used to evaluate the antibacterial activity of the Ca10-xAgx(PO4)6(OH)2 (x = 0 and 0.2). In vitro bacterial adhesion study indicated a significant difference between HAp (x = 0) and Ag:HAp (x = 0.2). The Ag:Hap nanopowder showed higher inhibition. PMID:22136671

Structural and physical properties of antibacterial Ag-doped nano-hydroxyapatite synthesized at 100°C

NASA Astrophysics Data System (ADS)

Ciobanu, Carmen Steluta; Massuyeau, Florian; Constantin, Liliana Violeta; Predoi, Daniela

2011-12-01

Synthesis of nanosized particle of Ag-doped hydroxyapatite with antibacterial properties is in the great interest in the development of new biomedical applications. In this article, we propose a method for synthesized the Ag-doped nanocrystalline hydroxyapatite. A silver-doped nanocrystalline hydroxyapatite was synthesized at 100°C in deionized water. Other phase or impurities were not observed. Silver-doped hydroxyapatite nanoparticles (Ag:HAp) were performed by setting the atomic ratio of Ag/[Ag + Ca] at 20% and [Ca + Ag]/P as 1.67. The X-ray diffraction studies demonstrate that powders made by co-precipitation at 100°C exhibit the apatite characteristics with good crystal structure and no new phase or impurity is found. The scanning electron microscopy (SEM) observations suggest that these materials present a little different morphology, which reveals a homogeneous aspect of the synthesized particles for all samples. The presence of calcium (Ca), phosphor (P), oxygen (O), and silver (Ag) in the Ag:HAp is confirmed by energy dispersive X-ray (EDAX) analysis. FT-IR and FT-Raman spectroscopies revealed that the presence of the various vibrational modes corresponds to phosphates and hydroxyl groups. The strain of Staphylococcus aureus was used to evaluate the antibacterial activity of the Ca10- x Ag x (PO4)6(OH)2 ( x = 0 and 0.2). In vitro bacterial adhesion study indicated a significant difference between HAp ( x = 0) and Ag:HAp ( x = 0.2). The Ag:Hap nanopowder showed higher inhibition.

Activation of Osteoblastic Function on Titanium Surface with Titanium-Doped Hydroxyapatite Nanoparticle Coating: An In Vitro Study.

PubMed

Nakazawa, Masahiro; Yamada, Masahiro; Wakamura, Masato; Egusa, Hiroshi; Sakurai, Kaoru

Titanium-doped hydroxyapatite (TiHA) nanoparticles contain titanium atoms in the hydroxyapatite lattice, which can physicochemically functionalize the titanium surface without modification of the surface topography. This study aimed to evaluate the physicochemical properties of machined or microroughened titanium surfaces coated with TiHA nanoparticles and the functions of osteoblasts cultured on them. Titanium disks with commercially available surface topography, such as machined or sandblasted, large-grit, and acid-etched (SLA) surfaces, were coated with TiHA. The disks with original or TiHA-coated surfaces were evaluated in topography, wettability, and chemical composition. Osteoblastic cells from rat femurs were cultured on the disks and evaluated in proliferation and differentiation. TiHA coating changed from hydrophobicity to hydrophilicity on both machined and SLA surfaces. Calcium and phosphate atoms were detected all over the surface with TiHA coating regardless of the surface topography. However, the considerable change in the inherent surface topographies was not observed on both types of surfaces after TiHA coating. Osteoblastic proliferative activity at day 4 was increased by TiHA coating on both types of surfaces. TiHA coating did not enhance expressions of bone matrix-related genes such as osteocalcin, osteopontin, bone sialoprotein, alkaline phosphatase, and collagen I. However, depositions of collagen, osteocalcin, and calcium in the culture at days 7 and 20 were increased on both types of surface topographies with TiHA coating. TiHA coating enhanced extracellular matrix formation on smooth and microroughened titanium surfaces by increasing osteoblastic proliferative activity without the deterioration of differentiation through hydrophilic and chemical functionalization.

Common Ion Effects In Zeoponic Substrates: Dissolution And Cation Exchange Variations Due to Additions of Calcite, Dolomite and Wollastonite

NASA Technical Reports Server (NTRS)

Beiersdorfer, R. E.; Ming, D. W.; Galindo, C., Jr.

2003-01-01

c1inoptilolite-rich tuff-hydroxyapatite mixture (zeoponic substrate) has the potential to serve as a synthetic soil-additive for plant growth. Essential plant macro-nutrients such as calcium, phosphorous, magnesium, ammonium and potassium are released into solution via dissolution of the hydroxyapatite and cation exchange on zeolite charged sites. Plant growth experiments resulting in low yield for wheat have been attributed to a Ca deficiency caused by a high degree of cation exchange by the zeolite. Batch-equilibration experiments were performed in order to determine if the Ca deficiency can be remedied by the addition of a second Ca-bearing, soluble, mineral such as calcite, dolomite or wollastonite. Variations in the amount of calcite, dolomite or wollastonite resulted in systematic changes in the concentrations of Ca and P. The addition of calcite, dolomite or wollastonite to the zeoponic substrate resulted in an exponential decrease in the phosphorous concentration in solution. The exponential rate of decay was greatest for calcite (5.60 wt. % -I), intermediate for wollastonite (2.85 wt.% -I) and least for dolomite (1.58 wt.% -I). Additions of the three minerals resulted in linear increases in the calcium concentration in solution. The rate of increase was greatest for calcite (3.64), intermediate for wollastonite (2.41) and least for dolomite (0.61). The observed changes in P and Ca concentration are consistent with the solubilities of calcite, dolomite and wollastonite and with changes expected from a common ion effect with Ca. Keywords: zeolite, zeoponics, common-ion effect, clinoptilolite, hydroxyapatite

Enamel-like apatite crown covering amorphous mineral in a crayfish mandible

PubMed Central

Bentov, Shmuel; Zaslansky, Paul; Al-Sawalmih, Ali; Masic, Admir; Fratzl, Peter; Sagi, Amir; Berman, Amir; Aichmayer, Barbara

2012-01-01

Carbonated hydroxyapatite is the mineral found in vertebrate bones and teeth, whereas invertebrates utilize calcium carbonate in their mineralized organs. In particular, stable amorphous calcium carbonate is found in many crustaceans. Here we report on an unusual, crystalline enamel-like apatite layer found in the mandibles of the arthropod Cherax quadricarinatus (freshwater crayfish). Despite their very different thermodynamic stabilities, amorphous calcium carbonate, amorphous calcium phosphate, calcite and fluorapatite coexist in well-defined functional layers in close proximity within the mandible. The softer amorphous minerals are found primarily in the bulk of the mandible whereas apatite, the harder and less soluble mineral, forms a wear-resistant, enamel-like coating of the molar tooth. Our findings suggest a unique case of convergent evolution, where similar functional challenges of mastication led to independent developments of structurally and mechanically similar, apatite-based layers in the teeth of genetically remote phyla: vertebrates and crustaceans. PMID:22588301

Preparation of inorganic/organic polymer hybrid microcapsules with high encapsulation efficiency by an electrospray technique.

PubMed

Yunoki, Ayumi; Tsuchiya, Eiko; Fukui, Yu; Fujii, Akihiro; Maruyama, Tatsuo

2014-08-13

Microcapsules composed of calcium phosphate and chitosan were prepared in a single step by electrospraying. An aqueous solution containing calcium chloride and chitosan was electrosprayed into a phosphate solution to form a calcium phosphate shell on the sprayed droplets. The resulting microcapsules were 350 μm in average diameter. Investigation using fluorescently labeled chitosan and XRD measurements revealed that the shells of the microcapsules were composed of calcium phosphate (mainly hydroxyapatite) and chitosan. Instead of chitosan, poly(diallyldimethylammonium chloride) and polyethylene glycol were also available for microcapsule production by electrospraying. Variations in the electrospraying conditions resulted in a variety of microcapsule shapes. Various types of substrates were successfully encapsulated in microcapsules with a high encapsulation efficiency (more than 80%). Finally, we succeeded in the encapsulation of living yeast cells in microcapsules, and observed their growth within these microcapsules.

Bioactive calcium phosphate–based glasses and ceramics and their biomedical applications: A review

PubMed Central

Islam, Md Towhidul; Felfel, Reda M; Abou Neel, Ensanya A; Grant, David M; Ahmed, Ifty; Hossain, Kazi M Zakir

2017-01-01

An overview of the formation of calcium phosphate under in vitro environment on the surface of a range of bioactive materials (e.g. from silicate, borate, and phosphate glasses, glass-ceramics, bioceramics to metals) based on recent literature is presented in this review. The mechanism of bone-like calcium phosphate (i.e. hydroxyapatite) formation and the test protocols that are either already in use or currently being investigated for the evaluation of the bioactivity of biomaterials are discussed. This review also highlights the effect of chemical composition and surface charge of materials, types of medium (e.g. simulated body fluid, phosphate-buffered saline and cell culture medium) and test parameters on their bioactivity performance. Finally, a brief summary of the biomedical applications of these newly formed calcium phosphate (either in the form of amorphous or apatite) is presented. PMID:28794848

Effect of pores formation process and oxygen plasma treatment to hydroxyapatite formation on bioactive PEEK prepared by incorporation of precursor of apatite.

PubMed

Yabutsuka, Takeshi; Fukushima, Keito; Hiruta, Tomoko; Takai, Shigeomi; Yao, Takeshi

2017-12-01

When bioinert substrates with fine-sized pores are immersed in a simulated body fluid (SBF) and the pH value or the temperature is increased, fine particles of calcium phosphate, which the authors denoted as 'precursor of apatite' (PrA), are formed in the pores. By this method, hydroxyapatite formation ability can be provided to various kinds of bioinert materials. In this study, the authors studied fabrication methods of bioactive PEEK by using the above-mentioned process. First, the fine-sized pores were formed on the surface of the PEEK substrate by H 2 SO 4 treatment. Next, to provide hydrophilic property to the PEEK, the surfaces of the PEEK were treated with O 2 plasma. Finally, PrA were formed in the pores by the above-mentioned process, which is denoted as 'Alkaline SBF' treatment, and the bioactive PEEK was obtained. By immersing in SBF with the physiological condition, hydroxyapatite formation was induced on the whole surface of the substrate within 1day. The formation of PrA directly contributed to hydroxyapatite formation ability. By applying the O 2 plasma treatment, hydroxyapatite formation was uniformly performed on the whole surface of the substrate. The H 2 SO 4 treatment contributed to a considerable enhancement of adhesive strength of the formed hydroxyapatite layer formed in SBF because of the increase of surface areas of the substrate. As a comparative study, the sandblasting method was applied as the pores formation process instead of the H 2 SO 4 treatment. Although hydroxyapatite formation was provided also in this case, however, the adhesion of the formed hydroxyapatite layer to the substrate was not sufficient even if the O 2 plasma treatment was conducted. This result indicates that the fine-sized pores should be formed on the whole surface of the substrate uniformly to achieve high adhesive strength of the hydroxyapatite layer. Therefore, it is considered that the H 2 SO 4 treatment before the O 2 plasma and the 'Alkaline SBF' treatment is an important factor to achieve high adhesive strength of hydroxyapatite layer to the PEEK substrate. This material is expected to be a candidate for next-generation implant materials with high bioactivity. Copyright © 2017 Elsevier B.V. All rights reserved.

Influence of pH, competing ions, and salinity on the sorption of strontium and cobalt onto biogenic hydroxyapatite

PubMed Central

Handley-Sidhu, Stephanie; Mullan, Thomas K.; Grail, Quentin; Albadarneh, Malek; Ohnuki, Toshihiko; Macaskie, Lynne E.

2016-01-01

Anthropogenic radionuclides contaminate a range of environments as a result of nuclear activities, for example, leakage from waste storage tanks/ponds (e.g. Hanford, USA or Sellafield sites, UK) or as a result of large scale nuclear accidents (e.g. Chernobyl, Ukraine or Fukushima, Japan). One of the most widely applied remediation techniques for contaminated waters is the use of sorbent materials (e.g. zeolites and apatites). However, a key problem at nuclear contaminated sites is the remediation of radionuclides from complex chemical environments. In this study, biogenic hydroxyapatite (BHAP) produced by Serratia sp. bacteria was investigated for its potential to remediate surrogate radionuclides (Sr2+ and Co2+) from environmentally relevant waters by varying pH, salinity and the type and concentration of cations present. The sorption capacity of the BHAP for both Sr2+ and Co2+ was higher than for a synthetically produced hydroxyapatite (HAP) in the solutions tested. BHAP also compared favorably against a natural zeolite (as used in industrial decontamination) for Sr2+ and Co2+ uptake from saline waters. Results confirm that hydroxyapatite minerals of high surface area and amorphous calcium phosphate content, typical for biogenic sources, are suitable restoration or reactive barrier materials for the remediation of complex contaminated environments or wastewaters. PMID:26988070

Influence of pH, competing ions, and salinity on the sorption of strontium and cobalt onto biogenic hydroxyapatite

NASA Astrophysics Data System (ADS)

Handley-Sidhu, Stephanie; Mullan, Thomas K.; Grail, Quentin; Albadarneh, Malek; Ohnuki, Toshihiko; Macaskie, Lynne E.

2016-03-01

Anthropogenic radionuclides contaminate a range of environments as a result of nuclear activities, for example, leakage from waste storage tanks/ponds (e.g. Hanford, USA or Sellafield sites, UK) or as a result of large scale nuclear accidents (e.g. Chernobyl, Ukraine or Fukushima, Japan). One of the most widely applied remediation techniques for contaminated waters is the use of sorbent materials (e.g. zeolites and apatites). However, a key problem at nuclear contaminated sites is the remediation of radionuclides from complex chemical environments. In this study, biogenic hydroxyapatite (BHAP) produced by Serratia sp. bacteria was investigated for its potential to remediate surrogate radionuclides (Sr2+ and Co2+) from environmentally relevant waters by varying pH, salinity and the type and concentration of cations present. The sorption capacity of the BHAP for both Sr2+ and Co2+ was higher than for a synthetically produced hydroxyapatite (HAP) in the solutions tested. BHAP also compared favorably against a natural zeolite (as used in industrial decontamination) for Sr2+ and Co2+ uptake from saline waters. Results confirm that hydroxyapatite minerals of high surface area and amorphous calcium phosphate content, typical for biogenic sources, are suitable restoration or reactive barrier materials for the remediation of complex contaminated environments or wastewaters.

Design of Natural Hydroxyapatite as bio-composite ceramics (HAP): Experimental and Numerical Study

NASA Astrophysics Data System (ADS)

Belghazi, Z.; Katundi, D.; Ayari, F.; Bayraktar, E.

2011-01-01

Hydroxyapatite (HAP—Ca10(PO4)6 (OH)2), which exhibits excellent biocompatibility in the body, is one of the most widely used bioactive ceramics for biomedical applications. Along with the ability to carry the load, one of the most important properties of materials used for bone replacement is biocompatibility. In fact, HAP is a bioactive material and it can incorporate into bone structures, supporting bone in-growth without breaking down or dissolving, and it interacts with the living tissue due to the presence of free calcium and phosphate compounds. Generally, Al2O3 powder is added to HAP powder in order to obtain high fracture toughness. Al2O3 has good mechanical properties as compared with HAP, and exhibits extremely high stability with human tissues [1-6]. In this paper, the effect of microwave sintering temperature on the relative density, hardness, and phase purity of compacted bovine Hydroxyapatite (BHA) powder was reported. This research is a comprehensive attempt to develop Hydroxyapatite bio composite ceramics reinforced with alumina—Al2O3, pure titanium and pure pulverised boron powder. A Finite Element (FEM) analysis is also used for modelling to simulate the macroscopic behaviour of this material, taking into account the relevant microscopic scales.

Novel Injectable Calcium Phosphate Bone Cement from Wet Chemical Precipitation Method

NASA Astrophysics Data System (ADS)

Hablee, S.; Sopyan, I.; Mel, M.; Salleh, H. M.; Rahman, M. M.; Singh, R.

2017-06-01

Calcium phosphate cement has been prepared via chemical precipitation method for injectable bone filling materials. Calcium hydroxide, Ca(OH)2, and diammonium hydrogen phosphate, (NH4)2HPO4, were used as calcium and phosphorus precursors respectively. The synthesized powder was mixed with water at different powder-to-liquid (P/L) ratios, which was adjusted at 0.8, 0.9, 1.0, 1.1 and 1.2. The influence of P/L ratio on the injectability, setting time and mechanical strength of calcium phosphate cement paste has been evaluated. The synthesized powder appeared as purely hydroxyapatite with nanosized and agglomerated spherical particles. All cement pastes show excellent injectability except for the paste with P/L ratio 1.2. Calcium phosphate cement with P/L ratio 1.1 shows the ideal cement for bone filler application with good injectability, the initial and final setting times of 30 min and 160 min, and the compression strength of 2.47 MPa. The result indicated that the newly developed calcium phosphate cement is physically suitable for bone filler application. This paper presents our investigation on the effect of P/L ratio on the handling and mechanical properties of calcium phosphate cement prepared via wet chemical precipitation method.

Complementary information on in vitro conversion of amorphous (precursor) calcium phosphate to hydroxyapatite from Raman microspectroscopy and wide-angle X-ray scattering.

PubMed

Kazanci, M; Fratzl, P; Klaushofer, K; Paschalis, E P

2006-11-01

In addition to mechanical functions, bones have an essential role in metabolic activity as mineral reservoirs that are able to absorb and release ions. Bioapatite, considered the major component in the mineralized part of mammalian bones, is a calcium phosphate mineral with a structure that closely resembles hydroxyapatite (HA, Ca10[PO4]6[OH]2) with variable chemical substitutions. It is important to note that it continues to be chemically active long after it has been initially deposited. Detailed understanding of changes in the mineral phase as HA matures is essential for understanding how normal bone achieves its remarkable mechanical performance, how it is altered in disease, as well as the effects of therapeutic interventions. A model system for investigation of the in vivo maturation of HA is available, namely, the in vitro conversion of amorphous calcium phosphate (ACP) to HA in a supersaturated solution of calcium and phosphate ions. In the present study, this system was employed to correlate with the changes in chemistry and poorly crystalline HAP crystal size, shape, and habit. The results of the X-ray diffraction as well as Raman analyses showed that as the crystallites mature in the 002 and 310 directions both the full width at half-height and wavelength at maximum of the Raman peaks change as a function of reaction extent and crystallite maturation, size, and shape. Moreover, such analyses can be performed in intact bone specimens through Raman microspectroscopic and imaging analyses with a spatial resolution of 0.6-1 mu, by far superior to the one offered by other microspectroscopic techniques, thus potentially yielding important new information on the organization and mineral quality of normal and fragile bone.

Bioactivity and biocompatibility of hydroxyapatite-based bioceramic coatings on zirconium by plasma electrolytic oxidation.

PubMed

Aktuğ, Salim Levent; Durdu, Salih; Yalçın, Emine; Çavuşoğlu, Kültigin; Usta, Metin

2017-02-01

In the present work, hydroxyapatite (HAP)-based plasma electrolytic oxide (PEO) coatings were produced on zirconium at different current densities in a solution containing calcium acetate and β-calcium glycerophosphate by a single step. The phase structure, surface morphology, functional groups, thickness and roughness of the coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), eddy current method and surface profilometer, respectively. The phases of cubic-zirconia, calcium zirconate and HAP were detected by XRD. The amount of HAP and calcium zirconate increased with increasing current density. The surface of the coatings was very porous and rough. Moreover, bioactivity and biocompatibility of the coatings were analyzed in vitro immersion simulated body fluid (SBF) and MTT (3-(4,5-dimethyl thiazol-2yl)-2,5-diphenyl tetrazolium bromide) assay, hemolysis assay and bacterial formation. The apatite-forming ability of the coatings was evaluated after immersion in SBF up to 28days. After immersion, the bioactivity of HAP-based coatings on zirconium was greater than the ones of uncoated zirconium and zirconium oxide-based surface. The bioactivity of PEO surface on zirconium was significantly improved under SBF conditions. The bacterial adhesion of the coatings decreased with increasing current density. The bacterial adhesion of the coating produced at 0.370A/cm 2 was minimum compared to uncoated zirconium coated at 0.260 and 0.292A/cm 2 . The hemocompatibility of HAP-based surfaces was improved by PEO. The cell attachment and proliferation of the PEO coatings were better than the one of uncoated zirconium according to MTT assay results. Copyright © 2016 Elsevier B.V. All rights reserved.

First-Row Transition Metal Doping in Calcium Phosphate Bioceramics: A Detailed Crystallographic Study

PubMed Central

Renaudin, Guillaume; Gomes, Sandrine; Nedelec, Jean-Marie

2017-01-01

Doped calcium phosphate bioceramics are promising materials for bone repair surgery because of their chemical resemblance to the mineral constituent of bone. Among these materials, BCP samples composed of hydroxyapatite (Ca10(PO4)6(OH)2) and β-TCP (Ca3(PO4)2) present a mineral analogy with the nano-multi-substituted hydroxyapatite bio-mineral part of bones. At the same time, doping can be used to tune the biological properties of these ceramics. This paper presents a general overview of the doping mechanisms of BCP samples using cations from the first-row transition metals (from manganese to zinc), with respect to the applied sintering temperature. The results enable the preparation of doped synthetic BCP that can be used to tailor biological properties, in particular by tuning the release amounts upon interaction with biological fluids. Intermediate sintering temperatures stabilize the doping elements in the more soluble β-TCP phase, which favors quick and easy release upon integration in the biological environment, whereas higher sintering temperatures locate the doping elements in the weakly soluble HAp phase, enabling a slow and continuous supply of the bio-inspired properties. An interstitial doping mechanism in the HAp hexagonal channel is observed for the six investigated cations (Mn2+, Fe3+, Co2+, Ni2+, Cu2+ and Zn2+) with specific characteristics involving a shift away from the center of the hexagonal channel (Fe3+, Co2+), cationic oxidation (Mn3+, Co3+), and also cationic reduction (Cu+). The complete crystallochemical study highlights a complex HAp doping mechanism, mainly realized by an interstitial process combined with calcium substitution for the larger cations of the series leading to potentially calcium deficient HAp. PMID:28772452

Caries protective agents in human milk and bovine milk: an in vitro study.

PubMed

Shetty, Vabitha; Hegde, Amitha M; Nandan, S; Shetty, Suchetha

2011-01-01

To estimate Calcium and Phosphorus withdrawal from hydroxyapatite in the presence of bovine milk and human milk from which the following protective fractions namely Casein, Whey protein, Lactose and Milk fat have been individually removed and to compare the above protective fractions in human and bovine milk. Human milk obtained from lactating mothers in the labor ward of Kshema hospital was subjected to immediate analysis. Bovine milk was obtained from a local dairy. Equal quantities of human milk and bovine milk (1 ml) were separately subjected to the systematic removal of the four milk fractions. As each fraction was removed, the remaining milk samples were subjected to testing. Powdered hydroxyapatite from human dental enamel was subjected to demineralization with the addition of the milk sample under test for 20 minutes. This mixture was then centrifuged. Aliquots of the supernatant were taken for calcium and Phosphorus analysis using photospectrometry. Ten demineralization tests were similarly carried out for every milk fraction for both human and bovine milk separately. Equal samples of whole bovine milk and whole human milk were also subjected to similar testing. The calcium and phosphorus dissolution values were higher when the individual fractions were eliminated from both human milk/enamel samples and bovine milk/enamel samples as compared to the values obtained from whole human milk/whole bovine milk/enamel samples. Further higher calcium and phosphorus dissolution values were observed when the fractions were individually and separately removed from the whole human milk/enamel samples as compared to the corresponding values obtained when these fractions were removed from bovine milk/enamel samples. The evaluated milk fraction in bovine milk namely casein, whey protein, lactose and milk fat were individually more caries protective when compared to the corresponding fractions in human milk.

Hydroxyapatite Deposition Disease

DTIC Science & Technology

2006-11-01

site of HADD is the hip, where calcifications are usually found in the gluteus medius tendon or along the femur at various sites of tendinous ...characterized by deposition of calcium phosphate crystals in periarticular tissues. The deposits frequently occur in tendons near their osseous...attachments, most commonly involving the supraspinatus tendon . The etiology of HADD is unclear, but may be related to repetitive trauma or metabolic

Neck Pain and Acute Dysphagia.

PubMed

Simões, João; Romão, José; Cunha, Anita; Paiva, Sofia; Miguéis, António

2017-02-01

The acute tendinitis of the longus colli muscle is an unusual diagnosis in the cases of acute dysphagia with cervical pain. Is a self-limiting condition caused by abnormal calcium hydroxyapatite deposition in the prevertebral space and can cause pharyngeal swelling with impaired swallow. It is absolutely critical to make the differential diagnosis with deep cervical infections in order to avoid invasive treatments.

Characterization of calcium phosphate coatings deposited by Nd:YAG laser ablation at 355 nm: influence of thickness.

PubMed

Fernández-Pradas, J M; Clèries, L; Sardin, G; Morenza, J L

2002-05-01

Calcium phosphate coatings were deposited by pulsed laser ablation with a radiation of 355 nm from a Nd:YAG laser. All the coatings were obtained at the same conditions, but deposition was stopped after different number of pulses to get coatings with different thickness. The influence of thickness in the structural and mechanical properties of the coatings was investigated. Coatings structure was characterised by scanning electron microscopy, grazing incidence X-ray diffractometry and Raman spectroscopy. The mechanical properties were evaluated by scratch test. The morphology of the coatings is dominated by the presence of droplets. The coatings are composed mainly of hydroxyapatite, alpha tricalcium phosphate and amorphous calcium phosphate. Thinner coatings withstand higher loads of failure in the scratch test.

Comparison of adsorption equilibrium models and error functions for the study of sulfate removal by calcium hydroxyapatite microfibrillated cellulose composite.

PubMed

Hokkanen, Sanna; Bhatnagar, Amit; Koistinen, Ari; Kangas, Teija; Lassi, Ulla; Sillanpää, Mika

2018-04-01

In the present study, the adsorption of sulfates of sodium sulfate (Na 2 SO 4 ) and sodium lauryl sulfate (SLS) by calcium hydroxyapatite-modified microfibrillated cellulose was studied in the aqueous solution. The adsorbent was characterized using elemental analysis, Fourier transform infrared, scanning electron microscope and elemental analysis in order to gain the information on its structure and physico-chemical properties. The adsorption studies were conducted in batch mode. The effects of solution pH, contact time, the initial concentration of sulfate and the effect of competing anions were studied on the performance of synthesized adsorbent for sulfate removal. Adsorption kinetics indicated very fast adsorption rate for sulfate of both sources (Na 2 SO 4 and SLS) and the adsorption process was well described by the pseudo-second-order kinetic model. Experimental maximum adsorption capacities were found to be 34.53 mg g -1 for sulfates of SLS and 7.35 mg g -1 for sulfates of Na 2 SO 4. The equilibrium data were described by the Langmuir, Sips, Freundlich, Toth and Redlich-Peterson isotherm models using five different error functions.

A novel route for synthesis of nanocrystalline hydroxyapatite from eggshell waste.

PubMed

Siva Rama Krishna, D; Siddharthan, A; Seshadri, S K; Sampath Kumar, T S

2007-09-01

The eggshell waste has been value engineered to a nanocrystalline hydroxyapatite (HA) by microwave processing. To highlight the advantages of eggshell as calcium precursor in the synthesis of HA (OHA), synthetic calcium hydroxide was also used to form HA (SHA) following similar procedure and were compared with a commercially available pure HA (CHA). All the HAs were characterized by X-ray powder diffraction (XRD) method, Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and specific surface area measurements. Nanocrystalline nature of OHA is revealed through characteristic broad peaks in XRD patterns, platelets of length 33-50 nm and width 8-14 nm in TEM micrograph and size calculations from specific surface area measurements. FT-IR spectra showed characteristic bands of HA and additionally peaks of carbonate ions. The cell parameter calculations suggest the formation of carbonated HA of B-type. The OHA exhibits superior sinterability in terms of hardness and density than both SHA and CHA may be due to larger surface area of its spherulite structure. The in vitro dissolution study shows longer stability in phosphate buffer and cell culture test using osteoblast cells establishes biocompatibility of OHA.

Caoxite-hydroxyapatite composition as consolidating material for the chalk stone from Basarabi-Murfatlar churches ensemble

NASA Astrophysics Data System (ADS)

Ion, Rodica-Mariana; Turcanu-Caruţiu, Daniela; Fierăscu, Radu-Claudiu; Fierăscu, Irina; Bunghez, Ioana-Raluca; Ion, Mihaela-Lucia; Teodorescu, Sofia; Vasilievici, Gabriel; Rădiţoiu, Valentin

2015-12-01

The development of new composition for surface conservation of some architectural monuments represents now an important research topic. The Basarabi-Murfatlar Ensemble, recognized as the first religious monument from mediaeval Dobrogea (Romania) (from 9th to 11th century), is one of the most impressive archaeological sites of Europe. This ensemble is built from amorphous calcium carbonate, very sensitive to humidity, frost, salts, etc. The aim of this paper is to test on chalk stone samples a new consolidant - hydroxyapatite (HAp) mixed with calcium oxalate trihydrate (caoxite) (COT). Some specific techniques for evaluation its impact on chalk stone surface are used, as follows: petrographical and physical-chemical techniques: SEM, OM, ICP-AES, TGA, FTIR and Raman spectroscopy, chromatic parameters changes, the accelerated weathering tests: heating, freeze-thaw, and their effects on porosity and capillary water uptake by the chalk surface. All these have been evaluated before and after treatment with COT-HAp, putting into evidence the effect of the new composition on the chalk stone surface. HAp induces COT stabilization, and their joint composition can bind weathered stone blocks providing a substantial reinforcement of chalk surface.

Novel method for early investigation of bioactivity in different borate bio-glasses

NASA Astrophysics Data System (ADS)

Abdelghany, A. M.

Some ternary borate glasses were prepared and corrosion behavior of such ternary borate glasses after immersion in aqueous dilute phosphate solution was studied using different immersion times. Fourier transform infrared (FTIR) absorption spectral measurements were done before and after immersion in the mentioned solution for extended times up to 2 days to justify the appearance of the characteristic FTIR bands due to calcium phosphate (hydroxyapatite (HA)) which is considered as the potential indication of bioactivity. Experimental IR data confirm the beginning of the appearance of FTIR bands at about 580 and 620 cm-1 after 3 days and the complete resolution with its characteristic split form after 1 week and more. Deconvolution analysis technique (DAT) of the FTIR spectrum was employed to investigate the bioactivity of such ternary borate system after a short period of immersion. The corrosion behavior of such glasses is explained in relation to a suggested hydrolysis followed by direct dissolution mechanism. The ease of dissolution of all the borate glasses constituents explains the formation of calcium phosphate and conversion to crystalline hydroxyapatite within the borate glass matrix. X-ray diffraction may be used to retrace the structural changes and degree of crystallinity of the prepared glasses.

Synthesis, characterization and modelling of zinc and silicate co-substituted hydroxyapatite.

PubMed

Friederichs, Robert J; Chappell, Helen F; Shepherd, David V; Best, Serena M

2015-07-06

Experimental chemistry and atomic modelling studies were performed here to investigate a novel ionic co-substitution in hydroxyapatite (HA). Zinc, silicate co-substituted HA (ZnSiHA) remained phase pure after heating to 1100 °C with Zn and Si amounts of 0.6 wt% and 1.2 wt%, respectively. Unique lattice expansions in ZnSiHA, silicate Fourier transform infrared peaks and changes to the hydroxyl IR stretching region suggested Zn and silicate co-substitution in ZnSiHA. Zn and silicate insertion into HA was modelled using density functional theory (DFT). Different scenarios were considered where Zn substituted for different calcium sites or at a 2b site along the c-axis, which was suspected in singly substituted ZnHA. The most energetically favourable site in ZnSiHA was Zn positioned at a previously unreported interstitial site just off the c-axis near a silicate tetrahedron sitting on a phosphate site. A combination of experimental chemistry and DFT modelling provided insight into these complex co-substituted calcium phosphates that could find biomedical application as a synthetic bone mineral substitute. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Water-based sol-gel synthesis of hydroxyapatite: process development.

PubMed

Liu, D M; Troczynski, T; Tseng, W J

2001-07-01

Hydroxyapatite (HA) ceramics were synthesized using a sol-gel route with triethyl phosphite and calcium nitrate as phosphorus and calcium precursors, respectively. Two solvents, water and anhydrous ethanol, were used as diluting media for HA sol preparation. The sols were stable and no gelling occurred in ambient environment for over 5 days. The sols became a white gel only after removal of the solvents at 60 degrees C. X-ray diffraction showed that apatitic structure first appeared at a temperature as low as 350 degrees C. The crystal size and the HA content in both gels increase with increasing calcination temperature. The type of initial diluting media (i.e., water vs. anhydrous ethanol) did not affect the microstructural evolution and crystallinity of the resulting HA ceramic. The ethanol-based sol dip-coated onto a Ti substrate, followed by calcination at 450 degrees C, was found to be porous with pore size ranging from 0.3 to 1 microm. This morphology is beneficial to the circulation of physiological fluid when the coating is used for biomedical applications. The satisfactory adhesion between the coating and substrate suggests its suitability for load-bearing uses.

Biomimetic fabrication of a three-level hierarchical calcium phosphate/collagen/hydroxyapatite scaffold for bone tissue engineering.

PubMed

Zhou, Changchun; Ye, Xingjiang; Fan, Yujiang; Ma, Liang; Tan, Yanfei; Qing, Fangzu; Zhang, Xingdong

2014-09-01

A three-level hierarchical calcium phosphate/collagen/hydroxyapatite (CaP/Col/HAp) scaffold for bone tissue engineering was developed using biomimetic synthesis. Porous CaP ceramics were first prepared as substrate materials to mimic the porous bone structure. A second-level Col network was then composited into porous CaP ceramics by vacuum infusion. Finally, a third-level HAp layer was achieved by biomimetic mineralization. The three-level hierarchical biomimetic scaffold was characterized using scanning electron microscopy, energy-dispersive x-ray spectra, x-ray diffraction and Fourier transform infrared spectroscopy, and the mechanical properties of the scaffold were evaluated using dynamic mechanical analysis. The results show that this scaffold exhibits a similar structure and composition to natural bone tissues. Furthermore, this three-level hierarchical biomimetic scaffold showed enhanced mechanical strength compared with pure porous CaP scaffolds. The biocompatibility and osteoinductivity of the biomimetic scaffolds were evaluated using in vitro and in vivo tests. Cell culture results indicated the good biocompatibility of this biomimetic scaffold. Faster and increased bone formation was observed in these scaffolds following a six-month implantation in the dorsal muscles of rabbits, indicating that this biomimetic scaffold exhibits better osteoinductivity than common CaP scaffolds.

Composition characteristics and regularities of dissolving of hydroxyapatite materials obtained in water solutions with varied content of silicate ions

NASA Astrophysics Data System (ADS)

Solonenko, A. P.

2018-01-01

Research aimed at developing new bioactive materials for the repair of defects in bone tissues, do not lose relevance due to the strengthening of the regenerative approach in medicine. From this point of view, materials based on calcium phosphates, including silicate ions, consider as one of the most promising group of substances. Methods of synthesis and properties of hydroxyapatite doped with various amounts of SiO4 4- ions are described in literature. In the present work synthesis of a solid phase in the systems Ca(NO3)2 - (NH4)2HPO4 - Na2SiO3 - NH4OH - H2O (Cca/CP = 1.70) performed with a wide range of sodium silicate additive concentration (y = CSi/CP = 0 ÷ 5). It is established that under the studied conditions at y ≥ 0.3 highly dispersed poorly crystallized apatite containing isomorphic impurities of CO3 2- and SiO4 4- precipitates in a mixture with calcium hydrosilicate and SiO2. It is shown that the resulting composites can gradually dissolve in physiological solution and initiate passive formation of the mineral component of hard tissues.

Laser engineered multilayer coating of biphasic calcium phosphate/titanium nanocomposite on metal substrates.

PubMed

Zhang, Martin Yi; Ye, Chang; Erasquin, Uriel Joseph; Huynh, Toan; Cai, Chengzhi; Cheng, Gary J

2011-02-01

In this work, laser coating of biphasic calcium phosphate/titanium (BCP/Ti) nanocomposite on Ti-6Al-4 V substrates was developed. A continuous wave neodymium-doped yttrium aluminium garnet (Nd:YAG) laser was used to form a robust multilayer of BCP/Ti nanocomposite starting from hydroxyapatite and titanium nanoparticles. In this process, low power coating is realized because of the strong laser-nanoparticle interaction and good sinterability of nanosized titanium. To guide the optimization of laser processing conditions for the coating process, a multiphysics model coupling electromagnetic module with heat transfer module was developed. This model was validated by laser coating experiments. Important features of the coated samples, including microstructures, chemical compositions, and interfacial bonding strength, were characterized. We found that a multilayer of BCP, consisting of 72% hydroxyapatite (HA) and 28% beta-tricalcium phosphate (β-TCP), and titanium nanocomposite was formed on Ti-6Al-4 V substrates. Significantly, the coating/substrate interfacial bonding strength was found to be two times higher than that of the commercial plasma sprayed coatings. Preliminary cell culture studies showed that the resultant BCP/Ti nanocomposite coating supported the adhesion and proliferation of osteoblast-like UMR-106 cells.

Characterisation and sintering of nanophase hydroxyapatite synthesised by a species of Serratia

NASA Astrophysics Data System (ADS)

LSammons, R.; Thackray, A. C.; Medina Ledo, H.; Marquis, P. M.; Jones, I. P.; Yong, P.; Macaskie, L. E.

2007-12-01

The bacterium Serratia sp. NCIMB40259, which grows as a biofilm on polymeric, glass and metal substrates, produces extracellular crystals of hydroxyapatite (HA) by enzymatic cleavage of β-glycerophosphate in the presence of calcium chloride. Following growth on polyurethane foam, biomineralisation and subsequent sintering, an HA scaffold is formed whose three-dimensional architecture replicates that of the foam and the biofilm. Serratia HA was characterised using X-ray diffraction (XRD), Fourier Transform Infra-Red Spectroscopy (FTIR), energy dispersive X-ray analysis (EDX) scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction (ED). The nascent, unsintered material consisted mainly of calcium-deficient HA (CDHA) with a Ca/P ratio of 1.61+/- 0.06 and crystal size (TEM) of 50 +/- 10nm length. ED of unsintered crystals and crystals sintered at 600° C showed resolvable ring (unsintered) or dot (600° C) patterns ascribed to (0002), (1122) and (0006) planes of crystalline HA. Material sintered at 1200° C consisted of needle-like crystals of length range 54-111nm (XRD) with lattice parameters of a = 9.441 Å and c = 6.875 Å, consistent with HA.

Differential osteogenic activity of osteoprogenitor cells on HA and TCP/HA scaffold of tissue engineered bone.

PubMed

Ng, Angela M H; Tan, K K; Phang, M Y; Aziyati, O; Tan, G H; Isa, M R; Aminuddin, B S; Naseem, M; Fauziah, O; Ruszymah, B H I

2008-05-01

Biomaterial, an essential component of tissue engineering, serves as a scaffold for cell attachment, proliferation, and differentiation; provides the three dimensional (3D) structure and, in some applications, the mechanical strength required for the engineered tissue. Both synthetic and naturally occurring calcium phosphate based biomaterial have been used as bone fillers or bone extenders in orthopedic and reconstructive surgeries. This study aims to evaluate two popular calcium phosphate based biomaterial i.e., hydroxyapatite (HA) and tricalcium phosphate/hydroxyapatite (TCP/HA) granules as scaffold materials in bone tissue engineering. In our strategy for constructing tissue engineered bone, human osteoprogenitor cells derived from periosteum were incorporated with human plasma-derived fibrin and seeded onto HA or TCP/HA forming 3D tissue constructs and further maintained in osteogenic medium for 4 weeks to induce osteogenic differentiation. Constructs were subsequently implanted intramuscularly in nude mice for 8 weeks after which mice were euthanized and constructs harvested for evaluation. The differential cell response to the biomaterial (HA or TCP/HA) adopted as scaffold was illustrated by the histology of undecalcified constructs and evaluation using SEM and TEM. Both HA and TCP/HA constructs showed evidence of cell proliferation, calcium deposition, and collagen bundle formation albeit lesser in the former. Our findings demonstrated that TCP/HA is superior between the two in early bone formation and hence is the scaffold material of choice in bone tissue engineering. Copyright 2007 Wiley Periodicals, Inc.

Ultrasound-assisted green economic synthesis of hydroxyapatite nanoparticles using eggshell biowaste and study of mechanical and biological properties for orthopedic applications.

PubMed

Ingole, Vijay H; Hany Hussein, Kamal; Kashale, Anil A; Ghule, Kalyani; Vuherer, Tomaž; Kokol, Vanja; Chang, Jia-Yaw; Ling, Yong-Chien; Vinchurkar, Aruna; Dhakal, Hom N; Ghule, Anil V

2017-11-01

Nanostructured hydroxyapatite (HAp) is the most favorable candidate biomaterial for bone tissue engineering because of its bioactive and osteoconductive properties. Herein, we report for the first time ultrasound-assisted facile and economic approach for the synthesis of nanocrystalline hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 ) using recycled eggshell biowaste referred as EHAp. The process involves the reaction of eggshell biowaste as a source of calcium and ammonium dihydrogen orthophosphate as a phosphate source. Ultrasound-mediated chemical synthesis of hydroxyapatite (HAp) is also carried out using similar approach wherein commercially available calcium hydroxide and ammonium dihydrogen orthophosphate were used as calcium and phosphate precursors, respectively and referred as CHAp for better comparison. The prepared materials were characterized by X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy to determine crystal structure, particle morphology, and the presence of chemical functional groups. The nanocrystalline EHAp and CHAp were observed to have spherical morphology with uniform size distribution. Furthermore, mechanical properties such as Vickers hardness, fracture toughness, and compression tests have been studied of the EHAp and CHAp samples showing promising results. Mechanical properties show the influence of calcination at 600°C EHAp and CHAp material. After calcination, in the case of EHAp material an average hardness, mechanical strength, elastic modulus, and fracture toughness were found 552 MPa, 46.6 MPa, 2824 MPa, and 3.85 MPa m 1/2 , respectively, while in the case of CHAp 618 MPa, 47.5 MPa, 2071 MPa, and 3.13 MPa m 1/2 . In vitro cell studies revealed that the EHAp and CHAp nanoparticles significantly increased the attachment and proliferation of the hFOB cells. Here, we showed that EHAp and CHAp provide promising biocompatible materials that do not affect the cell viability and proliferation with enhancing the osteogenic activity of osteoblasts. Moreover, hFOB cells are found to express Osteocalcin, Osteopontin, Collagen I, Osteonectin, BMP-2 on the EHAp and CHAp bone graft. This study demonstrates the formation of pure nanocrystalline HAp with promising properties justifying the fact that the eggshell biowaste could be successfully used for the synthesis of HAp with good mechanical and osteogenic properties. These findings may have significant implications for designing of biomaterial for use in orthopedic tissue regeneration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2935-2947, 2017. © 2017 Wiley Periodicals, Inc.

Ossifying tendinitis of the rotator cuff after arthroscopic excision of calcium deposits: report of two cases and literature review.

PubMed

Merolla, Giovanni; Dave, Arpit C; Paladini, Paolo; Campi, Fabrizio; Porcellini, Giuseppe

2015-03-01

Ossifying tendinitis (OT) is a type of heterotopic ossification, characterized by deposition of hydroxyapatite crystals in a histologic pattern of mature lamellar bone. It is usually associated with surgical intervention or trauma and is more commonly seen in Achilles or distal biceps tendons, and also in the gluteus maximus tendon. To our knowledge, there is no description of OT as a complication of calcifying tendinitis of the rotator cuff. In this report, we describe two cases in which the patients developed an OT of the supraspinatus after arthroscopic removal of calcium deposits. The related literature is reviewed.

Computer Tomograph (CT) imaging of mandibular anatomical substrate in animal model restored with nanostructured hydroxyapatite compounds

PubMed Central

Ciuluvică, R; Grădinaru, S; Popescu, M; Piticescu, RM; Cergan, R

2015-01-01

Introduction: This study was meant to test a new type of bone graft on an animal model. This material was a nanostructured hydroxyapatite. Materials and Methods: the study was conducted according to Ethic Committee Regulation on animal model (Oryctolagus cuniculus – rabbit) between August and November 2014, at “Carol Davila” University of Medicine and Pharmacy, Bucharest. The animals were tested by using a CT at the level of the mandible before and after using the nanostructured hydroxyapatite. Results: The animals were CT scanned at 1, 2 and respectively 3 months, noticing a growth of the mandibular bone density. After 3 months, a bone density equal with the density of the healthy bone was noticed. Conclusions: The use of the bone graft could be a viable alternative to available materials. The advantage was that bone recovery had a density similar to the density of the healthy bone and the cost of production was low because it was made out of Calcium azotate and monobasic ammonium phosphate. PMID:25914749

Self-Setting Calcium Orthophosphate Formulations

PubMed Central

Dorozhkin, Sergey V.

2013-01-01

In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are bioactive and biodegradable grafting bioceramics in the form of a powder and a liquid. After mixing, both phases form pastes, which set and harden forming either a non-stoichiometric calcium deficient hydroxyapatite or brushite. Since both of them are remarkably biocompartible, bioresorbable and osteoconductive, self-setting calcium orthophosphate formulations appear to be promising bioceramics for bone grafting. Furthermore, such formulations possess excellent molding capabilities, easy manipulation and nearly perfect adaptation to the complex shapes of bone defects, followed by gradual bioresorption and new bone formation. In addition, reinforced formulations have been introduced, which might be described as calcium orthophosphate concretes. The discovery of self-setting properties opened up a new era in the medical application of calcium orthophosphates and many commercial trademarks have been introduced as a result. Currently such formulations are widely used as synthetic bone grafts, with several advantages, such as pourability and injectability. Moreover, their low-temperature setting reactions and intrinsic porosity allow loading by drugs, biomolecules and even cells for tissue engineering purposes. In this review, an insight into the self-setting calcium orthophosphate formulations, as excellent bioceramics suitable for both dental and bone grafting applications, has been provided. PMID:24956191

Interactions between calcium precipitation and the polyphosphate-accumulating bacteria metabolism.

PubMed

Barat, R; Montoya, T; Borrás, L; Ferrer, J; Seco, A

2008-07-01

A sequencing batch reactor that is operated for biological phosphorus removal has been operated under different influent calcium concentrations to study the precipitation process and the possible effects of phosphorus precipitation in the biological phosphorus removal process. Four experiments were carried out under different influent calcium concentrations ranging from 10 to 90 g Ca m(-3). The experimental results and the equilibrium study, which are based on the saturation index calculation, confirm that the process controlling the calcium behaviour is the calcium phosphate precipitation. This precipitation takes place at two stages: initially, precipitation of the amorphous calcium phosphate, and later crystallization of hydroxyapatite. Also the accumulation of phosphorus precipitated was observed when the influent calcium concentration was increased. In all the experiments, the influent wastewater ratio P/COD was kept constant. It has been observed that, at high calcium concentration, the ratio between phosphate release and acetate uptake (P(rel)/Ac(uptake)) decreases. Changes in the polyphosphate-accumulating organism (PAO) population and in the glycogen-accumulating organism (GAO) population during the experimental period were ruled out by means of fluorescence in situ hybridization. These results could suggest that PAO are able to change their metabolic pathways based on external conditions, such as influent calcium concentration. The accumulation of phosphorus precipitated as calcium phosphate at high influent calcium concentration throughout the experimental period confirmed that phosphate precipitation is a process that can affect the PAO metabolism.

Preparation of thermally stable nanocrystalline hydroxyapatite by hydrothermal method.

PubMed

Prakash Parthiban, S; Elayaraja, K; Girija, E K; Yokogawa, Y; Kesavamoorthy, R; Palanichamy, M; Asokan, K; Narayana Kalkura, S

2009-12-01

Thermally stable hydroxyapatite (HAp) was synthesized by hydrothermal method in the presence of malic acid. X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), differential thermal analysis (DTA), thermogravimetric analysis (TGA) was done on the synthesized powders. These analyses confirmed the sample to be free from impurities and other phases of calcium phosphates, and were of rhombus morphology along with nanosized particles. IR and Raman analyses indicated the adsorption of malic acid on HAp. Thermal stability of the synthesized HAp was confirmed by DTA and TGA. The synthesized powders were thermally stable upto 1,400 degrees C and showed no phase change. The proposed method might be useful for producing thermally stable HAp which is a necessity for high temperature coating applications.

Synthesis, characterization, in vitro anti-proliferative and hemolytic activity of hydroxyapatite.

PubMed

Palanivelu, R; Ruban Kumar, A

2014-06-05

Hydroxyapatite (Ca10(PO4)6(OH)2, HAP) nanoparticles are widely used in several biomedical applications due to its compositional similarities to bone mineral, excellent biocompatibility and bioactivity, osteoconductivity. In this present investigation, HAP nanoparticles synthesized by precipitation technique using calcium nitrate and di-ammonium phosphate. The crystalline nature and the functional group analysis are confirmed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Fourier transform Raman spectroscopy (FT-Raman) respectively. The morphological observations are ascertained from field emission electron scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). In vitro anti-proliferative and hemolytic activities are carried out on the synthesized HAP samples and the studies reveals that HAP have mild activity against erythrocytes. Copyright © 2014 Elsevier B.V. All rights reserved.

Nucleation of hydroxyapatite on Antheraea pernyi (A. pernyi) silk fibroin film.

PubMed

Yang, Mingying; Shuai, Yajun; Zhou, Guanshan; Mandal, Namita; Zhu, Liangjun

2014-01-01

Antheraea pernyi (A. pernyi) silk fibroin, which is spun from a wild silkworm, has increasingly attracted interest in the field of tissue engineering. The aim of this study was to investigate the nucleation of hydroxyapatite (HAp) on A. pernyi fibroin film. Von Kossa staining proved that A. pernyi fibroin had Ca binding activity. The A. pernyi fibroin film was mineralized with HAp crystals by alternative soaking in calcium and phosphate solutions. Spherical crystals were nucleated on the A. pernyi fibroin film according to scanning electron microscopeimaging results. The FT-IR and X-ray diffraction spectra confirmed that these spherical crystals were HAp. The results of in vitro cell culture using MG-63 cells demonstrated that the mineralized A. pernyi fibroin film showed excellent cytocompatibility and sound improvement of the MG-63 cellviability.

Limitation of biocompatibility of hydrated nanocrystalline hydroxyapatite

NASA Astrophysics Data System (ADS)

Minaychev, V. V.; Teleshev, A. T.; Gorshenev, V. N.; Yakovleva, M. A.; Fomichev, V. A.; Pankratov, A. S.; Menshikh, K. A.; Fadeev, R. S.; Fadeeva, I. S.; Senotov, A. S.; Kobyakova, M. I.; Yurasova, Yu B.; Akatov, V. S.

2018-04-01

Nanostructured hydroxyapatite (HA) in the form of hydrated paste is considered to be a promising material for a minor-invasive surgical curing of bone tissue injure. However questions about adhesion of cells on this material and its biocompatibility still remain. In this study biocompatibility of paste-formed nanosized HA (nano-HA) by in vitro methods is investigated. Nano-HA (particles sized about 20 nm) was synthesized under conditions of mechano-acoustic activation of an aqueous reaction mixture of ammonium hydrophosphate and calcium nitrate. It was ascertained that nanocrystalline paste was not cytotoxic although limitation of adhesion, spreading and growth of the cells on its surface was revealed. The results obtained point on the need of modification of hydrated nano-HA in the aims of increasing its biocompatibility and osteoplastic potential.

Isolation and identification of calcium-chelating peptides from Pacific cod skin gelatin and their binding properties with calcium.

PubMed

Wu, Wenfei; Li, Bafang; Hou, Hu; Zhang, Hongwei; Zhao, Xue

2017-12-13

A calcium-chelating peptide is considered to have the ability to improve calcium absorption. In this study, Pacific cod skin gelatin hydrolysates treated with trypsin for 120 min exhibited higher calcium-chelating activity. Sequential chromatography, involving hydroxyapatite affinity chromatography and reversed phase high performance liquid chromatography, was used for the purification of calcium-chelating peptides. Two novel peptides with the typical characteristics of collagen were sequenced as GDKGESGEAGER and GEKGEGGHR based on LC-HRMS/MS, which showed a high affinity to calcium. Calcium-peptide complexation was further characterized by ESI-MS (MS and MS/MS) and FTIR spectroscopy. The results showed that the complexation of the two peptides with calcium was conducted mainly at the ratio of 1 : 1. The amino terminal group and the peptide bond of the peptide backbone as well as the amino group of the lysine side chain and the carboxylate of the glutamate side chain were the possible calcium binding sites for the two peptides. Meanwhile, several amino acid side chain groups, including the hydroxyl (Ser) and carboxylate (Asp) of GDKGESGEAGER and the imine (His) of GEKGEGGHR, were crucial in the complexation. The arginine residue in GEKGEGGHR also participated in the calcium coordination. Additionally, several active fragments with calcium-chelating activity were obtained using MS/MS spectra, including GDKGESGEAGE, GEAGER, GEK, EKG and KGE. This study suggests that gelatin-derived peptides have the potential to be used as a calcium-chelating ingredient to combat calcium deficiency.

How does bone sialoprotein promote the nucleation of hydroxyapatite? A molecular dynamics study using model peptides of different conformations.

PubMed

Yang, Yang; Cui, Qiang; Sahai, Nita

2010-06-15

Bone sialoprotein (BSP) is a highly phosphorylated, acidic, noncollagenous protein in bone matrix. Although BSP has been proposed to be a nucleator of hydroxyapatite (Ca(5)(PO(4))(3)OH), the major mineral component of bone, no detailed mechanism for the nucleation process has been elucidated at the atomic level to date. In the present work, using a peptide model, we apply molecular dynamics (MD) simulations to study the conformational effect of a proposed nucleating motif of BSP (a phosphorylated, acidic, 10 amino-acid residue sequence) on controlling the distributions of Ca(2+) and inorganic phosphate (Pi) ions in solution, and specifically, we explore whether a nucleating template for orientated hydroxyapatite could be formed in different peptide conformations. Both the alpha-helical conformation and the random coil structure have been studied, and inorganic solutions without the peptide are simulated as reference. Ca(2+) distributions around the peptide surface and interactions between Ca(2+) and Pi in the presence of the peptide are examined in detail. From the MD simulations, although in some cases for the alpha-helical conformation, we observe that a Ca(2+) equilateral triangle forms around the surface of peptide, which matches the distribution of Ca(2+) ions on the (001) face of the hydroxyapatite crystal, we do not consistently find a stable nucleating template formation in general for either the helical conformation or the random coil structure. Therefore, independent of conformations, the BSP nucleating motif is more likely to help nucleate an amorphous calcium phosphate cluster, which ultimately converts to crystalline hydroxyapatite.

An Aerobic Digestion of Lime Sludge.

DTIC Science & Technology

1982-07-01

removal. 1,2 After lime addition, phosphorus is considered to be in the form of calcium hydroxyapatite (Ca5-(OH)(P04 )3 ), which will not resolubilize...U: c a e - ~ -’ tr *cr. V. (r. C . -~~~ C c C C&c cj Ir u -. C Fy. - U C C - C F.~-cc 0.c gC - - gg MFC - - C -66 TABLE 20. SUMMARY OF LEAST

Comparative facile methods for preparing graphene oxide-hydroxyapatite for bone tissue engineering.

PubMed

Raucci, M G; Giugliano, D; Longo, A; Zeppetelli, S; Carotenuto, G; Ambrosio, L

2017-08-01

Motivated by the success of using graphene oxide (GO) as a nanofiller of composites, there is a drive to search for this new kind of carbon material as a bioactive component in ceramic materials. In the present study, biomineralized GO was prepared by two different approaches, represented by in situ sol-gel synthesis and biomimetic treatment. It was found that in the biocomposites obtained by the sol-gel approach, the spindle-like hydroxyapatite nanoparticles, with a diameter of ca. 5 ± 0.37 nm and a length of ca. 70 ± 2.5 nm, were presented randomly and strongly on the surface. The oxygen-containing functional groups, such as hydroxyl and carbonyl, present on the basal plane and edges of the GO sheets, play an important role in anchoring calcium ions, as demonstrated by FT-IR and TEM investigations. A different result was obtained for biocomposites after biomimetic treatment: an amorphous calcium phosphate on GO sheet was observed after 5 days of treatment. These different approaches resulted in a diverse effect on the proliferation and differentiation of osteogenic mesenchymal stem cells. In fact, in biocomposites prepared by the sol-gel approach the expression of an early marker of osteogenic differentiation, ALP, increases with the amount of GO in the first days of cell culture. Meanwhile, biomimetic materials sustain cell viability and proliferation, even if the expression of alkaline phosphatase activity in a basal medium is delayed. These findings may provide new prospects for utilizing GO-based hydroxyapatite biocomposites in bone repair, bone augmentation and coating of biomedical implants and broaden the application of GO sheets in biological areas. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Premixed calcium phosphate cements: synthesis, physical properties, and cell cytotoxicity.

PubMed

Xu, Hockin H K; Carey, Lisa E; Simon, Carl G; Takagi, Shozo; Chow, Laurence C

2007-04-01

Calcium phosphate cement (CPC) is a promising material for dental, periodontal, and craniofacial repairs. However, its use requires on-site powder-liquid mixing that increases the surgical placement time and raises concerns of insufficient and inhomogeneous mixing. The objective of this study was to determine a formulation of premixed CPC (PCPC) with rapid setting, high strength, and good in vitro cell viability. PCPCs were formulated from CPC powder+non-aqueous liquid+gelling agent+hardening accelerator. Five PCPCs were thus developed: PCPC-Tartaric, PCPC-Malonic, PCPC-Citric, PCPC-Glycolic, and PCPC-Malic. Formulations and controls were compared for setting time, diametral tensile strength, and osteoblast cell compatibility. Setting time (mean+/-S.D.; n=4) for PCPC-Tartaric was 8.2+/-0.8 min, significantly less than the 61.7+/-1.5 min for the Premixed Control developed previously (p<0.001). On 7th day immersion, the diametral tensile strength of PCPC-Tartaric reached 6.5+/-0.8 MPa, higher than 4.5+/-0.8 MPa of Premixed Control (p=0.036). Osteoblast cells displayed a polygonal morphology and attached to the nano-hydroxyapatite crystals in the PCPCs. All cements had similar live cell density values (p=0.126), indicating that the new PCPCs were as cell compatible as a non-premixed CPC control known to be biocompatible. Each of the new PCPCs had a cell viability that was not significantly different (p>0.1) from that of the non-premixed CPC control. PCPCs will eliminate the powder-liquid mixing during surgery and may also improve the cement performance. The new PCPCs supported cell attachment and yielded a high cell density and viability. Their mechanical strengths approached the reported strengths of sintered porous hydroxyapatite implants and cancellous bone. These nano-crystalline hydroxyapatite cements may be useful in dental, periodontal, and craniofacial repairs.

Synthesis of Hydroxyapatite using Precipitated Calcium Carbonate (PCC) from Limestones

NASA Astrophysics Data System (ADS)

Wardhani, Sri; Isnaini Azkiya, Noor; Triandi Tjahjanto, Rachmat

2018-01-01

Hydroxyapatite (HAp) is a material that widely applied in bone and teeth implant due to its biocompatibility and bioactivity. This material can be prepared from PCC by precipitation method using CaO and H3PO4 in ethanol. In this work, variations of phosphoric acid amount and aging time were investigated. The synthesized HAp was characterized by FT-IR, AAS, UV-Vis Spectrophotometer, PSA, SEM, and powder XRD. The results showed that the high concentration of calcium in PCC gives better yields in which PCC obtained from carbonation method has higher yield than that of caustic soda method. The determination of optimum phosphoric acid addition based on targeted Ca/P ratio (1.67) from HAp was obtained on the addition of 0.1271 mol phosphoric acid with Ca/P ratio of 1.66. The aging time gave significant effect to the particle size of synthesised HAp. The smallest particle size was obtained in aging time for 48 hours as high as 49.25 μm. FTIR spectra of the synthesized HAp show the presence of hydroxyl (-OH) group at 3438.8 cm-1, PO4 3- at 557.39 and 1035.7 cm-1, and CaO at 1413.72 cm-1. The synthesized HAp forms agglomeration solid based on the SEM analysis. The powder XRD data shows three highest peaks at 2θ i.e. 27.8296; 31.1037; and 34.3578 which corresponds to β-TCP (tricalcium phosphate) in accordance with JCPDS no.09-0169. The characteristic 2θ peak of hydroxyapatite with low intensity is observed from the synthesized HAp refer to the JCPDS data no. 09-0432.

Distribution of organic matrix in calcium oxalate renal calculi.

PubMed

Warpehoski, M A; Buscemi, P J; Osborn, D C; Finlayson, B; Goldberg, E P

1981-01-01

The quantity of protein and carbohydrate comprising the matrix of calcium oxalate monohydrate (COM) renal stones was found to decrease with distance from the surface of the stone. The average organic concentration of stones 3 to 30 mm in diameter ranged from 5.7% at the surface to 2.7% at the core. This concentration gradient suggests matrix involvement in a "growth front" on stone surfaces with migration of organic material from the "older" interior. The matrix distribution was not readily correlated with density variations or with the presence of hydroxyapatite or calcium oxalate dihydrate. Surface matrix concentrations were greater than amounts predicted by physical adsorption. Electron microscopy confirmed the presence of the organic-rich surface layer and also suggested that increase in stone size occurs predominantly by crystal growth with microcrystal aggregates as growth centers.

Role of magnesium on the biomimetic deposition of calcium phosphate

NASA Astrophysics Data System (ADS)

Sarma, Bimal K.; Sarma, Bikash

2016-10-01

Biomimetic depositions of calcium phosphate (CaP) are carried out using simulated body fluid (SBF), calcifying solution and newly developed magnesium containing calcifying solution. Calcium phosphate has a rich phase diagram and is well known for its excellent biocompatibility and bioactivity. The most common phase is hydroxyapatite (HAp), an integral component of human bone and tooth, widely used in orthopedic and dental applications. In addition, calcium phosphate nanoparticles show promise for the targeted drug delivery. The doping of calcium phosphate by magnesium, zinc, strontium etc. can change the protein uptake by CaP nanocrystals. This work describes the role of magnesium on the nucleation and growth of CaP on Ti and its oxide substrates. X-ray diffraction studies confirm formation of HAp nanocrystals which closely resemble the structure of bone apatite when grown using SBF and calcifying solution. It has been observed that magnesium plays crucial role in the nucleation and growth of calcium phosphate. A low magnesium level enhances the crystallinity of HAp while higher magnesium content leads to the formation of amorphous calcium phosphate (ACP) phase. Interestingly, the deposition of ACP phase is rapid when magnesium ion concentration in the solution is 40% of calcium plus magnesium ions concentration. Moreover, high magnesium content alters the morphology of CaP films.

Correlation of Salivary Statherin and Calcium Levels with Dental Calculus Formation: A Preliminary Study.

PubMed

Pateel, Deepak Gowda Sadashivappa; Gunjal, Shilpa; Math, Swarna Y; Murugeshappa, Devarasa Giriyapura; Nair, Sreejith Muraleedharan

2017-01-01

Salivary constituents have a wide range of functions including oral calcium homeostasis. Salivary proteins such as statherin inhibit crystal growth of calcium phosphate in supersaturated solutions and interact with several oral bacteria to adsorb on hydroxyapatite. Concurrently, saliva, which is supersaturated with respect to calcium phosphates, is the driving force for plaque mineralization and formation of calculus. Thus, the aim of the present study was to estimate and correlate salivary statherin and calcium concentration to the dental calculus formation. A cross-sectional study was conducted to assess the relationship between salivary statherin, calcium, and dental calculus among 70 subjects, aged 20-55 years. Subjects were divided into 3 groups based on the calculus scores as interpreted by Calculus Index which was followed by collection of whole saliva using Super•SAL™. Salivary calcium levels were assessed by calorimetric method using Calcium Assay kit (Cayman Chemical, Michigan, USA) and statherin levels by using ELISA Kit (Cusabio Biotech). Statherin levels showed a weak negative correlation with the calcium levels and with calculus formation. The mean salivary statherin and calcium concentration were found to be 0.96  μ g/ml and 3.87 mg/ml, respectively. Salivary statherin levels differed significantly among the three groups ( p < 0.05). Our preliminary data indicates that statherin could possibly play a role in the formation of dental calculus.

Hydroxyapatite, fluor-hydroxyapatite and fluorapatite produced via the sol-gel method: dissolution behaviour and biological properties after crystallisation.

PubMed

Tredwin, Christopher J; Young, Anne M; Abou Neel, Ensanya A; Georgiou, George; Knowles, Jonathan C

2014-01-01

Hydroxyapatite (HA), fluor-hydroxyapatite (FHA) with varying levels of fluoride ion substitution and fluorapatite (FA) were synthesised by the sol-gel method as possible implant coating or bone-grafting materials. Calcium nitrate and triethyl phosphite were used as precursors under an ethanol-water based solution. Different amounts of ammonium fluoride were incorporated for the preparation of the FHA and FA sol-gels. After heating and powdering the sol-gels, dissolution behaviour was assessed using ion chromatography to measure Ca(2+) and PO4 (3-) ion release. Biological behaviour was assessed using cellular proliferation with human osteosarcoma cells and alamarBlue™ assay. Statistical analysis was performed with a two way analysis of variance and post hoc testing with a Bonferroni correction. Increasing fluoride substitution into an apatite structure decreased the dissolution rate. Increasing the firing temperature of the HA, FHA and FA sol-gels up to 1,000 °C decreased the dissolution rate. There was significantly higher cellular proliferation on highly substituted FHA and FA than on HA or Titanium. The properties of an implant coating or bone grafting material can be tailored to meet specific requirements by altering the amount of fluoride that is incorporated into the original apatite structure. The dissolution behaviour can further be altered by the temperature at which the sol-gel is fired.

Amelogenin-assisted ex vivo remineralization of human enamel: effects of supersaturation degree and fluoride concentration

PubMed Central

Fan, Yuwei; Nelson, James R.; Alvarez, Jason R.; Hagan, Joseph; Berrier, Allison; Xu, Xiaoming

2011-01-01

The formation of organized nanocrystals that resemble enamel is crucial for successful enamel remineralization. Calcium, phosphate and fluoride ions and amelogenin are important ingredients for the formation of organized hydroxyapatite (HAP) crystals in vitro. However, the effects of these remineralization agents on the enamel crystal morphology have not been thoroughly studied. The objective of this study was to investigate the effects of fluoride ions, supersaturation degree and amelogenin on the crystal morphology and organization of ex vivo remineralized human enamel. Extracted third molars were sliced thin and acid-etched to provide the enamel surface for immersion in different remineralization solutions. The crystal morphology and mineral phase of the remineralized enamel surface were analyzed by FE-SEM, ATR-FTIR and XRD. The concentration of fluoride and supersaturation degree of hydroxyapatite had significant effects on the crystal morphology and crystal organization, which varied from plate-like loose crystals to rod-like densely packed nanocrystal arrays. Densely packed arrays of fluoridated hydroxyapatite nanorods were observed under the following conditions: σ(HAP) = 10.2±2.0 with fluoride 1.5±0.5 mg/L and amelogenin 40±10 µg/mL, pH 6.8±0.4. A phase diagram summarized the conditions that form dense or loose hydroxyapatite nanocrystal structures. This study provides the basis for the development of novel dental materials for caries management. PMID:21256987

Influence of SrO substitution for CaO on the properties of bioactive glass S53P4.

PubMed

Massera, Jonathan; Hupa, Leena

2014-03-01

Commercial melt-quenched bioactive glasses consist of the oxides of silicon, phosphorus, calcium and sodium. Doping of the glasses with oxides of some other elements is known to affect their capability to support hydroxyapatite formation and thus bone tissue healing but also to modify their high temperature processing parameters. In the present study, the influence of gradual substitution of SrO for CaO on the properties of the bioactive glass S53P4 was studied. Thermal analysis and hot stage microscopy were utilized to measure the thermal properties of the glasses. The in vitro bioactivity and solubility was measured by immersing the glasses in simulated body fluid for 6 h to 1 week. The formation of silica rich and hydroxyapatite layers was assessed from FTIR spectra analysis and SEM images of the glass surface. Increasing substitution of SrO for CaO decreased all characteristic temperatures and led to a slightly stronger glass network. The initial glass dissolution rate increased with SrO content. Hydroxyapatite layer was formed on all glasses but on the SrO containing glasses the layer was thinner and contained also strontium. The results suggest that substituting SrO for CaO in S53P4 glass retards the bioactivity. However, substitution greater than 10 mol% allow for precipitation of a strontium substituted hydroxyapatite layer.

Effect of modification substrate on the microstructure of hydroxyapatite coating

NASA Astrophysics Data System (ADS)

Realpe-Jaramillo, J.; Morales-Morales, J. A.; González-Sánchez, J. A.; Cabanzo, R.; Mejía-Ospino, E.; Rodríguez-Pereira, J.

2017-01-01

Bioactive hydroxyapatite (HA) coatings were fabricated by a precipitation, sol-gel and dip-coating method. The effects of the aging time and the base used to adjust pH and substrate materials on the phases and microstructures of HA coatings were studied by field emission scanning electron microscopy FESEM, energy dispersive spectroscopy EDS, X-ray photoelectron spectroscopy XPS, and the vibrations of the phosphate groups were determined by Raman spectroscopy. The results showed that all the films were composed of the phases of TiO2 and HA. With coated titanium substrate with TiO2, the crystallinity of the HA coating increases, the structure became more compact and the Ca/P ratio increased because of the loss of P in the films. The addition of sodium hydroxide (adjusting the pH level to about 10) can increase the HA content in the coating. XPS and EDS results for steel substrate and titanium showed poor calcium content as obtained with a Ca/P ratio of 1.38 and 1.58, respectively, composition is similar to that of natural apatite. However, spectroscopic results suggest the presence of a mixture of hydroxyapatite and octacalcium phosphate. The different substrate materials have a high influence on the microstructure of the separated double films. However, hydroxyapatite nanopowders coatings were obtained using a simple method, with potential biomedical applications.

Laser/LED phototherapy on the repair of tibial fracture treated with wire osteosynthesis evaluated by Raman spectroscopy.

PubMed

Pinheiro, Antônio L B; Soares, Luiz G P; da Silva, Aline C P; Santos, Nicole R S; da Silva, Anna Paula L T; Neves, Bruno Luiz R C; Soares, Amanda P; Silveira, Landulfo

2018-04-23

The aim of the present study was to assess, by means of Raman spectroscopy, the repair of complete surgical tibial fractures fixed with wire osteosynthesis (WO) treated or not with infrared laser (λ780 nm) or infrared light emitting diode (LED) (λ850 ± 10 nm) lights, 142.8 J/cm 2 per treatment, associated or not to the use of mineral trioxide aggregate (MTA) cement. Surgical tibial fractures were created on 18 rabbits, and all fractures were fixed with WO and some groups were grafted with MTA. Irradiated groups received lights at every other day during 15 days, and all animals were sacrificed after 30 days, being the tibia removed. The results showed that only irradiation with either laser or LED influenced the peaks of phosphate hydroxyapatite (~ 960 cm -1 ). Collagen (~ 1450 cm -1 ) and carbonated hydroxyapatite (~ 1070 cm -1 ) peaks were influenced by both the use of MTA and the irradiation with either laser or LED. It is concluded that the use of either laser or LED phototherapy associated to MTA cement was efficacious on improving the repair of complete tibial fractures treated with wire osteosynthesis by increasing the synthesis of collagen matrix and creating a scaffold of calcium carbonate (carbonated hydroxyapatite-like) and the subsequent deposition of phosphate hydroxyapatite.

Low-intensity pulsed ultrasound (LIPUS) stimulates mineralization of MC3T3-E1 cells through calcium and phosphate uptake.

PubMed

Tassinary, João Alberto Fioravante; Lunardelli, Adroaldo; Basso, Bruno de Souza; Dias, Henrique Bregolin; Catarina, Anderson Velasque; Stülp, Simone; Haute, Gabriela Viegas; Martha, Bianca Andrade; Melo, Denizar Alberto da Silva; Nunes, Fernanda Bordignon; Donadio, Márcio Vinícius Fagundes; Oliveira, Jarbas Rodrigues de

2018-03-01

The present study aimed to evaluate the effect of low-intensity pulsed ultrasound (LIPUS) on pre-osteoblast mineralization using in vitro bioassays. Pre-osteoblastic MC3T3-E1 cells were exposed to LIPUS at 1 MHz frequency, 0.2 W/cm 2 intensity and 20% duty cycle for 30 min. The analyses were carried out up to 336 h (14 days) after exposure. The concentration of collagen, phosphate, alkaline phosphatase, calcium and transforming growth factor beta 1 (TGF-β1) in cell supernatant and the presence of calcium deposits in the cells were analyzed. Our results showed that LIPUS promotes mineralized nodules formation. Collagen, phosphate, and calcium levels were decreased in cell supernatant at 192 h after LIPUS exposure. However, alkaline phosphatase and TGF-β1 concentrations remained unchanged. Therapeutic pulsed ultrasound is capable of stimulating differentiation and mineralization of pre-osteoblastic MC3T3-E1 cells by calcium and phosphate uptake with consequent hydroxyapatite formation. Copyright © 2017 Elsevier B.V. All rights reserved.

Calcium bodies of Titanethes albus (Crustacea: Isopoda): molt-related structural dynamics and calcified matrix-associated bacteria.

PubMed

Vittori, Miloš; Kostanjšek, Rok; Znidaršič, Nada; Zagar, Kristina; Ceh, Miran; Strus, Jasna

2012-10-01

Crustaceans form a variety of calcium deposits in which they store calcium necessary for the mineralization of their exoskeletons. Calcium bodies, organs containing large amounts of calcium, have been reported in some terrestrial isopod crustaceans, but have not yet been extensively studied. We analyzed the architecture of these organs during the molt cycle in the isopod Titanethes albus. Two pairs of calcium bodies are positioned ventrolaterally in posterior pereonites of T. albus. Individual organs are epithelial sacs that contain material arranged in concentric layers delimited by thin laminae. As demonstrated by electron microscopy and fluorescence in situ hybridization, abundant bacteria are present within the calcium bodies. Regardless of the molt cycle stage, crystalline concretions are present in the central areas of the calcium bodies. Energy dispersive X-ray spectrometry of the concretions demonstrated that they are composed predominantly of calcium and phosphorus and selected area electron diffraction indicated the presence of hydroxyapatite. In molting animals, a glassy layer of mineralized matrix is formed between the envelope and the outermost lamina of the calcium body. This layer consists of an amorphous calcium mineral which contains less phosphorus than the central concretions and is resorbed after molt. Since changes in the mineralized matrix are synchronized with the molt cycle, the calcium bodies likely function as a storage compartment that complements sternal deposits as a source of calcium for the mineralization of the exoskeleton. Bacteria associated with the mineralized matrix of calcium bodies are evidently involved in calcium dynamics. Copyright © 2012 Elsevier Inc. All rights reserved.

Wear characterization of nano-hydroxyapatite with addition of titanium (HA-Ti)

NASA Astrophysics Data System (ADS)

Rosmamuhamadani, R.; Arawi, A. Z. O.; Talari, M. K.; Mahat, M. M.; Bonnia, N. N.; Sabrina; Yahaya, M.; Sulaiman, S.; Ismail, M. I. S.

2018-04-01

Hydroxyapatite (Ca10 (PO4)6(OH)2, HA), is an attractive material of an inorganic compound whose chemical composition and crystallographic structures are similar to the composition of the bone. A natural source such as egg shells is composed of 94 wt. % of calcium carbonate (CaCO3), which can be calcined as calcium oxide (CaO) by the calcinations process. The efficient temperature to produce CaO is 900 °C for 2 hours. The synthesis of nano-HA was done by the mixing the diammonium phosphate (DAP) and calcium hydroxide (Ca(OH)2) and subjected into a microwave for 30 minutes at 1100 W irradiation power. Ball milling process was used for 30 minutes to mix the nano-HA with different compositions of titanium. These were pressed to form pallets by hand hydraulic pump (force=2300 psi). The pallets then were sintered at 1200 °C with the heating rate of 3 °C/min for 2 hours. The pallets were tested by several mechanical testing including hardness, compression strength and wear. From the results, HA-25wt. %Ti composite gave the highest hardness, compression and coefficient of friction for wear test values which were 89.6 Hv, 82.5MPa and 0.76μ respectively. It showed that by adding Ti to nano-HA, the mechanical properties of nano-HA could be enhanced. The microstructure analyses by optical micrograph showed that nano-HA-Ti particles displayed shape likes needle morphology. The particles showed the high tendency to form the agglomerations.

Dry mechanochemical synthesis of hydroxyapatites from DCPD and CaO: influence of instrumental parameters on the reaction kinetics.

PubMed

Mochales, Carolina; El Briak-BenAbdeslam, Hassane; Ginebra, Maria Pau; Terol, Alain; Planell, Josep A; Boudeville, Philippe

2004-01-01

Mechanochemistry is a possible route to synthesize calcium deficient hydroxyapatite (CDHA) with an expected molar calcium-to-phosphate (Ca/P) ratio +/-0.01. To optimize the experimental conditions of CDHA preparation from dicalcium phosphate dihydrate (DCPD) and calcium oxide by dry mechanosynthesis reaction, we performed the kinetic study varying some experimental parameters. This kinetic study was carried out with two different planetary ball mills (Retsch or Fritsch Instuments). Results obtained with the two mills led to the same conclusions although the values of the rate constants of DCPD disappearance and times for complete reaction were very different. Certainly, the origin of these differences was from the mills used, thus we investigated the influence of instrumental parameters such as the mass and the surface area of the balls or the rotation velocity on the mechanochemical reaction kinetics of DCPD with CaO. Results show that the DCPD reaction rate constant and the inverse of the time for complete disappearance of CaO both vary linearly with (i) the square of the rotation velocity, (ii) the square of eccentricity of the vial on the rotating disc and (iii) the product of the mass by the surface area of the balls. These observations comply with theoretical models developed for mechanical alloying. The consideration of these four parameters allows the transposition of experimental conditions from one mill to another or the comparison between results obtained with different planetary ball mills. These instrumental parameters have to be well described in papers concerning mechanochemistry or when grinding is an important stage in a process.

Inaccurate reporting of mineral composition by commercial stone analysis laboratories: implications for infection and metabolic stones.

PubMed

Krambeck, Amy E; Khan, Naseem F; Jackson, Molly E; Lingeman, James E; McAteer, James A; Williams, James C

2010-10-01

We determined the accuracy of stone composition analysis at commercial laboratories. A total of 25 human renal stones with infrared spectroscopy determined composition were fragmented into aliquots and studied with micro computerized tomography to ensure fragment similarity. Representative fragments of each stone were submitted to 5 commercial stone laboratories for blinded analysis. All laboratories agreed on the composition of 6 pure stones. Only 2 of 4 stones (50%) known to contain struvite were identified as struvite at all laboratories. Struvite was reported as a component by some laboratories for 4 stones previously determined not to contain struvite. Overall there was disagreement regarding struvite in 6 stones (24%). For 9 calcium oxalate stones all laboratories reported some mixture of calcium oxalate but the quantity of subtypes differed significantly among laboratories. In 6 apatite containing stones apatite was missed by the laboratories in 20% of samples. None of the laboratories identified atazanavir in a stone containing that antiviral drug. One laboratory reported protein in every sample while all others reported it in only 1. Nomenclature for apatite differed among laboratories with 1 reporting apatite as carbonate apatite and never hydroxyapatite, another never reporting carbonate apatite and always reporting hydroxyapatite, and a third reporting carbonate apatite as apatite with calcium carbonate. Commercial laboratories reliably recognize pure calculi. However, variability in the reporting of mixed calculi suggests a problem with the accuracy of stone analysis results. There is also a lack of standard nomenclature used by laboratories. Copyright © 2010 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Phase Composition Control of Calcium Phosphate Nanoparticles for Tunable Drug Delivery Kinetics and Treatment of Osteomyelitis. Part 1: Preparation and Drug Release

PubMed Central

Uskoković, Vuk; Desai, Tejal A.

2012-01-01

Developed in this study is a multifunctional material for simultaneous osseoinduction and drug delivery, potentially applicable in the treatment of osteomyelitis. It is composed of agglomerates of nanoparticles of calcium phosphate (CAP) with different monophasic contents. The drug loading capacity and the release kinetics were investigated on two model drug compounds with different chemical structures, sizes and adsorption propensities: bovine serum albumin and fluorescein. Loading of CAP powders with small molecule drugs was achieved by physisorption and desiccation-induced agglomeration of nanoparticulate subunits into microscopic blocks. The material dissolution rate and the drug release rate depended on the nature of the CAP phase, decreasing from monocalcium phosphate to monetite to amorphous CAP and calcium pyrophosphate to hydroxyapatite. The sustained release of the two model drugs was shown to be directly relatable to the degradation rate of CAP carriers. It was demonstrated that the degradation rate of the carrier and the drug release kinetics could be made tunable within the time scale of 1–2 h for the most soluble CAP phase, monocalcium phosphate, to 1–2 years for the least soluble one, hydroxyapatite. From the standpoint of antibiotic therapy for osteomyelitis, typically lasting for six weeks, the most prospective CAP powder was amorphous CAP with its release time scale for a small organic molecule, the same category to which antibiotics belong, of 1 – 2 months under the conditions applied in our experiments. By combining these different CAP phases in various proportions, drug release profiles could be tailored to the therapeutic occasion. PMID:23115118

Structural and mechanical characterization of boron doped biphasic calcium phosphate produced by wet chemical method and subsequent thermal treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albayrak, Onder, E-mail: albayrakonder@mersin.edu.tr

In the current study, boron doped biphasic calcium phosphate bioceramics consisting of a mixture of boron doped hydroxyapatite (BHA) and beta tricalcium phosphate (β-TCP) of varying BHA/β-TCP ratios were obtained after sintering stage. The effects of varying boron contents and different sintering temperatures on the BHA/β-TCP ratios and on the sinterability of the final products were investigated. Particle sizes and morphologies of the obtained precipitates were determined using SEM. XRD and FTIR investigation were conducted to detect the boron formation in the structure of HA and quantitative analysis was performed to determine the BHA/β-TCP ratio before and after sintering stage.more » In order to determine the sinterability of the obtained powders, pellets were prepared and sintered; the rates of densification were calculated and obtained results were correlated by SEM images. Also Vickers microhardness values of the sintered samples were determined. The experimental results verified that boron doped hydroxyapatite powders were obtained after sintering stage and the structure consists of a mixture of BHA and β-TCP. As the boron content used in the precipitation stage increases, β-TCP content of the BHA/β-TCP ratio increases but sinterability, density and microhardness deteriorate. As the sintering temperature increases, β-TCP content, density and microhardness of the samples increase and sinterability improves. - Highlights: • This is the first paper about boron doped biphasic calcium phosphate bioceramics. • Boron doping affects the structural and mechanical properties. • BHA/β-TCP ratio can be adjustable with boron content and sintering temperature.« less

Electrospun oriented gelatin-hydroxyapatite fiber scaffolds for bone tissue engineering.

PubMed

Salifu, Ali A; Lekakou, Constantina; Labeed, Fatima H

2017-07-01

Tissue engineering of human fetal osteoblast cells was investigated on gelatin-hydroxyapatite (HA), crosslinked, electrospun oriented fiber scaffolds at the different HA concentrations of 0, 10, 20, and 25 wt % in the dry fibers and different fiber diameter, pore size and porosity of scaffolds. Rheological tests and proton nuclear magnetic resonance spectroscopy were conducted for all solutions used for electrospinning. It was found that 25 wt % HA-gelatin scaffolds electrospun at 20 kV led to the greatest cell attachment, cell proliferation and extracellular matrix (ECM) production while fiber orientation improved the mechanical properties, where crosslinked electrospun 25 wt % HA-gelatin fiber scaffolds yielded a Young's modulus in the range of 0.5-0.9 GPa and a tensile strength in the range of 4-10 MPa in the fiber direction for an applied voltage of 20-30 kV, respectively, in the electrospinning of scaffolds. Biological characterization of cell seeded scaffolds yielded the rate of cell growth and ECM (collagen and calcium) production by the cells as a function of time; it included cell seeding efficiency tests, alamar blue cell proliferation assay, alkaline phosphate (ALP) assay, collagen assay, calcium colorimetric assay, fluorescence microscopy for live and dead cells, and scanning electron microscopy for cell culture from 1 to 18 days. After 18 days, cells seeded and grown on the 25 wt % HA-gelatin scaffold, electrospun at 20 kV, reached production of collagen at 370 μg/L and calcium production at 0.8 mM. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1911-1926, 2017. © 2017 Wiley Periodicals, Inc.

Characterization of derived natural hydroxyapatite (HAp) obtained from different types of tilapia fish bones and scales

NASA Astrophysics Data System (ADS)

Fara, A. N. K. A.; Abdullah, H. Z.

2015-07-01

Hydroxyapatite, (HAp), Ca10(PO4)6(OH)2, is recognised as a biomaterial that is widely used for bone implant due to its chemical and structural similarity to the mineral components in human bone and enamel. The elements of HAp are primarily composed of calcium and phosphorus molar ratio of calcium to phosphorous is 1.67 capable to promote bone in-growth into prosthetic implant. Enormous amounts of by-product waste produced from fish factories generated an undesirable environmental impact. Thus, this study was conducted to obtain natural biological HAp from different types of tilapia fish bones and scales from fishery waste. Therefore, fish bones and scales can be as cheap source to produce biological HAp for medical applications. For this purpose, fish bones and scales of tilapia fish were boiled at 100°C to remove adhering meat and other impurities. Later, fish bones and scales were separated into several groups and subjected to different calcination temperatures of 800° C and 900° C for 3h respectively. Afterward, all calcined samples were crushed to form a fine powder. The XRD result revealed the presence of derived Hapfrom the samples powder and were identical with standard Hap. Thermo Gravimetric Analysis was carried out to show the thermal stability of the HAp powder from different types of fish bones and scales. SEM results show porous structure appeared in calcined samples compared to raw samples. The findings are the promising alternative to produce calcium and phosphorus from fishery wastes that beneficial to medical applications.

Synthesis and structural characterization of nano-hydroxyapatite biomaterials prepared by microwave processing

NASA Astrophysics Data System (ADS)

Ramli, Rosmamuhamadani; Arawi, Ainaa Zafirah Omar; Talari, Mahesh Kumar; Mahat, Mohd Muzamir; Jais, Umi Sarah

2012-07-01

Synthetic hydroxyapatite, (HA, Ca10(PO4)6(OH)2), is an attractive and widely utilized bio-ceramic material for orthopedic and dental implants because of its close resemblance of native tooth and bone crystal structure. Synthetic HA exhibits excellent osteoconductive properties. Osteoconductivity means the ability to provide the appropriate scaffold or template for bone formation. Calcium phosphate biomaterials [(HA), tri-calcium phosphate (TCP) and biphasic calcium phosphate (HA/TCP)] with appropriate three-dimensional geometry are able to bind and concentrate endogenous bone morphogenetic proteins in circulation, and may become osteoinductive and can be effective carriers of bone cell seeds. This HA can be used in bio-implants as well as drug delivery application due to the unique properties of HA. Biomaterials synthesized from the natural species like mussel shells have additional benefits such as high purity, less expensive and high bio compatibility. In this project, HA-nanoparticles of different crystallite size were prepared by microwave synthesis of precursors. High purity CaO was extracted from the natural mussel shells for the synthesis of nano HA. Dried nano HA powders were analyzed using X-Ray Diffraction (XRD) technique for the determination of crystal structure and impurity content. Scanning Electron Microscopic (SEM) investigation was employed for the morphological investigation of nano HA powders. From the results obtained, it was concluded that by altering the irradiation time, nano HA powders of different crystallite sizes and morphologies could be produced. Crystallite sizes calculated from the XRD patterns are found to be in the range of 10-55 nm depending on the irradiation time.

Microwave hydrothermal transformation of amorphous calcium carbonate nanospheres and application in protein adsorption.

PubMed

Qi, Chao; Zhu, Ying-Jie; Chen, Feng

2014-03-26

Calcium carbonate and calcium phosphate are the main components of biominerals. Among all of the forms of biominerals, amorphous calcium carbonate (ACC) and amorphous calcium phosphate (ACP) are the most important forms because they play a pivotal role in the process of biomineralization and are the precursors to the crystalline polymorphs. In this work, we first synthesized ACC in vitro using adenosine 5'-triphosphate disodium salt (ATP) as the stabilizer and investigated the transformation of the ACC under microwave hydrothermal conditions, and ACC/ACP composite nanospheres and carbonated hydroxyapatite (CHA) nanospheres were successfully prepared. In this novel strategy, ATP has two main functions: it serves as the stabilizer for ACC and the phosphorus source for ACP and CHA. Most importantly, the morphology and the size of the ACC precursor can be well-preserved after microwave heating, so it provides a new method for the preparation of calcium phosphate nanostructured materials using phosphorus-containing biomolecule-stabilized ACC as the precursor. Furthermore, the as-prepared ACC/ACP composite nanospheres have excellent biocompatibility and high protein adsorption capacity, indicating that they are promising for applications in biomedical fields such as drug delivery and protein adsorption.

Contrast Agents for Micro-Computed Tomography of Microdamage in Bone

DTIC Science & Technology

2009-01-01

carboxylate (reported in January 2009), phosphonate and bisphosphonate groups (Fig. 2). The presence of functional groups was verified by FT- IR (Fig. 3...carboxylic acid, (b) phosphonate or (c) bisphosphonate groups for calcium binding damaged tissue. (a) (b) (c) Fig. 3. FT- IR spectra for Au NPs...functional group. Quantitative measurements of the binding affinity were performed by adding hydroxyapatite (HA) crystals to functionalized Au NP solutions in

Hydroxylapatite chromatography.

PubMed

Broadhurst, A V

2001-05-01

Hydroxylapatite (also called hydroxyapatite), a form of calcium phosphate, can be used as a matrix for the chromatography of both proteins and nucleic acids. Protocols are provided for both standard low-pressure chromatography of a protein mixture using a hydroxylapatite column prepared in the laboratory, and an HPLC method, applicable to proteins and nucleic acids, that uses a commercially available column. Alternate protocols describe column chromatography using a step gradient or batch binding and step-gradient elution.

Uncarboxylated Osteocalcin and Gprc6a Axis Produce Intratumoral Androgens in Castration-Resistant Prostate Cancer

DTIC Science & Technology

2015-03-01

interacts with bone extracellular matrix associated calcium and hydroxyapatite and deposited in the bone matrix. Some Osteocalcin is released into...fluorescence protein as control) Osteocalcin and mutant Osteocalcin using lentivirus mediated stable infections. 2. Determined the gene expression of Gprc61... used a lentiviral system for expressing Osteocalcin and mutated Osteocalcin. Osteocalcin is mutated at three positions where glutamic acid residue at

Energetic basis for the molecular-scale organization of bone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tao, Jinhui; Battle, Keith C.; Pan, Haihua

2014-12-24

The remarkable properties of bone derive from a highly organized arrangement of co-aligned nm-scale apatite platelets within a fibrillar collagen matrix. The origin of this arrangement is poorly understood and the crystal structures of hydroxyapatite (HAP) and the non-mineralized collagen fibrils alone do not provide an explanation. Moreover, little is known about collagen-apatite interaction energies, which should strongly influence both the molecular-scale organization and the resulting mechanical properties of the composite. We investigated collagen-mineral interactions by combining dynamic force spectroscopy (DFS) measurements of binding energies with molecular dynamics (MD) simulations of binding and AFM observations of collagen adsorption on singlemore » crystals of calcium phosphate for four mineral phases of potential importance in bone formation. In all cases, we observe a strong preferential orientation of collagen binding, but comparison between the observed orientations and TEM analyses native tissues shows only calcium-deficient apatite (CDAP) provides an interface with collagen that is consistent with both. MD simulations predict preferred collagen orientations that agree with observations and results from both MD and DFS reveal large values for the binding energy due to multiple binding sites. These findings reconcile apparent contradictions inherent in a hydroxyapatite or carbonated apatite (CAP) model of bone mineral and provide an energetic rationale for the molecular scale organization of bone.« less

Bioactivation of calcium deficient hydroxyapatite with foamed gelatin gel. A new injectable self-setting bone analogue.

PubMed

Dessì, M; Alvarez-Perez, M A; De Santis, R; Ginebra, M P; Planell, J A; Ambrosio, L

2014-02-01

An alternative approach to bone repair for less invasive surgical techniques, involves the development of biomaterials directly injectable into the injury sites and able to replicate a spatially organized platform with features of bone tissue. Here, the preparation and characterization of an innovative injectable bone analogue made of calcium deficient hydroxyapatite and foamed gelatin is presented. The biopolymer features and the cement self-setting reaction were investigated by rheological analysis. The porous architecture, the evolution of surface morphology and the grains dimension were analyzed with electron microscopy (SEM/ESEM/TEM). The physico-chemical properties were characterized by X-ray diffraction and FTIR analysis. Moreover, an injection test was carried out to prove the positive effect of gelatin on the flow ensuing that cement is fully injectable. The cement mechanical properties are adequate to function as temporary substrate for bone tissue regeneration. Furthermore, MG63 cells and bone marrow-derived human mesenchymal stem cells (hMSCs) were able to migrate and proliferate inside the pores, and hMSCs differentiated to the osteoblastic phenotype. The results are paving the way for an injectable bone substitute with properties that mimic natural bone tissue allowing the successful use as bone filler for craniofacial and orthopedic reconstructions in regenerative medicine.

The Antimicrobial Properties of Zinc-Releasing Bioceramics

NASA Astrophysics Data System (ADS)

He, Xin

Up to 80% of nosocomial infections are caused by biofilm-producing bacteria such as Staphylococci and Pseudomonas aeruginosa. These types of microorganisms can become resistant to antibiotics and are difficult to eliminate. As such, there is tremendous interest in developing bioactive implant materials that can help to minimize these post- operative infections. Using water-based chemistry, we developed an economical, biodegradable and biocompatible orthopedic implant material consisting of zinc- doped hydroxyapatite (HA), which mimics the main inorganic component of the bone. Because the crystallinity of HA is typically too compact for efficient drug release, we substituted calcium ions in HA with zinc during the synthesis step to perturb the crystal structure. An added benefit is that zinc itself is a microelement of the human body with anti-inflammatory property, and we hypothesized that Zn-doped HA is an inherently antibacterial material. All HA samples were synthesized by a co-precipitation method using aqueous solutions of Zinc nitrate, Calcium Nitrate, and Ammonium Phosphate. XRD data showed that Zn was successfully incorporated into the HA. The effectiveness of Zn-doped HA against a model biofilm-forming bacterium is currently being evaluated using a wild-type strain and a streptomycin- resistant strain of Pseudomonas syringae pv. papulans (Psp) which is a plant pathogen isolated from diseased apples. Key words: Hydroxyapatite, Zinc, Citrate, Pseudomonas, Antibacterial.

Stem cell engineered bone with calcium-phosphate coated porous titanium scaffold or silicon hydroxyapatite granules for revision total joint arthroplasty.

PubMed

García-Gareta, Elena; Hua, Jia; Rayan, Faizal; Blunn, Gordon W

2014-06-01

Aseptic loosening in total joint replacements (TJRs) is mainly caused by osteolysis which leads to a reduction of the bone stock necessary for implant fixation in revision TJRs. Our aim was to develop bone tissue-engineered constructs based on scaffolds of clinical relevance in revision TJRs to reconstitute the bone stock at revision operations by using a perfusion bioreactor system (PBRS). The hypothesis was that a PBRS will enhance mesenchymal stem cells (MSCs) proliferation and osteogenic differentiation and will provide an even distribution of MSCs throughout the scaffolds when compared to static cultures. A PBRS was designed and implemented. Scaffolds, silicon substituted hydroxyapatite granules and calcium-phosphate coated porous TiAl6V4 cylinders, were seeded with MSCs and cultured either in static conditions or in the PBRS at 0.75 mL/min. Statistically significant increased cell proliferation and alkaline phosphatase activity was found in samples cultured in the PBRS. Histology revealed a more even cell distribution in the perfused constructs. SEM showed that cells arranged in sheets. Long cytoplasmic processes attached the cells to the scaffolds. We conclude that a novel tissue engineering approach to address the issue of poor bone stock at revision operations is feasible by using a PBRS.

Biological Assessment of a Calcium Silicate Incorporated Hydroxyapatite-Gelatin Nanocomposite: A Comparison to Decellularized Bone Matrix

PubMed Central

Lee, Dong Joon; Padilla, Ricardo; Zhang, He; Hu, Wei-Shou; Ko, Ching-Chang

2014-01-01

Our laboratory utilized biomimicry to develop a synthetic bone scaffold based on hydroxyapatite-gelatin-calcium silicate (HGCS). Here, we evaluated the potential of HGCS scaffold in bone formation in vivo using the rat calvarial critical-sized defect (CSD). Twelve Sprague-Dawley rats were randomized to four groups: control (defect only), decellularized bone matrix (DECBM), and HGCS with and without multipotent adult progenitor cells (MAPCs). DECBM was prepared by removing all the cells using SDS and NH4OH. After 12 weeks, the CSD specimens were harvested to evaluate radiographical, histological, and histomorphometrical outcomes. The in vitro osteogenic effects of the materials were studied by focal adhesion, MTS, and alizarin red. Micro-CT analysis indicated that the DECBM and the HGCS scaffold groups developed greater radiopaque areas than the other groups. Bone regeneration, assessed using histological analysis and fluorochrome labeling, was the highest in the HGCS scaffold seeded with MAPCs. The DECBM group showed limited osteoinductivity, causing a gap between the implant and host tissue. The group grafted with HGCS+MAPCs resulting in twice as much new bone formation seems to indicate a role for effective bone regeneration. In conclusion, the novel HGCS scaffold could improve bone regeneration and is a promising carrier for stem cell-mediated bone regeneration. PMID:25054149

X-ray diffraction investigation of amorphous calcium phosphate and hydroxyapatite under ultra-high hydrostatic pressure

NASA Astrophysics Data System (ADS)

Lam, Elisa; Gu, Qinfen; Swedlund, Peter J.; Marchesseau, Sylvie; Hemar, Yacine

2015-11-01

The changes in the crystal structures of synthetically prepared amorphous calcium phosphate (ACP) and hydroxyapatite (HAP) in water (1:1 mass ratio) were studied by synchrotron X-ray diffraction (XRD) under ultra-high hydrostatic pressures as high as 2.34 GPa for ACP and 4 GPa for HAP. At ambient pressure, the XRD patterns of the ACP and HAP samples in capillary tubes and their environmental scanning electron micrographs indicated amorphous and crystalline characteristics for ACP and HAP, respectively. At pressures greater than 0.25 GPa, an additional broad peak was observed in the XRD pattern of the ACP phase, indicating a partial phase transition from an amorphous phase to a new high-pressure amorphous phase. The peak areas and positions of the ACP phase, as obtained through fitting of the experimental data, indicated that the ACP exhibited increased pseudo-crystalline behavior at pressures greater than 0.96 GPa. Conversely, no structural changes were observed for the HAP phase up to the highest applied pressure of 4 GPa. For HAP, a unit-cell reduction during compression was evidenced by a reduction in both refined lattice parameters a and c. Both ACP and HAP reverted to their original structures when the pressure was fully released to ambient pressure.

Evaluation of Heating and Shearing on the Viscoelastic Properties of Calcium Hydroxyapatite Used in Injection Laryngoplasty.

PubMed

Mahboubi, Hossein; Mohraz, Ali; Verma, Sunil P

2016-03-01

To compare the viscoelastic properties of calcium hydroxyapatite (CaHA) to carboxymethylcellulose (CMC) injectables used for injection laryngoplasty and determine if they are affected by heating and shearing. Experimental. University laboratory. Vocal fold injection laryngoplasty with CaHA is oftentimes challenging due to the amount of pressure necessary to push the injectate through a needle. Anecdotal techniques, such as heating the product, have been suggested to facilitate injection. The viscoelastic properties of CaHA and CMC were measured with a rheometer. The effects of heating and shearing on sample viscoelasticity were recorded. CaHA was 9.5 times more viscous than CMC (43,100 vs 4540 Pa·s). Heating temporarily decreased the viscosity of CaHA by 32%. However, it also caused the viscosity to subsequently increase after time. Shearing of CaHA reduced its viscosity by 26%. Heating and shearing together temporarily reduced the viscosity of CaHA by 52%. A combination of heating and shearing had a more profound effect than heating or shearing alone on the viscosity of CaHA, potentially making it easier to inject temporarily. Long-term and in vivo studies are required to further analyze the effect of heating and shearing on CaHA injectables. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2016.

Label-free nonlinear optical microscopy detects early markers for osteogenic differentiation of human stem cells.

PubMed

Hofemeier, Arne D; Hachmeister, Henning; Pilger, Christian; Schürmann, Matthias; Greiner, Johannes F W; Nolte, Lena; Sudhoff, Holger; Kaltschmidt, Christian; Huser, Thomas; Kaltschmidt, Barbara

2016-05-26

Tissue engineering by stem cell differentiation is a novel treatment option for bone regeneration. Most approaches for the detection of osteogenic differentiation are invasive or destructive and not compatible with live cell analysis. Here, non-destructive and label-free approaches of Raman spectroscopy, coherent anti-Stokes Raman scattering (CARS) and second harmonic generation (SHG) microscopy were used to detect and image osteogenic differentiation of human neural crest-derived inferior turbinate stem cells (ITSCs). Combined CARS and SHG microscopy was able to detect markers of osteogenesis within 14 days after osteogenic induction. This process increased during continued differentiation. Furthermore, Raman spectroscopy showed significant increases of the PO4(3-) symmetric stretch vibrations at 959 cm(-1) assigned to calcium hydroxyapatite between days 14 and 21. Additionally, CARS microscopy was able to image calcium hydroxyapatite deposits within 14 days following osteogenic induction, which was confirmed by Alizarin Red-Staining and RT- PCR. Taken together, the multimodal label-free analysis methods Raman spectroscopy, CARS and SHG microscopy can monitor osteogenic differentiation of adult human stem cells into osteoblasts with high sensitivity and spatial resolution in three dimensions. Our findings suggest a great potential of these optical detection methods for clinical applications including in vivo observation of bone tissue-implant-interfaces or disease diagnosis.

Label-free nonlinear optical microscopy detects early markers for osteogenic differentiation of human stem cells

NASA Astrophysics Data System (ADS)

Hofemeier, Arne D.; Hachmeister, Henning; Pilger, Christian; Schürmann, Matthias; Greiner, Johannes F. W.; Nolte, Lena; Sudhoff, Holger; Kaltschmidt, Christian; Huser, Thomas; Kaltschmidt, Barbara

2016-05-01

Tissue engineering by stem cell differentiation is a novel treatment option for bone regeneration. Most approaches for the detection of osteogenic differentiation are invasive or destructive and not compatible with live cell analysis. Here, non-destructive and label-free approaches of Raman spectroscopy, coherent anti-Stokes Raman scattering (CARS) and second harmonic generation (SHG) microscopy were used to detect and image osteogenic differentiation of human neural crest-derived inferior turbinate stem cells (ITSCs). Combined CARS and SHG microscopy was able to detect markers of osteogenesis within 14 days after osteogenic induction. This process increased during continued differentiation. Furthermore, Raman spectroscopy showed significant increases of the PO43- symmetric stretch vibrations at 959 cm-1 assigned to calcium hydroxyapatite between days 14 and 21. Additionally, CARS microscopy was able to image calcium hydroxyapatite deposits within 14 days following osteogenic induction, which was confirmed by Alizarin Red-Staining and RT- PCR. Taken together, the multimodal label-free analysis methods Raman spectroscopy, CARS and SHG microscopy can monitor osteogenic differentiation of adult human stem cells into osteoblasts with high sensitivity and spatial resolution in three dimensions. Our findings suggest a great potential of these optical detection methods for clinical applications including in vivo observation of bone tissue-implant-interfaces or disease diagnosis.

Label-free nonlinear optical microscopy detects early markers for osteogenic differentiation of human stem cells

PubMed Central

Hofemeier, Arne D.; Hachmeister, Henning; Pilger, Christian; Schürmann, Matthias; Greiner, Johannes F. W.; Nolte, Lena; Sudhoff, Holger; Kaltschmidt, Christian; Huser, Thomas; Kaltschmidt, Barbara

2016-01-01

Tissue engineering by stem cell differentiation is a novel treatment option for bone regeneration. Most approaches for the detection of osteogenic differentiation are invasive or destructive and not compatible with live cell analysis. Here, non-destructive and label-free approaches of Raman spectroscopy, coherent anti-Stokes Raman scattering (CARS) and second harmonic generation (SHG) microscopy were used to detect and image osteogenic differentiation of human neural crest-derived inferior turbinate stem cells (ITSCs). Combined CARS and SHG microscopy was able to detect markers of osteogenesis within 14 days after osteogenic induction. This process increased during continued differentiation. Furthermore, Raman spectroscopy showed significant increases of the PO43− symmetric stretch vibrations at 959 cm−1 assigned to calcium hydroxyapatite between days 14 and 21. Additionally, CARS microscopy was able to image calcium hydroxyapatite deposits within 14 days following osteogenic induction, which was confirmed by Alizarin Red-Staining and RT- PCR. Taken together, the multimodal label-free analysis methods Raman spectroscopy, CARS and SHG microscopy can monitor osteogenic differentiation of adult human stem cells into osteoblasts with high sensitivity and spatial resolution in three dimensions. Our findings suggest a great potential of these optical detection methods for clinical applications including in vivo observation of bone tissue–implant-interfaces or disease diagnosis. PMID:27225821

Degradable biocomposite of nano calcium-deficient hydroxyapatite-multi(amino acid) copolymer

PubMed Central

Li, Hong; Gong, Min; Yang, Aiping; Ma, Jian; Li, Xiangde; Yan, Yonggang

2012-01-01

Background and methods A nano calcium-deficient hydroxyapatite (n-CDHA)-multi(amino acid) copolymer (MAC) composite bone substitute biomaterial was prepared using an in situ polymerization method. The composition, structure, and compressive strength of the composite was characterized, and the in vitro degradability in phosphate-buffered solution and preliminary cell responses to the composite were investigated. Results The composite comprised n-CDHA and an amide linkage copolymer. The compressive strength of the composite was in the range of 88–129 MPa, varying with the amount of n-CDHA in the MAC (ranging from 10 wt% to 50 wt%). Weight loss from the composite increased (from 32.2 wt% to 44.3 wt%) with increasing n-CDHA content (from 10 wt% to 40 wt%) in the MAC after the composite was soaked in phosphate-buffered solution for 12 weeks. The pH of the soaking medium varied from 6.9 to 7.5. MG-63 cells with an osteogenic phenotype were well adhered and spread on the composite surface. Viability and differentiation increased with time, indicating that the composite had no negative effects on MG-63 cells. Conclusion The n-CDHA-MAC composite had good cytocompatibility and has potential to be used as a bone substitute. PMID:22457591

The thermal stability of hydroxyapatite in biphasic calcium phosphate ceramics.

PubMed

Nilen, R W N; Richter, P W

2008-04-01

Biphasic calcium phosphate ceramics (BCP) comprising a mix of non-resorbable hydroxyapatite (HA) and resorbable beta-tricalcium phosphate (beta-TCP) are particularly suitable materials for synthetic bone substitute applications. In this study, HA synthesised by solid state reaction was mechanically mixed with beta-TCP, then sintered to form a suite of BCP materials with a wide range of HA/beta-TCP phase content ratios. The influence of sintering temperature and composition on the HA thermal stability was quantified by X-ray diffraction (XRD). The pre-sinter beta-TCP content was found to strongly affect the post-sinter HA/beta-TCP ratio by promoting the thermal decomposition of HA to beta-TCP, even at sintering temperatures as low as 850 degrees C. For BCP material with pre-sinter HA/beta-TCP = 40/60 wt%, approximately 80% of the HA decomposed to beta-TCP during sintering at 1000 degrees C. Furthermore, the HA content appeared to influence the reverse transformation of alpha-TCP to beta-TCP expected upon gradual cooling from sintering temperatures greater than 1125 degrees C. Because the HA/beta-TCP ratio dominantly determines the rate and extent of BCP resorption in vivo, the possible thermal decomposition of HA during BCP synthesis must be considered, particularly if high temperature treatments are involved.

Energetic basis for the molecular-scale organization of bone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tao, Jinhui; Battle, Keith C.; Pan, Haihua

The remarkable properties of bone derive from a highly organized arrangement of co-aligned nm-scale apatite platelets within a fibrillar collagen matrix. The origin of this arrangement is poorly understood and the crystal structures of hydroxyapatite (HAP) and the non-mineralized collagen fibrils alone do not provide an explanation. Moreover, little is known about collagen-apatite interaction energies, which should strongly influence both the molecular-scale organization and the resulting mechanical properties of the composite. We investigated collagen-mineral interactions by combining dynamic force spectroscopy (DFS) measurements of binding energies with molecular dynamics (MD) simulations of binding and AFM observations of collagen adsorption on singlemore » crystals of calcium phosphate for four mineral phases of potential importance in bone formation. In all cases, we observe a strong preferential orientation of collagen binding, but comparison between the observed orientations and TEM analyses native tissues shows only calcium-deficient apatite (CDAP) provides an interface with collagen that is consistent with both. MD simulations predict preferred collagen orientations that agree with observations and results from both MD and DFS reveal large values for the binding energy due to multiple binding sites. These findings reconcile apparent contradictions inherent in a hydroxyapatite or carbonated apatite (CAP) model of bone mineral and provide an energetic rationale for the molecular scale organization of bone.« less

Better early osteogenesis of electroconductive hydroxyapatite-calcium titanate composites in a rabbit animal model.

PubMed

Mallik, Prafulla Kumar; Basu, Bikramjit

2014-03-01

In view of the fact that bone healing can be enhanced due to external electric field application, it is important to assess the influence of the implant conductivity on the bone regeneration in vivo. To address this issue, this study reports the in vivo biocompatibility property of multistage spark plasma sintered hydroxyapatite (HA)-80 wt % calcium titanate (CaTiO3 ) composites and monolithic HA, which have widely different conductivity property (14 orders of magnitude difference). The ability of bone regeneration was assessed by implantation in cylindrical femoral bone defects of rabbit animal model for varying time period of 1, 4, and 12 weeks. The overall assessment of the histology results suggests that the progressive healing of bone defects around HA-80 wt % CaTiO3 is associated with a better efficacy with respect to (w.r.t) early stage neobone formation, which is histomorphometrically around 140% higher than monolithic HA. Overall, this study demonstrates that the in vivo biocompatibility property of HA-80 wt % CaTiO3 with respect to local effects after 12 weeks of implantation is not compromised both qualitatively and quantitatively, and a comparison with control implant (HA) points toward the critical role of electrical conductivity on better early stage bone regeneration. Copyright © 2013 Wiley Periodicals, Inc.

Hydroxyapatite and Other Calcium Phosphates for the Conservation of Cultural Heritage: A Review

PubMed Central

2018-01-01

The present paper reviews the methods and the performance of in situ formation of calcium phosphates (CaP) for the conservation of materials belonging to cultural heritage. The core idea is to form CaP (ideally hydroxyapatite, HAP, the most stable CaP at pH > 4) by reaction between the substrate and an aqueous solution of a phosphate salt. Initially proposed for the conservation of marble and limestone, the treatment has been explored for a variety of different substrates, including sandstones, sulphated stones, gypsum stuccoes, concrete, wall paintings, archaeological bones and paper. First, the studies aimed at identifying the best treatment conditions (e.g., nature and concentration of the phosphate precursor, solution pH, treatment duration, ionic and organic additions to the phosphate solution, mineralogical composition of the new CaP phases) are summarized. Then, the treatment performance on marble and limestone is reviewed, in terms of protective and consolidating effectiveness, compatibility (aesthetic, microstructural and physical) and durability. Some pilot applications in real case studies are also reported. Recent research aimed at extending the phosphate treatment to other substrates is then illustrated. Finally, the strengths of the phosphate treatment are summarized, in comparison with alternative products, and some aspects needing future research are outlined. PMID:29617322

Novel method for early investigation of bioactivity in different borate bio-glasses.

PubMed

Abdelghany, A M

2013-01-01

Some ternary borate glasses were prepared and corrosion behavior of such ternary borate glasses after immersion in aqueous dilute phosphate solution was studied using different immersion times. Fourier transform infrared (FTIR) absorption spectral measurements were done before and after immersion in the mentioned solution for extended times up to 2 days to justify the appearance of the characteristic FTIR bands due to calcium phosphate (hydroxyapatite (HA)) which is considered as the potential indication of bioactivity. Experimental IR data confirm the beginning of the appearance of FTIR bands at about 580 and 620 cm(-1) after 3 days and the complete resolution with its characteristic split form after 1 week and more. Deconvolution analysis technique (DAT) of the FTIR spectrum was employed to investigate the bioactivity of such ternary borate system after a short period of immersion. The corrosion behavior of such glasses is explained in relation to a suggested hydrolysis followed by direct dissolution mechanism. The ease of dissolution of all the borate glasses constituents explains the formation of calcium phosphate and conversion to crystalline hydroxyapatite within the borate glass matrix. X-ray diffraction may be used to retrace the structural changes and degree of crystallinity of the prepared glasses. Copyright © 2012 Elsevier B.V. All rights reserved.

Choroid vascular occlusion and ischemic optic neuropathy after facial calcium hydroxyapatite injection- a case report.

PubMed

Chou, Chien-Chih; Chen, Hsin-Han; Tsai, Yi-Yu; Li, You-Ling; Lin, Hui-Ju

2015-03-08

We reported a case of sudden monocular vision loss after calcium hydroxyapatite (CaHA) injection into the nasal tip and dorsum with detailed retina images. A healthy, 35-year-old woman received CaHA filler injection for nose augmentation. Ten minutes after the procedure, she developed nausea, vomiting, headache, ptosis, and left periorbital pain. After 30 minutes, she complained of progressively blurring vision in the left eye. The best-corrected visual acuity (BCVA) in her left eye was 30 cm ahead of hand motion. Left exotropia was noted in primary gaze. Limitations in adduction, supraduction, and infraduction of the left eye were also observed. Slit lamp examination of the left eye revealed a pink conjunctiva, a clear cornea, a mild anterior chamber reaction, a sluggish papillary light reflex, and a semi-dilated pupil. A positive relative afferent pupillary defect was observed in the left eye. Fundus examination revealed optic disc edema and some linear whitish opacity over the superior and temporal sites in the left eye, suggesting multiple CaHA emboli in the choroid vessels. Although the majority of adverse reactions are mild and transient, surgeons should be alert about extremely rare serious adverse events such as visual loss.

Synthesis, characterization, biocompatibility of hydroxyapatite-natural polymers nanocomposites for dentistry applications.

PubMed

Chung, Jin-Hwan; Kim, Young Kyung; Kim, Kyo-Han; Kwon, Tae-Yub; Vaezmomeni, Seyede Ziba; Samiei, Mohammad; Aghazadeh, Marzyeh; Davaran, Soodabeh; Mahkam, Mehrdad; Asadi, Ghale; Akbarzadeh, Abolfazl

2016-01-01

Hydroxyapatite (HA), the main mineral component of bones and teeth, was synthesized by using the reaction between calcium nitrate tetrahydrate Ca(NO3)2∙4H2O and diammonium hydrogen phosphate (NH4)2HPO4 (DAHP) with a chemical precipitation method. The objective of this study is to utilize novel inorganic-organic nanocomposites for biomedical applications. HA is an inorganic component (75% w) and chitosan, alginate and albumin (Egg white) are organic components of nanocomposites (25% w). Nanocomposites were prepared in deionized water solutions, at room temperature, using a mechanical and magnetic stirrer for 48 h. The microstructure and morphology of sintered n-HAP were tested at different preheating temperature and laser sintering speed with scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR).

Thermal stability of a modified sol-gel derived hydroxyapatite nanopowders

NASA Astrophysics Data System (ADS)

Herradi, S.; El Bali, B.; Khaldi, M.; Lachkar, M.

2017-03-01

Hydroxyapatite Ca10(PO4)6(OH)2 (HA) powder was successfully synthesized by a modified sol-gel method using a solution of calcium nitrate in ethanol, along with a solution of diammonium hydrogen phosphate in water and NH4OH as starting materials. The Ca/P molar ratio was maintained at 1.67. The powder was subjected to furnace and microwave heating to compare the decomposition of HA and study the crystallite sizes. It was found that microwave heated powders were pure HAP up to 230°C with absence of secondary phases. However, XRD patterns show that furnace heated powders convert completely to β-TCP when treated at 750°C and 1000°C. This result was confirmed by the absence of hydroxyl bands in the FT-IR spectra for these temperatures.

Thermal effects of carbonated hydroxyapatite modified by glycine and albumin

NASA Astrophysics Data System (ADS)

Gerk, S. A.; Golovanova, O. A.; Kuimova, M. V.

2017-01-01

In this work calcium phosphate powders were obtained by precipitation method from simulated solutions of synovial fluid containing glycine and albumin. X-ray diffraction and IR spectroscopy determined that all samples are single-phase and are presented by carbonate containing hydroxyapatite (CHA). The thermograms of solid phases of CHA were obtained and analyzed; five stages of transformation in the temperature range of 25-1000°C were marked. It is shown that in this temperature range dehydration, decarboxylation and thermal degradation of amino acid and protein connected to the surface of solid phase occur. The tendency of temperature lowering of the decomposition of powders synthesized from a medium containing organic substances was determined. Results demonstrate a direct dependence between the concentration of the amino acid in a model solution and its content in the solid phase.

Hydroxyapatite coatings produced on commercially pure titanium by micro-arc oxidation.

PubMed

Huang, Yong; Wang, Yingjun; Ning, Chengyun; Nan, Kaihui; Han, Yong

2007-09-01

A porous hydroxyapatite (HA) coating on commercially pure titanium was prepared by micro-arc oxidation (MAO) in electrolytic solution containing calcium acetate and beta-glycerol phosphate disodium salt pentahydrate (beta-GP). The thickness, phase, composition morphology and biocompatibility of the oxide coating were characterized by x-ray diffraction (XRD), electron probe microanalysis (EPMA), scanning electron microscopy (SEM) with an energy dispersive x-ray spectrometer (EDS) and cell culture. The thickness of the MAO film was about 20 microm, and the coating was porous and uneven without any apparent interface to the titanium substrates. The result of XRD showed that the porous coating was made up of HA film. The favorable osteoblast cell affinity gives HA film good biocompatibility. HA coatings are expected to have significant uses for medical applications such as dental implants and artificial bone joints.

Application of X-ray synchrotron microscopy instrumentation in biology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gasperini, F. M.; Pereira, G. R.; Granjeiro, J. M.

2011-07-01

X-ray micro-fluorescence imaging technique has been used as a significant tool in order to investigate minerals contents in some kinds of materials. The aim of this study was to evaluate the elemental distribution of calcium and zinc in bone substitute materials (nano-hydroxyapatite spheres) and cortical bones through X-Ray Micro-fluorescence analysis with the increment of Synchrotron Radiation in order to evaluate the characteristics of the newly formed bone and its interface, the preexisting bone and biomaterials by the arrangement of collagen fibers and its birefringence. The elemental mapping was carried out at Brazilian Synchrotron Light Laboratory, Campinas - Sao Paulo, Brazilmore » working at D09-XRF beam line. Based on this study, the results suggest that hydroxyapatite-based biomaterials are biocompatible, promote osteo-conduction and favored bone repair. (authors)« less

3D silicon doped hydroxyapatite scaffolds decorated with Elastin-like Recombinamers for bone regenerative medicine.

PubMed

Vila, Mercedes; García, Ana; Girotti, Alessandra; Alonso, Matilde; Rodríguez-Cabello, Jose Carlos; González-Vázquez, Arlyng; Planell, Josep A; Engel, Elisabeth; Buján, Julia; García-Honduvilla, Natalio; Vallet-Regí, María

2016-11-01

The current study reports on the manufacturing by rapid prototyping technique of three-dimensional (3D) scaffolds based on silicon substituted hydroxyapatite with Elastin-like Recombinamers (ELRs) functionalized surfaces. Silicon doped hydroxyapatite (Si-HA), with Ca 10 (PO 4 ) 5.7 (SiO 4 ) 0.3 (OH) 1.7 h 0.3 nominal formula, was surface functionalized with two different types of polymers designed by genetic engineering: ELR-RGD that contain cell attachment specific sequences and ELR-SN A 15/RGD with both hydroxyapatite and cells domains that interact with the inorganic phase and with the cells, respectively. These hybrid materials were subjected to in vitro assays in order to clarify if the ELRs coating improved the well-known biocompatible and bone regeneration properties of calcium phosphates materials. The in vitro tests showed that there was a total and homogeneous colonization of the 3D scaffolds by Bone marrow Mesenchymal Stromal Cells (BMSCs). In addition, the BMSCs were viable and able to proliferate and differentiate into osteoblasts. Bone tissue engineering is an area of increasing interest because its main applications are directly related to the rising life expectancy of the population, which promotes higher rates of several bone pathologies, so innovative strategies are needed for bone tissue regeneration therapies. Here we use the rapid prototyping technology to allow moulding ceramic 3D scaffolds and we use different bio-polymers for the functionalization of their surfaces in order to enhance the biological response. Combining the ceramic material (silicon doped hydroxyapatite, Si-HA) and the Elastin like Recombinamers (ELRs) polymers with the presence of the integrin-mediate adhesion domain alone or in combination with SNA15 peptide that possess high affinity for hydroxyapatite, provided an improved Bone marrow Mesenchymal Stromal Cells (BMSCs) differentiation into osteoblastic linkage. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Monolithic Pellets, Composites and Thick Films of Hydroxyapatite: Correlation of Mechanical Properties with Microstructure.

NASA Astrophysics Data System (ADS)

Wang, Pauchiu Either

Hydroxyapatite Ca_{10}(PO _4)_6(OH)_2 (abbreviated as HA) has great biocompatibility. Poor mechanical properties of HA implants and decomposition of HA during processing are the major obstacles for widespread uses of HA. In the present thesis we have attempted to understand the sintering behavior of monolithic HA and metal-reinforced HA-matrix composites, and the mechanism of formation of HA coating in the solutions at the normal temperature. The powders of two calcium phosphates, namely hydroxyapatite and dicalcium phosphate (DCP: chemical formula Ca_2P_2O_7), were sintered at various temperatures and in various environments. The density, flexural strength and knoop hardness of both phosphates sintered in air for 4 h initially increased with the sintering temperature, reaching maxima at around 1000-1150 ^circC, and then decreased due to decomposition. To reduce dehydroxylation, HA powder was sintered in moisture at various temperatures up to 1350^circ C and X-ray diffraction study did not indicate any decomposition at the highest sintering temperature. It is seen that dehydroxylation did not hinder sintering, but decomposition obstructed sintering of both HA and DCP. Ductile-phase reinforcement of hydroxyapatite was achieved by addition of silver particulates (5-30 vol.%) in HA powder compacts. A composite made by sintering 10 vol.% Ag and balance HA at 1200^circ C for 1 h in air had flexural strength of 75 +/- 7 MPa, which was almost double that of pure HA sintered under an identical condition. Silver in the composite melted during sintering, but due to poor wetting, did not spread in between HA particles. The increase in the flexural strength of the composites was thought to be due to crack-bridging and crack-arrest by silver inclusions. Thick films (several μm) of hydroxyapatite were deposited on silicon single crystal placed in close proximity to a plate of apatite- and wollastonite -containing glass and dipped into a simulated body fluid (SBF) at 36^circC. Amorphous calcium phosphate phase present in the glass leached into the SBF, causing supersaturation of Ca^ {2+} and (PO_4)^ {3-} ions. HA films grown on Si(111) showed strong (102) texture. As a contrast hardly any HA film could be grown on Si(100) surface. Our results suggest that the driving force for formation of apatite films arises from lowering of free energy of the supersatured solution by deposition of ions in certain crystallographic arrangements on suitable substrates with low interface energies.

Facile synthesis of both needle-like and spherical hydroxyapatite nanoparticles: effect of synthetic temperature and calcination on morphology, crystallite size and crystallinity.

PubMed

Wijesinghe, W P S L; Mantilaka, M M M G P G; Premalal, E V A; Herath, H M T U; Mahalingam, S; Edirisinghe, M; Rajapakse, R P V J; Rajapakse, R M G

2014-09-01

Synthetic hydroxyapatite (HA) nanoparticles, that mimic natural HA, are widely used as biocompatible coatings on prostheses to repair and substitute human bones. In this study, HA nanoparticles are prepared by precipitating them from a precursor solution containing calcium sucrate and ammonium dihydrogen orthophosphate, at a Ca/P mole ratio of 1.67:1, at temperatures, ranging from 10°C to 95°C. A set of products, prepared at different temperatures, is analyzed for their crystallinity, crystallite size, morphology, thermal stability and composition, by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopic techniques, while the other set is analyzed after calcining the respective products, soon after their synthesis, for 3h, at 700°C. The as-prepared products, after 2h of drying, without any calcination, are not crystalline, but they grow very slowly into needle-like morphologies, as they are ripened with time. The percentage crystallinity of the final products increases from 15% to 52%, with increasing the preparative temperature. The calcined samples always produce spherical nanoparticles of essentially the same diameter, between 90 nm and 100 nm, which does not change due to aging and preparative temperatures. Therefore, the same method can be utilized to synthesize both spherical and needle-like nanoparticles of hydroxyapatite, with well-defined sizes and shapes. The ability to use readily available cheap raw materials, for the synthesis of such well-defined crystallites of hydroxyapatite, is an added advantage of this method, which may be explored further for the scaling up of the procedures to suit to industrial scale synthesis of such hydroxyapatite nanoparticles. Copyright © 2014 Elsevier B.V. All rights reserved.

Preparation of in situ hardening composite microcarriers: Calcium phosphate cement combined with alginate for bone regeneration

PubMed Central

Park, Jung-Hui; Lee, Eun-Jung; Knowles, Jonathan C

2014-01-01

Novel microcarriers consisting of calcium phosphate cement and alginate were prepared for use as three-dimensional scaffolds for the culture and expansion of cells that are effective for bone tissue engineering. The calcium phosphate cement-alginate composite microcarriers were produced by an emulsification of the composite aqueous solutions mixed at varying ratios (calcium phosphate cement powder/alginate solution = 0.8–1.2) in an oil bath and the subsequent in situ hardening of the compositions during spherodization. Moreover, a porous structure could be easily created in the solid microcarriers by soaking the produced microcarriers in water and a subsequent freeze-drying process. Bone mineral-like apatite nanocrystallites were shown to rapidly develop on the calcium phosphate cement–alginate microcarriers under moist conditions due to the conversion of the α-tricalcium phosphate phase in the calcium phosphate cement into a carbonate–hydroxyapatite. Osteoblastic cells cultured on the microspherical scaffolds were proven to be viable, with an active proliferative potential during 14 days of culture, and their osteogenic differentiation was confirmed by the determination of alkaline phosphatase activity. The in situ hardening calcium phosphate cement–alginate microcarriers developed herein may be used as potential three-dimensional scaffolds for cell delivery and tissue engineering of bone. PMID:23836845

Calcium Orthophosphate Cements and Concretes

PubMed Central

Dorozhkin, Sergey V.

2009-01-01

In early 1980s, researchers discovered self-setting calcium orthophosphate cements, which are a bioactive and biodegradable grafting material in the form of a powder and a liquid. Both phases form after mixing a viscous paste that after being implanted, sets and hardens within the body as either a non-stoichiometric calcium deficient hydroxyapatite (CDHA) or brushite, sometimes blended with unreacted particles and other phases. As both CDHA and brushite are remarkably biocompartible and bioresorbable (therefore, in vivo they can be replaced with newly forming bone), calcium orthophosphate cements represent a good correction technique for non-weight-bearing bone fractures or defects and appear to be very promising materials for bone grafting applications. Besides, these cements possess an excellent osteoconductivity, molding capabilities and easy manipulation. Furthermore, reinforced cement formulations are available, which in a certain sense might be described as calcium orthophosphate concretes. The concepts established by calcium orthophosphate cement pioneers in the early 1980s were used as a platform to initiate a new generation of bone substitute materials for commercialization. Since then, advances have been made in the composition, performance and manufacturing; several beneficial formulations have already been introduced as a result. Many other compositions are in experimental stages. In this review, an insight into calcium orthophosphate cements and concretes, as excellent biomaterials suitable for both dental and bone grafting application, has been provided.

Short-fibre reinforcement of calcium phosphate bone cement.

PubMed

Buchanan, F; Gallagher, L; Jack, V; Dunne, N

2007-02-01

Calcium phosphate cement (CPC) sets to form hydroxyapatite, a major component of mineral bone, and is gaining increasing interest in bone repair applications. However, concerns regarding its brittleness and tendency to fragment have limited its widespread use. In the present study, short-fibre reinforcement of an apatitic calcium phosphate has been investigated to improve the fracture behaviour. The fibres used were polypropylene (PP) fibres, 50 microm in diameter and reduced in length by cryogenic grinding. The compressive strength and fracture behaviour were examined. Fibre addition of up to 10 wt % had a significant effect on composite properties, with the energy absorbed during failure being significantly increased, although this tended to be accompanied with a slight drop in compressive strength. The fibre reinforcement mechanisms appeared to be crack bridging and fibre pull-out. The setting time of the CPC with fibre reinforcement was also investigated and was found to increase with fibre volume fraction.

Sol-gel synthesis, phase composition, morphological and structural characterization of Ca10(PO4)6(OH)2: XRD, FTIR, SEM, 3D SEM and solid-state NMR studies

NASA Astrophysics Data System (ADS)

Kareiva, Simonas; Klimavicius, Vytautas; Momot, Aleksandr; Kausteklis, Jonas; Prichodko, Aleksandra; Dagys, Laurynas; Ivanauskas, Feliksas; Sakirzanovas, Simas; Balevicius, Vytautas; Kareiva, Aivaras

2016-09-01

Aqueous sol-gel chemistry route based on ammonium-hydrogen phosphate as the phosphorus precursor, calcium acetate monohydrate as source of calcium ions, and 1,2-ethylendiaminetetraacetic acid (EDTA), or 1,2-diaminocyclohexanetetracetic acid (DCTA), or tartaric acid (TA), or ethylene glycol (EG), or glycerol (GL) as complexing agents have been used to prepare calcium hydroxyapatite (Ca10(PO4)6(OH)2, CHAp). The phase transformations, composition, and structural changes in the polycrystalline samples were studied by infrared spectroscopy (FTIR), X-ray powder diffraction analysis (XRD), and scanning electron microscopy (SEM). The local short-range (nano- and mezo-) scale effects in CHAp were studied using solid-state NMR spectroscopy. The spatial 3D data from the SEM images of CHAp samples obtained by TA, EG and GL sol-gel routes were recovered for the first time to our knowledge.

Interactions of casein micelles with calcium phosphate particles.

PubMed

Tercinier, Lucile; Ye, Aiqian; Anema, Skelte G; Singh, Anne; Singh, Harjinder

2014-06-25

Insoluble calcium phosphate particles, such as hydroxyapatite (HA), are often used in calcium-fortified milks as they are considered to be chemically unreactive. However, this study showed that there was an interaction between the casein micelles in milk and HA particles. The caseins in milk were shown to bind to the HA particles, with the relative proportions of bound β-casein, αS-casein, and κ-casein different from the proportions of the individual caseins present in milk. Transmission electron microscopy showed no evidence of intact casein micelles on the surface of the HA particles, which suggested that the casein micelles dissociated either before or during binding. The HA particles behaved as ion chelators, with the ability to bind the ions contained in the milk serum phase. Consequently, the depletion of the serum minerals disrupted the milk mineral equilibrium, resulting in dissociation of the casein micelles in milk.

Hierarchically porous structure, mechanical strength and cell biological behaviors of calcium phosphate composite scaffolds prepared by combination of extrusion and porogen burnout technique and enhanced by gelatin.

PubMed

Feng, Shenglei; He, Fupo; Ye, Jiandong

2018-01-01

In this study, hierarchically porous calcium phosphate scaffolds (HTCP) with unidirectional pores, transversely interconnected pores, and micropores were fabricated by the combination of extrusion and porogen burnout technique. Gelatin was incorporated into the HTCP scaffolds by vacuum-impregnation of gelatin solution and subsequent freeze-drying. The phase composition, microstructure, physical and cytobiological properties were analyzed. The results showed that the HTCP scaffolds were composed of β-tricalcium phosphate with minor hydroxyapatite. The HTCP scaffolds had unidirectional pores (~400μm), transversely interconnected pores (~130μm) and micropores (~1μm). The incorporation of gelatin significantly increased the compressive strength, toughness, and cell seeding of the HTCP scaffolds. The composite scaffolds showed excellent cytocompatibility. The hierarchically porous calcium phosphate composite scaffolds may have potential application prospects in bone tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

Growth of hydroxyapatite in a biocompatible mesoporous ordered silica.

PubMed

Díaz, A; López, T; Manjarrez, J; Basaldella, E; Martínez-Blanes, J M; Odriozola, J A

2006-03-01

A novel biomaterial (HA-SBA-15) has been developed based on the growth of calcium phosphate hydroxyapatite (HA) nanoparticles within an organized silica structure (SBA-15). Characterization of the material was carried out using a combination of X-ray diffraction, X-ray fluorescence, transmission electron microscopy, N2 adsorption-desorption isotherms and nuclear magnetic resonance. Transmission electron microscopy observations and N2 porosimetry revealed the crystallization of hydroxyapatite nanoparticles inside the mesopore cavities of the silica structure. Specific surface areas of 760 m2 g(-1) and 260 m2 g(-1) were measured for the SBA-15 and the HA-SBA-15 material, respectively. The hydroxyl groups present in the silica nanostructure surface have brought about cationic defects in the silicium sites, mainly with those of tetrahedral symmetry, and promoted the formation of siloxanes. 29Si MAS-NMR analysis shows a significant reduction of the silanol groups concentration with HA growing within the base (SBA-15) material. Studies and brain tissue biocompatibility tests were carried out. Histopathological studies on the SBA-15 implant material showed no changes to the tissue nearby. The results confirmed the synthesis of a silica-based composite containing HA nanoparticles with the potential for biomedical applications.

Bone-like apatite layer formation on hydroxyapatite prepared by spark plasma sintering (SPS).

PubMed

Gu, Y W; Khor, K A; Cheang, P

2004-08-01

Hydroxyapatite (HA) compacts with high density and superior mechanical properties were fabricated by spark plasma sintering (SPS) using spray-dried HA powders as feedstock. The formation of bone-like apatite layer on SPS consolidated HA compacts were investigated by soaking the HA compacts in simulated body fluid (SBF) for various periods (maximum of 28 days). The structural changes in HA post-SBF were analyzed with scanning electron microscopy, grazing incidence X-ray diffraction and X-ray photoelectron spectroscopy. It was found that a layer consisting microcrystalline carbonate-containing hydroxyapatite was formed on the surface of HA compacts after soaking for 24h. The formation mechanism of apatite on the surface of HA compacts after soaking in SBF was attributed to the ion exchange between HA compacts and the SBF solution. The increase in ionic concentration of calcium and phosphorus as well as the increase in pH after SBF immersion resulted in an increase in ionic activity product of apatite in the solution, and provided a specific surface with a low interface energy that is conducive to the nucleation of apatite on the surface of HA compacts.

The potential of materials analysis by electron rutherford backscattering as illustrated by a case study of mouse bones and related compounds.

PubMed

Vos, Maarten; Tökési, Károly; Benkö, Ilona

2013-06-01

Electron Rutherford backscattering (ERBS) is a new technique that could be developed into a tool for materials analysis. Here we try to establish a methodology for the use of ERBS for materials analysis of more complex samples using bone minerals as a test case. For this purpose, we also studied several reference samples containing Ca: calcium carbonate (CaCO(3)) and hydroxyapatite and mouse bone powder. A very good understanding of the spectra of CaCO(3) and hydroxyapatite was obtained. Quantitative interpretation of the bone spectrum is more challenging. A good fit of these spectra is only obtained with the same peak widths as used for the hydroxyapatite sample, if one allows for the presence of impurity atoms with a mass close to that of Na and Mg. Our conclusion is that a meaningful interpretation of spectra of more complex samples in terms of composition is indeed possible, but only if widths of the peaks contributing to the spectra are known. Knowledge of the peak widths can either be developed by the study of reference samples (as was done here) or potentially be derived from theory.

Optimisation of entrapped activated carbon conditions to remove coloured compounds from winery wastewaters.

PubMed

Devesa-Rey, R; Bustos, G; Cruz, J M; Moldes, A B

2011-06-01

The objective of this work was to study the entrapped conditions of activated carbon in calcium-alginate beads for the clarification of winery wastewaters. An incomplete 3(3) factorial design was carried out to study the efficiency of activated carbon (0.5-2%); sodium alginate (1-5%); and calcium chloride (0.050-0.900 M), on the following dependent variables: colour reduction at 280, 465, 530 and 665 nm. The activated carbon and calcium chloride were the most influential variables in the colour reduction. Nearly 100% colour reductions were found for the wavelengths assayed when employing 2% of activated carbon, 5% of sodium alginate and intermediate concentrations of calcium chloride (0.475 M). Instead, other conditions like, 2% of activated carbon, 4% of sodium alginate and 0.580 M of calcium chloride can also give absorbance reductions close to 100%. Copyright © 2011 Elsevier Ltd. All rights reserved.

Progressive renal papillary calcification and ureteral stone formation in mice deficient for Tamm-Horsfall protein

PubMed Central

Liu, Yan; Mo, Lan; Goldfarb, David S.; Evan, Andrew P.; Liang, Fengxia; Khan, Saeed R.; Lieske, John C.

2010-01-01

Mammalian urine contains a range of macromolecule proteins that play critical roles in renal stone formation, among which Tamm-Horsfall protein (THP) is by far the most abundant. While THP is a potent inhibitor of crystal aggregation in vitro and its ablation in vivo predisposes one of the two existing mouse models to spontaneous intrarenal calcium crystallization, key controversies remain regarding the role of THP in nephrolithiasis. By carrying out a long-range follow-up of more than 250 THP-null mice and their wild-type controls, we demonstrate here that renal calcification is a highly consistent phenotype of the THP-null mice that is age and partially gene dosage dependent, but is gender and genetic background independent. Renal calcification in THP-null mice is progressive, and by 15 mo over 85% of all the THP-null mice develop spontaneous intrarenal crystals. The crystals consist primarily of calcium phosphate in the form of hydroxyapatite, are located more frequently in the interstitial space of the renal papillae than intratubularly, particularly in older animals, and lack accompanying inflammatory cell infiltration. The interstitial deposits of hydroxyapatite observed in THP-null mice bear strong resemblances to the renal crystals found in human kidneys bearing idiopathic calcium oxalate stones. Compared with 24-h urine from the wild-type mice, that of THP-null mice is supersaturated with brushite (calcium phosphate), a stone precursor, and has reduced urinary excretion of citrate, a stone inhibitor. While less frequent than renal calcinosis, renal pelvic and ureteral stones and hydronephrosis occur in the aged THP-null mice. These results provide direct in vivo evidence indicating that normal THP plays an important role in defending the urinary system against calcification and suggest that reduced expression and/or decreased function of THP could contribute to nephrolithiasis. PMID:20591941

Changing composition of renal calculi in patients with musculoskeletal anomalies.

PubMed

Gnessin, Ehud; Mandeville, Jessica A; Handa, Shelly E; Lingeman, James E

2011-09-01

Calculi from patients with musculoskeletal (MS) anomalies who are largely immobile and prone to urinary infections have been traditionally composed primarily of struvite and carbonate apatite. Because of substantial improvements in the care of these patients in recent decades, stone etiology may have shifted from infectious to metabolic. We assessed the composition of renal calculi and metabolic characteristics in a contemporary cohort of patients with MS anomalies who underwent percutaneous nephrolithotomy (PCNL). Retrospective analysis of patients who underwent PCNL between April 1999 and June 2009 and had follow-up 24-hour urine studies was performed. Patients with MS anomalies included spinal cord injury, myelomeningocele, muscular dystrophy, multiple sclerosis, cerebral palsy, or other clinical syndromes causing kyphoscoliosis and contractures. Our cohort included 33 patients with MS anomalies and 334 consecutive patients as a control group who underwent PCNL and had metabolic workup. Stones were infectious in etiology in 18.4% and 6.2% in MS and control groups, respectively. Thus, most patients harbored stones of metabolic origin. Metabolic stones in the MS group were composed of 52.7% hydroxyapatite, 10.5% calcium oxalate, 7.9% brushite, 2.6% uric acid, 0% cystine, and 7.9% other. Metabolic stones in the control group were 50.5% calcium oxalate, 16.4% hydroxyapatite, 11.5% brushite, 10.8% uric acid, 4.3% cystine, and 0.3% other. Mean 24-hour urine values for patients with metabolic stones in MS/control groups were volume 2.18/1.87 L/d, pH 6.78/6.05, calcium to creatinine ratio 220/151 mg/g, and oxalate 44.8/39.5 mg/d. Although patients with MS anomalies are traditionally thought to harbor infection-related calculi, most will be found to have calculi of metabolic etiology. The incidence of calcium phosphate stones is high in this group of patients, perhaps reflecting their high urinary pH.

Formation of Fluorohydroxyapatite with Silver Diamine Fluoride

PubMed Central

Mei, M.L.; Nudelman, F.; Marzec, B.; Walker, J.M.; Lo, E.C.M.; Walls, A.W.; Chu, C.H.

2017-01-01

Silver diamine fluoride (SDF) is found to promote remineralization and harden the carious lesion. Hydroxyapatite crystallization is a crucial process in remineralization; however, the role of SDF in crystal formation is unknown. We designed an in vitro experiment with calcium phosphate with different SDF concentrations (0.38, 1.52, 2.66, 3.80 mg/mL) to investigate the effect of this additive on the nucleation and growth of apatite crystals. Two control groups were also prepared—calcium phosphate (CaCl2·2H2O + K2HPO4 in buffer solution) and SDF (Ag[NH3]2F in buffer solution). After incubation at 37 oC for 24 h, the shape and organization of the crystals were examined by bright-field transmission electron microscopy and electron diffraction. Unit cell parameters of the obtained crystals were determined with powder X-ray diffraction. The vibrational and rotational modes of phosphate groups were analyzed with Raman microscopy. The transmission electron microscopy and selected-area electron diffraction confirmed that all solids precipitated within the SDF groups were crystalline and that there was a positive correlation between the increased percentage of crystal size and the concentration of SDF. The powder X-ray diffraction patterns indicated that fluorohydroxyapatite and silver chloride were formed in all the SDF groups. Compared with calcium phosphate control, a contraction of the unit cell in the a-direction but not the c-direction in SDF groups was revealed, which suggested that small localized fluoride anions substituted the hydroxyl anions in hydroxyapatite crystals. This was further evidenced by the Raman spectra, which displayed up-field shift of the phosphate band in all the SDF groups and confirmed that the chemical environment of the phosphate functionalities indeed changed. The results suggested that SDF reacted with calcium and phosphate ions and produced fluorohydroxyapatite. This preferential precipitation of fluorohydroxyapatite with reduced solubility could be one of the main factors for arrest of caries lesions treated with SDF. PMID:28521107

Injectable calcium sulfate/mineralized collagen-based bone repair materials with regulable self-setting properties.

PubMed

Chen, Zonggang; Liu, Huanye; Liu, Xi; Cui, Fu-Zhai

2011-12-15

An injectable and self-setting bone repair materials (nano-hydroxyapatite/collagen/calcium sulfate hemihydrate, nHAC/CSH) was developed in this study. The nano-hydroxyapatite/collagen (nHAC) composite, which is the mineralized fibril by self-assembly of nano-hydrocyapatite and collagen, has the same features as natural bone in both main hierarchical microstructure and composition. It is a bioactive osteoconductor due to its high level of biocompatibility and appropriate degradation rate. However, this material lacks handling characteristics because of its particle or solid-preformed block shape. Herein, calcium sulfate hemihydrate (CSH) was introduced into nHAC to prepare an injectable and self-setting in situ bone repair materials. The morphology of materials was observed using SEM. Most important and interesting of all, calcium sulfate dihydrate (CSD), which is not only the reactant of preparing CSH but also the final solidified product of CSH, was introduced into nHAC as setting accelerator to regulate self-setting properties of injectable nHAC/CSH composite, and thus the self-setting time of nHAC/CSH composite can be regulated from more than 100 min to about 30 min and even less than 20 min by adding various amount of setting accelerator. The compressive properties of bone graft substitute after final setting are similar to those of cancellous bone. CSD as an excellent setting accelerator has no significant effect on the mechanical property and degradability of bone repair materials. In vitro biocompatibility and in vivo histology studies demonstrated that the nHAC/CSH composite could provide more adequate stimulus for cell adhesion and proliferation, embodying favorable cell biocompatibility and a strong ability to accelerate bone formation. It can offer a satisfactory biological environment for growing new bone in the implants and for stimulating bone formation. Copyright © 2011 Wiley Periodicals, Inc.

Nanoparticles of cobalt-substituted hydroxyapatite in regeneration of mandibular osteoporotic bones.

PubMed

Ignjatović, Nenad; Ajduković, Zorica; Savić, Vojin; Najman, Stevo; Mihailović, Dragan; Vasiljević, Perica; Stojanović, Zoran; Uskoković, Vuk; Uskoković, Dragan

2013-02-01

Indications exist that paramagnetic calcium phosphates may be able to promote regeneration of bone faster than their regular, diamagnetic counterparts. In this study, analyzed was the influence of paramagnetic cobalt-substituted hydroxyapatite nanoparticles on osteoporotic alveolar bone regeneration in rats. Simultaneously, biocompatibility of the material was tested in vitro, on osteoblastic MC3T3-E1 and epithelial Caco-2 cells in culture. The material was shown to be biocompatible and nontoxic when added to epithelial monolayers in vitro, while it caused a substantial decrease in the cell viability as well as deformation of the cytoskeleton and cell morphology when incubated with the osteoblastic cells. In the course of 6 months after the implantation of the material containing different amounts of cobalt, ranging from 5 to 12 wt%, in the osteoporotic alveolar bone of the lower jaw, the following parameters were investigated: histopathological parameters, alkaline phosphatase and alveolar bone density. The best result in terms of osteoporotic bone tissue regeneration was observed for hydroxyapatite nanoparticles with the largest content of cobalt ions. The histological analysis showed a high level of reparatory ability of the nanoparticulate material implanted in the bone defect, paralleled by a corresponding increase in the alveolar bone density. The combined effect of growth factors from autologous plasma admixed to cobalt-substituted hydroxyapatite was furthermore shown to have a crucial effect on the augmented osteoporotic bone regeneration upon the implantation of the biomaterial investigated in this study.

Eggshell-Derived Hydroxyapatite: A New Era in Bone Regeneration.

PubMed

Kattimani, Vivekanand; Lingamaneni, Krishna Prasad; Chakravarthi, Pandi Srinivas; Kumar, T S Sampath; Siddharthan, Arjunan

2016-01-01

Defects of maxillofacial skeleton lead to personal (functional and aesthetic), social and behavioral problems; which make the person to isolate from the main stream of society. So, bone regeneration is the need for proper structure, function, and aesthetics following cyst enucleation, trauma, and tumor ablative surgery; which helps for overall health of the individual. The preliminary study is planned to evaluate and compare the efficacy of eggshell-derived hydroxyapatite (EHA) and synthetic hydroxyapatite (SHA) following cystectomy. Microwave-processed calcium deficient EHA and commercially available SHA are used for grafting. Total 20 patients enrolled in this study, consisting 10 in each group between 20 and 45 years of age. All the patients were evaluated for bone regeneration at first, second, third, and sixth month's interval, postsurgically, using radiovisiograph and clinical parameters. The bone formation characteristics vary at second month when compared to SHA. This difference may be because of the kinetics involved in the regeneration pattern. The pattern of bone healing was trabecular after third month, indicating complete bone formation. The study showed constant raise of density and remained same at the end of study period. Both EHA and SHA graft materials are equally efficient in early bone regeneration. Within the limitations of this study the EHA showed promising results. Which indicates the eggshell waste-bio mineral is worthwhile raw material for the production of HA and is a Go Green procedure. Eggshell-derived hydroxyapatite is economic, compared with SHA.

Nanoparticles of cobalt-substituted hydroxyapatite in regeneration of mandibular osteoporotic bones

PubMed Central

Ignjatović, Nenad; Ajduković, Zorica; Savić, Vojin; Najman, Stevo; Mihailović, Dragan; Vasiljević, Perica; Stojanović, Zoran; Uskoković, Vuk; Uskoković, Dragan

2012-01-01

Indications exist that paramagnetic calcium phosphates may be able to promote regeneration of bone faster than their regular, diamagnetic counterparts. In this study, analyzed was the influence of paramagnetic cobalt-substituted hydroxyapatite nanoparticles on osteoporotic alveolar bone regeneration in rats. Simultaneously, biocompatibility of the material was tested in vitro, on osteoblastic MC3T3-E1 and epithelial Caco-2 cells in culture. The material was shown to be biocompatible and nontoxic when added to epithelial monolayers in vitro, while it caused a substantial decrease in the cell viability as well as deformation of the cytoskeleton and cell morphology when incubated with the osteoblastic cells. In the course of six months after the implantation of the material containing different amounts of cobalt, ranging from 5 – 12 wt%, in the osteoporotic alveolar bone of the lower jaw, the following parameters were investigated: histopathological parameters, alkaline phosphatase and alveolar bone density. The best result in terms of osteoporotic bone tissue regeneration was observed for hydroxyapatite nanoparticles with the largest content of cobalt ions. The histological analysis showed a high level of reparatory ability of the nanoparticulate material implanted in the bone defect, paralleled by a corresponding increase in the alveolar bone density. The combined effect of growth factors from autologous plasma admixed to cobalt-substituted hydroxyapatite was furthermore shown to have a crucial effect on the augmented osteoporotic bone regeneration upon the implantation of the biomaterial investigated in this study. PMID:23090835

Substitutions of aspartic acid for glycine-220 and of arginine for glycine-664 in the triple helix of the pro alpha 1(I) chain of type I procollagen produce lethal osteogenesis imperfecta and disrupt the ability of collagen fibrils to incorporate crystalline hydroxyapatite.

PubMed Central

Culbert, A A; Lowe, M P; Atkinson, M; Byers, P H; Wallis, G A; Kadler, K E

1995-01-01

We identified two infants with lethal (type II) osteogenesis imperfecta (OI) who were heterozygous for mutations in the COL1A1 gene that resulted in substitutions of aspartic acid for glycine at position 220 and arginine for glycine at position 664 in the product of one COL1A1 allele in each individual. In normal age- and site-matched bone, approximately 70% (by number) of the collagen fibrils were encrusted with plate-like crystallites of hydroxyapatite. In contrast, approximately 5% (by number) of the collagen fibrils in the probands' bone contained crystallites. In contrast with normal bone, the c-axes of hydroxyapatite crystallites were sometimes poorly aligned with the long axis of fibrils obtained from OI bone. Chemical analysis showed that the OI samples contained normal amounts of calcium. The probands' bone samples contained type I collagen, overmodified type I collagen and elevated levels of type III and V collagens. On the basis of biochemical and morphological data, the fibrils in the OI samples were co-polymers of normal and mutant collagen. The results are consistent with a model of fibril mineralization in which the presence of abnormal type I collagen prevents normal collagen in the same fibril from incorporating hydroxyapatite crystallites. Images Figure 1 Figure 2 Figure 3 PMID:7487936

Prevalence of dental erosion in adolescent competitive swimmers exposed to gas-chlorinated swimming pool water.

PubMed

Buczkowska-Radlińska, J; Łagocka, R; Kaczmarek, W; Górski, M; Nowicka, A

2013-03-01

The purpose of this study was to analyze the prevalence of dental erosion among competitive swimmers of the local swimming club in Szczecin, Poland, who train in closely monitored gas-chlorinated swimming pool water. The population for this survey consisted of a group of junior competitive swimmers who had been training for an average of 7 years, a group of senior competitive swimmers who had been training for an average of 10 years, and a group of recreational swimmers. All subjects underwent a clinical dental examination and responded to a questionnaire regarding aspects of dental erosion. In pool water samples, the concentration of calcium, magnesium, phosphate, sodium, and potassium ions and pH were determined. The degree of hydroxyapatite saturation was also calculated. Dental erosion was found in more than 26 % of the competitive swimmers and 10 % of the recreational swimmers. The lesions in competitive swimmers were on both the labial and palatal surfaces of the anterior teeth, whereas erosions in recreational swimmers developed exclusively on the palatal surfaces. Although the pH of the pool water was neutral, it was undersaturated with respect to hydroxyapatite. The factors that increase the risk of dental erosion include the duration of swimming and the amount of training. An increased risk of erosion may be related to undersaturation of pool water with hydroxyapatite components. To decrease the risk of erosion in competitive swimmers, the degree of dental hydroxyapatite saturation should be a controlled parameter in pool water.

A simple model for the effect of flouride ions on remineralization of partly demineralized tooth enamel

NASA Astrophysics Data System (ADS)

Christoffersen, J.; Christoffersen, M. R.; Arends, J.

1984-06-01

A model is presented for remineralization of partly demineralized tooth enamel, taking the effect of the presence of fluoride ions into account. The model predicts that, in the absence of precipitation of other phases than calcium hydroxyapatite (HAP) and fluroridized HAP, which are assumed to model enamel, there exists a maximum value of the fluoride concentration gradient, above which lesions cannot be successfully repaired.

Application of fluoridated hydroxyapatite thin film coatings using KrF pulsed laser deposition.

PubMed

Hashimoto, Yoshiya; Ueda, Mamoru; Kohiga, Yu; Imura, Kazuki; Hontsu, Shigeki

2018-06-08

Fluoridated hydroxyapatite (FHA) was investigated for application as an implant coating for titanium bone substitute materials in dental implants. A KrF pulsed excimer deposition technique was used for film preparation on a titanium plate. The compacts were ablated by laser irradiation at an energy density of 1 J/cm 2 on an area 1×1 mm 2 with the substrate at room temparature. Energydispersive spectrometric analysis of the FHA film revealed peaks of fluorine in addition to calcium and phosphorus. X-ray diffraction revealed the presence of crystalline FHA on the FHA film after a 10 h post annealing treatment at 450°C. The FHA film coating exhibited significant dissolution resistance to sodium phosphate buffer for up to 21 days, and favorable cell attachment of human mesenchymal stem cells compared with HA film. The results of this study suggest that FHA coatings are suitable for real-world implantation applications.

New technologies in dentistry

NASA Astrophysics Data System (ADS)

Zanin, Fatima A. A.; Brugnera, Aldo, Jr.; Pecora, Jesus D.

1999-05-01

The technology in dentistry has been developed significantly lately, increasing the technological level of new materials, methods and equipment have been developed. Undoubtedly the CO2 laser has contributed to this evolution particular to the treatment of the infected dentin. CO2 laser can sterilize and promote increase 6 to 8 times of dentin resistance, through the transformation the hydroxyapatite in calcium-phosphato-hydroxyapatite. We can reassure our patients about the use of pulsed CO2 laser due to better preservation of dental structure and its benefits permitting advanced esthetic treatments. The CEREC system, registers a tri-dimensional image of the preparation through a scan system, and sends it to the computer and the operator will edit the restorations so the equipment will finish porcelain restoration. The authors used a new laser 650 nm for caries detection and the other low lever laser (670 nm and 730 nm) considered an auxiliary method to prevent and treat the hypersensitivity in dentin.

Structural analysis of strontium in human teeth treated with surface pre-reacted glass-ionomer filler eluate by using extended X-ray absorption fine structure analysis.

PubMed

Uo, Motohiro; Wada, Takahiro; Asakura, Kiyotaka

2017-03-31

The bioactive effects of strontium released from surface pre-reacted glass-ionomer (S-PRG) fillers may aid in caries prevention. In this study, the local structure of strontium taken up by teeth was estimated by extended X-ray absorption fine structure analysis. Immersing teeth into S-PRG filler eluate increased the strontium content in enamel and dentin by more than 100 times. The local structure of strontium in enamel and dentin stored in distilled water was the same as that in synthetic strontium-containing hydroxyapatite (SrHAP). Moreover, the local structure of strontium in enamel and dentin after immersion in the S-PRG filler eluate was also similar to that of SrHAP. After immersion in the S-PRG filler eluate, strontium was suggested to be incorporated into the hydroxyapatite (HAP) of enamel and dentin at the calcium site in HAP.

A Comparative Evaluation of the Mechanical Properties of Two Calcium Phosphate/Collagen Composite Materials and Their Osteogenic Effects on Adipose-Derived Stem Cells

PubMed Central

Li, Qing; Wang, Tong; Zhang, Gui-feng; Yu, Xin; Zhang, Jing; Zhou, Gang; Tang, Zhi-hui

2016-01-01

Adipose-derived stem cells (ADSCs) are ideal seed cells for use in bone tissue engineering and they have many advantages over other stem cells. In this study, two kinds of calcium phosphate/collagen composite scaffolds were prepared and their effects on the proliferation and osteogenic differentiation of ADSCs were investigated. The hydroxyapatite/β-tricalcium phosphate (HA/β-TCP) composite scaffolds (HTPSs), which have an additional β-tricalcium phosphate, resulted in better proliferation of ADSCs and showed osteogenesis-promoting effects. Therefore, such composite scaffolds, in combination with ADSCs or on their own, would be promising for use in bone regeneration and potential clinical therapy for bone defects. PMID:27239204

Composition and distribution of elements and ultrastructural topography of a human cardiac calculus.

PubMed

Cheng, Ching-Li; Chang, Hsiao-Huang; Huang, Pei-Jung; Chu, Yu-Ting; Lin, Shan-Yang

2013-04-01

Trace elements (TEs) may contribute to the formation of calculi or stones or be involved in the aetiopathogenesis of stone diseases. The compositions and spatial distribution of elements from the inner nucleus to outer crust of the cardiac calculus were investigated by energy-dispersive X-ray fluorescence (EDXRF) spectrometer. The surface topograph, distribution map of elements, elemental and chemical compositions were also determined by environmental scanning electron microscope (ESEM)-energy-dispersive X-ray (EDX) analysis. Twenty-five elements were identifiable from 18 positions on the cardiac calculus by EDXRF spectrometer, in which the highest concentrations of toxic TEs (Ni, Pt, Hg, Sn, Pb, W, Au, Al, Si) and higher levels of essential TEs (Ca, Sr, Cr, P) were detected. A moderate positive Pearson's correlation between TEs concentrations of Mg, Ca or P and location differences from centre to periphery in the cardiac calculus was observed. A positive correlation was also found for Ca/Zn and Ca/Cu, indicating the gradual increase of calcium concentration from inner nucleus to outer crust of cardiac calculus. The drop-like nodules/crystals on the surface of petrous part of cardiac calculus were observed from ESEM analysis. ESEM-EDX analysis determined the calculus to be predominantly composed of calcium hydroxyapatite and cholesterol, as indicated by the petrous surface and drop-like nodules/crystals, respectively. This composition was confirmed using a portable Raman analyser. The spatial distribution analysis indicated a gradual increase in Mg, P and Ca concentrations from the inner nucleus to the outer crust of the cardiac calculus. The major chemical compositions of calcium hydroxyapatite and cholesterol were detected on this cardiac calculus.

Ion reactivity of calcium-deficient hydroxyapatite in standard cell culture media.

PubMed

Gustavsson, J; Ginebra, M P; Engel, E; Planell, J

2011-12-01

Solution-mediated surface reactions occur for most calcium phosphate-based biomaterials and may influence cellular response. A reasonable extrapolation of such processes observed in vitro to in vivo performance requires a deep understanding of the underlying mechanisms. We therefore systematically investigated the nature of ion reactivity of calcium-deficient hydroxyapatite (CDHA) by exposing it for different periods of time to standard cell culture media of different chemical composition (DMEM and McCoy medium, with and without osteogenic supplements and serum proteins). Kinetic ion interaction studies of principal extracellular ions revealed non-linear sorption of Ca²⁺ (∼50% sorption) and K⁺ (∼8%) as well as acidification of all media during initial contact with CDHA (48h). Interestingly, inorganic phosphorus (P(i)) was sorbed from McCoy medium (∼50%) or when using osteogenic media containing β-glycerophosphate, but not from DMEM medium. Non-linear sorption data could be perfectly described by pseudo-first-order and pseudo-second-order sorption models. At longer contact time (21 days), and with frequent renewal of culture medium, sorption of Ca²⁺ remained constant throughout the experiment, while sorption of P(i) gradually decreased in McCoy medium. In great contrast, CDHA began to release P(i) slowly with time when using DMEM medium. Infrared spectra showed that CDHA exposed to culture media had a carbonated surface chemistry, suggesting that carbonate plays a key role in the ion reactivity of CDHA. Our data show that different compositions of the aqueous environment may provoke opposite ion reactivity of CDHA, and this must be carefully considered when evaluating the osteoinductive potential of the material. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Strontium-Doped Calcium Phosphate and Hydroxyapatite Granules Promote Different Inflammatory and Bone Remodelling Responses in Normal and Ovariectomised Rats

PubMed Central

Xia, Wei; Emanuelsson, Lena; Norlindh, Birgitta; Omar, Omar; Thomsen, Peter

2013-01-01

The healing of bone defects may be hindered by systemic conditions such as osteoporosis. Calcium phosphates, with or without ion substitutions, may provide advantages for bone augmentation. However, the mechanism of bone formation with these materials is unclear. The aim of this study was to evaluate the healing process in bone defects implanted with hydroxyapatite (HA) or strontium-doped calcium phosphate (SCP) granules, in non-ovariectomised (non-OVX) and ovariectomised (OVX) rats. After 0 (baseline), six and 28d, bone samples were harvested for gene expression analysis, histology and histomorphometry. Tumour necrosis factor-α (TNF-α), at six days, was higher in the HA, in non-OVX and OVX, whereas interleukin-6 (IL-6), at six and 28d, was higher in SCP, but only in non-OVX. Both materials produced a similar expression of the receptor activator of nuclear factor kappa-B ligand (RANKL). Higher expression of osteoclastic markers, calcitonin receptor (CR) and cathepsin K (CatK), were detected in the HA group, irrespective of non-OVX or OVX. The overall bone formation was comparable between HA and SCP, but with topological differences. The bone area was higher in the defect centre of the HA group, mainly in the OVX, and in the defect periphery of the SCP group, in both non-OVX and OVX. It is concluded that HA and SCP granules result in comparable bone formation in trabecular bone defects. As judged by gene expression and histological analyses, the two materials induced different inflammatory and bone remodelling responses. The modulatory effects are associated with differences in the spatial distribution of the newly formed bone. PMID:24376855

The processing and characterization of animal-derived bone to yield materials with biomedical applications. Part II: milled bone powders, reprecipitated hydroxyapatite and the potential uses of these materials.

PubMed

Johnson, G S; Mucalo, M R; Lorier, M A; Gieland, U; Mucha, H

2000-11-01

Further studies on the processing and use of animal-bone-derived calcium phosphate materials in biomedical applications are presented. Bone powders sourced either from the direct crushing and milling of bovine, ovine and cervine bone or after being subjected to defatting and acid digestion/NaOH reprecipitation and sodium hypochlorite hydrogen peroxide treatment of animal bones were characterized using Fourier transform infra-red (FTIR) spectroscopy, 13C solid state magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, atomic absorption (AA) and inductively coupled plasma (ICP) spectrometric techniques. Bone powders were trialled for their potential use as a substrate for phosphine coupling and enzyme immobilization as well as a feedstock powder for plasma spraying on titanium metal substrates. Results indicated that enzyme immobilization by phosphine coupling could be successfully achieved on milled cervine bone with the immobilized enzyme retaining some activity. It was found that the presence of impurities normally carried down with the processing of the bone materials (viz., fat and collagen) played an important role in influencing the adsorbency and reactivity of the powders. Plasma spraying studies using reprecipitated bovine-derived powders produced highly adherent coatings on titanium metal, the composition of which was mostly hydroxyapatite (Ca10(PO4)6(OH)2) with low levels of alpha-tricalcium phosphate (alpha-Ca3(PO4)2) and tetracalcium phosphate (Ca4P2O9) also detected. In general, animal derived calcium phosphate materials constitute a potentially cheaper source of calcium phosphate materials for biomedical applications and make use of a largely under-utilized resource from abattoir wastes. Copyright 2000 Kluwer Academic Publishers

Effect of pyrophosphate ions on the conversion of calcium-lithium-borate glass to hydroxyapatite in aqueous phosphate solution.

PubMed

Fu, Hailuo; Rahaman, Mohamed N; Day, Delbert E; Huang, Wenhai

2010-10-01

The conversion of glass to a hydroxyapatite (HA) material in an aqueous phosphate solution is used as an indication of the bioactive potential of the glass, as well as a low temperature route for preparing biologically useful materials. In this work, the effect of varying concentrations of pyrophosphate ions in the phosphate solution on the conversion of a calcium-lithium-borate glass to HA was investigated. Particles of the glass (150-355 μm) were immersed for up to 28 days in 0.25 M K(2)HPO(4) solution containing 0-0.1 M K(4)P(2)O(7). The kinetics of degradation of the glass particles and their conversion to HA were monitored by measuring the weight loss of the particles and the ionic concentration of the solution. The structure and composition of the conversion products were analyzed using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. For K(4)P(2)O(7) concentrations of up to 0.01 M, the glass particles converted to HA, but the time for complete conversion increased from 2 days (no K(4)P(2)O(7)) to 10 days (0.01 M K(4)P(2)O(7)). When the K(4)P(2)O(7) concentration was increased to 0.1 M, the product consisted of an amorphous calcium phosphate material, which eventually crystallized to a pyrophosphate product (predominantly K(2)CaP(2)O(7) and Ca(2)P(2)O(7)). The consequences of the results for the formation of HA materials and devices by the glass conversion route are discussed.

Optimization of calcium phosphate fine ceramic powders preparation

NASA Astrophysics Data System (ADS)

Sezanova, K.; Tepavitcharova, S.; Rabadjieva, D.; Gergulova, R.; Ilieva, R.

2013-12-01

The effect of biomimetic synthesis method, reaction medium and further precursor treatments on the chemical and phase composition, crystal size and morphology of calcium phosphates was examined. Nanosized calcium phosphate precursors were biomimetically precipitated by the method of continuous precipitation in three types of reaction media at pH 8: (i) SBF as an inorganic electrolyte system; (ii) organic (glycerine) modified SBF (volume ratio of 1:1); (iii) polymer (10 g/l xanthan gum or 10 g/l guar gum) modified SBF (volume ratio of 1:1). After maturation (24 h) the samples were lyophilized, calcinated at 300°C for 3 hours, and washed with water, followed by new gelation, lyophilization and step-wise (200, 400, 600, 800, and 1000°C, each for 3 hours) sintering. The reaction medium influenced the chemical composition and particle size but not the morphology of the calcium phosphate powders. In all studied cases bi-phase calcium phosphate fine powders with well-shaped spherical grains, consisting of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) with a Ca/P ratio of 1.3 - 1.6 were obtained. The SBF modifiers decreased the particle size of the product in the sequence guar gum ˜ xanthan gum < glycerin < SBF medium.

Recombinant DNA technology and click chemistry: a powerful combination for generating a hybrid elastin-like-statherin hydrogel to control calcium phosphate mineralization

PubMed Central

Misbah, Mohamed Hamed; Santos, Mercedes; Quintanilla, Luis; Günter, Christina; Alonso, Matilde; Taubert, Andreas

2017-01-01

Understanding the mechanisms responsible for generating different phases and morphologies of calcium phosphate by elastin-like recombinamers is supreme for bioengineering of advanced multifunctional materials. The generation of such multifunctional hybrid materials depends on the properties of their counterparts and the way in which they are assembled. The success of this assembly depends on the different approaches used, such as recombinant DNA technology and click chemistry. In the present work, an elastin-like recombinamer bearing lysine amino acids distributed along the recombinamer chain has been cross-linked via Huisgen [2 + 3] cycloaddition. The recombinamer contains the SNA15 peptide domains inspired by salivary statherin, a peptide epitope known to specifically bind to and nucleate calcium phosphate. The benefit of using click chemistry is that the hybrid elastin-like-statherin recombinamers cross-link without losing their fibrillar structure. Mineralization of the resulting hybrid elastin-like-statherin recombinamer hydrogels with calcium phosphate is described. Thus, two different hydroxyapatite morphologies (cauliflower- and plate-like) have been formed. Overall, this study shows that crosslinking elastin-like recombinamers leads to interesting matrix materials for the generation of calcium phosphate composites with potential applications as biomaterials. PMID:28487820

Fabrication of mineralized electrospun PLGA and PLGA/gelatin nanofibers and their potential in bone tissue engineering.

PubMed

Meng, Z X; Li, H F; Sun, Z Z; Zheng, W; Zheng, Y F

2013-03-01

Surface mineralization is an effective method to produce calcium phosphate apatite coating on the surface of bone tissue scaffold which could create an osteophilic environment similar to the natural extracellular matrix for bone cells. In this study, we prepared mineralized poly(D,L-lactide-co-glycolide) (PLGA) and PLGA/gelatin electrospun nanofibers via depositing calcium phosphate apatite coating on the surface of these nanofibers to fabricate bone tissue engineering scaffolds by concentrated simulated body fluid method, supersaturated calcification solution method and alternate soaking method. The apatite products were characterized by the scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), and X-ray diffractometry (XRD) methods. A large amount of calcium phosphate apatite composed of dicalcium phosphate dihydrate (DCPD), hydroxyapatite (HA) and octacalcium phosphate (OCP) was deposited on the surface of resulting nanofibers in short times via three mineralizing methods. A larger amount of calcium phosphate was deposited on the surface of PLGA/gelatin nanofibers rather than PLGA nanofibers because gelatin acted as nucleation center for the formation of calcium phosphate. The cell culture experiments revealed that the difference of morphology and components of calcium phosphate apatite did not show much influence on the cell adhesion, proliferation and activity. Copyright © 2012 Elsevier B.V. All rights reserved.

Sol gel-derived hydroxyapatite films over porous calcium polyphosphate substrates for improved tissue engineering of osteochondral-like constructs.

PubMed

Lee, Whitaik David; Gawri, Rahul; Pilliar, Robert M; Stanford, William L; Kandel, Rita A

2017-10-15

Integration of in vitro-formed cartilage on a suitable substrate to form tissue-engineered implants for osteochondral defect repair is a considerable challenge. In healthy cartilage, a zone of calcified cartilage (ZCC) acts as an intermediary for mechanical force transfer from soft to hard tissue, as well as an effective interlocking structure to better resist interfacial shear forces. We have developed biphasic constructs that consist of scaffold-free cartilage tissue grown in vitro on, and interdigitated with, porous calcium polyphosphate (CPP) substrates. However, as CPP degrades, it releases inorganic polyphosphates (polyP) that can inhibit local mineralization, thereby preventing the formation of a ZCC at the interface. Thus, we hypothesize that coating CPP substrate with a layer of hydroxyapatite (HA) might prevent or limit this polyP release. To investigate this we tested both inorganic or organic sol-gel processing methods, asa barrier coating on CPP substrate to inhibit polyP release. Both types of coating supported the formation of ZCC in direct contact with the substrate, however the ZCC appeared more continuous in the tissue formed on the organic HA sol gel coated CPP. Tissues formed on coated substrates accumulated comparable quantities of extracellular matrix and mineral, but tissues formed on organic sol-gel (OSG)-coated substrates accumulated less polyP than tissues formed on inorganic sol-gel (ISG)-coated substrates. Constructs formed with OSG-coated CPP substrates had greater interfacial shear strength than those formed with ISG-coated and non-coated substrates. These results suggest that the OSG coating method can modify the location and distribution of ZCC and can be used to improve the mechanical integrity of tissue-engineered constructs formed on porous CPP substrates. Articular cartilage interfaces with bone through a zone of calcified cartilage. This study describes a method to generate an "osteochondral-like" implant that mimics this organization using isolated deep zone cartilage cells and a sol-gel hydroxyapatite coated bone substitute material composed of calcium polyphosphate (CPP). Developing a layer of calcified cartilage at the interface should contribute to enhancing the success of this "osteochondral-like" construct following implantation to repair cartilage defects. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Biocalcite, a multifunctional inorganic polymer: Building block for calcareous sponge spicules and bioseed for the synthesis of calcium phosphate-based bone

PubMed Central

Schröder, Heinz C; Müller, Werner E G

2014-01-01

Summary Calcium carbonate is the material that builds up the spicules of the calcareous sponges. Recent results revealed that the calcium carbonate/biocalcite-based spicular skeleton of these animals is formed through an enzymatic mechanism, such as the skeleton of the siliceous sponges, evolutionarily the oldest animals that consist of biosilica. The enzyme that mediates the calcium carbonate deposition has been identified as a carbonic anhydrase (CA) and has been cloned from the calcareous sponge species Sycon raphanus. Calcium carbonate deposits are also found in vertebrate bones besides the main constituent, calcium phosphate/hydroxyapatite (HA). Evidence has been presented that during the initial phase of HA synthesis poorly crystalline carbonated apatite is deposited. Recent data summarized here indicate that during early bone formation calcium carbonate deposits enzymatically formed by CA, act as potential bioseeds for the precipitation of calcium phosphate mineral onto bone-forming osteoblasts. Two different calcium carbonate phases have been found during CA-driven enzymatic calcium carbonate deposition in in vitro assays: calcite crystals and round-shaped vaterite deposits. The CA provides a new target of potential anabolic agents for treatment of bone diseases; a first CA activator stimulating the CA-driven calcium carbonate deposition has been identified. In addition, the CA-driven calcium carbonate crystal formation can be frozen at the vaterite state in the presence of silintaphin-2, an aspartic acid/glutamic acid-rich sponge-specific protein. The discovery that calcium carbonate crystals act as bioseeds in human bone formation may allow the development of novel biomimetic scaffolds for bone tissue engineering. Na-alginate hydrogels, enriched with biosilica, have recently been demonstrated as a suitable matrix to embed bone forming cells for rapid prototyping bioprinting/3D cell printing applications. PMID:24991497

Biocalcite, a multifunctional inorganic polymer: Building block for calcareous sponge spicules and bioseed for the synthesis of calcium phosphate-based bone.

PubMed

Wang, Xiaohong; Schröder, Heinz C; Müller, Werner E G

2014-01-01

Calcium carbonate is the material that builds up the spicules of the calcareous sponges. Recent results revealed that the calcium carbonate/biocalcite-based spicular skeleton of these animals is formed through an enzymatic mechanism, such as the skeleton of the siliceous sponges, evolutionarily the oldest animals that consist of biosilica. The enzyme that mediates the calcium carbonate deposition has been identified as a carbonic anhydrase (CA) and has been cloned from the calcareous sponge species Sycon raphanus. Calcium carbonate deposits are also found in vertebrate bones besides the main constituent, calcium phosphate/hydroxyapatite (HA). Evidence has been presented that during the initial phase of HA synthesis poorly crystalline carbonated apatite is deposited. Recent data summarized here indicate that during early bone formation calcium carbonate deposits enzymatically formed by CA, act as potential bioseeds for the precipitation of calcium phosphate mineral onto bone-forming osteoblasts. Two different calcium carbonate phases have been found during CA-driven enzymatic calcium carbonate deposition in in vitro assays: calcite crystals and round-shaped vaterite deposits. The CA provides a new target of potential anabolic agents for treatment of bone diseases; a first CA activator stimulating the CA-driven calcium carbonate deposition has been identified. In addition, the CA-driven calcium carbonate crystal formation can be frozen at the vaterite state in the presence of silintaphin-2, an aspartic acid/glutamic acid-rich sponge-specific protein. The discovery that calcium carbonate crystals act as bioseeds in human bone formation may allow the development of novel biomimetic scaffolds for bone tissue engineering. Na-alginate hydrogels, enriched with biosilica, have recently been demonstrated as a suitable matrix to embed bone forming cells for rapid prototyping bioprinting/3D cell printing applications.

Formation of apatitic calcium phosphates in a Na-K-phosphate solution of pH 7.4.

PubMed

Tas, A C; Aldinger, F

2005-02-01

Poorly crystalline, apatitic calcium phosphate powders have been synthesized by slowly adding a Na- and K-containing reference phosphate solution with a pH value of 7.4 to an aqueous calcium nitrate solution at 37 degrees C. Nano-particulated apatitic powders obtained were shown to contain small amounts of Na and K, which render them more similar in chemical composition to that of the bone mineral. Precipitated and dried powders were found to exhibit self-hardening cement properties when kneaded in a mortar with a sodium citrate- and sodium phosphate-containing starter solution. The same phosphate solution used in powder synthesis was found to be able to partially convert natural, white and translucent marble pieces of calcite (CaCO3) into calcium-deficient hydroxyapatite upon aging the samples in that solution for 3 days at 60 degrees C. Sample characterization was performed by using scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, inductively-coupled plasma atomic emission spectroscopy, and simultaneous thermogravimetry and differential thermal analysis.

Sintering Effects on Morphology, Thermal Stability and Surface Area of Sol-Gel Derived Nano-Hydroxyapatite Powder

NASA Astrophysics Data System (ADS)

Kapoor, Seema; Batra, Uma; Kohli, Suchita

2011-12-01

Hydroxyapatite (HAP) ceramics have been recognized as substitute materials for bone and teeth in orthopedic and dentistry field due to their chemical and biological similarity to human hard tissue. The nanosized and nanocrystalline forms of HAP have great potential to revolutionize the hard tissue-engineering field, starting from bone repair and augmentation to controlled drug delivery systems. This paper reports the synthesis of biomimetic nano-hydroxyapatite (HAP) by sol-gel method using calcium nitrate tetrahydrate (CNT) and potassium dihydrogen phosphate (KDP) as calcium and phosphorus precursors, respectively to obtain a desired Ca/P ratio of 1.67. Deionized water was used as a diluting media for HAP sol preparation and ammonia was used to adjust the pH to 11. After aging, the HAP gel was dried at 55 °C and sintered to different temperatures (200 °C, 400 °C, 600 °C, 800 °C, 1000 °C and 1200 °C). The dried and sintered powders were characterized for phase composition using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The particle size and morphology was studied using transmission electron microscopy (TEM). The thermal behavior of the dried HAP nanopowder was studied in the temperature range of 55 °C to 1000 °C using thermal gravimetric analyser (TGA). The BET surface area of absorbance was determined by Nitrogen adsorption using Brunauer-Emmett-Teller (BET) method. The presence of characteristic peaks of the phosphate and OH groups in FTIR spectrums confirmed the formation of pure HAP in dried as well as sintered powders. XRD results also confirmed the formation of stoichiometric nano-HAP. Sintering revealed that with increase in temperature, both the crystallinity and crystallite size of nano-HAP particles increased. The synthesized nano-HAP powder was found to be stable upto 1000 °C without any additional phase other than HAP, whereas peak of β-TCP (tricalcium phosphate) was observed at 1200 °C. Photomicrograph of TEM showed that the nanopowder sintered at 600 °C is composed of hydroxyapatite nanoparticles (26.0-45.6 nm), which is well in agreement with the crystallite size calculated using XRD data. TGA study showed the thermal stability of the synthesized nano-HAP powder. The BET surface area decreased with increase in sintering temperature.

Image Based Biomarker of Breast Cancer Risk: Analysis of Risk Disparity Among Minority Populations

DTIC Science & Technology

2014-03-01

attenuation coefficient of calcium hydroxyapatite ; is a parameter controlling the contrast of MCs in synthetic images (0< ə); and is the linear...effect of acquisition parameters and quantum noise," Med Phys, 37, 1591-600 (2010). [13] M. J. Yaffe, J. M. Boone, N. Packard, O. Alonzo-Proulx, S. Y...the acquisition of individual mammograms, the use of linear transformations does not seem appropriate for mammogram registration. Non-linear

National Academy of Sciences - National Research Council Resident Research Associateship Program (RRA)

DTIC Science & Technology

1992-03-11

calcim phosphate ceranuc- organic acid composites were prepared from hydroxyapatite , tricalcium phosphate, or zinc calcium phosphate, with malic acid...pressures during deposition. The film processing parameters and the basic mechanisms for the optimized conditions have been established for a possible...encountered laboratory influences detrimental to your Proposed research? Explain. Comments: JI - ve r " i O wt4 w 4 h0 - Ic hto cm pxtc 1/C Brie.f resume oa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moussa, Sana Ben; Bachouâ, Hassen; Gruselle, Michel, E-mail: michel.gruselle@upmc.fr

The present article details the formation of calcium hydroxyapatite synthesized by the hydrothermal way, in presence of glycine or sarcosine. The presence of these amino-acids during the synthetic processes reduces the crystalline growthing through the formation of hybrid organic-inorganic species The crystallite sizes are decreasing and the morphology is modified with the increase of the amino-acid concentration. - Graphical abstract: Formation of Ca carboxylate salt leading to the grafting of glycine and sarcosine on the Ca=Hap surface (R= H, CH3).

Emission properties of biomimetic composites for dentistry

NASA Astrophysics Data System (ADS)

Seredin, P. V.; Goloshchapov, D. L.; Kashkarov, V. M.; Ippolitov, Yu. A.; Prutskij, T.

Biocomposites based on carbonate-substituted hydroxyapatite synthesized from the biological source of calcium (Goloshchapov et al., 2013) and organic primer on the basis of amino acids found in the enamel tubules of teeth, namely, arginine, histidine, lysine and hyaluronic acid were obtained and studied in this work. Incorporation of organic primer into biocomposite formulation allowed us to obtain the emission characteristics (luminescence) that were identical to those inherent to the native tissues of the human tooth (enamel and dentine).

Dual-Energy Computed Tomography Gemstone Spectral Imaging: A Novel Technique to Determine Human Cardiac Calculus Composition.

PubMed

Cheng, Ching-Li; Chang, Hsiao-Huang; Ko, Shih-Chi; Huang, Pei-Jung; Lin, Shan-Yang

2016-01-01

Understanding the chemical composition of any calculus in different human organs is essential for choosing the best treatment strategy for patients. The purpose of this study was to assess the capability of determining the chemical composition of a human cardiac calculus using gemstone spectral imaging (GSI) mode on a single-source dual-energy computed tomography (DECT) in vitro. The cardiac calculus was directly scanned on the Discovery CT750 HD FREEdom Edition using GSI mode, in vitro. A portable fiber-optic Raman spectroscopy was also applied to verify the quantitative accuracy of the DECT measurements. The results of spectral DECT measurements indicate that effective Z values in 3 designated positions located in this calculus were 15.02 to 15.47, which are close to values of 15.74 to 15.86, corresponding to the effective Z values of calcium apatite and hydroxyapatite. The Raman spectral data were also reflected by the predominant Raman peak at 960 cm for hydroxyapatite and the minor peak at 875 cm for calcium apatite. A potential single-source DECT with GSI mode was first used to examine the morphological characteristics and chemical compositions of a giant human cardiac calculus, in vitro. The CT results were consistent with the Raman spectral data, suggesting that spectral CT imaging techniques could be accurately used to diagnose and characterize the compositional materials in the cardiac calculus.

Energetic basis for the molecular-scale organization of bone

DOE PAGES

Tao, Jinhui; Battle, Keith C.; Pan, Haihua; ...

2014-12-24

Here, the remarkable properties of bone derive from a highly organized arrangement of co-aligned nm-scale apatite platelets within a fibrillar collagen matrix. The origin of this arrangement is poorly understood and the crystal structures of hydroxyapatite (HAP) and the non-mineralized collagen fibrils alone do not provide an explanation. Moreover, little is known about collagen-apatite interaction energies, which should strongly influence both the molecular-scale organization and the resulting mechanical properties of the composite. We investigated collagen-mineral interactions by combining dynamic force spectroscopy (DFS) measurements of binding energies with molecular dynamics (MD) simulations of binding and AFM observations of collagen adsorption onmore » single crystals of calcium phosphate for four mineral phases of potential importance in bone formation. In all cases, we observe a strong preferential orientation of collagen binding, but comparison between the observed orientations and TEM analyses native tissues shows only calcium-deficient apatite (CDAP) provides an interface with collagen that is consistent with both. MD simulations predict preferred collagen orientations that agree with observations and results from both MD and DFS reveal large values for the binding energy due to multiple binding sites. These findings reconcile apparent contradictions inherent in a hydroxyapatite or carbonated apatite (CAP) model of bone mineral and provide an energetic rationale for the molecular scale organization of bone.« less

Extraordinary biological properties of a new calcium hydroxyapatite/poly(lactide-co-glycolide)-based scaffold confirmed by in vivo investigation.

PubMed

Jokanović, Vukoman; Čolović, Božana; Marković, Dejan; Petrović, Milan; Soldatović, Ivan; Antonijević, Djordje; Milosavljević, Petar; Sjerobabin, Nikola; Sopta, Jelena

2017-05-24

This study examined the potential of a new porous calcium hydroxyapatite scaffold covered with poly (lactide-co-glycolide) (PLGA) as a bone substitute, identifying its advantages over Geistlich Bio-Oss®, considered the gold standard, in in vivo biofunctionality investigations. Structural and morphological properties of the new scaffold were analyzed by scanning electron and atomic force microscopy. The biofunctionality assays were performed on New Zealand white rabbits using new scaffold for filling full-thickness defects of critical size. The evaluated parameters were: the presence of macrophages, giant cells, monoocytes, plasma cells, granulocytes, neoangiogenesis, fibroplasia, and the percentage of mineralization. Parallel biofunctionality assays were performed using Geistlich Bio-Oss®. The appearance of bone defects 12 weeks after the new scaffold implantation showed the presence of a small number of typical immune response cells. Furthermore, significantly reduced number of capillary buds, low intensity of fibroplasia and high degree of mineralization in a lamellar pattern indicated that the inflammation process has been almost completely overcome and that the new bone formed was in the final phase of remodeling. All biofunctionality assays proved the new scaffold's suitability as a bone substitute for applications in maxillofacial surgery. It showed numerous biological advantages over Geistlich Bio-Oss® which was reflected mainly as a lower number of giant cells surrounding implanted material and higher degree of mineralization in new formed bone.

Biomaterials for periodontal regeneration

PubMed Central

Shue, Li; Yufeng, Zhang; Mony, Ullas

2012-01-01

Periodontal disease is characterized by the destruction of periodontal tissues. Various methods of regenerative periodontal therapy, including the use of barrier membranes, bone replacement grafts, growth factors and the combination of these procedures have been investigated. The development of biomaterials for tissue engineering has considerably improved the available treatment options above. They fall into two broad classes: ceramics and polymers. The available ceramic-based materials include calcium phosphate (eg, tricalcium phosphate and hydroxyapatite), calcium sulfate and bioactive glass. The bioactive glass bonds to the bone with the formation of a layer of carbonated hydroxyapatite in situ. The natural polymers include modified polysaccharides (eg, chitosan,) and polypeptides (collagen and gelatin). Synthetic polymers [eg, poly(glycolic acid), poly(L-lactic acid)] provide a platform for exhibiting the biomechanical properties of scaffolds in tissue engineering. The materials usually work as osteogenic, osteoconductive and osteoinductive scaffolds. Polymers are more widely used as a barrier material in guided tissue regeneration (GTR). They are shown to exclude epithelial downgrowth and allow periodontal ligament and alveolar bone cells to repopulate the defect. An attempt to overcome the problems related to a collapse of the barrier membrane in GTR or epithelial downgrowth is the use of a combination of barrier membranes and grafting materials. This article reviews various biomaterials including scaffolds and membranes used for periodontal treatment and their impacts on the experimental or clinical management of periodontal defect. PMID:23507891

Microcalcifications in breast cancer: novel insights into the molecular mechanism and functional consequence of mammary mineralisation

PubMed Central

Cox, R F; Hernandez-Santana, A; Ramdass, S; McMahon, G; Harmey, J H; Morgan, M P

2012-01-01

Background: Mammographic microcalcifications represent one of the most reliable features of nonpalpable breast cancer yet remain largely unexplored and poorly understood. Methods: We report a novel model to investigate the in vitro mineralisation potential of a panel of mammary cell lines. Primary mammary tumours were produced by implanting tumourigenic cells into the mammary fat pads of female BALB/c mice. Results: Hydroxyapatite (HA) was deposited only by the tumourigenic cell lines, indicating mineralisation potential may be associated with cell phenotype in this in vitro model. We propose a mechanism for mammary mineralisation, which suggests that the balance between enhancers and inhibitors of physiological mineralisation are disrupted. Inhibition of alkaline phosphatase and phosphate transport prevented mineralisation, demonstrating that mineralisation is an active cell-mediated process. Hydroxyapatite was found to enhance in vitro tumour cell migration, while calcium oxalate had no effect, highlighting potential consequences of calcium deposition. In addition, HA was also deposited in primary mammary tumours produced by implanting the tumourigenic cells into the mammary fat pads of female BALB/c mice. Conclusion: This work indicates that formation of mammary HA is a cell-specific regulated process, which creates an osteomimetic niche potentially enhancing breast tumour progression. Our findings point to the cells mineralisation potential and the microenvironment regulating it, as a significant feature of breast tumour development. PMID:22233923

Energetic basis for the molecular-scale organization of bone.

PubMed

Tao, Jinhui; Battle, Keith C; Pan, Haihua; Salter, E Alan; Chien, Yung-Ching; Wierzbicki, Andrzej; De Yoreo, James J

2015-01-13

The remarkable properties of bone derive from a highly organized arrangement of coaligned nanometer-scale apatite platelets within a fibrillar collagen matrix. The origin of this arrangement is poorly understood and the crystal structures of hydroxyapatite (HAP) and the nonmineralized collagen fibrils alone do not provide an explanation. Moreover, little is known about collagen-apatite interaction energies, which should strongly influence both the molecular-scale organization and the resulting mechanical properties of the composite. We investigated collagen-mineral interactions by combining dynamic force spectroscopy (DFS) measurements of binding energies with molecular dynamics (MD) simulations of binding and atomic force microscopy (AFM) observations of collagen adsorption on single crystals of calcium phosphate for four mineral phases of potential importance in bone formation. In all cases, we observe a strong preferential orientation of collagen binding, but comparison between the observed orientations and transmission electron microscopy (TEM) analyses of native tissues shows that only calcium-deficient apatite (CDAP) provides an interface with collagen that is consistent with both. MD simulations predict preferred collagen orientations that agree with observations, and results from both MD and DFS reveal large values for the binding energy due to multiple binding sites. These findings reconcile apparent contradictions inherent in a hydroxyapatite or carbonated apatite (CAP) model of bone mineral and provide an energetic rationale for the molecular-scale organization of bone.

Effect of amorphous phases during the hydraulic conversion of α-TCP into calcium-deficient hydroxyapatite.

PubMed

Hurle, Katrin; Neubauer, Juergen; Bohner, Marc; Doebelin, Nicola; Goetz-Neunhoeffer, Friedlinde

2014-09-01

Powders of α-tricalcium phosphate (α-TCP), which readily react with water to form calcium-deficient hydroxyapatite (CDHA), are frequently used in bone cements. As, for clinical applications, it is important to adjust the setting reaction of the cements to a reasonable reaction time, exact knowledge of the hydration mechanism is essential. It is known that prolonged milling results in partial amorphization of α-TCP powders and that dissolution of the amorphous phase significantly accelerates the hydration, but it is not clear yet when the amorphous phase reacts in comparison to the crystalline α-TCP. Therefore the aim of this study was to investigate the development of quantitative phase content of α-TCP samples during hydration. For this purpose, three α-TCP powders, containing 0, 16 and 71wt.% of amorphous phase (ATCP), were mixed with either deionized water or a 0.1M Na2HPO4 aqueous solution. The crystalline evolution of the paste was assessed quantitatively during the first 48h of hydration at 23°C by G-factor quantification. The present investigations demonstrate that ATCP reacted earlier than crystalline α-TCP. The results also suggest the formation of an X-ray amorphous phase during the hydraulic conversion formation of α-TCP into CDHA. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Direct bioactive ceramics coating via reactive Growing Integration Layer method on α-Ti-alloy.

PubMed

Huang, Chi-Huang; Chen, Rong-Sheng; Yoshimura, Masahiro

2017-07-01

This paper demonstrates Ca-P-rich bio-ceramic and hydroxyapatite (HA) coatings formed directly from the solution of calcium acetate (CA) and sodium dihydrogen phosphate (SDP) on α-Ti-alloy substrates by Growing Integration Layer (GIL) technology under DC power supply. The composition of the α-Ti-alloy was Ti7Cu5Sn. The GIL coated films formed in 30min time with different voltages applied had porous and rough ceramic surfaces. They consisted mostly of various oxides like rutile, anatase, and calcium phosphates (including hydroxyapatite) that reduce corrosion rate and increase biocompatibility. An important feature was the reduction of Cu at the surfaces of the alloys. Furthermore, along with the applied voltage, the content of HA, the size of micro-pores, and hardness all increased, while the number of micro-pores in the ceramic membrane got reduced. The potential, current and resistance of corrosion were identified by potentiodynamic (PD) polarization and electrochemical impedance spectroscopy (EIS). The higher applied voltage improved the surface quality, HA formation rate, and the anti-corrosion behavior. Consequently, the samples - prepared at 350V and surface current density of 3A/cm 2 - possessed the most compact HA films, and also had the best corrosion resistance - in 0.9wt% NaCl solution at 37±1°C. Copyright © 2017. Published by Elsevier B.V.

Premixed calcium phosphate cements: Synthesis, physical properties, and cell cytotoxicity

PubMed Central

Xu, Hockin H.K.; Carey, Lisa E.; Simon, Carl G.; Takagi, Shozo; Chow, Laurence C.

2009-01-01

Objectives Calcium phosphate cement (CPC) is a promising material for dental, periodontal, and craniofacial repairs. However, its use requires on-site powder–liquid mixing that increases the surgical placement time and raises concerns of insufficient and inhomogeneous mixing. The objective of this study was to determine a formulation of premixed CPC (PCPC) with rapid setting, high strength, and good in vitro cell viability. Methods PCPCs were formulated from CPC powder + non-aqueous liquid + gelling agent + hardening accelerator. Five PCPCs were thus developed: PCPC-Tartaric, PCPC-Malonic, PCPC-Citric, PCPC-Glycolic, and PCPC-Malic. Formulations and controls were compared for setting time, diametral tensile strength, and osteoblast cell compatibility. Results Setting time (mean ± S.D.; n = 4) for PCPC-Tartaric was 8.2 ± 0.8 min, significantly less than the 61.7 ± 1.5 min for the Premixed Control developed previously (p < 0.001). On 7th day immersion, the diametral tensile strength of PCPC-Tartaric reached 6.5 ± 0.8 MPa, higher than 4.5 ± 0.8 MPa of Premixed Control (p = 0.036). Osteoblast cells displayed a polygonal morphology and attached to the nano-hydroxyapatite crystals in the PCPCs. All cements had similar live cell density values (p = 0.126), indicating that the new PCPCs were as cell compatible as a non-premixed CPC control known to be biocompatible. Each of the new PCPCs had a cell viability that was not significantly different (p > 0.1) from that of the non-premixed CPC control. Significance PCPCs will eliminate the powder–liquid mixing during surgery and may also improve the cement performance. The new PCPCs supported cell attachment and yielded a high cell density and viability. Their mechanical strengths approached the reported strengths of sintered porous hydroxyapatite implants and cancellous bone. These nano-crystalline hydroxyapatite cements may be useful in dental, periodontal, and craniofacial repairs. PMID:16678895

Effect of aging temperature on formation of sol-gel derived fluor-hydroxyapatite nanoparticles.

PubMed

Joughehdoust, S; Behnamghader, A; Jahandideh, R; Manafi, S

2010-04-01

Synthetic hydroxyapatite (HA) has been recognized as one of the most important bone substitute materials in orthopaedics and dentistry over past few decades because of its chemical and biological similarity to the mineral phase of human bone. One solution for reduction the solubility of HA in biological environments is replacing F- by OH in HA structure and forming fluor-hydroxyapatite (FHA) solid solution. In this paper, FHA nanoparticles were successfully synthesized by a sol-gel method. Also, the influence of aging temperature on formation of FHA powder was studied. Equimolar solutions of calcium nitrate tetrahydrate, triethyl phosphite and ammonium fluoride in ethanol were used as Ca, P and F precursors. After aging at different temperatures, the synthesized powders were heat treated at 550 degrees C. The powders were investigated with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), selected area electron diffraction pattern (SAED), energy dispersive analysis of X-ray (EDAX) and zetasizer measurement. The results of XRD proved the presence of fluorapatite (FA) and HA in all samples. In addition, the formation of FHA was confirmed by FT-IR results. XRD studies also showed that the crystallites were in nanometric scale. At the same time, this result was in good agreement with the result of zetasizer analysis.

Manipulation of partially oriented hydroxyapatite building blocks to form flowerlike bundles without acid-base regulation.

PubMed

Wen, Zhenliang; Wang, Zihao; Chen, Jingdi; Zhong, Shengnan; Hu, Yimin; Wang, Jianhua; Zhang, Qiqing

2016-06-01

The application of hydroxyapatite (HAP) in different fields depends greatly on its morphology, composition and structure. Besides, the main inorganic building blocks of human bones and teeth are also HAP. Therefore, accurate shape and aggregation control and of hydroxyapatite particles will be of great interest. Herein, oriented bundles of flowerlike HAP nanorods were successfully prepared through hydrothermal treatment without acid-base regulation, with the mono-alkyl phosphate (MAP) and sodium citrate as surfactant and chelating agent, respectively. The prepared samples were characterized by the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and zeta potential, the pH value and conductivity value of suspension were characterized by pH meter and conductivity measurement. The results showed that the MAP and citrate play an important role in assembly of HAP nanorods without acid-base regulation. Citrate calcium complex could decompose slowly and release citrate ions at hydrothermal conditions. Besides, the further decomposition of citrate ions could release aconitic acid as the reaction time prolongs. Moreover, the possible scheme for the formation process was discussed in detail. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of Physical-chemical and Mechanical Properties of Chlorapatite and Hydroxyapatite Plasma Sprayed Coatings

PubMed Central

Demnati, Imane; Grossin, David; Marsan, Olivier; Bertrand, Ghislaine; Collonges, Gérard; Combes, Christèle; Parco, Maria; Braceras, Inigo; Alexis, Joel; Balcaen, Yannick; Rey, Christian

2015-01-01

Chlorapatite can be considered a potential biomaterial for orthopaedic applications. Its use as plasma-sprayed coating could be of interest considering its thermal properties and particularly its ability to melt without decomposition unlike hydroxyapatite. Chlorapatite (ClA) was synthesized by a high-temperature ion exchange reaction starting from commercial stoichiometric hydroxyapatites (HA). The ClA powder showed similar characteristics as the original industrial HA powder, and was obtained in the monoclinic form. The HA and ClA powders were plasma-sprayed using a low-energy plasma spraying system with identical processing parameters. The coatings were characterized by physical-chemical methods, i.e. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy, including distribution mapping of the main phases detected such as amorphous calcium phosphate (ACP), oxyapatite (OA), and HA or ClA. The unexpected formation of oxyapatite in ClA coatings was assigned to a side reaction with contaminating oxygenated species (O2, H2O). ClA coatings exhibited characteristics different from HA, showing a lower content of oxyapatite and amorphous phase. Although their adhesion strength was found to be lower than that of HA coatings, their application could be an interesting alternative, offering, in particular, a larger range of spraying conditions without formation of massive impurities. PMID:25893015

TSDC and impedance spectroscopy measurements on hydroxyapatite, β-tricalcium phosphate and hydroxyapatite/β-tricalcium phosphate biphasic bioceramics

NASA Astrophysics Data System (ADS)

Prezas, P. R.; Melo, B. M. G.; Costa, L. C.; Valente, M. A.; Lança, M. C.; Ventura, J. M. G.; Pinto, L. F. V.; Graça, M. P. F.

2017-12-01

Bone grafting and surgical interventions related with orthopaedic disorders consist in a big business, generating large revenues worldwide every year. There is a need to replace the biomaterials that currently still dominate this market, i.e., autografts and allografts, due to their disadvantages, such as limited availability, need for additional surgeries and diseases transmission possibilities. The most promising replacement materials are biomaterials with bioactive properties, such as the calcium phosphate-based bioceramics group. The bioactivity of these materials, i.e., the rate at which they promote the growth and directly bond with the new host biological bone, can be enhanced through their electrical polarization. In the present work, the electrical polarization features of pure hydroxyapatite (Hap), pure β-tricalcium phosphate (β-TCP) and biphasic hydroxyapatite/β-tricalcium phosphate composites (HTCP) were analyzed by measuring thermally stimulated depolarization currents (TSDC). The samples were thermoelectrically polarized at 500 °C under a DC electric field with a magnitude of 5 kV/cm. The biphasic samples were also polarized under electric fields with different magnitudes: 2, 3, 4 and 5 kV/cm. Additionally, the depolarization processes detected in the TSDC measurements were correlated with dielectric relaxation processes observed in impedance spectroscopy (IS) measurements. The results indicate that the β-TCP crystalline phase has a considerable higher ability to store electrical charge compared with the Hap phase. This indicates that it has a suitable composition and structure for ionic conduction and establishment of a large electric charge density, providing great potential for orthopaedic applications.

Recent Developments in Suspension Plasma Sprayed Titanium Oxide and Hydroxyapatite Coatings

NASA Astrophysics Data System (ADS)

Jaworski, R.; Pawlowski, L.; Pierlot, C.; Roudet, F.; Kozerski, S.; Petit, F.

2010-01-01

The paper aims at reviewing of the recent studies related to the development of suspension plasma sprayed TiO2 and Ca5(PO4)3OH (hydroxyapatite, HA) coatings as well as their multilayer composites obtained onto stainless steel, titanium and aluminum substrates. The total thickness of the coatings was in the range 10 to 150 μm. The suspensions on the base of distilled water, ethanol and their mixtures were formulated with the use of fine commercial TiO2 pigment crystallized as rutile and HA milled from commercial spray-dried powder or synthesized from calcium nitrate and ammonium phosphate in an optimized reaction. The powder was crystallized as hydroxyapatite. Pneumatic and peristaltic pump liquid feeders were applied. The injection of suspension to the plasma jet was studied carefully with the use of an atomizer injector or a continuous stream one. The injectors were placed outside or inside of the anode-nozzle of the SG-100 plasma torch. The stream of liquid was tested under angle right or slightly backwards with regard to the torch axis. The sprayed deposits were submitted to the phase analysis by the use of x-ray diffraction. The content of anatase and rutile was calculated in the titanium oxide deposits as well as the content of the decomposition phases in the hydroxyapatite ones. The micro-Raman spectroscopy was used to visualize the area of appearance of some phases. Scratch test enabled to characterize the adhesion of the deposits, their microhardness and friction coefficient. The electric properties including electron emission, impedance spectroscopy, and dielectric properties of some coatings were equally tested.

Synergistic Effect of Hydrotrope and Surfactant on Solubility and Dissolution of Atorvastatin Calcium: Screening Factorial Design Followed by Ratio Optimization

PubMed Central

Patel, V. F.; Sarai, J.

2014-01-01

The present study was aimed at investigating the effect of hydrotrope and surfactant on poor solubility of atorvastatin calcium. Excipients screening followed by factorial design was performed to study effect of excipients and manufacturing methods on solubility of drug. Three independent factors (carrier, surfactant and manufacturing method) were evaluated at two levels using solubility as a dependant variable. Solid-state characterisation was performed using Fourier transform infrared spectroscopy and differential scanning calorimetry. Optimised complex were incorporated into orally disintegrating micro tablets and in vitro dissolution test was performed. Nicotinamide, Plasdone and sodium dodecyl sulphate were emerged as promising excipients from excipient screening. General regression analysis revealed only the type of carrier has significantly enhanced (P<0.05) the solubility of drug while other factors were found to be nonsignificant. Ratio optimisation trial revealed that drug to nicotinamide ratio is more critical in enhancing the solubility of drug (40 fold increases in solubility compared to pure drug) in comparison to drug-surfactant ratio; however the presence of surfactant deemed essential. Significantly higher rate and extent of dissolution was observed from solid dispersion complex and tablets compared to dissolution of pure drug (P<0.05). Study revealed hydrotrope and surfactant have synergistic effect on solubility and dissolution of atorvastatin calcium and this can be explored further. PMID:25593381

[Symptomatic hypocalcaemia on denosumab use].

PubMed

Baptista Lopes, Vania; Robbrecht, Debbie; van Thiel, Sjoerd; van Guldener, Coen

2013-01-01

Bone resorption inhibitors such as denosumab may induce symptomatic hypocalcaemia if a vitamin D deficiency is present. Amongst other causes, this type of deficiency may arise following bariatric surgery. We describe a 51-year-old woman who, a few years after undergoing bariatric surgery, developed symptomatic hypocalcaemia after she started taking denosumab. An adequate calcium and vitamin D status is a general condition before prescribing medication to treat osteoporosis. Therefore we recommend that before starting treatment with a bone resorption inhibitor that not only the calcium but also the vitamin D status should be determined, and if necessary, optimised.

Femur-bending properties as influenced by gravity. V - Strength vs. calcium and gravity in rats exposed for 2 weeks

NASA Technical Reports Server (NTRS)

Wunder, Charles C.; Cook, Kenneth M.; Watkins, Stanley R.; Moressi, William J.

1987-01-01

The dependence of gravitationally related changes in femur bone strength on the comparable changes in calcium content was investigated in rats exposed to chronic simulations of altered gravity from the 28th to 42nd day of age. Zero G was simulated by harness suspension and 3 G by centrifugation. Bone strength (S) was determined by bending (using modified quasi-static cantilever bending methods and equipment described by Wunder et al., 1977 and 1979) and Ca content (C, by mass pct) determined by atomic absorption spectrometry; results were compared with data obtained on both normal and harnessed control animals at 1 G. Multiple regression showed significant dependence of S upon earth's gravity, independent from C, for which there was no significant coefficient of partial regression. It is suggested that the lack of S/C correlation might have been due to the fact that considerable fraction of the calcium in these young, developing bones has not yet crystallized into the hydroxyapatite which provides strength.

Ultrastructural and elemental analysis of sialoliths and their comparison with nephroliths.

PubMed

Rakesh, Nagaraju; Bhoomareddy Kantharaj, Yashoda Devi; Agarwal, Manjushree; Agarwal, Kunal

2014-02-01

Sialoliths are common in the submandibular gland and its duct system, although their exact cause of formation is still a matter of debate. The aims of this study were to: (a) analyze sialoliths ultrastructurally, and to determine the role of foreign bodies or organic materials in the formation of sialolith nuclei; and (b) compare nephroliths with sialoliths ultrastructurally. Three sialoliths and two nephroliths were analyzed ultrastructurally by a scanning electron microscope and X-ray diffractometer. The main structures of the sialoliths were found to be hydroxyapatite crystals. No organic cores were observed in the central parts of the sialoliths. In nephroliths, calcium oxalate, calcium phosphate, and struvite crystals were found. The energy-dispersive X-ray microanalysis found that sialoliths and nephroliths were predominantly composed of elements comprising calcium, phosphorous, magnesium, sodium, chloride, silicon, iron, and potassium. Sialoliths in the submandibular salivary glands might form secondary to sialadenitis, but not via a luminal organic nidus. © 2014 Wiley Publishing Asia Pty Ltd.

Tailoring the structure of biphasic calcium phosphate via synthesis procedure

NASA Astrophysics Data System (ADS)

Mansour, S. F.; El-dek, S. I.; Ahmed, M. K.

2017-12-01

Nano calcium phosphate ceramics (CaPC) were synthesized using simple co-precipitation method at different preparation conditions. The selected Ca/P ratio with a variation of pH value lead to formation of dicalcium phosphate dihydrate (DCPD) at pH 5 and 6 while, hydroxyapatite (HAP) nano particles were formed at pH 9 and 12 at room temperature. The crystallite size was in the range of 15-55 nm depending on the obtained crystalline phase. The study displayed variation of decomposition depending on the annealing temperature. The significant note is the different transformation trend of each phase depending on the starting pH value. The HRTEM illustrated that the DCPD phase was formed as fibers with diameter around 4-6 nm, while HAP was formed in rod shape. The aspect ratio decreased from 6.6 at pH 9 to 4 at pH 12 which refer to the great influence of pH value on the morphology of calcium phosphates.

Mesoscale crystallization of calcium phosphate nanostructures in protein (casein) micelles.

PubMed

Thachepan, Surachai; Li, Mei; Mann, Stephen

2010-11-01

Aqueous micelles of the multi-protein calcium phosphate complex, casein, were treated at 60°C and pH 7 over several months. Although partial dissociation of the micelles into 12 nm sized amorphous calcium phosphate (ACP)/protein nanoparticles occurred within a period of 14 days, crystallization of the ACP nanoclusters into bundles of hydroxyapatite (HAP) nanofilaments was not observed until after 12 weeks. The HAP nanofilaments were formed specifically within the partially disrupted protein micelles suggesting a micelle-mediated pathway of mesoscale crystallization. Similar experiments using ACP-containing synthetic micelles prepared from ß-casein protein alone indicated that co-aligned bundles of HAP nanofilaments were produced within the protein micelle interior after 24 hours at temperatures as low as 35°C. The presence of Mg²(+) ions in the casein micelles, as well as a possible synergistic effect associated with the multi-protein nature of the native aggregates, could account for the marked inhibition in mesoscale crystallization observed in the casein micelles compared with the single-component b-casein constructs.

Covalent attachment of a bioactive hyperbranched polymeric layer to titanium surface for the biomimetic growth of calcium phosphates

PubMed Central

Tsiourvas, D.; Arkas, M.; Diplas, S.; Mastrogianni, E.

2010-01-01

This work is investigating the chemical grafting on Ti surface of a polymer/calcium phosphate coating of improved adhesion for enhanced bioactivity. For this purpose, a whole new methodology was developed based on covalently attaching a hyperbranched poly(ethylene imine) layer on Ti surface able to promote calcium phosphate formation in a next deposition stage. This was achieved through an intermediate surface silanization step. The research included optimization both of the reaction conditions for covalently grafting the intermediate organosilicon and the subsequent hyperbranched poly(ethylene imine) layers, as well as of the conditions for the mechanical and chemical pretreatment of Ti surface before coating. The reaction steps were monitored employing FTIR and XPS analyses, whereas the surface morphology and structure of the successive coating layers were studied by SEM combined with EDS. The analysis confirmed the successful grafting of the hybrid layer which demonstrated very good ability for hydroxyapatite growth in simulated body fluid. PMID:21069559

Mechanical properties of calcium phosphate scaffolds fabricated by robocasting.

PubMed

Miranda, Pedro; Pajares, Antonia; Saiz, Eduardo; Tomsia, Antoni P; Guiberteau, Fernando

2008-04-01

The mechanical behavior under compressive stresses of beta-tricalcium phosphate (beta-TCP) and hydroxyapatite (HA) scaffolds fabricated by direct-write assembly (robocasting) technique is analyzed. Concentrated colloidal inks prepared from beta-TCP and HA commercial powders were used to fabricate porous structures consisting of a 3-D tetragonal mesh of interpenetrating ceramic rods. The compressive strength and elastic modulus of these model scaffolds were determined by uniaxial testing to compare the relative performance of the selected materials. The effect of a 3-week immersion in simulated body fluid (SBF) on the strength of the scaffolds was also analyzed. The results are compared with those reported in the literature for calcium phosphate scaffolds and human bone. The robocast calcium phosphate scaffolds were found to exhibit excellent mechanical performances in terms of strength, especially the HA structures after SBF immersion, indicating a great potential of this type of scaffolds for use in load-bearing bone tissue engineering applications. Copyright 2007 Wiley Periodicals, Inc.

Covalent attachment of a bioactive hyperbranched polymeric layer to titanium surface for the biomimetic growth of calcium phosphates.

PubMed

Tsiourvas, D; Tsetsekou, A; Arkas, M; Diplas, S; Mastrogianni, E

2011-01-01

This work is investigating the chemical grafting on Ti surface of a polymer/calcium phosphate coating of improved adhesion for enhanced bioactivity. For this purpose, a whole new methodology was developed based on covalently attaching a hyperbranched poly(ethylene imine) layer on Ti surface able to promote calcium phosphate formation in a next deposition stage. This was achieved through an intermediate surface silanization step. The research included optimization both of the reaction conditions for covalently grafting the intermediate organosilicon and the subsequent hyperbranched poly(ethylene imine) layers, as well as of the conditions for the mechanical and chemical pretreatment of Ti surface before coating. The reaction steps were monitored employing FTIR and XPS analyses, whereas the surface morphology and structure of the successive coating layers were studied by SEM combined with EDS. The analysis confirmed the successful grafting of the hybrid layer which demonstrated very good ability for hydroxyapatite growth in simulated body fluid.

A construction of novel iron-foam-based calcium phosphate/chitosan coating biodegradable scaffold material.

PubMed

Wen, Zhaohui; Zhang, Liming; Chen, Chao; Liu, Yibo; Wu, Changjun; Dai, Changsong

2013-04-01

Slow corrosion rate and poor bioactivity restrict iron-based implants in biomedical application. In this study, we design a new iron-foam-based calcium phosphate/chitosan coating biodegradable composites offering a priority mechanical and bioactive property for bone tissue engineering through electrophoretic deposition (EPD) followed by a conversion process into a phosphate buffer solution (PBS). Tensile test results showed that the mechanical property of iron foam could be regulated through altering the construction of polyurethane foam. The priority coatings were deposited from 40% nano hydroxyapatite (nHA)/ethanol suspension mixed with 60% nHA/chitosan-acetic acid aqueous solution. In vitro immersion test showed that oxidation-iron foam as the matrix decreased the amount of iron implanted and had not influence on the bioactivity of this implant, obviously. So, this method could also be a promising method for the preparation of a new calcium phosphate/chitosan coating on foam construction. Copyright © 2012. Published by Elsevier B.V.

Mineralization and biocompatibility of Antheraea pernyi (A. pernyi) silk sericin film for potential bone tissue engineering.

PubMed

Yang, Mingying; Mandal, Namita; Shuai, Yajun; Zhou, Guanshan; Min, Sijia; Zhu, Liangjun

2014-01-01

This study aimed to investigate the mineralization of Antheraea pernyi (A. pernyi) silk sericin. Mineralization of A. pernyi sericin was performed by alternative soaking in calcium and phosphate. The inhibition of precipitation of calcium carbonate and von Kossa staining on A. pernyi sericin were tested, and the corresponding results prove that A. pernyi sericin has Ca binding activity. Scanning electron microscope (SEM) observation shows that spherical crystals could be nucleated on the A. pernyi sericin film. These crystals were confirmed to be hydroxyapatite according to FT-IR and XRD spectra, indicating that A. pernyi sericin is capable of mineralization. In addition, cell adhesion and growth activity assay demonstrate that A. pernyi sericin shows excellent biocompatibility for the growth of MG-63 cells.

Characterisation of a novel transmission Raman spectroscopy platform for non-invasive detection of breast micro-calcifications

NASA Astrophysics Data System (ADS)

Ghita, Adrian; Matousek, Pavel; Stone, Nick

2018-02-01

Our work focuses on the development of a medical Raman spectroscopy based platform to non-invasively detect and determine in-vivo molecular information deep inside biological tissues by monitoring the chemical composition of breast calcifications. The ultimate goal is to replace a needle biopsy which typically follows the detection of an abnormality in mammographic images. Here we report the non-invasive detection of calcium oxalate monohydrate in tissue through 40 mm of phantom tissues using our recently developed advanced Raman instrument complementing our previous detection of calcium hydroxyapatite through this thickness of tissue. The ability to detect these two key types of calcifications opens avenues for the development of non-invasive in-vivo breast cancer diagnostic tool in the future.

Effect of Mg2+ on acidic calcium phosphate phases grown by electrodeposition

NASA Astrophysics Data System (ADS)

Correia, Matheus Bento; Júnior, José Pedro Gualberto; Macedo, Michelle Cardinale S. S.; Resende, Cristiane Xavier; dos Santos, Euler Araujo

2017-10-01

In this work, the effect of Mg2+ ions on the electrodeposition of dicalcium phosphate dihydrate (DCPD), octacalcium phosphate (OCP) and calcium-deficient hydroxyapatite (CDHA) crystals on a commercially pure titanium (cp-Ti) substrate was evaluated. We demonstrated that Mg2+ ions could change the morphology of the coatings by inhibiting the growth rate of the OCP and CDHA crystals and diminishing the crystallite size of DCPD. The inhibition effect on OCP and CDHA was most likely due to a surface adsorption mechanism since no evidence of a doping process was observed using Rietveld refinement and electron diffraction analyses. Conversely, the presence of Mg2+ ions generated a favorable condition for the nucleation of a new Mg2+-rich DCPD crystal population, presenting smaller crystallite sizes.

Rietveld Refinement on X-Ray Diffraction Patterns of Bioapatite in Human Fetal Bones

PubMed Central

Meneghini, Carlo; Dalconi, Maria Chiara; Nuzzo, Stefania; Mobilio, Settimio; Wenk, Rudy H.

2003-01-01

Bioapatite, the main constituent of mineralized tissue in mammalian bones, is a calcium-phosphate-based mineral that is similar in structure and composition to hydroxyapatite. In this work, the crystallographic structure of bioapatite in human fetuses was investigated by synchrotron radiation x-ray diffraction (XRD) and microdiffraction (μ-XRD) techniques. Rietveld refinement analyses of XRD and μ-XRD data allow for quantitative probing of the structural modifications of bioapatite as functions of the mineralization process and gestational age. PMID:12609904

Studies of the Ossicles from the Ciliate Protozoan Spirostomum ambiguum

NASA Astrophysics Data System (ADS)

Takagui, Regina; Silveira, Marina

1999-09-01

Spirostomum ambiguum is able to concentrate intracellular deposits of calcium phosphate. This mineralization process is dependent on the age of the culture and can be stimulated by an applied piezoelectric potential. Crystalline deposits induced to form in laboratory cultures were analysed both in situ and after isolation from the cells, using transmission and scanning electron microscopies, energy dispersive microanalysis, and optical spectrophotometry. The ratio of Ca:P (1.57±0.01) fits with the expected value for hydroxyapatite.

Scaffolds with a standardized macro-architecture fabricated from several calcium phosphate ceramics using an indirect rapid prototyping technique

PubMed Central

Wilson, C. E.; van Blitterswijk, C. A.; Verbout, A. J.; de Bruijn, J. D.

2010-01-01

Calcium phosphate ceramics, commonly applied as bone graft substitutes, are a natural choice of scaffolding material for bone tissue engineering. Evidence shows that the chemical composition, macroporosity and microporosity of these ceramics influences their behavior as bone graft substitutes and bone tissue engineering scaffolds but little has been done to optimize these parameters. One method of optimization is to place focus on a particular parameter by normalizing the influence, as much as possible, of confounding parameters. This is difficult to accomplish with traditional fabrication techniques. In this study we describe a design based rapid prototyping method of manufacturing scaffolds with virtually identical macroporous architectures from different calcium phosphate ceramic compositions. Beta-tricalcium phosphate, hydroxyapatite (at two sintering temperatures) and biphasic calcium phosphate scaffolds were manufactured. The macro- and micro-architectures of the scaffolds were characterized as well as the influence of the manufacturing method on the chemistries of the calcium phosphate compositions. The structural characteristics of the resulting scaffolds were remarkably similar. The manufacturing process had little influence on the composition of the materials except for the consistent but small addition of, or increase in, a beta-tricalcium phosphate phase. Among other applications, scaffolds produced by the method described provide a means of examining the influence of different calcium phosphate compositions while confidently excluding the influence of the macroporous structure of the scaffolds. PMID:21069558

Mesoscale crystallization of calcium phosphate nanostructures in protein (casein) micelles

NASA Astrophysics Data System (ADS)

Thachepan, Surachai; Li, Mei; Mann, Stephen

2010-11-01

Aqueous micelles of the multi-protein calcium phosphate complex, casein, were treated at 60 °C and pH 7 over several months. Although partial dissociation of the micelles into 12 nm sized amorphous calcium phosphate (ACP)/protein nanoparticles occurred within a period of 14 days, crystallization of the ACP nanoclusters into bundles of hydroxyapatite (HAP) nanofilaments was not observed until after 12 weeks. The HAP nanofilaments were formed specifically within the partially disrupted protein micelles suggesting a micelle-mediated pathway of mesoscale crystallization. Similar experiments using ACP-containing synthetic micelles prepared from β-casein protein alone indicated that co-aligned bundles of HAP nanofilaments were produced within the protein micelle interior after 24 hours at temperatures as low as 35 °C. The presence of Mg2+ ions in the casein micelles, as well as a possible synergistic effect associated with the multi-protein nature of the native aggregates, could account for the marked inhibition in mesoscale crystallization observed in the casein micelles compared with the single-component β-casein constructs.Aqueous micelles of the multi-protein calcium phosphate complex, casein, were treated at 60 °C and pH 7 over several months. Although partial dissociation of the micelles into 12 nm sized amorphous calcium phosphate (ACP)/protein nanoparticles occurred within a period of 14 days, crystallization of the ACP nanoclusters into bundles of hydroxyapatite (HAP) nanofilaments was not observed until after 12 weeks. The HAP nanofilaments were formed specifically within the partially disrupted protein micelles suggesting a micelle-mediated pathway of mesoscale crystallization. Similar experiments using ACP-containing synthetic micelles prepared from β-casein protein alone indicated that co-aligned bundles of HAP nanofilaments were produced within the protein micelle interior after 24 hours at temperatures as low as 35 °C. The presence of Mg2+ ions in the casein micelles, as well as a possible synergistic effect associated with the multi-protein nature of the native aggregates, could account for the marked inhibition in mesoscale crystallization observed in the casein micelles compared with the single-component β-casein constructs. Electronic supplementary information (ESI) available: Particle size histograms, TEM, EDX and electron diffraction data. See DOI: 10.1039/c0nr00158a

Application of a nuclear microprobe to the study of calcified tissues

NASA Astrophysics Data System (ADS)

Coote, Graeme E.; Vickridge, Ian C.

1988-03-01

The mineral fraction of calcified tissue is largely calcium hydroxyapatite (bones and teeth) or calcium carbonate (shells and fish otoliths). Apatite has such a strong affinity for fluoride ions that the F/Ca ratio can vary markedly with position in a bone or tooth, depending on the amount of fluoride present at the time of calcification or partial recrystallization. New biological information can be obtained by introducing extra fluoride into the diet of an animal and using a microprobe later to scan sections of bones or teeth. In suitable burial sites extra fluoride is introduced after death, and the new distribution may have applications in forensic science and archaeology. Fish otoliths are also of interest since a new carbonate layer is formed each day and the distribution of trace elements may record some aspects of the fish's life history. Results from the following studies are presented: fluorine distributions in the teeth of sheep which ingested extra fluoride for known periods; distributions of calcium and fluorine in femurs of rats which drank water high in fluoride for periods from 2 to 15 weeks; calcium and fluorine distributions in artificially-prepared lesions in tooth enamel; diffusion profiles in archaeological human teeth and animal bones; patterns in the strontium/calcium ratio in sectioned otoliths of several species of fish.

Measurement of the efficacy of calcium silicate for the protection and repair of dental enamel.

PubMed

Parker, Alexander S; Patel, Anisha N; Al Botros, Rehab; Snowden, Michael E; McKelvey, Kim; Unwin, Patrick R; Ashcroft, Alexander T; Carvell, Mel; Joiner, Andrew; Peruffo, Massimo

2014-06-01

To investigate the formation of hydroxyapatite (HAP) from calcium silicate and the deposition of calcium silicate onto sound and acid eroded enamel surfaces in order to investigate its repair and protective properties. Calcium silicate was mixed with phosphate buffer for seven days and the resulting solids analysed for crystalline phases by Raman spectroscopy. Deposition studies were conducted on bovine enamel surfaces. Acid etched regions were produced on the enamel surfaces using scanning electrochemical cell microscopy (SECCM) with acid filled pipettes and varying contact times. Following treatment with calcium silicate, the deposition was visualised with FE-SEM and etch pit volumes were measured by AFM. A second set of bovine enamel specimens were pre-treated with calcium silicate and fluoride, before acid exposure with the SECCM. The volumes of the resultant acid etched pits were measured using AFM and the intrinsic rate constant for calcium loss was calculated. Raman spectroscopy confirmed that HAP was formed from calcium silicate. Deposition studies demonstrated greater delivery of calcium silicate to acid eroded than sound enamel and that the volume of acid etched enamel pits was significantly reduced following one treatment (p<0.05). In the protection study, the intrinsic rate constant for calcium loss from enamel was 0.092 ± 0.008 cm/s. This was significantly reduced, 0.056 ± 0.005 cm/s, for the calcium silicate treatments (p<0.0001). Calcium silicate can transform into HAP and can be deposited on acid eroded and sound enamel surfaces. Calcium silicate can provide significant protection of sound enamel from acid challenges. Calcium silicate is a material that has potential for a new approach to the repair of demineralised enamel and the protection of enamel from acid attacks, leading to significant dental hard tissue benefits. © 2014 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yusoff, Yusriha Mohd; Salimi, Midhat Nabil Ahmad; Anuar, Adilah

Many studies have been carried out in order to prepare hydroxyapatite (HAp) by various methods. In this study, we focused on the preparation of HAp nanoparticles by using sol-gel technique in which few parameters are optimized which were stirring rate, aging time and sintering temperature. HAp nanoparticles were prepared by using precursors of calcium nitrate tetrahydrate, Ca(NO{sub 3}){sub 2}.4H{sub 2}O and phosphorous pentoxide, P{sub 2}O{sub 5}. Both precursors are mixed in ethanol respectively before they were mixed together in which it formed a stable sol. Fourier transform infrared (FTIR), X-ray diffraction (XRD) and Scanning electron microscopy (SEM) were used formore » its characterization in terms of functional group, phase composition, crystallite size and morphology of the nanoparticles produced. FTIR spectra showed that the functional groups that present in all five samples were corresponding to the formation of HAp. Besides, XRD shows that only one phase was formed which was hydroxyapatite. Meanwhile, SEM shows that the small particles combine together to form agglomeration.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lytkina, D. N., E-mail: darya-lytkina@yandex.ru; Shapovalova, Y. G., E-mail: elena.shapovalova@ro.ru; Rasskazova, L. A., E-mail: ly-2207@mail.ru

Relevance of the work is due to the need for new materials that are used in medicine (orthopedics, surgery, dentistry, and others) as a substitute for natural bone tissue injuries, fractures, etc. The aim of presented work is developing of a method of producing biocompatible materials based on polyesters of hydroxycarboxylic acids and calcium phosphate ceramic (hydroxyapatite, HA) with homogeneous distribution of the inorganic component. Bioactive composites based on poly-L-lactide (PL) and hydroxyapatite with homogeneous distribution were prepared. The results of scanning electron microscopy confirm homogeneous distribution of the inorganic filler in the polymer matrix. The positive effect of ultrasoundmore » on the homogeneity of the composites was determined. The rate of hydrolysis of composites was evaluated. The rate of hydrolysis of polylactide as an individual substance is 7 times lower than the rate of hydrolysis of the polylactide as a part of the composite. It was found that materials submarines HA composite and do not cause a negative response in the cells of the immune system, while contributing to anti-inflammatory cytokines released by cells.« less

Synthesis of alginate bioencapsulated nano-hydroxyapatite composite for selective fluoride sorption.

PubMed

Pandi, Kalimuthu; Viswanathan, Natrayasamy

2014-11-04

This article focuses on the development of eco-friendly adsorbent by alginate (Alg) bioencapsulating nano-hydroxyapatite (n-HAp) namely n-HApAlg composite for defluoridation studies in batch mode. n-HAp powder utilized as a promising defluoridating material, but it causes a significant pressure drop during field applications. To overcome such technological bottlenecks, n-HApAlg composite was synthesized. The defluoridation capacity (DC) of synthesized n-HApAlg composite possesses an enhanced DC of 3870 mg F(-)/kg when compared to n-HAp and calcium alginate (CaAlg) composite which possess DC of 1296 and 680 mg F(-)/kg, respectively. The biocomposite features were characterized using FTIR and SEM with EDAX analysis. The various adsorption influencing parameters like contact time, pH, co-anions, initial fluoride concentration and temperature were optimized. The adsorption process was enlightened by various isotherms and kinetic models. The suitability of the biocomposite at field conditions was also tested. Copyright © 2014 Elsevier Ltd. All rights reserved.

Bioglass: A novel biocompatible innovation.

PubMed

Krishnan, Vidya; Lakshmi, T

2013-04-01

Advancement of materials technology has been immense, especially in the past 30 years. Ceramics has not been new to dentistry. Porcelain crowns, silica fillers in composite resins, and glass ionomer cements have already been proved to be successful. Materials used in the replacement of tissues have come a long way from being inert, to compatible, and now regenerative. When hydroxyapatite was believed to be the best biocompatible replacement material, Larry Hench developed a material using silica (glass) as the host material, incorporated with calcium and phosphorous to fuse broken bones. This material mimics bone material and stimulates the regrowth of new bone material. Thus, due to its biocompatibility and osteogenic capacity it came to be known as "bioactive glass-bioglass." It is now encompassed, along with synthetic hydroxyapatite, in the field of biomaterials science known as "bioactive ceramics." The aim of this article is to give a bird's-eye view, of the various uses in dentistry, of this novel, miracle material which can bond, induce osteogenesis, and also regenerate bone.

Microwave-induced biomimetic approach for hydroxyapatite coatings of chitosan scaffolds.

PubMed

Kaynak Bayrak, Gökçe; Demirtaş, T Tolga; Gümüşderelioğlu, Menemşe

2017-02-10

Simulated body fluid (SBF) can form calcium phosphates on osteoinductive materials, so it is widely used for coating of bone scaffolds to mimic natural extracellular matrix (ECM). However, difficulties of bulk coating in 3D scaffolds and the necessity of long process times are the common problems for coating with SBF. In the present study, a microwave-assisted process was developed for rapid and internal coating of chitosan scaffolds. The scaffolds were fabricated as superporous hydrogel (SPH) by combining microwave irradiation and gas foaming methods. Then, they were immersed into 10x  SBF-like solution and homogenous bone-like hydroxyapatite (HA) coating was achieved by microwave treatment at 600W without the need of any nucleating agent. Cell culture studies with MC3T3-E1 preosteoblasts showed that microwave-assisted biomimetic HA coating process could be evaluated as an efficient and rapid method to obtain composite scaffolds for bone tissue engineering. Copyright © 2016 Elsevier Ltd. All rights reserved.

Self-assembled structures of hydroxyapatite in the biomimetic coating on a bioinert ceramic substrate.

PubMed

Chakraborty, Jui; Sarkar, Soumi Dey; Chatterjee, Saradiya; Sinha, Mithlesh Kumar; Basu, Debabrata

2008-10-15

The tribological properties of alumina ceramic are excellent due in part to a high wettability because of the hydrophilic surface and fluid film lubrication that minimizes the adhesive wear. Such surfaces are further modified with bioactive glass/ceramic coating to promote direct bone apposition in orthopedic applications. The present communication reports the biomimetic coating of calcium hydroxyapatite (HAp) on dense (2-3% porosity) alumina (alpha-Al(2)O(3)) substrate (1cm x 1cm x 0.5 cm), at 37 degrees C. After a total period of 6 days immersion in simulated body fluid (SBF), at 37 degrees C, linear self-assembled porous (pore size: approximately 0.2 microm) structures (length: approximately 375.39 microm and width: 5-6 microm) of HAp were obtained. The phenomenon has been demonstrated by self-assembly and diffusion-limited aggregation (DLA) principles. Structural and compositional characterization of the coating was carried out using SEM with EDX facility, XRD and FT-IR data.

Long wavelength identification of microcalcifications in breast cancer tissue using a quantum cascade laser and upconversion detection

NASA Astrophysics Data System (ADS)

Tseng, Y. P.; Bouzy, P.; Stone, N.; Pedersen, C.; Tidemand-Lichtenberg, P.

2018-02-01

Spectral imaging in the long-wave infrared regime has great potential for medical diagnostics. Breast cancer is the most common cancer amongst females in the US. The pathological features and the occurrence of the microcalcifications are still poorly understood. However, two types of microcalcifications have been identified as unique biomarkers: type I consisting of calcium oxalate (benign lesions) and type II composed of hydroxyapatite (benign or invasive lesions). In this study, we propose a new approach based on vibrational spectroscopy that is non-destructive, label-free and chemically specific for breast cancer detection. Long-wave infrared spectroscopy combining quantum cascade lasers (QCL) and upconversion detection, offer to improve signal-to-noise ratios compared to standard long-wave infrared spectroscopy. We demonstrated long-wave identification of synthetic samples of carbonated hydroxyapatite and of microcalcification in breast cancer tissue using upconversion detection. Absorbance spectra and upconverted images of in situ breast cancer biopsy are compared with that of Fourier-transform infrared (FTIR) spectroscopy.

Influence of Magnesium Ion Substitution on Structural and Thermal Behavior of Nanodimensional Hydroxyapatite

NASA Astrophysics Data System (ADS)

Batra, Uma; Kapoor, Seema; Sharma, Sonia

2013-06-01

Hydroxyapatite (HA), incorporating small amount of magnesium, shows attractive biological performance in terms of improved bone metabolism, osteoblast and osteoclast activity, and bone in-growth. This article reports a systematic investigation on the influence of magnesium (Mg) substitution on structural and thermal behavior of nanodimensional HA. HA and Mg-substituted HA nanopowders were synthesized through sol-gel route. The morphology and size of nanopowders were characterized by transmission electron microscopy. The BET surface area was evaluated from N2 adsorption isotherms. Structural analysis and thermal behavior were investigated by means of Fourier transform infrared spectroscopy, x-ray diffraction, thermogravimetry, and differential thermal analysis. As-synthesized powders consisted of flake-like agglomerates of HA and calcium-deficient HA. The incorporation of magnesium in HA resulted in decrease of crystallite size, crystallinity, and lattice parameters a and c and increase in BET surface area. β-tricalcium phosphate formation occured at lower calcination temperature in Mg-substituted HA than HA.

[Calcium kidney stones. Diagnostic and preventive prospects].

PubMed

Arcidiacono, T; Terranegra, A; Biasion, R; Soldati, L; Vezzoli, G

2007-01-01

Kidney stone disease is one of the main causes of hospitalization in Italy. Its prevalence increased in the last century and is probably still increasing. The pathogenesis of the disease is not known, although two main theories have been elaborated. The first hypothesizes that hydroxyapatite deposition in the interstitium of the renal papillae (Randall's plaque) precedes urinary calcium oxalate precipitation on the ulcered surface of the papilla to form a stone. The second presumes the tubular lumen of Bellini's duct to be the site where calcium-oxalate salts precipitate to form the nucleus for stone formation within the urinary tract. These pathogenetic processes may be favored by different dietary and genetic factors. The genes involved are not known, although many studies have been performed. Polymorphisms of genes coding for the vitamin D receptor, calcium-sensing receptor, interleukin-1 receptor antagonist, and urokinase were found to be associated with kidney stones, but these results have not been replicated. Different nutrients are suspected to predispose patients to calcium kidney stone disease. A high intake of animal proteins, sodium, vitamin C and oxalate has been implicated in stone formation, whereas calcium, alkalis and phytate may have a protective effect. The prevention of calcium stone formation is based on the recognition of risk factors like those already mentioned here. Furthermore, a family history of kidney stones may be useful in identifying subjects predisposed to become calcium stone formers. However, the expectations of the scientific community are turned to the advances in genetics and to the findings of genetic studies, which may provide diagnostic tools and criteria to define the risk profile of the single individual.

Surface Modification of Zirconia Substrate by Calcium Phosphate Particles Using Sol-Gel Method.

PubMed

Jin, So Dam; Um, Sang Cheol; Lee, Jong Kook

2015-08-01

Surface modification with a biphasic composition of hydroxyapatite (HA) and tricalcium phosphate (TCP) was performed on a zirconia substrate using a sol-gel method. An initial calcium phosphate sol was prepared by mixing a solution of Ca(NO3)2 · 4H20 and (C2H5O)3P(O), while both porous and dense zirconia were used as substrates. The sol-gel coating was performed using a spin coater. The coated porous zirconia substrate was re-sintered at 1350 °C 2 h, while coated dense zirconia substrate was heat-treated at 750 °C 1 h. The microstructure of the resultant HA/TCP coatings was found to be dependent on the type of zirconia substrate used. With porous zirconia as a starting substrate, numerous isolated calcium phosphate particles (TCP and HA) were uniformly dispersed on the surface, and the particle size and covered area were dependent on the viscosity of the calcium phosphate sol. Conversely, when dense zirconia was used as a starting substrate, a thick film of nano-sized HA particles was obtained after heat treatment, however, substantial agglomeration and cracking was also observed.

Intraosseous calcium migration in calcifying tendinitis: a rare cause of single sclerotic injury in the humeral head (2010: 2b).

PubMed

Martin, S; Rapariz, J M

2010-05-01

Intratendinous deposits of hydroxyapatite crystals are very common, particularly in the rotator cuff. In rare cases, the calcium located in the thickness of the supraspinatus tendon can suffer intraosseous migration into the greater tuberosity. We present a case of this rare entity: a 28-year-old patient who attended with pain and functional weakness in the left shoulder. The plain radiograph showed a sclerotic lesion in the greater tuberosity of the humeral head with a radiolucent halo. The MRI showed a lytic lesion containing the calcium inside and associated with an extensive pattern of oedema of the accompanying bone marrow. A plain radiograph taken 6 months before showed a calcifying tendinitis in the thickness of the supraspinatus tendon. A large number of entities can present as single sclerotic lesions of the humeral head. The diagnostic key lies in the existence of the calcifying tendinitis in the earlier study. The treatment of this disease consists of surgical removal of the calcium. The recognition of this entity is important to avoid unnecessary complementary tests and aggressive surgery, given that the surgical treatment is curative and leads to disappearance of the symptoms.

Reusing effluent of flue gas desulfurization wastewater treatment process as an economical calcium source for phosphorus removal.

PubMed

Dou, Weixiao; Zhou, Zhen; Ye, Jiongjiong; Huang, Rongwei; Jiang, Lu-Man; Chen, Guofeng; Fei, Xiaoyun

2017-09-01

Flue gas desulfurization (FGD) wastewater treatment by conventional neutralization, chemical precipitation and coagulation process removes most suspended solids and heavy metals, and provides an effluent rich in calcium, alkalinity and chloride, which obstructs its reclamation and reuse but is in favor of phosphorus (P) precipitation. The goals of this study were to investigate feasibility of reusing FGD effluent as a calcium source for P removal from P-rich wastewater. Results revealed that increasing the volumetric ratio between FGD effluent and P-rich wastewater achieved higher pH value and Ca/P ratio, and thus enhanced P removal efficiency to 94.3% at the ratio of 40%. X-ray diffraction and scanning electron microscope analysis of harvested precipitates showed that increasing pH from 8 to 10 induced the conversion of hydroxyapatite to tri-calcium phosphate, and then to whitlockite. This study demonstrated that for reusing FGD effluent for P removal was highly feasible, both technically and economically. This process not only saves the cost of precipitants for P removal, but also provides an economical alternative for current zero liquid discharge technology for FGD wastewater, which requires high energy consumption and capital costs.

The effect of crystal structure of TiO2 nanotubes on the formation of calcium phosphate coatings during biomimetic deposition

NASA Astrophysics Data System (ADS)

Liu, Yi; Kim, Sun; McLeod, John A.; Li, Jun; Guo, Xiaoxuan; Sham, Tsun-Kong; Liu, Lijia

2017-02-01

The crystallization process of bioactive calcium phosphate (CaP) species via biomimetic deposition onto anodic TiO2 nanotubes is investigated. The porous surface of nanostructured TiO2 provides an ideal substrate for CaP crystallization. The compositions of CaP coatings are studied using X-ray absorption near-edge structures (XANES) at the Ca K-edge. Using detection modes with different probing depths, both the surface of the CaP coating and the CaP-TiO2 interface are simultaneously analyzed. Calcium phosphate (CaP) species, such as hydroxyapatite (HAp), octacalcium phosphate (Ca8(HPO4)2(PO4)4·5H2O, OCP), brushite (CaHPO4·2H2O, DCPD), and amorphous calcium phosphate (ACP), are found in the CaP coatings. TiO2 nanotubes of amorphous and anatase phases are comparatively studied to determine their effect on the efficiency of CaP formation and the phase transformation among CaP species in prolonged deposition time. It is found the composition of CaP coating has a strong dependency on the crystal structure of TiO2 substrate and the kinetics (deposition time).

Formation and characterization of calcium orthophosphates in the presence of two different acidic macromolecules

NASA Astrophysics Data System (ADS)

Pelin, Irina M.; Maier, Vasilica; Suflet, Dana M.; Popescu, Irina; Darie-Nita, Raluca N.; Aflori, Magdalena; Butnaru, Maria

2017-10-01

The synthetic nanocrystalline calcium orthophosphates have a notable bioactivity due to the chemical similarity with biological apatite from calcified tissues. In mineralized tissues, the highly ordered structures come from organized assemblies of biomacromolecules and inorganic nanoparticles. One of the purposes of this work was to study the effect of two types of acidic macromolecules: atelocollagen and phosphorylated curdlan onto calcium orthophosphates formation after 30 days of maturation at 2 ± 2 °C. The resulted samples after a long aging time, either calcium orthophosphates or composites, were first investigated by FT-IR spectroscopy and X-ray diffractometry and the results indicated that precipitated hydroxyapatite with low crystallinity was obtained when the synthesis was performed in the presence of phosphorylated curdlan. The macromolecules influenced the morphology of the particles as shown by scanning and transmission electron microscopy. The presence of macromolecules as demonstrated by thermal investigation also influenced the rheological properties of the samples. The second purpose of the work was to evaluate the cytotoxicity of the samples using the MTT assay, and the results revealed very good cells viability. The preliminary results are encouraging regarding the use of these materials for further tests in order to develop injectable bone substitutes.

A novel strontium(II)-modified calcium phosphate bone cement stimulates human-bone-marrow-derived mesenchymal stem cell proliferation and osteogenic differentiation in vitro.

PubMed

Schumacher, M; Lode, A; Helth, A; Gelinsky, M

2013-12-01

In the present study, the in vitro effects of novel strontium-modified calcium phosphate bone cements (SrCPCs), prepared using two different approaches on human-bone-marrow-derived mesenchymal stem cells (hMSCs), were evaluated. Strontium ions, known to stimulate bone formation and therefore already used in systemic osteoporosis therapy, were incorporated into a hydroxyapatite-forming calcium phosphate bone cement via two simple approaches: incorporation of strontium carbonate crystals and substitution of Ca(2+) by Sr(2+) ions during cement setting. All modified cements released 0.03-0.07 mM Sr(2+) under in vitro conditions, concentrations that were shown not to impair the proliferation or osteogenic differentiation of hMSCs. Furthermore, strontium modification led to a reduced medium acidification and Ca(2+) depletion in comparison to the standard calcium phosphate cement. In indirect and direct cell culture experiments with the novel SrCPCs significantly enhanced cell proliferation and differentiation were observed. In conclusion, the SrCPCs described here could be beneficial for the local treatment of defects, especially in the osteoporotic bone. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Hydrothermal synthesis and characterization of Si and Sr co-substituted hydroxyapatite nanowires using strontium containing calcium silicate as precursors.

PubMed

Zhang, Na; Zhai, Dong; Chen, Lei; Zou, Zhaoyong; Lin, Kaili; Chang, Jiang

2014-04-01

In the absence of any organic surfactants and solvents, the silicon (Si) and strontium (Sr) co-substituted hydroxyapatite [Ca10(PO4)6(OH)2, Si/Sr-HAp] nanowires were synthesized via hydrothermal treatment of the Sr-containing calcium silicate (Sr-CS) powders as the precursors in trisodium phosphate (Na3PO4) aqueous solution. The morphology, phase, chemical compositions, lattice constants and the degradability of the products were characterized. The Si/Sr-HAp nanowires with diameter of about 60nm and up to 2μm in length were obtained after hydrothermal treatment of the Sr-CS precursors. The Sr and Si substitution amount of the HAp nanowires could be well regulated by facile tailoring the Sr substitution level of the precursors and the reaction ratio of the precursor/solution, respectively. The SiO4 tetrahedra and Sr(2+) ions occupied the crystal sites of the HAp, and the lattice constants increased apparently with the increase of the substitution amount. EDS mapping also suggested the uniform distribution of Si and Sr in the synthetic nanowires. Moreover, the Si/Sr-substitution apparently improved the degradability of the HAp materials. Our study suggested that the precursor transformation method provided a facile approach to synthesize the Si/Sr co-substituted HAp nanowires with controllable substitution amount, and the synthetic Si/Sr-HAp nanowires might be used as bioactive materials for hard tissue regeneration applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of the calcification of cardiac valve bioprostheses by environmental scanning electron microscopy and vibrational spectroscopy.

PubMed

Delogne, Christophe; Lawford, Patricia V; Habesch, Steven M; Carolan, Vikki A

2007-10-01

Bioprosthetic heart valve tissue and associated calcification were studied in their natural state, using environmental scanning electron microscopy (ESEM). Energy dispersive X-ray micro-analysis, X-ray diffraction, Fourier-transform infrared and Raman spectroscopy were used to characterize the various calcific deposits observed with ESEM. The major elements present in calcified valves were also analyzed by inductively coupled plasma-optical emission spectroscopy. To better understand the precursor formation of the calcific deposits, results from the elemental analyses were statistically correlated. ESEM revealed the presence of four broad types of calcium phosphate crystal morphology. In addition, two main patterns of organization of calcific deposits were observed associated with the collagen fibres. Energy dispersive X-ray micro-analysis identified the crystals observed by ESEM as salts containing mainly calcium and phosphate with ratios from 1.340 (possibly octacalcium phosphate, which has a Ca/P ratio of 1.336) to 2.045 (possibly hydroxyapatite with incorporation of carbonate and metal ion contaminants, such as silicon and magnesium, in the crystal lattice). Raman and fourier-transform infrared spectroscopy also identified the presence of carbonate and the analyses showed spectral features very similar to a crystalline hydroxyapatite spectrum, also refuting the presence of precursor phases such as beta-tricalcium phosphate, octacalcium phosphate and dicalcium phosphate dihydrate. The results of this study raised the possibility of the presence of precursor phases associated with the early stages of calcification.

Synchrotron radiation microbeam X-ray fluorescence analysis of zinc concentration in remineralized enamel in situ.

PubMed

Matsunaga, Tsunenori; Ishizaki, Hidetaka; Tanabe, Shuji; Hayashi, Yoshihiko

2009-05-01

Remineralization is an indispensable phenomenon during the natural healing process of enamel decay. The incorporation of zinc (Zn) into enamel crystal could accelerate this remineralization. The present study was designed to investigate the concentration and distribution of Zn in remineralized enamel after gum chewing. The experiment was performed at the Photon Factory. Synchrotron radiation was monochromatized and X-rays were focused into a small beam spot. The X-ray fluorescence (XRF) from the sample was detected with a silicon (Si) (lithium (Li)) detector. X-ray beam energy was tuned to detect Zn. The examined samples were small enamel fragments remineralized after chewing calcium phosphate-containing gum in situ. The incorporation of Zn atom into hydroxyapatite (OHAP), the main component of enamel, was measured using Zn K-edge extended X-ray absorption fine structure (EXAFS) with fluorescence mode at the SPring-8. A high concentration of Zn was detected in a superficial area 10-microm deep of the sectioned enamel after gum chewing. This concentration increased over that in the intact enamel. The atomic distance between Zn and O in the enamel was calculated using the EXAFS data. The analyzed atomic distances between Zn and O in two sections were 0.237 and 0.240 nm. The present experiments suggest that Zn is effectively incorporated into remineralized enamel through the physiological processes of mineral deposition in the oral cavity through gum-chewing and that Zn substitution probably occurred at the calcium position in enamel hydroxyapatite.

A Biphasic Calcium Sulphate/Hydroxyapatite Carrier Containing Bone Morphogenic Protein-2 and Zoledronic Acid Generates Bone

PubMed Central

Raina, Deepak Bushan; Isaksson, Hanna; Hettwer, Werner; Kumar, Ashok; Lidgren, Lars; Tägil, Magnus

2016-01-01

In orthopedic surgery, large amount of diseased or injured bone routinely needs to be replaced. Autografts are mainly used but their availability is limited. Commercially available bone substitutes allow bone ingrowth but lack the capacity to induce bone formation. Thus, off-the-shelf osteoinductive bone substitutes that can replace bone grafts are required. We tested the carrier properties of a biphasic, calcium sulphate and hydroxyapatite ceramic material, containing a combination of recombinant human bone morphogenic protein-2 (rhBMP-2) to induce bone, and zoledronic acid (ZA) to delay early resorption. In-vitro, the biphasic material released 90% of rhBMP-2 and 10% of ZA in the first week. No major changes were found in the surface structure using scanning electron microscopy (SEM) or in the mechanical properties after adding rhBMP-2 or ZA. In-vivo bone formation was studied in an abdominal muscle pouch model in rats (n = 6/group). The mineralized volume was significantly higher when the biphasic material was combined with both rhBMP-2 and ZA (21.4 ± 5.5 mm3) as compared to rhBMP-2 alone (10.9 ± 2.1 mm3) when analyzed using micro computed tomography (μ-CT) (p < 0.01). In the clinical setting, the biphasic material combined with both rhBMP-2 and ZA can potentially regenerate large volumes of bone. PMID:27189411

The effect of Ca/P concentration and temperature of simulated body fluid on the growth of hydroxyapatite coating on alkali-treated 316L stainless steel.

PubMed

Lin, Feng-Huei; Hsu, Yao-Shan; Lin, Shih-Hsun; Sun, Jui-Sheng

2002-10-01

316L-SS is one of the important materials both in orthopaedics and dentistry for bone screw/plate, intra-medullary rod, fixation wire, HIP joint, and knee joint. However, the biocompatibility and bone-bonding ability troubled researches for years. In the study, a simple chemical method was tried so as to establish and induce a bioactive HA layer on the surface of 316L stainless steel. When the metallic substrates treated with 10 M NaOH aqueous solution and subsequently heated at 600 degrees C, a thin sodium chromium oxide layer was formed on the surfaces as the linking layer for HA and 316L-SS. After 316L-SS treated with alkali solution, it would soak into a simulated body fluid with higher concentration of calcium and phosphorous ions to increase the possibility of nucleation of HA. However, the iron oxide and iron chromium oxides were formed on the surface when calcium and phosphorous ions increased. This resulted in loosening the HA layer. When the alkali-treated 316L-SS was soaked into SBF at a temperature of 80 degrees C, it could form a dense and uniform bone-like hydroxyapatite layer on the surface. In the research, the mechanism of the formation of sodium chromium oxide and HA would also be described by the analysis of X-ray diffractometer, scanning electron microscope, energy-dispersion spectrophotometer, and Fourier transformation infrared.

Chemical characterization of hydroxyapatite obtained by wet chemistry in the presence of V, Co, and Cu ions.

PubMed

Moseke, Claus; Gelinsky, Michael; Groll, Jürgen; Gbureck, Uwe

2013-04-01

A model system for the precipitation of hydroxyapatite (HA) from saturated solutions at basic pH was utilized to investigate the effects of V, Co, and Cu ions on crystallography and stoichiometry of the produced apatites. X-ray diffraction (XRD) was applied to analyze phase composition and crystallinity of powders obtained with different metal ion concentrations and annealed at different sintering temperatures. This procedure used the temperature-dependent phase transitions and decompositions of calcium phosphates to analyze the particular influences of the metal ions on apatite mineralization. Comparative XRD measurements showed that all metal ion species reduced crystallinity and crystallite size of the produced apatites. Furthermore the transformation of amorphous calcium phosphate (ACP) to HA was partially inhibited, as was deduced from the formation of α-tricalcium phosphate (α-TCP) peaks in XRD patterns of the heated powders as well as from the reduced intensity of the OH stretch vibration in FTIR spectra. The thermally induced formation of β-TCP indicated a significantly reduced Ca/P ratio as compared to stoichiometric HA. This effect was more pronounced with rising metal ion content. In addition, the appearance of metal oxides in the XRD patterns of samples heated to higher temperatures indicated the incorporation of metal ions in the precipitated apatites. Peak shifts showed that both the apatitic as well as the β-TCP phase apparently had incorporated metal ions. Copyright © 2012 Elsevier B.V. All rights reserved.

Improvement of mechanical strength and osteogenic potential of calcium sulfate-based hydroxyapatite 3-dimensional printed scaffolds by ε-polycarbonate coating.

PubMed

Kim, Beom-Su; Yang, Sun-Sik; Park, Ho; Lee, Se-Hwan; Cho, Young-Sam; Lee, Jun

2017-09-01

Powder-based three-dimensional (3D) printing is an excellent method to fabricate complex-shaped scaffolds for tissue engineering. However, their lower mechanical strength restricts their application in bone tissue engineering. Here, we created a 3D-printed scaffold coated with a ε-polycaprolactone (PCL) polymer solution (5 and 10 w/v %) to improve the mechanical strength of the scaffold. The 3D scaffold was fabricated from calcium sulfate hemihydrate powder (CaSO 4 -1/2 H 2 O), transformed into hydroxyapatite (HAp) by treatment with a hydrothermal reaction in an NH 4 H 2 PO 4 solution. The surface properties and composition of the scaffold were evaluated using scanning electron microscopy and X-ray diffraction analysis. We demonstrated that the 3D scaffold coated with PCL had an improved mechanical modulus. Coating with 5 and 10% PCL increased the compressive strength significantly, by about 2-fold and 4-fold, respectively, compared with that of uncoated scaffolds. However, the porosity was reduced significantly by coating with 10% PCL. In vitro biological evaluation demonstrated that MG-63 cells adhered well and proliferated on the 3D scaffold coated with PCL, and the scaffold was not cytotoxic. In addition, alkaline phosphatase activity and real time polymerase chain reaction demonstrated that osteoblast differentiation also improved in the PCL-coated 3D scaffolds. These results indicated that PCL polymer coating could improve the compressive strength and biocompatibility of 3D HAp scaffolds for bone tissue engineering applications.

Development of nanocomposites based on hydroxyapatite/sodium alginate: Synthesis and characterisation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rajkumar, M.; Meenakshisundaram, N.; Rajendran, V., E-mail: veerajendran@gmail.com

2011-05-15

In this study, a novel method was used to produce a nanostructured composite consisting of hydroxyapatite and sodium alginate by varying the composition of sodium alginate. The structure, morphology, simulated body fluid response and mechanical properties of the synthesised nanocomposites were characterised. From X-ray diffraction analysis, an increase in crystallite size and degree of crystallinity with an increase in the composition of sodium alginate up to 1.5 wt.% was observed. Further, it was found to decrease with an increase in the composition of sodium alginate. A notable peak shift from 1635 to 1607 cm{sup -1} and 1456 to 1418 cm{supmore » -1} in the Fourier transform infrared spectra of the nanocomposite was observed towards the lower wave number side when compared with pure hydroxyapatite. It reveals a strong interaction between the positively charged calcium (Ca{sup 2+}) and the negatively charged carboxyl group (COO{sup -}) in sodium alginate. Transmission electron microscopy images of pure hydroxyapatite showed a short nanorod-like morphology with an average particle size of 13 nm. Bioresorbability of the samples was observed by immersing them in simulated body fluid medium for 14 days to evaluate the changes in pH and Ca{sup 2+} ion strength. Microhardness shows an increasing trend with an increase in the composition of sodium alginate from 1.5 to 3.0 wt.%, which is similar to that in the density. - Research Highlights: {yields} We have prepared nanohydroxyapatite/sodium alginate as a composite. {yields} Effect of sodium alginate on the properties of nanohydrroxyapatite has been studied. {yields} The sodium alginate ranges from 0 to 3.75 wt.% has been used. {yields} Composites show improved biological and mechanical properties.« less

Development of gelatin-chitosan-hydroxyapatite based bioactive bone scaffold with controlled pore size and mechanical strength.

PubMed

Maji, Kanchan; Dasgupta, Sudip; Kundu, Biswanath; Bissoyi, Akalabya

2015-01-01

Hydroxyapatite-chitosan/gelatin (HA:Chi:Gel) nanocomposite scaffold has potential to serve as a template matrix to regenerate extra cellular matrix of human bone. Scaffolds with varying composition of hydroxyapatite, chitosan, and gelatin were prepared using lyophilization technique where glutaraldehyde (GTA) acted as a cross-linking agent for biopolymers. First, phase pure hydroxyapatite-chitosan nanocrystals were in situ synthesized by coprecipitation method using a solution of 2% acetic acid dissolved chitosan and aqueous solution of calcium nitrate tetrahydrate [Ca(NO3)2,4H2O] and diammonium hydrogen phosphate [(NH4)2H PO4]. Keeping solid loading constant at 30 wt% and changing the composition of the original slurry of gelatin, HA-chitosan allowed control of the pore size, its distribution, and mechanical properties of the scaffolds. Microstructural investigation by scanning electron microscopy revealed the formation of a well interconnected porous scaffold with a pore size in the range of 35-150 μm. The HA granules were uniformly dispersed in the gelatin-chitosan network. An optimal composition in terms of pore size and mechanical properties was obtained from the scaffold with an HA:Chi:Gel ratio of 21:49:30. The composite scaffold having 70% porosity with pore size distribution of 35-150 μm exhibited a compressive strength of 3.3-3.5 MPa, which is within the range of that exhibited by cancellous bone. The bioactivity of the scaffold was evaluated after conducting mesenchymal stem cell (MSC) - materials interaction and MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay using MSCs. The scaffold found to be conducive to MSC's adhesion as evident from lamellipodia, filopodia extensions from cell cytoskeleton, proliferation, and differentiation up to 14 days of cell culture.

The role of grain boundaries and transient porosity increase as fluid pathways for reaction front propagation

NASA Astrophysics Data System (ADS)

Jonas, Laura; John, Timm; Geisler, Thorsten; Putnis, Andrew

2013-04-01

The pseudomorphic replacement of Carrara marble by calcium phosphates was studied as a model system to examine the influence of different fluid pathways for reaction front propagation induced by fluid-rock interaction. In this model system, the grain boundaries present in the rock and the transient porosity structures developing throughout the replacement reaction enable the reaction front to progress further into the rock as well as to the center of each single grain until complete transformation. Hydrothermal treatment of the marble using phosphate bearing solutions at temperature levels of 150° C and 200° C for different durations lead to the formation of two product phases which were identified as hydroxyapatite [Ca5(PO4)3OH] as well as β-tricalcium phosphate [β-Ca3(PO4)2] (β-TCP). The formation of β-TCP was probably favored by the presence of ~0.6wt.% of Mg in the parent phase. Completely transformed single grains show a distinctive zoning, both in composition and texture. Whereas areas next to the grain boundary consist of nearly pure hydroxyapatite and show a coarse porosity, areas close to the center of the single grains show a high amount of β-TCP and a very fine porous microstructure. If F was added as an additional solution component, the formation of β-TCP was avoided and up to 3wt.% of F were incorporated into the product apatite. The use of the isotope 18O as a chronometer for the replacement reaction makes it possible to reconstruct the chronological development of the calcium phosphate reaction front. Raman analysis revealed that the incorporation of 18O in the PO4 tetrahedron of hydroxyapatite results in the development of distinct profiles in the calcium phosphate reaction front perpendicular to the grain boundaries of the marble. Through the use of the 18O chronometer, it is possible to estimate and compare the time effectiveness of the different fluid pathways in this model system. The results show that the grain boundaries serve as a very effective pathway that enable the fluid to penetrate the rock more than one order of magnitude faster compared to the newly developing channel-like porosity structures which act as pathways towards the center of single mineral grains. Thus, it may be possible for the fluid to progress relatively large distances along the grain boundaries after only short reaction durations without producing broad reaction fronts along the path.

Studying metal impurities (Mn2+, Cu2+, Fe3+) in calcium phosphates by electron paramagnetic resonance

NASA Astrophysics Data System (ADS)

Iskhakova, K.; Murzakhanov, F.; Mamin, G.; Putlyaev, V.; Klimashina, E.; Fadeeva, I.; Fomin, A.; Barinov, S.; Maltsev, A.; Bakhteev, S.; Yusupov, R.; Gafurov, M.; Orlinskii, S.

2018-05-01

Calcium phosphates (CaP) are exploited in many fields of science, including geology, chemistry, biology and medicine due to their abundance in the nature and presence in the living organism. Various analytical and biochemical methods are used for controlling their chemical content, structure, morphology, etc. Unfortunately, magnetic resonance techniques are usually not even considered as necessary tools for CaP inspection. Some aspects of application of the commercially realized electron paramagnetic resonance (EPR) approaches for characterization of CaP powders and ceramics (including the nanosized materails) such as hydroxyapatite and tricalcium phosphates of biogenic and synthetic origins containing intrinsic impurities or intentional dopants are demonstrated. The key features and advantages of the EPR techniques for CaP based materials characterization that could compliment the data obtained with the recognized analytical methods are pointed out.

Structural characterization and mechanical performance of calcium phosphate scaffolds and natural bones: a comparative study.

PubMed

Fuentes, Elena; Sáenz de Viteri, Virginia; Igartua, Amaya; Martinetti, Roberta; Dolcini, Laura; Barandika, Gotzone

2010-01-01

The knowledge of the mechanical response of bones and their substitutes is pertinent to numerous medical problems. Understanding the effects of mechanical influence on the body is the first step toward developing innovative treatment and rehabilitation concepts for orthopedic disorders. This was a comparative study of 5 synthetic scaffolds based on porous calcium phosphates and natural bones, with regard to their microstructural, chemical, and mechanical characterizations. The structural and chemical characterizations of the scaffolds were examined by means of X-ray diffraction, scanning electron microscopy, and X-ray spectroscopy analysis. The mechanical characterization of bones and bone graft biomaterials was carried out through compression tests using samples with noncomplex geometry. Analysis of the chemical composition, surface features, porosity, and compressive strength indicates that hydroxyapatite-based materials and trabecular bone have similar properties.

Phosphate reduction in a hydroxyapatite fluoride removal system

NASA Astrophysics Data System (ADS)

Egner, A.

2012-12-01

Fluorosis is a widespread disease that occurs as a result of excess fluoride consumption and can cause severe tooth and bone deformations. To combat fluorosis, several previous studies have examined the potential to replace traditional bone char filters with synthetic hydroxyapatite. Calcite particles with a synthetic hydroxyapatite coating have been shown to effectively removed fluoride, yet the low-cost method for forming these particles leaves high amounts of phosphate both in synthesis waste-water and in filter effluent. High phosphate in filter effluent is problematic because consumption of extremely high phosphate can leach calcium from bones, further exacerbating the fluoride effect. This study examines ways of reducing and reusing waste. In particular, a method of fluoride removal is explored in which fluorapatite coatings may be formed directly. In preliminary studies, batches of 4.1g of Florida limestone (<710 μm) were equilibrated with 100 mL of 10ppm fluoride. In a control batch containing lime but no added phosphate, 14% treatment was achieved, but with added phosphate, 100% treatment was achieved in all batches. Batches with lower levels of phosphate took longer to reach 100% treatment, ranging from less than 24 hours in the highest phosphate batches to approximately 42 hours in the lowest batches. The lower levels tested were well within reasonable levels for drinking water and reached 0ppm fluoride in 42 hours or less.

The drug release study of ceftriaxone from porous hydroxyapatite scaffolds.

PubMed

Al-Sokanee, Zeki N; Toabi, Abedl Amer H; Al-Assadi, Mohammed J; Alassadi, Erfan A S

2009-01-01

Hydroxyapatite (HAP) is an important biomedical material that is used for grafting osseous defects. It has an excellent bioactivity and biocompatibility properties. To isolate hydroxyapatite, pieces of cleaned cattle's bone were heated at different temperature range from 400 degrees C up to 1,200 degrees C. A reasonable yield of 60.32% w/w HAP was obtained at temperature range from 1,000 degrees C to 1,200 degrees C. Fourier transform infrared spectra and the thermogravimetric measurement showed a clear removal of organic at 600 degrees C as well as an excellent isolation of HAP from the bones which was achieved at 1,000-1,200 degrees C. This was also confirmed from X-ray diffraction of bone sample heated at 1,200 degrees C. The concentration ions were found to be sodium, potassium, lithium, zinc, copper, iron, calcium, magnesium, and phosphate present in bones within the acceptable limits for its role in the bioactivity property of HAP. Glucose powder was used as a porosifier. Glucose was novel and excellent as porogen where it was completely removed by heating, giving an efficient porosity in the used scaffolds. The results exhibited that the ceftriaxone drug release was increased with increasing the porosity. It was found that a faster, higher, and more regular drug release was obtained from the scaffold with a porosity of 10%.

Evaluation of the Ca/P concentration ratio in hydroxyapatite by STEM-EDXS: influence of the electron irradiation dose and temperature processing

NASA Astrophysics Data System (ADS)

Benhayoune, H.; Charlier, D.; Jallot, E.; Laquerriere, P.; Balossier, G.; Bonhomme, P.

2001-01-01

Biomaterials used in dental and orthopaedic surgery to fill bony loss and to coat prostheses are either of natural or synthetic origin. Amongst these biomaterials, hydroxyapatites (HA) offer good properties of biocompatibility and bioactivity when they interact with bone. This interaction depends mainly on the physico-chemical properties of HA particles. In this work, using a scanning transmission electronic microscope equipped with an Si(Li) detector for x-ray analysis, we analysed three kinds of hydroxyapatite: non-sintered particles, 600 °C sintered particles and 1180 °C sintered particles. Then, we determined the Ca/P concentration ratio in order to observe the influence of the temperature processing on this ratio. Concurrently, we carried out measurements on the HA powders by varying the electron irradiation dose either with the current density or with irradiation time. When the electron irradiation dose varied with the current density (at constant and short irradiation time), the Ca/P concentration ratio did not vary. But, at fixed current density and increasing irradiation time, the calcium and phosphorus intensities decreased, leading to an increase of the Ca/P concentration ratio at high electron irradiation dose. This phenomenon represents a mass loss of the specimen during electronic bombardment. We propose an experimental procedure to avoid all these problems.

Acute and 3-month effects of microcrystalline hydroxyapatite, calcium citrate and calcium carbonate on serum calcium and markers of bone turnover: a randomised controlled trial in postmenopausal women.

PubMed

Bristow, Sarah M; Gamble, Greg D; Stewart, Angela; Horne, Lauren; House, Meaghan E; Aati, Opetaia; Mihov, Borislav; Horne, Anne M; Reid, Ian R

2014-11-28

Ca supplements are used for bone health; however, they have been associated with increased cardiovascular risk, which may relate to their acute effects on serum Ca concentrations. Microcrystalline hydroxyapatite (MCH) could affect serum Ca concentrations less than conventional Ca supplements, but its effects on bone turnover are unclear. In the present study, we compared the acute and 3-month effects of MCH with conventional Ca supplements on concentrations of serum Ca, phosphate, parathyroid hormone and bone turnover markers. We randomised 100 women (mean age 71 years) to 1 g/d of Ca as citrate or carbonate (citrate-carbonate), one of two MCH preparations, or a placebo. Blood was sampled for 8 h after the first dose, and after 3 months of daily supplementation. To determine whether the acute effects changed over time, eight participants assigned to the citrate dose repeated 8 h of blood sampling at 3 months. There were no differences between the citrate and carbonate groups, or between the two MCH groups, so their results were pooled. The citrate-carbonate dose increased ionised and total Ca concentrations for up to 8 h, and this was not diminished after 3 months. MCH increased ionised Ca concentrations less than the citrate-carbonate dose; however, it raised the concentrations of phosphate and the Ca-phosphate product. The citrate-carbonate and MCH doses produced comparable decreases in bone resorption (measured as serum C-telopeptide (CTX)) over 8 h and bone turnover (CTX and procollagen type-I N-terminal propeptide) at 3 months. These findings suggest that Ca preparations, in general, produce repeated sustained increases in serum Ca concentrations after ingestion of each dose and that Ca supplements with smaller effects on serum Ca concentrations may have equivalent efficacy in suppressing bone turnover.

Effect of proteins and their conformation change during brushite transformation to hydroxyapatite

NASA Astrophysics Data System (ADS)

Xie, Jing

2000-10-01

Hydroxyapatite (HA, Ca5(PO4)3OH) coatings on metallic orthopedic implant are being used to achieve implant integration. However, HA is stable in physiological solutions, other more reactive calcium phosphate ceramics (CPC) such as brushite (CaHPO4·2H 2O) have been found to release calcium and phosphate ions during their transformation to HA. The release of these ions may induce faster bone growth and enhance implant integration. This work examines the biocompatibility of the CPC phases that form during the transformation process. Since biocompatibility is associated with cellular response, which in turn is initiated by protein adsorption, this work focuses on the mutual effect between protein adsorption and CPC transformation. The first part of the study is focused on the influence of protein adsorption on transformation kinetics and chemistry. Brushite coated samples immersed in protein free and proteinaceous physiological solutions were retrieved after different exposures times. These were examined using XRD, EDS and FTIR/reflectance. Results show that the presence of Bovine Serum Albumin (BSA) in physiological solution retards the transformation, but the presence of Fibronectin (FN) accelerates the transformation to HA. Interestingly, neither BSA nor FN alters the transformation chemistry. Due to the limitations of the techniques used, this part of the work does not monitor the effect of transformation on adsorbed proteins but only the effect of adsorbed protein on the transforming calcium phosphate coating. The second part of the work examines in situ conformational changes of adsorbed proteins during the CPC transformation using FTIR/ATR. Protein adsorbed on different surfaces such as germanium, CPC, zinc selenide and titanium shows different conformation indicated by the Amide I and II absorption bands in the infrared spectra. During the transformation of brushite to HA, both BSA and FN show a continuous change in conformation, which suggests that the transformation of CPC coating influences adsorbed protein structure.

Magnesium substitution in the structure of orthopedic nanoparticles: A comparison between amorphous magnesium phosphates, calcium magnesium phosphates, and hydroxyapatites.

PubMed

Nabiyouni, Maryam; Ren, Yufu; Bhaduri, Sarit B

2015-01-01

As biocompatible materials, magnesium phosphates have received a lot of attention for orthopedic applications. During the last decade multiple studies have shown advantages for magnesium phosphate such as lack of cytotoxicity, biocompatibility, strong mechanical properties, and high biodegradability. The present study investigates the role of Mg(+2) and Ca(+2) ions in the structure of magnesium phosphate and calcium phosphate nanoparticles. To directly compare the effect of Mg(+2) and Ca(+2) ions on structure of nanoparticles and their biological behavior, three groups of nanoparticles including amorphous magnesium phosphates (AMPs) which release Mg(+2), calcium magnesium phosphates (CMPs) which release Mg(+2) and Ca(+2), and hydroxyapatites (HAs) which release Ca(+2) were studied. SEM, TEM, XRD, and FTIR were used to evaluate the morphology, crystallinity, and chemical properties of the particles. AMP particles were homogeneous nanospheres, whereas CMPs were combinations of heterogeneous nanorods and nanospheres, and HAs which contained heterogeneous nanosphere particles. Cell compatibility was monitored in all groups to determine the cytotoxicity effect of particles on studied MC3T3-E1 preosteoblasts. AMPs showed significantly higher attachment rate than the HAs after 1 day and both AMPs and CMPs showed significantly higher proliferation rate when compared to HAs after 7days. Gene expression level of osteoblastic markers ALP, COL I, OCN, OPN, RUNX2 were monitored and they were normalized to GAPDH housekeeping gene. Beta actin expression level was monitored as the second housekeeping gene to confirm the accuracy of results. In general, AMPs and CMPs showed higher expression level of osteoblastic genes after 7 days which can further confirm the stimulating role of Mg(+2) and Ca(+2) ions in increasing the proliferation rate, differentiation, and mineralization of MC3T3-E1 preosteoblasts. Copyright © 2015 Elsevier B.V. All rights reserved.

Eudragit® S100 coated calcium pectinate microspheres of curcumin for colon targeting.

PubMed

Zhang, Lin; Cao, Fengliang; Ding, Buyun; Li, Qilu; Xi, Yanwei; Zhai, Guangxi

2011-01-01

Currently, colon-specific drug delivery systems have been investigated for drugs that can exert their bioactivities in the colon. In this study, Eudragit® S100 coated calcium pectinate microsphere, a pH-dependent and enzyme-dependent system, as colon-specific delivery carrier for curcumin was investigated. Curcumin-loaded calcium pectinate microspheres were prepared by emulsification-linkage method, and the preparation technology was optimised by uniform experimental design. The morphology of microspheres was observed under scanning electron microscopy. Interactions between drug and polymers were investigated with differential scanning calorimetry (DSC) and X-ray diffraction. In vitro drug release studies were performed in simulated colonic fluid in the presence of Pectinex Ultra SP-L or 1% (w/v) rat caecal content, and the results indicated that the release of curcumin was significantly increased in the presence of 1% (w/v) rat caecal contents. It could be concluded that Eudragit® S100 coated calcium pectinate microsphere was a potential carrier for colon delivery of curcumin.

A new use of hydroxyapatite-based consolidant: cleaning and consolidation of stones in one step by reaction with gypsum crust

NASA Astrophysics Data System (ADS)

Molina Piernas, Eduardo; Rueda Quero, Lucia; Cultrone, Giuseppe; Ruiz Agudo, Encarnación

2015-04-01

The reaction between diammonium hydrogen phosphate (DAP) and calcite in the stone to form hydroxyapatite (HAP) had provided a new product to consolidate limestone or Ca-rich stones, for example sandstones with carbonatic cement. However, what does it happen with the stones without Ca-bearing compounds? Obviously, HAP cannot form. In the other hand, recent research about consolidation with DAP show a good interaction between carbonatic stones and HAP, improving their mechanical properties. For these reasons, we propose a new method for the consolidation of building stone capable of cleaning the gypsum crust and consolidating stones at the same time, based in the Ferroni-Dini method [1] and using DAP. Based on this method, we aim at obtaining a consolidating component reacting DAP (instead of ammonium carbonate) and the gypsum contained in the crust of weathered stones in polluted environments. As an advantage, we do not need to use barium hydroxide (the second step required in the Ferroni-Dini method), thereby reducing the time necessary to carry out the consolidation. Here, we report different tests to evaluate this new procedure. In a first set of experiments, a DAP solution was poured on a gypsum (dihydrate calcium sulphate) saturated solution and by monitoring the free calcium content of the solution using an ion-selective electrode we have evaluated the fluctuations in the content in calcium of the solution and the speed of the reaction. Once the reaction finished, we analyzed the solids formed to verify the formation of hydroxyapatite by FTIR and microRAMAN. The second test consisted in the alteration of limestone blocks with sulfuric acid to obtain a crust of gypsum and, after that, the samples were consolidated by means of cellulose compress soaked in DAP 3M during different reaction times (30 minutes, 1 hour and 4 hours, at controlled temperature -20 °C- and relative humidity -40% HR-). The samples were then analyzed by XRD, FTIR, microRAMAN and SEM-EDX to verify the formation of hydroxyapatite and the elimination of gypsum by transformation into ammonium sulphate (highly soluble). Our preliminary results show that the reaction occurs at room temperature in a short period of time. The amount of gypsum decreases with reaction time, while the amount of HAP significantly increases, with the gypsum being almost completely removed after 4 hours of reaction. We can conclude that this procedure is an optimal solution to remove the gypsum contained in the crust of the weathered stones and to consolidate them, independently of the mineralogical composition of the stone. Acknowledgements: This study was financially supported by Research Group RNM179 of the Junta de Andalucía and by the Research Project MAT2012-34473. [1] M. Matteini, "In review: An assessment of Florentine Methods of Wall Painting Conservation Based on the Use of Mineral Treatments", in "The Conservation of Wall Paintings: Proceedings of a Symposium organized by the Courtauld Institute of Art and the Getty Conservation Institute", London, 1987, pp. 137-146.

Effect of addition of nano-hydroxyapatite on physico-chemical and antibiofilm properties of calcium silicate cements.

PubMed

Guerreiro-Tanomaru, Juliane Maria; Vázquez-García, Fernando Antonio; Bosso-Martelo, Roberta; Bernardi, Maria Inês Basso; Faria, Gisele; Tanomaru, Mario

2016-01-01

Mineral Trioxide Aggregate (MTA) is a calcium silicate cement composed of Portland cement (PC) and bismuth oxide. Hydroxyapatite has been incorporated to enhance mechanical and biological properties of dental materials. This study evaluated physicochemical and mechanical properties and antibiofilm activity of MTA and PC associated with zirconium oxide (ZrO2) and hydroxyapatite nanoparticles (HAn). White MTA (Angelus, Brazil); PC (70%)+ZrO2 (30%); PC (60%)+ZrO2 (30%)+HAn (10%); PC (50%)+ZrO2 (30%)+HAn (20%) were evaluated. The pH was assessed by a digital pH-meter and solubility by mass loss. Setting time was evaluated by using Gilmore needles. Compressive strength was analyzed by mechanical test. Samples were radiographed alongside an aluminum step wedge to evaluate radiopacity. For the antibiofilm evaluation, materials were placed in direct contact with E. faecalis biofilm induced on dentine blocks. The number of colony-forming units (CFU mL-1) in the remaining biolfilm was evaluated. The results were submitted to ANOVA and the Tukey test, with 5% significance. There was no difference in pH levels of PC+ZrO2, PC+ZrO2+HAn (10%) and PC+ZrO2+HAn (20%) (p>0.05) and these cements presented higher pH levels than MTA (p<0.05). The highest solubility was observed in PC+ZrO2+HAn (10%) and PC+ZrO2+HAn (20%) (p<0.05). MTA had the shortest initial setting time (p<0.05). All the materials showed radiopacity higher than 3 mmAl. PC+ZrO2 and MTA had the highest compressive strength (p<0.05). Materials did not completely neutralize the bacterial biofilm, but the association with HAn provided greater bacterial reduction than MTA and PC+ZrO2 (p<0.05) after the post-manipulation period of 2 days. The addition of HAn to PC associated with ZrO2 harmed the compressive strength and solubility. On the other hand, HAn did not change the pH and the initial setting time, but improved the radiopacity (HAn 10%), the final setting time and the E. faecalis antibiofilm activity of the cement.

Fabrication and characterization of poly(DL-lactic-co-glycolic acid)/zirconia-hybridized amorphous calcium phosphate composites

PubMed Central

WHITED, BRYCE M.; GOLDSTEIN, AARON S.; SKRTIC, DRAGO; LOVE, BRIAN J.

2010-01-01

Several minerals, such as hydroxyapatite and β-tricalcium phosphate, have been incorporated into bioresorbable polyester bone scaffolds to increase the osteoconductivity both in vitro and in vivo. More soluble forms of calcium phosphate that release calcium and phosphate ions have been postulated as factors that increase osteoblast differentiation and mineralization. Recently, a zirconia-hybridized pyrophosphate-stabilized amorphous calcium phosphate (Zr-ACP) has been synthesized allowing controlled release of calcium and phosphate ions. When incorporated into bioresorbable scaffolds, Zr-ACP has the potential to induce osteoconductivity. In this study, 80–90% (w/v) porous poly(DL-LActic-co-glycolic acid) (PLGA) scaffolds were formed by thermal phase separation from dioxane while incorporating Zr-ACP. Scanning electron microscopy revealed a highly porous structure with a pore size ranging from a few μm to about 100 μm, smaller than we had hoped for. Zr-ACP particles were evenly dispersed in the composite structure and incorporated into the pore walls. The amorphous structure of the Zr-ACP was maintained during composite fabrication, as found by X-ray diffraction. Composite scaffolds had larger compressive yield strengths and moduli compared to pure polymer scaffolds. These initial efforts demonstrate that PLGA/Zr-ACP composites can be formed in ways that ultimately serve as promising bone scaffolds in tissue engineering. PMID:16768292

A Morphologic and Biochemical Study of Nutritional Nephrocalcinosis in Female Rats Fed Semipurified Diets

PubMed Central

Woodard, James C.

1971-01-01

Nephrocalcinosis occurred in weanling female rats fed a semipurified diet for 8 weeks. Mineralization of the inner cortex began after 3 weeks on the semipurified diet, and was most severe after 8 weeks. Intraluminal calcification was observed first in the pars recta of the proximal convoluted tubule; calcification of cytoplasmic organelles or basement membranes of the tubular epithelium was not observed. At the end of 8 weeks, some mineral deposits were seen within Henle's loops of the outer medulla. Histochemical studies demonstrated that the deposits contained calcium and phosphorus and had a glycoprotein matrix; electron diffraction studies indicated that the main mineral phase was hydroxyapatite. No differences in serum calcium or phosphorus or in the ultrastructural characteristics of the thyroid parafollicular cells and the parathyroid parenchymal cells were observed between animals fed the semipurified diet and those fed a commercial chow. The urinary excretion of calcium and magnesium was less and urinary citrate excretion was greater in animals fed the semipurified diet. ImagesFig 1Fig 2Fig 3Fig 4Fig 5Fig 8Fig 9Fig 6Fig 7 PMID:5096368

Method of coating a substrate with a calcium phosphate compound

DOEpatents

Gao, Yufei; Campbell, Allison A.

2000-01-01

The present invention is a method of coating a substrate with a calcium phosphate compound using plasma enhanced MOCVD. The substrate is a solid material that may be porous or non-porous, including but not limited to metal, ceramic, glass and combinations thereof. The coated substrate is preferably used as an implant, including but not limited to orthopaedic, dental and combinations thereof. Calcium phosphate compound includes but is not limited to tricalcium phosphate (TCP), hydroxyapatite (HA) and combinations thereof. TCP is preferred on a titanium implant when implant resorbability is desired. HA is preferred when the bone bonding of new bone tissue into the structure of the implant is desired. Either or both of TCP and/or HA coated implants may be placed into a solution with an agent selected from the group of protein, antibiotic, antimicrobial, growth factor and combinations thereof that can be adsorbed into the coating before implantation. Once implanted, the release of TCP will also release the agent to improve growth of new bone tissues and/or to prevent infection.

Nucleation, growth and evolution of calcium phosphate films on calcite.

PubMed

Naidu, Sonia; Scherer, George W

2014-12-01

Marble, a stone composed of the mineral calcite, is subject to chemically induced weathering in nature due to its relatively high dissolution rate in acid rain. To protect monuments and sculpture from corrosion, we are investigating the application of thin layers of hydroxyapatite (HAP) onto marble. The motivation for using HAP is its low dissolution rate and crystal and lattice compatibility with calcite. A mild, wet chemical synthesis route, in which diammonium hydrogen phosphate salt was reacted with marble, alone and with cationic and anionic precursors under different reaction conditions, was used to produce inorganic HAP layers on marble. Nucleation and growth on the calcite substrate was studied, as well as metastable phase evolution, using scanning electron microscopy, grazing incidence X-ray diffraction, and atomic force microscopy. Film nucleation was enhanced by surface roughness. The rate of nucleation and the growth rate of the film increased with cationic (calcium) and anionic (carbonate) precursor additions. Calcium additions also influenced phase formation, introducing a metastable phase (octacalcium phosphate) and a different phase evolution sequence. Copyright © 2014 Elsevier Inc. All rights reserved.

Efficacy of tooth whitening with different calcium phosphate-based formulations.

PubMed

Jin, Jian; Xu, Xiaohui; Lai, Guangyun; Kunzelmann, Karl-Heinz

2013-08-01

The aim of this in-vitro study was to evaluate the efficacy of tooth whitening using different calcium phosphate-based formulations. Teeth were treated with three different hydroxyapatite preparations at different concentrations and with two control preparations; each tooth was treated a total of three times. After application of the last material, hydrodynamic shear force was applied to mimic mechanical loading. After each treatment, tooth color was measured using a dental spectrophotometer, and the mean changes in L*a*b* values between different measurements were expressed as ∆E. The results indicated significant differences between the materials, but neither dose- nor time-dependent associations were found. The suspension containing tricalcium phosphate (10 wt%) showed the most obvious color change (∆E = 2.20 ± 0.90), while the suspension containing zinc-carbonate-apatite (20 wt%) showed the least obvious color change (∆E = 0.91 ± 0.50). Calcium phosphate-based formulations that can adhere to the enamel surface and contribute to tooth whitening have promising tooth-whitening potential. © 2013 Eur J Oral Sci.

Optical characteristics of novel bulk and nanoengineered laser host materials

NASA Astrophysics Data System (ADS)

Prasad, Narasimha S.; Sova, Stacey; Kelly, Lisa; Bevan, Talon; Arnold, Bradley; Cooper, Christopher; Choa, Fow-Sen; Singh, N. B.

2018-02-01

The hexagonal apatite single crystals have been investigated for their applications as laser host materials. Czochralksi and flux growth methods have been utilized to obtain single crystals. For low temperature processing (<100 0C), several techniques for crystal growth have been developed. The hexagonal apatite structure (space group P63/m) is characteristic of several compounds, some of which have extremely interesting and useful properties as laser hosts and bone materials. Calcium lanthanum silicate (Nd-doped) and lanthanum aluminate material systems were studied in detail. Nanoengineered calcium and lanthanum based silicates were synthesized by a solution method and their optical and morphological characteristics were compared with Czochralski grown bulk hydroxyapatite single crystals. Materials were evaluated by absorbance, fluorescence and Raman characteristics. Neodymium, iron and chromium doped crystals grown by a solution method showed weak but similar optical properties to that of Czochralski grown single crystals.

The innovative applications of therapeutic nanostructures in dentistry.

PubMed

Elkassas, Dina; Arafa, Abla

2017-05-01

Nanotechnology has paved multiple ways in preventing, reversing or restoring dental caries which is one of the major health care problems. Nanotechnology aided in processing variety of nanomaterials with innovative dental applications. Some showed antimicrobial effect helping in the preventive stage. Others have remineralizing potential intercepting early lesion progression as nanosized calcium phosphate, carbonate hydroxyapatite nanocrystals, nanoamorphous calcium phosphate and nanoparticulate bioactive glass particularly with provision of self-assembles protein that furnish essential role in biomimetic repair. The unique size of nanomaterials makes them fascinating carriers for dental products. Thus, it is recentlyclaimedthat fortifying the adhesives with nanomaterials that possess biological meritsdoes not only enhance the mechanical and physical properties of the adhesives, but also help to attain and maintain a durable adhesive joint and enhanced longevity. Accordingly, this review will focus on the current status and the future implications of nanotechnology in preventive and adhesive dentistry. Copyright © 2017 Elsevier Inc. All rights reserved.

Mechanical properties of experimental composites with different calcium phosphates fillers.

PubMed

Okulus, Zuzanna; Voelkel, Adam

2017-09-01

Calcium phosphates (CaPs)-containing composites have already shown good properties from the point of view of dental restorative materials. The purpose of this study was to examine the crucial mechanical properties of twelve hydroxyapatite- or tricalcium phosphate-filled composites. The raw and surface-treated forms of both CaP fillers were applied. As a reference materials two experimental glass-containing composites and one commercial dental restorative composite were applied. Nano-hardness, elastic modulus, compressive, flexural and diametral tensile strength of all studied materials were determined. Application of statistical methods (one-way analysis of variance and cluster agglomerative analysis) allowed for assessing the similarities between examined materials according to the values of studied parameters. The obtained results show that in almost all cases the mechanical properties of experimental CaPs-composites are comparable or even better than mechanical properties of examined reference materials. Copyright © 2017 Elsevier B.V. All rights reserved.

The effect of the type of HA on the degradation of PLGA/HA composites.

PubMed

Naik, Ashutosh; Shepherd, David V; Shepherd, Jennifer H; Best, Serena M; Cameron, Ruth E

2017-01-01

The aim of this study is to explore the importance of the potentially competing effects of buffering effects of the calcium phosphate filler and particle-mediated water sorption on the degradation products of poly(d,l lactide-co-glycolide (50:50))(PLGA)/hydroxyapatite(HA) composites. Further the influence of type of HA on the mechanical properties of the composites was investigated. Phase pure HA was synthesised via a reaction between aqueous solutions of calcium hydroxide and orthophosphoric acid. The powder produced was either used as produced (uncalcined) or calcined in air or calcined in a humidified argon atmosphere. An in-vitro degradation study was carried out in phosphate buffered saline (PBS). The results obtained indicated that the degradation rate of the composite might be better understood if both the buffering effects and the rate of water sorption by the composites are considered. Copyright © 2016 Elsevier B.V. All rights reserved.

Bioactivity of calcium phosphate bioceramic coating fabricated by laser cladding

NASA Astrophysics Data System (ADS)

Zhu, Yizhi; Liu, Qibin; Xu, Peng; Li, Long; Jiang, Haibing; Bai, Yang

2016-05-01

There were always strong expectations for suitable biomaterials used for bone regeneration. In this study, to improve the biocompatiblity of titanium alloy, calcium phosphate bioceramic coating was obtained by laser cladding technology. The microstructure, phases, bioactivity, cell differentiation, morphology and resorption lacunae were investigated by optical microscope (OM), x-ray diffraction (XRD), methyl thiazolyl tetrazolium (MTT) assay, tartrate-resistant acid phosphatase (TRAP) staining and scanning electronic microscope (SEM), respectively. The results show that bioceramic coating consists of three layers, which are a substrate, an alloyed layer and a ceramic layer. Bioactive phases of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) were found in ceramic coating. Osteoclast precursors have excellent proliferation on the bioceramic surface. The bioceramics coating could be digested by osteoclasts, which led to the resorption lacunae formed on its surface. It revealed that the gradient bioceramic coating has an excellent bioactivity.

In situ synthesis of hydroxyapatite coating by laser cladding.

PubMed

Wang, D G; Chen, C Z; Ma, J; Zhang, G

2008-10-15

HA bioceramic coatings were synthesized on titanium substrate by laser cladding using cheap calcium carbonate and calcium hydrogen phosphate. The thermodynamic condition for synthesizing HA was calculated by software Matlab 5.0, the microstructure and phase analysis of laser clad HA bioceramic coatings were studied by electron probe microanalyser (EPMA), X-ray diffractometer (XRD) and transmission electron microscopy (TEM). The theoretical results show that the Gibbs free enthalpy for the synthesis of HA phase is satisfied, and the presence of HA phase in the clad coatings was then further verified by XRD and the selected area diffraction patterns. When the laser power is 600W and the scanning speed is 3.5mm/s, the compact HA bioceramic coatings were obtained, which have cellular dendritic structure and consist of the phases of HA, alpha-Ca(2)P(2)O(7), CaO and CaTiO(3).

Management of segmental bony defects: the role of osteoconductive orthobiologics.

PubMed

McKee, Michael D

2006-01-01

Our knowledge about, and the availability of, orthobiologic materials has increased exponentially in the last decade. Although previously confined to the experimental or animal-model realm, several orthobiologics have been shown to be useful in a variety of clinical situations. As surgical techniques in vascular anastomosis, soft-tissue coverage, limb salvage, and fracture stabilization have improved, the size and frequency of bony defects (commensurate with the severity of the initial injury) have increased, as well. Because all methods of managing segmental bony defects have drawbacks, a need remains for a readily available, void-filling, inexpensive bone substitute. Such a bone substitute fulfills a permissive role in allowing new bone to grow into a given defect. Such potential osteoconductive materials include ceramics, calcium sulfate or calcium phosphate compounds, hydroxyapatite, deproteinized bone, corals, and recently developed polymers. Some materials that have osteoinductive properties, such as demineralized bone matrix, also display prominent osteoconductive properties.

Improvement of physical properties of calcium phosphate cement by elastin-like polypeptide supplementation.

PubMed

Jang, Ji-Hyun; Shin, Sumi; Kim, Hyun-Jung; Jeong, Jinyoung; Jin, Hyo-Eon; Desai, Malav S; Lee, Seung-Wuk; Kim, Sun-Young

2018-03-26

Calcium phosphate cements (CPCs) are synthetic bioactive cements widely used as hard tissue substitutes. Critical limitations of use include their poor mechanical properties and poor anti-washout behaviour. To address those limitations, we combined CPC with genetically engineered elastin-like polypeptides (ELPs). We investigated the effect of the ELPs on the physical properties and biocompatibility of CPC by testing ELP/CPC composites with various liquid/powder ratios. Our results show that the addition of ELPs improved the mechanical properties of the CPC, including the microhardness, compressive strength, and washout resistance. The biocompatibility of ELP/CPC composites was also comparable to that of the CPC alone. However, supplementing CPC with ELPs functionalized with octaglutamate as a hydroxyapatite binding peptide increased the setting time of the cement. With further design and modification of our biomolecules and composites, our research will lead to products with diverse applications in biology and medicine.

Dissolution and precipitation behaviors of silicon-containing ceramic coating on Mg-Zn-Ca alloy in simulated body fluid.

PubMed

Pan, Yaokun; Chen, Chuanzhong; Wang, Diangang; Huang, Danlan

2014-10-01

We prepared Si-containing and Si-free coatings on Mg-1.74Zn-0.55Ca alloy by micro-arc oxidation. The dissolution and precipitation behaviors of Si-containing coating in simulated body fluid (SBF) were discussed. Corrosion products were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), fourier transform infrared spectrometer (FT-IR) and X-ray photoelectron spectrometer (XPS). Electrochemical workstation, inductively coupled plasma atomic emission spectrometer (ICP-AES), flame atomic absorption spectrophotometer (AAS) and pH meter were employed to detect variations of electrochemical parameter and ions concentration respectively. Results indicate that the fast formation of calcium phosphates is closely related to the SiOx(n-) groups, which induce the heterogeneous nucleation of amorphous hydroxyapatite (HA) by sorption of calcium and phosphate ions. Copyright © 2014 Elsevier B.V. All rights reserved.

Preparation of magnetic and bioactive calcium zinc iron silicon oxide composite for hyperthermia treatment of bone cancer and repair of bone defects.

PubMed

Jiang, Yumin; Ou, Jun; Zhang, Zhanhe; Qin, Qing-Hua

2011-03-01

In this paper, a calcium zinc iron silicon oxide composite (CZIS) was prepared using the sol-gel method. X-ray diffraction (XRD) was then employed to test the CZIS composite. The results from the test showed that the CZIS had three prominent crystalline phases: Ca(2)Fe(1.7)Zn(0.15)Si(0.15)O(5), Ca(2)SiO(4), and ZnFe(2)O(4). Calorimetric measurements were then performed using a magnetic induction furnace. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis were conducted to confirm the growth of a precipitated hydroxyapatite phase after immersion in simulated body fluid (SBF). Cell culture experiments were also carried out, showing that the CZIS composite more visibly promoted osteoblast proliferation than ZnFe(2)O(4) glass ceramic and HA, and osteoblasts adhered and spread well on the surfaces of composite samples.

Biodegradable ceramic-polymer composites for biomedical applications: A review.

PubMed

Dziadek, Michal; Stodolak-Zych, Ewa; Cholewa-Kowalska, Katarzyna

2017-02-01

The present work focuses on the state-of-the-art of biodegradable ceramic-polymer composites with particular emphasis on influence of various types of ceramic fillers on properties of the composites. First, the general needs to create composite materials for medical applications are briefly introduced. Second, various types of polymeric materials used as matrices of ceramic-containing composites and their properties are reviewed. Third, silica nanocomposites and their material as well as biological characteristics are presented. Fourth, different types of glass fillers including silicate, borate and phosphate glasses and their effect on a number of properties of the composites are described. Fifth, wollastonite as a composite modifier and its effect on composite characteristics are discussed. Sixth, composites containing calcium phosphate ceramics, namely hydroxyapatite, tricalcium phosphate and biphasic calcium phosphate are presented. Finally, general possibilities for control of properties of composite materials are highlighted. Copyright © 2016 Elsevier B.V. All rights reserved.

A prospective, randomized controlled preclinical trial to evaluate different formulations of biphasic calcium phosphate in combination with a hydroxyapatite collagen membrane to reconstruct deficient alveolar ridges.

PubMed

Nevins, Myron; Nevins, Marc L; Schupbach, Peter; Kim, Soo-Woo; Lin, Zhao; Kim, David M

2013-04-01

Many patients and clinicians would prefer a synthetic particulate bone replacement graft, but most available alloplastic biomaterials have limited osteogenic potential. An alloplast with increased regenerative capacity would be advantageous for the treatment of localized alveolar ridge defects. This prospective, randomized controlled preclinical trial utilized 6 female foxhounds to analyze the osteogenic impact of different formulations of biphasic calcium phosphate (BCP) in combination with an hydroxyapatite-collagen membrane and their ability to reconstruct deficient alveolar ridges for future implant placement. The grafted sites were allowed to heal 3 months, and then trephine biopsies were obtained to perform light microscopic and histomorphometric analyses. All treated sites healed well with no early membrane exposure or adverse soft tissue responses during the healing period. The grafted sites exhibited greater radiopacity than the surrounding native bone with BCP particles seen as radiopaque granules. The graft particles appeared to be well-integrated and no areas of loose particles were observed. Histologic evaluation demonstrated BCP particles embedded in woven bone with dense connective tissue/marrow space. New bone growth was observed around the graft particles as well as within the structure of the graft particulate. There was intimate contact between the graft particles and newly formed bone, and graft particles were bridged by the newly formed bone in all biopsies from the tested groups. The present study results support the potential of these BCP graft particulates to stimulate new bone formation. Clinical studies are recommended to confirm these preclinical findings.

Synthesis and investigation of physico-chemical, antibacterial, biomymetic properties of silver and zinc containing hydroxyapatite

NASA Astrophysics Data System (ADS)

Zhuk, Ilya; Rasskazova, Lyudmila; Korotchenko, Natalia; Kozik, Vladimir; Kurzina, Irina

2017-11-01

In the work we carried out microwave synthesis of modified hydroxyapatites (HA) with different content of ions. A solid solution based on HA remains a single-phase sample when the calcium ions are substituted by silver and zinc ions up to 5 % by weight (0.5 mole fraction). The microstructure parameters, morphology and the particle powders size were studied by X-ray diffraction analysis, IR spectroscopy, and scanning electron microscopy (SEM). It is shown that the modification of HA by silver (AgHA) and zinc (ZnHA) ions increases the size of its particles, the degree of crystallinity, and the pore sizes of the samples while reducing their specific surface and uniformity of their forms. Elemental analysis and distribution of elements over the surface of HA, AgHA, and ZnHA powders were performed by X-ray spectral microanalysis (RSMA). The ratio of Ca/P is within the range of 1.66-1.77 and corresponds to the ratio of Ca/P in stoichiometric HA and the HA entering bone tissue. The ability of AgHA- and ZnHA-substrates to form on their surface a calcium-phosphate layer from the simulated body fluid (SBF) at 37 °C is determined. This ability decreases in the order: in ZnHA it is less than in AgHA, but greater than in HA. The antibacterial activity of the samples was analyzed. The AgHA sample has both bactericidal and persistent bacteriostatic properties in the case of direct contact with Escherichia coli cells.

Nano-hydroxyapatite and calcium-enriched mixture for pulp capping of sound primary teeth: a randomized clinical trial.

PubMed

Haghgoo, Roza; Asgary, Saeed; Mashhadi Abbas, Fatemeh; Montazeri Hedeshi, Roshanak

2015-01-01

Nano-hydroxyapatite (NHA) has been used for regeneration of osseous defects. Calcium-enriched mixture (CEM) cement is also used for various dental treatments. This trial compared the efficacy of NHA and CEM cement for direct pulp capping (DPC) of sound primary teeth. In this randomized clinical trial with split-mouth design, after attaining informed consent, 20 sound primary canines scheduled for orthodontic extraction, were selected. After mechanical pulp exposure, the exposed site was capped with either NHA or CEM cement and then immediately restored with glass-ionomer and resin composite. The teeth were extracted after two months and examined histologically. Parameters of hard tissue bridge (HTB) formation, its type and quality as well as pulpal inflammation scores were compared between the two experimental groups. The data were analyzed using the Mann Whitney U and Fisher's exact test. The level of significance was set at 0.001. All CEM specimens showed inflammation score of 0 (less than 10%). However, in NHA group, inflammation scores of 0 (less than 10%), 1 (10%-30%) and 2 (30%-50%) were observed in 2 (20%), 4 (40%) and 4 (40%) specimens, respectively (P<0.001). HTB was formed in all CEM specimens while it was developed in 2 specimens of NHA (20%; P<0.001). All CEM specimens showed normal pulp; only two cases in NHA group (20%) demonstrated uninflamed normal pulp. CEM cement was superior to NHA as a DPC agent in terms of HTB formation and pulp inflammation scores. It is a suitable material for the DPC of primary teeth.

Synthesis of sodium caseinate-calcium carbonate microspheres and their mineralization to bone-like apatite

NASA Astrophysics Data System (ADS)

Xu, Zhewu; Liang, Guobin; Jin, Lin; Wang, Zhenling; Xing, Chao; Jiange, Qing; Zhang, Zhiguang

2014-06-01

Phosphoproteins can induce and stabilize calcium carbonate (CaCO3) vaterite, which has desirable features for high reactivity. The purpose of this study was to synthesize bioactive CaCO3 microspheres for bone regeneration. Sodium caseinate (NaCas)-containing CaCO3 microspheres, with the crystal phase of vaterite, were synthesized by fast precipitation in an aqueous solution of CaCl2, Na2CO3, and 2 mg/mL of NaCas. The uniform microspheres exhibited rougher surfaces and lower negative charges than CaCO3 particles without NaCas addition. Fourier-transform infrared spectroscopy (FT-IR) of the microspheres showed characteristic peaks or bands corresponding to phosphate and hydroxyl groups. Thermogravimetric analysis (TGA) curves exhibited approximately 5% weight loss below 600 °C due to the decomposition of NaCas. Scanning electron microscope (SEM) images showed lath-like hydroxyapatite (HAp) on the surface after soaking in simulated body fluid (SBF) at 37 °C for 5 and 10 days. Energy dispersive X-ray spectrometry (EDS) revealed that the agglomerates were composed of Ca, C, O, P, Na, and Mg elements, and the Ca/P ratios ranged from 1.53 to 1.56. X-ray diffraction (XRD) patterns exhibited peaks characteristic of hydroxyapatite. The results of this study demonstrated that the addition of NaCas induced the formation of vaterite microspheres which possesses an enhanced apatite formation after soaking in SBF at 37 °C for 5 and 10 days. These NaCas-CaCO3 microspheres may be a potential biomaterial for bone regeneration.

Structural changes in precipitates and cell model for the conversion of amorphous calcium phosphate to hydroxyapatite during the initial stage of precipitation

NASA Astrophysics Data System (ADS)

Zyman, Z.; Rokhmistrov, D.; Glushko, V.

2012-08-01

A new insight on the conversion of an amorphous calcium phosphate, ACP, to hydroxyapatite, HA, has been proposed. The ACP has been precipitated under appropriate conditions of the nitrous method (low concentrations of reactants, pH>10, 25 °С, fast mixing). The ACP to HA conversion has been found to commence immediately after the ACP precipitation. The conversion reveals itself in the first detected shift of the diffuse maximum from 29.5° 2θ (ACP) to about 32° 2θ (the position of principal peaks of HA) in the XRD patterns for the precipitates of 2 min-6 h lifetimes. The precipitates are biphasic mixtures of ACP and nanocrystalline HA, nHA, with increasing nHA/ACP ratio for longer lifetimes. Characteristics of the simulated XRD profiles calculated proceeding on such a picture are excellently confirmed by experimental results. At the end of the conversion, HA nanocrystals start growing. This follows from the appearance of broadened diffraction maxima, which gradually sharpen, along with the appearance and gradual increase of splitting of the initially featureless υ3 and υ4PO43- bands in the IR spectra of precipitates with their aging (after 6 h of the precipitation). Based on the detected structural and compositional peculiarities of ACP in the early stage of precipitation, a cell model for the HA crystallization has been proposed. Proceeding on the model, the principal data in this and earlier studies, considering the ACP to HA conversion as an internal rearrangement process in the ACP particles, has been reasonably explained.

Ceramic modifications of porous titanium: effects on macrophage activation.

PubMed

Scislowska-Czarnecka, A; Menaszek, E; Szaraniec, B; Kolaczkowska, E

2012-12-01

Porous titanium is one of the most widely used implant materials because of its mechanical properties, however, it is also characterised by low bioactivity. To improve the above parameter we prepared three modifications of the porous (30 wt%) titanium (Ti) surface by covering it with bioactive hydroxyapatite (HA), bioglass (BG) and calcium silicate (CS). Subsequently we tested the impact of the modifications on macrophages directing the inflammatory response that might compromise the implant bioactivity. In the study we investigated the in vitro effects of the materials on murine cell line RAW 264.7 macrophage adherence, morphology and activation (production/release of metalloproteinase MMP-9 and pro- and anti-inflammatory cytokines). CS Ti decreased the macrophage adherence and up-regulated the release of several pro-inflammatory mediators, including TNF-α, IL-6, IL-12. Also HA Ti reduced the cell adherence but other parameters were generally not increased, except of TNF-α. In contrast, BG Ti improved macrophage adherence and either decreased production of multiple mediators (MMP-9, TNF-α, IFN-γ, MCP-1) or did not change it in comparison to the porous titanium. We can conclude that analyzing the effects on the inflammatory response initiated by macrophages in vitro, calcium silicate did not improve the biological properties of the porous titanium. The improved bioactivity of titanium was, however, achieved by the application of the hydroxyapatite and bioglass layers. The present in vitro results suggest that these materials, HA Ti and especially BG Ti, may be suitable for in vivo application and thus justify their further investigation. Copyright © 2012 Elsevier Ltd. All rights reserved.

Porous biphasic calcium phosphate ceramics coated with nano-hydroxyapatite and seeded with mesenchymal stem cells for reconstruction of radius segmental defects in rabbits.

PubMed

Hu, Jianzhong; Yang, Zhiming; Zhou, Yongchun; Liu, Yong; Li, Kaiyang; Lu, Hongbin

2015-11-01

The osteoconduction of porous biphasic calcium phosphate (BCP) ceramics has been widely reported. In a previous study, we demonstrated that applying a nano-hydroxyapatite (nHA) coating enhances the osteoinductive potential of BCP ceramics, making these scaffolds more suitable for bone tissue engineering applications. The aim of the present study was to determine the effects of reconstructing radius defects in rabbits using nHA-coated BCP ceramics seeded with mesenchymal stem cells (MSCs) and to compare the bone regeneration induced by different scaffolds. Radius defects were created in 20 New Zealand rabbits, which were divided into four groups by treatment: porous BCP ceramics (Group A), nHA-coated porous BCP ceramics (Group B), porous BCP ceramics seeded with rabbit MSCs (Group C), and nHA-coated porous BCP ceramics seeded with rabbit MSCs (Group D). After in vitro incubation, the cell/scaffold complexes were implanted into the defects. Twelve weeks after implantation, the specimens were examined macroscopically and histologically. Both the nHA coating and seeding with MSCs enhanced the formation of new bone tissue in the BCP ceramics, though the osteoinductive potential of the scaffolds with MSCs was greater than that of the nHA-coated scaffolds. Notably, the combination of nHA coating and MSCs significantly improved the bone regeneration capability of the BCP ceramics. Thus, MSCs seeded into porous BCP ceramics coated with nHA may be an effective bone substitute to reconstruct bone defects in the clinic.

Bioactivity tests of calcium phosphates with variant molar ratios of main components.

PubMed

Pluta, Klaudia; Sobczak-Kupiec, Agnieszka; Półtorak, Olga; Malina, Dagmara; Tyliszczak, Bożena

2018-03-09

Calcium phosphates constitute attractive materials of biomedical applications. Among them particular attention is devoted to bioactive hydroxyapatite (HAp) and bioresorbable tricalcium phosphate (TCP) that possess ability to bind to living bones and can be used clinically as important bone substitutes. Notably, in vivo bone bioactivity can be predicted from apatite formation of bone immersed in SBF fluids. Thus, analyses of behavior of calcium phosphates immersed in various bio fluids are of great importance. Recently, stoichiometric HAp and TCP structures have been widely studied, whereas only limited number of publications have been devoted to analyses of nonstoichiometric calcium phosphates. Here, we report physicochemical analysis of natural and synthetic phosphates with variable Ca/P molar ratios. Subsequently attained structures were subjected to incubation in either artificial saliva or Ringer's fluids. Both pH and conductivity of such fluids were determined before and after incubation. Furthermore, the influence of the Ca/P values on such parameters was exemplified. Physicochemical analysis of received materials was performed by XRD and FT-IR characterization techniques. Their potential antibacterial activity and behavior in the presence of infectious microorganisms as Escherichia coli and Staphylococcus aureus was also evaluated. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2018. © 2018 Wiley Periodicals, Inc.

Macroporous Calcium Phosphate/Chitosan Composites Prepared via Unidirectional Ice Segregation and Subsequent Freeze-Drying

PubMed Central

Aranaz, Inmaculada; Martínez-Campos, Enrique; Moreno-Vicente, Carolina; Civantos, Ana; García-Arguelles, Sara; del Monte, Francisco

2017-01-01

Calcium phosphate chitosan-based composites have gained much interest in recent years for biomedical purposes. In this paper, three-dimensional calcium phosphate chitosan-based composites with different mineral contents were produced using a green method called ice segregation induced self-assembly (ISISA). In this methodology, ice crystals were used as a template to produce porous structures from an aqueous solution of chitosan (CS) and hydroxyapatite (Hap) also containing acetic acid (pH = 4.5). For better characterization of the nature of the inorganic matter entrapped within the resulting composite, we performed either oxygen plasma or calcination processes to remove the organic matter. The nature of the phosphate salts was studied by XRD and NMR studies. Amorphous calcium phosphate (ACP) was identified as the mineral phase in the composites submitted to oxygen plasma, whereas crystalline Hap was obtained after calcination. SEM microscopy revealed the formation of porous structures (porosity around 80–85%) in the original composites, as well as in the inorganic matrices obtained after calcination, with porous channels of up to 50 µm in diameter in the former case and of up to 20 µm in the latter. The biocompatibility of the composites was assessed using two different cell lines: C2C12GFP premyoblastic cells and MC3T3 preosteoblastic cells. PMID:28772874

Ectopic Osteoid and Bone Formation by Three Calcium-Phosphate Ceramics in Rats, Rabbits and Dogs

PubMed Central

Wang, Liao; Zhang, Bi; Bao, Chongyun; Habibovic, Pamela; Hu, Jing; Zhang, Xingdong

2014-01-01

Calcium phosphate ceramics with specific physicochemical properties have been shown to induce de novo bone formation upon ectopic implantation in a number of animal models. In this study we explored the influence of physicochemical properties as well as the animal species on material-induced ectopic bone formation. Three bioceramics were used for the study: phase-pure hydroxyapatite (HA) sintered at 1200°C and two biphasic calcium phosphate (BCP) ceramics, consisting of 60 wt.% HA and 40 wt.% TCP (β-Tricalcium phosphate), sintered at either 1100°C or 1200°C. 108 samples of each ceramic were intramuscularly implanted in dogs, rabbits, and rats for 6, 12, and 24 weeks respectively. Histological and histomorphometrical analyses illustrated that ectopic bone and/or osteoid tissue formation was most pronounced in BCP sintered at 1100°C and most limited in HA, independent of the animal model. Concerning the effect of animal species, ectopic bone formation reproducibly occurred in dogs, while in rabbits and rats, new tissue formation was mainly limited to osteoid. The results of this study confirmed that the incidence and the extent of material-induced bone formation are related to both the physicochemical properties of calcium phosphate ceramics and the animal model. PMID:25229501

Complementary effects of multi-protein components on biomineralization in vitro

PubMed Central

Ba, Xiaolan; Rafailovich, Miriam; Meng, Yizhi; Pernodet, Nadine; Wirick, Sue; Füredi-Milhofer, Helga; Qin, Yi-Xian; DiMasi, Elaine

2016-01-01

The extracellular matrix (ECM) is composed of mixed protein fibers whose precise composition affects biomineralization. New methods are needed to probe the interactions of these proteins with calcium phosphate mineral and with each other. Here we follow calcium phosphate mineralization on protein fibers self-assembled in vitro from solutions of fibronectin, elastin and their mixture. We probe the surface morphology and mechanical properties of the protein fibers during the early stages. The development of mineral crystals on the protein matrices is also investigated. In physiological mineralization solution, the elastic modulus of the fibers in the fibronectin-elastin mixture increases to a greater extent than that of the fibers from either pure protein. In the presence of fibronectin, longer exposure in the mineral solution leads to the formation of amorphous calcium phosphate particles templated along the self-assembled fibers, while elastin fibers only collect calcium without any mineral observed during early stage. TEM images confirm that small needle-shape crystals are confined inside elastin fibers which suppress the release of mineral outside the fibers during late stage, while hydroxyapatite crystals form when fibronectin is present. These results demonstrate complementary actions of the two ECM proteins fibronectin and elastin to collect cations and template mineral, respectively. PMID:20035875

Magnesium-containing mixed coatings on zirconia for dental implants: mechanical characterization and in vitro behavior.

PubMed

Pardun, Karoline; Treccani, Laura; Volkmann, Eike; Streckbein, Philipp; Heiss, Christian; Gerlach, Juergen W; Maendl, Stephan; Rezwan, Kurosch

2015-07-01

An important challenge in the field of dental and orthopedic implantology is the preparation of implant coatings with bioactive functions that feature a high mechanical stability and at the same time mimic structural and compositional properties of native bone for a better bone ingrowth. This study investigates the influence of magnesium addition to zirconia-calcium phosphate coatings. The mixed coatings were prepared with varying additions of either magnesium oxide or magnesium fluoride to yttria-stabilized zirconia and hydroxyapatite. The coatings were deposited on zirconia discs and screw implants by wet powder spraying. Microstructure studies confirm a porous coating with similar roughness and firm adhesion not hampered by the coating composition. The coating morphology, mechanical flexural strength and calcium dissolution showed a magnesium content-dependent effect. Moreover, the in vitro results obtained with human osteoblasts reveal an improved biological performance caused by the presence of Mg(2+) ions. The magnesium-containing coatings exhibited better cell proliferation and differentiation in comparison to pure zirconia-calcium phosphate coatings. In conclusion, these results demonstrate that magnesium addition increases the bioactivity potential of zirconia-calcium phosphate coatings and is thus a highly suitable candidate for bone implant coatings. © The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Calcium carbonate gallstones in children.

PubMed

Stringer, Mark D; Soloway, Roger D; Taylor, Donald R; Riyad, Kallingal; Toogood, Giles

2007-10-01

In the United States, cholesterol stones account for 70% to 95% of adult gallstones and black pigment stones for most of the remainder. Calcium carbonate stones are exceptionally rare. A previous analysis of a small number of pediatric gallstones from the north of England showed a remarkably high prevalence of calcium carbonate stones. The aims of this study were to analyze a much larger series of pediatric gallstones from our region and to compare their chemical composition with a series of adult gallstones from the same geographic area. A consecutive series of gallbladder stones from 63 children and 50 adults from the north of England were analyzed in detail using Fourier transform infrared microspectroscopy. Demographic and clinical data were collected on all patients. The relative proportions of each major stone component were assessed: cholesterol, protein and calcium salts of bilirubin, fatty acids, calcium carbonate, and hydroxyapatite. Thirty-nine (78%) adults had typical cholesterol stones, 7 (14%) had black pigment bilirubinate stones, and only 2 (4%) had calcium carbonate stones. In contrast, 30 (48%) children had black pigment stones, 13 (21%) had cholesterol stones, 15 (24%) had calcium carbonate stones, 3 (5%) had protein dominant stones, and 2 (3%) had brown pigment stones. In children, cholesterol stones were more likely in overweight adolescent girls with a family history of gallstones, whereas black pigment stones were equally common in boys and girls and associated with hemolysis, parenteral nutrition, and neonatal abdominal surgery. Calcium carbonate stones were more common in boys, and almost half had undergone neonatal abdominal surgery and/or required neonatal intensive care. The composition of pediatric gallstones differs significantly from that found in adults. In particular, one quarter of the children in this series had calcium carbonate stones, previously considered rare. Geographic differences are not the major reason for the high prevalence of calcium carbonate gallstones in children.

Addition of a Fluoride-containing Radiopacifier Improves Micromechanical and Biological Characteristics of Modified Calcium Silicate Cements.

PubMed

Antonijevic, Djordje; Jeschke, Anke; Colovic, Bozana; Milovanovic, Petar; Jevremovic, Danimir; Kisic, Danilo; vom Scheidt, Annika; Hahn, Michael; Amling, Michael; Jokanovic, Vukoman; Busse, Björn; Djuric, Marija

2015-12-01

Calcium silicate cements (CSCs) with the addition of nanohydroxyapatite and calcium carbonate play a critical role in dental applications. To further improve their properties, particularly radiopacity and biointeractivity, the fluoride-containing radiopacifier ytterbium trifluoride (YbF3) was added to their composition, and biological and mechanical characteristics were evaluated. YbF3 was added to 3 different CSCs: cement I (CSC + calcium carbonate), cement II (CSC + nanohydroxyapatite), and Portland cement. Material characterization encompassed measurements of pH, calcium, ytterbium, and fluoride ion release; radiopacity; setting time; porosity; microindentation properties; wettability; and Fourier transform infrared spectroscopic, x-ray diffraction, and scanning electron microscopic analyses. Osteoblast- and osteoclast-like cells were grown on the materials' surface to evaluate their adherence. The addition of calcium carbonate, nanohydroxyapatite, and 30 wt% of YbF3 improved radiopacity and the setting time of experimental cements. The pH values did not differ among the groups. The greatest ytterbium and fluoride releases occurred in the Portland cement + YbF3 group. Combined x-ray diffraction and Fourier transform infrared spectroscopic analysis showed the presence of calcium hydroxide and calcium silicate hydrates. In addition, the presence of calcium ytterbium fluoride and ytterbium oxide proved that YbF3 reacted with cement compounds. Wettability of cement I + YbF3 was superior to other formulations, but its porosity and microindentation properties were weaker than in the Portland cement + YbF3 mixture. Cement II + YbF3 presented micromechanical indentation and porosity characteristics similar to the Portland-based cement formulation. Osteoclast- and osteoblast-like cells adhered to the cements' surfaces without alteration of the cell structural integrity. YbF3-containing CSCs with nanostructured hydroxyapatite and calcium carbonate are well suited for dental application. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Synergistic anticancer efficacy of Bendamustine Hydrochloride loaded bioactive Hydroxyapatite nanoparticles: In-vitro, ex-vivo and in-vivo evaluation.

PubMed

Thomas, Shindu C; Sharma, Harshita; Rawat, Purnima; Verma, Anita K; Leekha, Ankita; Kumar, Vijay; Tyagi, Aakriti; Gurjar, Bahadur S; Iqbal, Zeenat; Talegaonkar, Sushama

2016-10-01

The present work evaluates the synergistic anticancer efficacy of bioactive Hydroxyapatite (HA) nanoparticles (HA NPs) loaded with Bendamustine HCl. Hydroxyapatite is a material with an excellent biological compatibility, a well-known fact which was also supported by the results of the Hemolytic studies and a high IC50 value observed in the MTT assay. HA NPs were prepared by the chemical precipitation method and loaded with the drug via physical adsorption. In-vitro release study was performed, which confirmed the sustained release of the drug from the drug loaded HA NPs. MTT assay, Cell Uptake and FACS studies on JURKAT E6.1 cell line and in-vivo pharmacokinetic studies in Wistar rats revealed that the drug loaded HA NPs could be easily internalized by the cells and release drug in a sustained manner. The drug loaded HA NPs showed cytotoxicity similar to the drug solution at 1/10th of the drug content, which indicates a possible synergism between the activity of the anticancer drug and calcium ions derived from the carrier. An increase in intracellular Ca(2+) ions is reported to induce apoptosis in cells. Tumor regression study in Balb/c mice Ehrlich's ascites model presented a similar synergistic efficacy. The drug solution was able to decrease the tumor volume by half, while the drug loaded HA NPs reduced the tumor size by 6 times. Copyright © 2016 Elsevier B.V. All rights reserved.

Improved degradation and bioactivity of amorphous aerosol derived tricalcium phosphate nanoparticles in poly(lactide-co-glycolide)

NASA Astrophysics Data System (ADS)

Loher, Stefan; Reboul, Valentine; Brunner, Tobias J.; Simonet, Marc; Dora, Claudio; Neuenschwander, Peter; Stark, Wendelin J.

2006-04-01

The industrially used flame synthesis of silica polymer fillers was extended to amorphous tricalcium phosphate (a-TCP) nanoparticles and resulted in a similar morphology as the traditionally used polymer fillers. Doping of poly(lactide-co-glycolide) (PLGA) with such highly agglomerated a-TCP was investigated for mechanical properties, increased in vitro biodegradation and the formation of a hydroxyapatite layer on the surface of the nanocomposite. PLGA films with particle loadings ranging from 0 to 30 wt% were prepared by solvent casting. Degradation in simulated body fluid (SBF) at 37 °C under sterile conditions for up to 42 days was followed by Raman spectroscopy, scanning electron microscopy (SEM), thermal analysis and tensile tests. The presence of nanoparticles in the PLGA matrix slightly increased the Young's modulus up to 30% compared to pure polymer reference materials. The nanoparticle doped films showed a significantly increased loss of polymer mass during degradation. Scanning electron microscopy images of doped films showed that the SBF degraded the PLGA by corrosion as facilitated by the incorporation of nanoparticulate calcium phosphate. Raman spectroscopy revealed that the deposition of about 10 nm sized hydroxyapatite crystallites on the surface of doped PLGA films was strongly increased by the addition of tricalcium phosphate fillers. The combination of increased hydroxyapatite formation and enhanced polymer degradation may suggest the use of such amorphous, aerosol derived a-TCP fillers for applications in non-load-bearing implant sites.

Synthesis and characterisation of composite based biohydroxyapatite bovine bone mandible waste (BHAp) doped with 10 wt % amorphous SiO{sub 2} from rice husk by solid state reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asmi, Dwi, E-mail: dwiasmi82@yahoo.com, E-mail: dwi.asmi@fmipa.unila.ac.id; Sulaiman, Ahmad, E-mail: ahmadsulaiman@yahoo.co.id; Oktavia, Irene Lucky, E-mail: ireneluckyo@gmail.com

Effect of 10 wt% amorphous SiO{sub 2} from rice husk addition on the microstructures of biohydroxyapatite (BHAp) obtained from bovine bone was synthesized by solid state reaction. In this study, biohydroxyapatite powder was obtained from bovine bone mandible waste heat treated at 800 °C for 5 h and amorphous SiO{sub 2} powder was extracted from citric acid leaching of rice husk followed by combustion at 700°C for 5 h. The composite powder then mixed and sintered at 1200 °C for 3 h. X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy and Scanning electron microscopy (SEM) techniques are utilized to characterize the phase relations,more » functional group present and morphology of the sample. The study has revealed that the processing procedures played an important role in microstructural development of BHAp-10 wt% SiO{sub 2} composite. The XRD study of the raw material revealed that the primary phase material in the heat treated of bovine bone mandible waste is hydroxyapatite and in the combustion of rice husk is amorphous SiO{sub 2}. However, in the composite the hydroxyapatite, β-tricalcium phosphate, and calcium phosphate silicate were observed. The FTIR result show that the hydroxyl stretching band in the composite decrease compared with those of hydroxyapatite spectra and the evolution of morphology was occurred in the composite.« less