These are representative sample records from related to your search topic.
For comprehensive and current results, perform a real-time search at

Osteoinduction by calcium phosphate biomaterials  

Microsoft Academic Search

Different materials were implanted in muscles of dogs to study the osteoinduction of calcium phosphate biomaterials. Bone formation was only seen in calcium phosphate biomaterials with micropores, and could be found in hydroxyapatite (HA) ceramic, tricalcium phosphate\\/hydroxyapatite ceramic (BCP), ß-TCP ceramic and calcium phosphate cement. The osteoinductive potential was different in different materials. The results indicate that osteoinduction can be

Huipin Yuan; Zongjian Yang; Yubao Li; Xingdong Zhang; J. D. De Bruijn; K. De Groot



Calcium Phosphate Biomaterials: An Overview  

Microsoft Academic Search

Calcium phosphates are used by our body to build bones and are being applied to produce biomaterials for bone repair. It is\\u000a well-known that calcium phosphate biomaterials guide new bone formation, form a tight bond with the newly formed bone, and\\u000a are therefore, by definition, osteoconductive. Besides their osteoconductive property, it was found that calcium phosphate\\u000a biomaterials, only with specific



Thermochemical studies on amorphous calcium phosphate  

Microsoft Academic Search

Previous studies have indicated that synthetically-precipitated amorphous calcium phosphate, even though not a periodically regular structure, possesses a chemically definable local unit of structure. The present paper is a report of thermochemical studies performed to more clearly define this local chemical unit. Upon ignition in the absence of water, freezedried amorphous calcium phosphate preparations converted into crystalline ?-and\\/or ?-tricalcium phosphates.

E. D. EAglES



The Nature of PO Bonds in the Precipitated Amorphous Calcium Phosphates and Calcium Magnesium Phosphates  

Microsoft Academic Search

The nature of the P-O bonds in amorphous calcium phosphates and calcium magnesium phosphates precipitated from aqueous solutions of monophosphate in the presence of crystallization inhibitors (diphosphate and the magnesium salt) is studied by Raman spectroscopy.

V. A. Sinyayev; E. S. Shustikova; D. Griggs; D. V. Dorofeev



Next generation calcium phosphate-based biomaterials  

PubMed Central

It has been close to a century since calcium phosphate materials were first used as bone graft substitutes. Numerous studies conducted in the last two decades have produced a wealth of information on the chemistry, in vitro properties, and biological characteristics of granular calcium phosphates and calcium phosphate cement biomaterials. An in depth analysis of several key areas of calcium phosphate cement properties is presented with the aim of developing strategies that could lead to break-through improvements in the functional efficacies of these materials. PMID:19280963

LC, Chow



Enzyme-catalysed synthesis of calcium phosphates  

Microsoft Academic Search

A biomimetic method is described for the precipitation of nanosized calcium phosphates using the alkaline phosphatase (EC\\u000a, which is responsible for hydrolysis of organic and inorganic phosphates in vivo. Buffered solutions containing glycerol-2-phosphate\\u000a and CaCl2 in addition to MgCl2 and the respective enzyme were prepared for calcium phosphate precipitation. The phosphate group of glycerol-2-phosphate\\u000a was cleaved through enzymatic hydrolysis. The

Christiane Hoffmann; Cordt Zollfrank; Günter Ziegler



Green chemical synthesis of calcium phosphate bioceramics.  


A standard preparation technique of the graft relevant calcium phosphates (which includes the dissolution of watersoluble compounds containing calcium cations and phosphate anions, the slow addition of one solution into another under alkaline pH, followed by aging, suspension separation, washing off, drying and sintering at elevated temperatures) has been reconsidered from an environmental point of view. The entire process has been simplified to a single stage, and a number of intermediate stages have been excluded without influencing the quality of the final products. In this report, we launch a new environmentally friendly preparation technique of calcium phosphate bioceramics for potential use as bone grafts. PMID:20740453

Dorozhkin, S V



Calcium phosphate, bile acids and colorectal cancer.  


The biochemical and nutritional studies discussed here are consistent with the model presented in Figure 1. As shown in vitro, bile acids are precipitated by insoluble calcium phosphate. This calcium phosphate dependent precipitation drastically inhibits their cytotoxicity. A diet-induced increase in luminal surfactant concentration stimulates lytic activity of faecal water and intestinal cell damage resulting in an increased proliferation. The increase in luminal surfactant concentration and lytic activity of faecal water can be counteracted by supplemental dietary calcium phosphate. Supplemental calcium in humans increases the formation of insoluble calcium-phosphate-bile acid complexes in faeces, decreases the soluble fatty acid concentration and decreases lytic activity of faecal water. This sequence of effects offers a molecular explanation of the protective effects of supplemental calcium on proliferation as frequently observed (see studies cited above). It should be realised that this chain of evidence still lacks final proof of a preventive effect of dietary calcium on colorectal cancer. Until now, only protective effects on the first stage of development of colorectal cancer (hyperproliferation) have been observed. More well-designed studies in patients and healthy volunteers are needed using a combined biochemical, nutritional and clinical approach to elucidate the complex mechanism of the protective effect of calcium on colon cancer. PMID:1842734

Van der Meer, R; Kleibeuker, J H; Lapré, J A



Calcium phosphate deposition from balanced salt solutions  

Microsoft Academic Search

Minimal levels of calcium and phosphate ions necessary to induce mineral deposition within 24 hours at 37° from balanced salt solutions buffered in the physiological pH range are described. It is concluded that most physiological fluids apparently have the potential to form calcium phosphatede novo in the absence of any nucleating catalyst or inhibitory agent. The possible effects that external

J. D. Termine; E. D. Eanes



Thermally Triggered Calcium Phosphate Formation from Calcium-Loaded Liposomes  

E-print Network

Thermally Triggered Calcium Phosphate Formation from Calcium-Loaded Liposomes Phillip B 15, 1997X A thermally triggered liposome-based mineralization system is described that is metastable liposome suspension whose bulk ionic concentration was highly supersaturated with respect to hydroxyapatite


Direct complexometric titration of calcium phosphates.  


Calcium was determined in calcium phosphate samples by dissolving the sample in hydrochloric acid, adding hydroxynaphthol blue indicator and triethanolamine, adjusting the pH to 12.3--12.5 with potassium hydroxide solution, and titrating with standard disodium ethylenediaminetetraacetate solution. Time can be saved and the formation of a precipitate (which dissolves readily during the titration) can be avoided by adding at least 85% of the amount of complexing agent required for titration before adjusting the pH. PMID:903881

Tuckerman, M M; Sanchez de Ramos, M E



Effects of humic material on the precipitation of calcium phosphate  

Microsoft Academic Search

Soil organic acids such as humic and fulvic acids can play an important role in influencing inorganic phosphate availability in P-fertilized soils by inhibiting formation of thermodynamically stable calcium phosphates. Calcium phosphate phases which are important in these systems may include amorphous calcium phosphate (Ca9(PO4)6·nH2O; ACP), dicalcium phosphate dihydrate (CaHPO4·2H2O; DCPD, also known as brushite), octacalcium phosphate (Ca8H2(PO4)6·5H2O; OCP) and

Rebeca Alvarez; Louise A. Evans; Paul J. Milham; Michael A. Wilson



Preparation of Calcium-Loaded Liposomes and Their Use in Calcium Phosphate Formation  

E-print Network

Preparation of Calcium-Loaded Liposomes and Their Use in Calcium Phosphate Formation Phillip B Received October 15, 1997X Liposome encapsulation technology has been used to entrap aqueous calcium salts of unencapsulated calcium by ion exchange resulted in calcium-loaded liposome suspensions with calcium concentration


Effects of supplemental dietary calcium on the intestinal association of calcium, phosphate, and bile acids.  


It has been suggested that supplemental dietary calcium decreases hyperproliferation of colonic epithelial cells because calcium precipitates and thus inactivates luminal bile acids. Therefore, 12 healthy men were studied before and after dietary calcium supplementation (35.5 mmol/day) to quantify intestinal associations of calcium, phosphate, and bile acids. The supplemental dietary calcium was almost completely (95%) recovered, mainly in feces. Calcium increased the fecal excretion of both phosphate (31%) and bile acids (53%) and decreased the ratio of dihydroxy to trihydroxy bile acids in duodenal bile almost twofold. In vitro studies showed that precipitation of glycodeoxycholic acid was caused by the formation of insoluble calcium phosphate. Water-soluble and calcium-associated amounts of phosphate and bile acids in feces were measured by resolubilization studies, using the calcium chelator ethylenediaminetetraacetate. In both the control and calcium periods, significant amounts of phosphate (80% and 90%) and bile acids (33% and 50%) were calcium-associated. Moreover, the calcium-induced increments in fecal phosphate and bile acids were completely calcium-associated. Calcium decreased the amount of water-soluble phosphate but not of bile acids. These results indicate that supplemental calcium stimulates formation of insoluble calcium phosphate in the intestinal lumen and thus increases binding of luminal bile acids. PMID:2121581

Van der Meer, R; Welberg, J W; Kuipers, F; Kleibeuker, J H; Mulder, N H; Termont, D S; Vonk, R J; De Vries, H T; De Vries, E G



de Lange Lab Calcium Phosphate Transfection of 293T Cells  

E-print Network

de Lange Lab 1 Calcium Phosphate Transfection of 293T Cells Required Solutions and Reagents Lysis. . #12;Calcium Phosphate Transfection of 293T cells 2 Transfection 1. Twenty-four hours prior to transfection, inoculate 1 to 2 x106 cells/10 cm plate (or, inoculate 3x106 cells/plate 16-hours prior

de Lange, Titia


Biphasic calcium phosphate bioceramics: preparation, properties and applications  

Microsoft Academic Search

Biphasic calcium phosphate (BCP) bioceramics belong to a group of bone substitute biomaterials that consist of an intimate mixture of hydroxyapatite (HA), Ca10(PO4)6(OH)2, and beta-tricalcium phosphate (ß-TCP), Ca3(PO4)2, of varying HA\\/ß-TCP ratios. BCP is obtained when a synthetic or biologic calcium-deficient apatite is sintered at temperatures at and above 700 °C. Calcium deficiency depends on the method of preparation (precipitation,

R. Z. LeGeros; S. Lin; R. Rohanizadeh; D. Mijares; J. P. LeGeros



Calcium phosphate nanoparticles for transcutaneous vaccine delivery.  


The main objective of this study was to investigate the potential of calcium phosphate (CAP) nanoparticles for transcutaneous vaccine delivery. CAP nanoparticles were prepared by nanoprecipitation method followed by sequential adsorption of sugars and ovalbumin. Nanoparticles were characterized using dynamic light scattering, XRD, ATR-FTIR, and microscopy methods. In-vitro release of ovalbumin from nanoparticles was studied in phosphate buffer (pH 7.4). In-vivo immunization studies were carried out in Balb/C mice. The size and zeta potential of ovalbumin-sugar adsorbed CAP nanoparticles was 350 +/- 22.5 nm and -12.93 +/- 1.02 mV respectively. Around 60% ovalbumin was released from nanoparticles within 24 hrs. To test the feasibility for transcutaneous vaccine delivery, the nanoparticles were applied in mice after removing the stratum corneum by tape-stripping. In the positive control group, the nanoparticles were administered by intradermal injection. Ovalbumin-sugar coated CAP nanoparticles showed significantly higher antibody titers (Total IgG and IgG1) compared to ovalbumin alone. IgG2a antibodies were only seen with intradermal injection. Both topical and intradermal treatment groups showed splenocyte proliferation when re-stimulated with ovalbumin. The results from this study demonstrate the potential of using CAP nanoparticles for transcutaneous vaccine delivery. PMID:23627076

Sahdev, Preety; Podaralla, Satheesh; Kaushik, Radhey S; Perumal, Omathanu



Chemistry misconceptions associated with understanding calcium and phosphate homeostasis  

NSDL National Science Digital Library

Successful learning of many aspects in physiology depends on a meaningful understanding of fundamental chemistry concepts. Two conceptual diagnostic questions measured student understanding of the chemical equilibrium underlying calcium and phosphate homeostasis. One question assessed the ability to predict the change in phosphate concentration when calcium ions were added to a saturated calcium phosphate solution. Fifty-two percent of the students correctly predicted that the phosphate concentration would decrease in accord with the common ion effect. Forty-two percent of the students predicted that the phosphate concentration would not change. Written explanations showed that most students failed to evoke the idea of competing chemical equilibria. A second question assessed the predicted change in calcium concentration after solid calcium phosphate was added to a saturated solution. Only 11% of the students correctly predicted no change in calcium concentration; 86% of the students predicted an increase, and many based their prediction on a mistaken application of Le Chatelier's principle to heterogeneous equilibria. These results indicate that many students possess misconceptions about chemical equilibrium that may hamper understanding of the processes of calcium and phosphate homeostasis. Instructors can help students gain greater understanding of these physiochemical phenomena by adopting strategies that enable students achieve more accurate conceptions of chemical equilibria.

William H. Cliff (Niagara University Biology)



Biological calcium phosphates and Posner's cluster  

NASA Astrophysics Data System (ADS)

A calcium phosphate amorphous to x-ray diffraction (ACP) exists in bone mineral in addition to the main bone apatite component, such as hydroxyapatite (HA). Experimental studies found that ACP has definite local atomic order and contains microcrystallites about 9.5 Å in extent rather than a random network structure. Experimental evidence indicates that Posner's cluster (PC), Ca9(PO4)6, could be the basic component of ACP. In addition, it is present in various simulated body fluids and could be the growth unit of HA. In the transformation from ACP to HA, ACP need only dissociate into the clusters rather than undergo complete ionic solvation. Although PC could bridge the biologically important gap between ACP and HA, the form it is likely to take in body fluids is not known. In this study, we have performed ab initio density functional calculations to investigate the structure and stability of PC alone in vacuum and in the presence of H+, OH-, Na+, and Cl- ions mimicing the interaction with water and other constituents of body fluids. We find that the cluster with C1 symmetry is the most stable isomer in vacuum. The interaction of PC with sodium ions and especially with protons leads to a great increase in its stability and surprisingly, the cluster with six protons and six OH- recovers the C3 symmetry and similar atomic arrangement it has as a structural unit in HA crystal. This may be a key factor in the transformation from ACP to HA crystal.

Yin, Xilin; Stott, Malcolm J.



Review of casein phosphopeptides-amorphous calcium phosphate.  


Casein phosphopeptides-amorphous calcium phosphate (CPP-ACP) is a bioactive agent with a base of milk products, which has been formulated from two parts: casein phosphopeptides (CPP) and amorphous calcium phosphate (ACP). CPP was produced from milk protein casein and has a remarkable ability to stabilize calcium phosphate in solution and to substantially increase the level of calcium phosphate in dental plaque. CPP-ACP buffers the free calcium and phosphate ion activities, thereby helping to maintain a state of supersaturation with respect to tooth enamel, reducing demineralisation and promoting remineralisation. The free calcium and phosphate ions move out of the CPP, enter the enamel rods and reform onto apatite crystals. Laboratory, animal and human studies have shown that CPP-ACP inhibits cariogenic activity. CPP-ACP is useful in the treatment of white spot lesions, hypomineralised enamel, mild fluorosis, tooth sensitivity and erosion, and prevents plaque accumulation around brackets and other orthodontic appliances. CPP-ACP also facilitates a normal post-eruptive maturation process and is ideal for protecting primary teeth at a time when oral care is difficult. CPP-ACP has commercial potential as an additive to foods, soft drinks and chewing gum, as well as additive to toothpastes and mouthwashes to control dental caries. PMID:25028684

Reema, Sharma Dhar; Lahiri, Prateek Kumar; Roy, Shantanu Sen



Chemistry Misconceptions Associated with Understanding Calcium and Phosphate Homeostasis  

ERIC Educational Resources Information Center

Successful learning of many aspects in physiology depends on a meaningful understanding of fundamental chemistry concepts. Two conceptual diagnostic questions measured student understanding of the chemical equilibrium underlying calcium and phosphate homeostasis. One question assessed the ability to predict the change in phosphate concentration…

Cliff, William H.



Original article Acid gelation of colloidal calcium phosphate-  

E-print Network

Original article Acid gelation of colloidal calcium phosphate- depleted preheated milk Marie Research, RD 128, 91767 Palaiseau Cedex, France Received 25 September 2008 ­ Accepted 23 March 2009 of milk. Milks were depleted in Calcium (Ca) by dialysis against milk permeate containing a cation

Paris-Sud XI, Université de


Oral phosphate binders in CKD - is calcium the (only) answer?  


All-cause mortality and cardiovascular- related mortality have both been linked to abnormal serum phosphate concentrations in chronic kidney disease (CKD). Aberrant serum phosphate concentration in patients with CKD has also been associated with adverse cardiac and renal outcomes. Early prevention or management of rising or high serum phosphate concentrations in patients with CKD is now considered to be an important intervention to prevent downstream complications resulting from the poor management of serum calcium and parathyroid hormone (PTH). It is widely considered that starting phosphate binder therapy early, with concurrent dietary management of serum phosphate, constitutes an effective course of interventions, although normalization of serum phosphate in dialysis patients remains atypical, unless specific dialytic measures are also undertaken. Calcium- based phosphate binders are often the first type of binders prescribed due to their low cost. Evidence shows that most phosphate binders are roughly equally effective in lowering serum phosphate concentrations in adults compared to placebo, with a small probability that sevelamer hydrochloride is better than calcium acetate or lanthanum carbonate. However, not all binders are created equal in regards to their safety profiles. The potential for accumulations and toxicities does exist with very long-term continuous exposure. We discuss these issues in the course of this review. PMID:25017668

Goldsmith, David; Covic, Adrian



Osteoinductivity of Calcium Phosphate Mediated by Connexin 43  

PubMed Central

Recent reports have alluded to the osteoinductive properties of calcium phosphate, yet the cellular processes behind this are not well understood. To gain insight into the molecular mechanisms of this phenomenon, we have conducted a series of in vitro and in vivo experiments using a scaffoldless three dimensional (3D) dental pulp cell (DPC) construct as a physiologically relevant model. We demonstrate that amorphous calcium phosphate (ACP) alters cellular functions and 3D spatial tissue differentiation patterns by increasing local calcium concentration, which modulates connexin 43 (Cx43)-mediated gap junctions. These observations indicate a chemical mechanism for osteoinductivity of calcium phosphates. These results provide new insights for possible roles of mineral phases in bone formation and remodeling. This study also emphasizes the strong effect of scaffold materials on cellular functions and is expected to advance the design of future tissue engineering materials. PMID:23465492

Syed-Picard, Fatima N.; Jayaraman, Thottala; Lam, Raymond S.K.; Beniash, Elia; Sfeir, Charles



ESR spectra of VO 2+ ions adsorbed on calcium phosphates  

Microsoft Academic Search

Summary  The ESR spectra of oxovanadium(IV) ions, (VO2+), adsorbed on hydroxyapatite(OHAp), fluorhydroxyapatite(FHAp), Mg-containing tricalcium phosphate(Mg-TCP), octacalcium phosphate\\u000a (OCP), dicalcium phosphate dihydrate (DCPD), and amorphous calcium phosphate(ACP) were measured at room temperature. The ESR\\u000a parameters of VO2+ adsorbed on these compounds were slightly different from one another and accordingly, the ESR technique by use of VO2+ was useful for an analysis of

T. Oniki; Y. Doi



Differences in gastrointestinal calcium absorption after the ingestion of calcium-free phosphate binders.  


Both calcium-containing and noncalcium-containing phosphate binders can increase gastrointestinal calcium absorption. Previously, we observed that lanthanum carbonate administration to rats with renal failure is not associated with increased calciuria. Additionally, lanthanum carbonate treatment in dialysis patients has been associated with a less pronounced initial decrease in serum parathyroid hormone compared with other phosphate binders. For 8 days, male Wistar rats received a diet supplemented with 2% lanthanum carbonate, 2% sevelamer, 2% calcium carbonate, or 2% cellulose. Calciuria was found to be increased in animals with normal renal function treated with sevelamer or calcium carbonate but not with lanthanum carbonate. In animals with renal failure, cumulative calcium excretion showed similar results. In rats with normal renal function, serum ionized calcium levels were increased after 2 days of treatment with sevelamer, while calcium carbonate showed a smaller increase. Lanthanum carbonate did not induce differences. In animals with renal failure, no differences were found between sevelamer-treated, calcium carbonate-treated, and control groups. Lanthanum carbonate, however, induced lower ionized calcium levels within 2 days of treatment. These results were confirmed in normal human volunteers, who showed lower net calcium absorption after a single dose of lanthanum carbonate compared with sevelamer carbonate. In conclusion, these two noncalcium-containing phosphate-binding agents showed a differential effect on gastrointestinal calcium absorption. These findings may help to improve the management of calcium balance in patients with renal failure, including concomitant use of vitamin D. PMID:24197066

Behets, Geert J; Dams, Geert; Damment, Stephen J; Martin, Patrick; De Broe, Marc E; D'Haese, Patrick C



The stability mechanisms of an injectable calcium phosphate ceramic suspension  

PubMed Central

Calcium phosphate ceramics are widely used as bone substitutes in dentistry and orthopedic applications. For minimally invasive surgery an injectable calcium phosphate ceramic suspension (ICPCS) was developed. It consists in a biopolymer (hydroxypropylmethylcellulose: HPMC) as matrix and bioactive calcium phosphate ceramics (biphasic calcium phosphate: BCP) as fillers. The stability of the suspension is essential to this generation of “ready to use” injectable biomaterial. But, during storage, the particles settle down. The engineering sciences have long been interested in models describing the settling (or sedimentation) of particles in viscous fluids. Our work is dedicated to the comprehension of the effect of the formulation on the stability of calcium phosphate suspension before and after steam sterilization. The rheological characterization revealed the macromolecular behavior of the suspending medium. The investigations of settling kinetics showed the influence of the BCP particle size and the HPMC concentration on the settling velocity and sediment compactness before and after sterilization. To decrease the sedimentation process, the granule size has to be smaller and the polymer concentration has to increase. A much lower sedimentation velocity, as compared to Stokes law, is observed and interpreted in terms of interactions between the polymer network in solution and the particles. This experimentation highlights the granules spacer property of hydrophilic macromolecules that is a key issue for interconnection control, one of the better ways to improve osteoconduction and bioactivity. PMID:20229185

Fatimi, Ahmed; Tassin, Jean-Francois; Axelos, Monique A. V.; Weiss, Pierre



In vitro calcium phosphate growth over surface modified PMMA film.  


In vitro nucleation of calcium phosphate phase was studied over functionalized polymethyl methacrylate (PMMA) films using Fourier transform infrared spectroscopy, electron spectroscopy, scanning electron microscopy and energy dispersive X-ray analysis. PMMA films were prepared by dissolving commercial grade pellets in chloroform and cast into thin sheets. The films were immersed in a methanol solution of sodium hydroxide before treating with 1.5% solution of adenosine triphosphate (ATP) at a pH of 5.2 for 24 h. ATP treated films were then soaked in saturated lime solution for 4 days to initiate formation of calcium phosphate precursor phase over their surface. The above films immersed in simulated body fluid solution (1.5 x SBF) for more than 5 days led to the nucleation of apatitic calcium phosphate phase all over the film surface. The ATP coupled film not subjected to lime treatment did not show calcium phosphate nucleation behaviour upon immersion in SBF solution. The Ca/P ratio of the calcium phosphate phase increase with increase in soaking time in SBF solution. PMID:12419631

Varma, H K; Sreenivasan, K; Yokogawa, Y; Hosumi, A



Amorphous calcium phosphate in casein micelles of bovine milk.  


The calcium phosphate remaining after hydrazine deproteination of casein micelles isolated from bulk skim milk exhibits under the electron microscope a very fine and uniform granularity being formed by small subunits with a true diameter of approximately 2.5 nm. This material, which is about 10 percent by weight citrate, termed calcium phosphate citrate (CPC) complex, also contains Mg and Zn at molar ratios of 0.03 and 0.003 respectively. Radial distribution function (RDF) and infrared analyses show that CPC is a Mg-containing amorphous calcium phosphate (ACP) similar to synthetic and cytoplasmic ACP. presence of CPC in casein micelles as an amorphous colloid bonded with phosphoproteins provides the means for storing in milk large amounts of Ca (16 mM) and Pi (10 mM) in a readily utilizable form but at a higher ion concentration than found in biological solutions. PMID:6652558

McGann, T C; Kearney, R D; Buchheim, W; Posner, A S; Betts, F; Blumenthal, N C



Phosphate-bonded calcium aluminate cements  


A method is described for making a rapid-setting phosphate-bonded cementitious material. A powdered aluminous cement is mixed with an aqueous solution of ammonium phosphate. The mixture is allowed to set to form an amorphous cementitious material which also may be hydrothermally treated at a temperature of from about 120 C to about 300 C to form a crystal-containing phosphate-bonded material. Also described are the cementitious products of this method and the cement composition which includes aluminous cement and ammonium polyphosphate. 10 figures.

Sugama, T.



Fiber-enriched double-setting calcium phosphate bone cement.  


Calcium phosphate bone cements are useful in orthopedics and traumatology, their main advantages being their biocompatibility and bioactivity, which render bone tissue osteoconductive, providing in situ hardening and easy handling. However, their low mechanical strength, which, in the best of cases, is equal to the trabecular bone, and their very low toughness are disadvantages. Calcium phosphate cement compositions with mechanical properties more closely resembling those of human bone would broaden the range of applications, which is currently limited to sites subjected to low loads. This study investigated the influence of added polypropylene, nylon, and carbon fibers on the mechanical properties of double setting alpha-tricalcium phosphate-based cement, using calcium phosphate cement added to an in situ polymerizable acrylamide-based system recently developed by the authors. Although the addition of fibers was found to reduce the compression strength of the double-setting calcium phosphate cement because of increased porosity, it strongly increased the cement's toughness (J(IC)) and tensile strength. The composites developed in this work, therefore, have a potential application in shapes subjected to flexure. PMID:12734819

dos Santos, Luís Alberto; Carrodéguas, Raúl Garcia; Boschi, Anselmo Ortega; Fonseca de Arruda, Antônio Celso



Gelatin powders accelerate the resorption of calcium phosphate cement and improve healing in the alveolar ridge.  


The aim of this study was to show the effectiveness of combining calcium phosphate cement and gelatin powders to promote bone regeneration in the canine mandible. We mixed gelatin powders with calcium phosphate cement to create a macroporous composite. In four beagle dogs, two saddle-type bone defects were created on each side of the mandible, and calcium phosphate cement alone or calcium phosphate cement containing composite gelatin powders was implanted in each of the defects. After a healing period of six months, mandibles were removed for µCT and histological analyses. The µCT and histological analyses showed that at experimental sites at which calcium phosphate cement alone had been placed new bone had formed only around the periphery of the residual calcium phosphate cement and that there had been little or no ingrowth into the calcium phosphate cement. On the other hand, at experimental sites at which calcium phosphate cement containing composite gelatin powders had been placed, we observed regenerated new bone in the interior of the residual calcium phosphate cement as well as around its periphery. The amount of resorption of calcium phosphate cement and bone regeneration depended on the mixing ratio of gelatin powders to calcium phosphate cement. New bone replacement was significantly better in the sites treated with calcium phosphate cement containing composite gelatin powders than in those treated with calcium phosphate cement alone. PMID:24105428

Matsumoto, Goichi; Sugita, Yoshihiko; Kubo, Katsutoshi; Yoshida, Waka; Ikada, Yoshito; Sobajima, Satoshi; Neo, Masashi; Maeda, Hatsuhiko; Kinoshita, Yukihiko



Lanthanum Oxide Effects on the Structure of Calcium Phosphate Glasses  

Microsoft Academic Search

Calcium phosphate glasses, in which part of calcium oxide was replaced by lanthanum oxide, were prepared by using the conventional melt quench method. The structures of xLa2O3 · (50-x)CaO · 50P2O5 (x = 0, 1, 3, 6, 12 mol%) samples were investigated by X-ray diffraction (XRD), Raman spectrum, Fourier transform infrared spectrum (FTIR), and differential scanning calorimetry (DSC). The results show that lanthanum oxide acts as network

Xiaofeng Liang; Guangfu Yin; Shiyuan Yang; Yuanming Lai; Junxia Wang



Stabilization of amorphous calcium phosphate by Mg and ATP  

Microsoft Academic Search

Summary A synergistic effect has been demonstrated when magnesium and adenosine triphosphate (ATP) are used together in solution to delay the conversion of a slurry of amorphous calcium phosphate (ACP) to crystalline hydroxyapatite (HA). Conversion is delayed in some instances more than 10 times as long as with either ATP or Mg alone. In all experiments conversion did not begin

N. C. Blumenthal; F. Betts; A. S. Posner



Calcium phosphate porous composites and ceramics prospective as bone implants  

NASA Astrophysics Data System (ADS)

Two types of calcium phosphate materials prospective as bone implants were prepared in the shape of granules and their biochemical behavior was tested by in vivo studies: (i) composite materials consisting of gelatin and bi-phase ion modified calcium phosphate Mg,Zn-(HA + ?-TCP); and (ii) ceramics of ion modified calcium phosphate Mg,Zn-(HA + ?-TCP). The starting fine powders were prepared by the method of biomimetic precipitation of the precursors followed by hightemperature treatment. Then granules were prepared by dispersion in liquid paraffin of a thick suspension containing 20% of gelatin gel and thus prepared calcium phosphate powders (1:1 ratios). The composite granules were obtained by subsequent hardening in a glutaraldehyde solution, while the highly porous ceramic granules - by further sintering at 1100°C. The in vivo behavior of both types of granules was tested in experimental rat models. Bone defects were created in rat tibia and were filled with the implants. Biochemical studies were performed. Three months after operation both bio-materials displayed analogous behavior.

Rabadjieva, D.; Tepavitcharova, S.; Gergulova, R.; Sezanova, K.; Ilieva, R.; Gabrashanska, M.; Alexandrov, M.



Dissolution behaviour of calcium phosphate coatings obtained by laser ablation  

Microsoft Academic Search

Pulsed laser deposited calcium phosphate coating on titanium alloy have been tested under simulated physiological conditions in order to evaluate the changes in morphology, composition and structure. The coatings were deposited under different conditions to obtain different crystalline structures, ranging from amorphous and mixed crystalline phases to pure crystalline hydroxyapatite (HA). The coated samples were immersed in a Ca-free Hank’s

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



Biomimetic calcium phosphate coatings on recombinant spider silk fibres  

Microsoft Academic Search

Calcium phosphate ceramic coatings, applied on surfaces of metallic and polymeric biomaterials, can improve their performance in bone repair and regeneration. Spider silk is biocompatible, strong and elastic, and hence an attractive biomaterial for applications in connective tissue repair. Recently, artificial spider silk, with mechanical and structural characteristics similar to those of native spider silk, has been produced from recombinant

Liang Yang; My Hedhammar; Tobias Blom; Klaus Leifer; Jan Johansson; Pamela Habibovic; Clemens A. van Blitterswijk



Mechanical properties of calcium phosphate coatings deposited by laser ablation  

Microsoft Academic Search

Amorphous calcium phosphate and crystalline hydroxyapatite coatings with different morphologies were deposited onto Ti–6Al–4V substrates by means of the laser ablation technique. The strength of adhesion of the coatings to the substrate and their mode of fracture were evaluated through the scratch test technique and scanning electron microscopy. The effect of wet immersion on the adhesion was also assessed. The

L Clèries; E Mart??nez; J. M Fernández-Pradas; G Sardin; J Esteve; J. L Morenza



Atomic Structure of Intracellular Amorphous Calcium Phosphate Deposits  

Microsoft Academic Search

The radial distribution function calculated from x-ray diffraction of mineralized cytoplasmic structures isolated from the hepatopancreas of the blue crab (Callinectes sapidus) is very similar to that previously found for synthetic amorphous calcium phosphate. Both types of mineral apparently have only short-range atomic order, represented as a neutral ion cluster of about 10 angstrom in longest dimension, whose probable composition

F. Betts; N. C. Blumenthal; A. S. Posner; G. L. Becker; A. L. Lehninger



In vitro investigation of novel calcium phosphates using osteogenic cultures.  


A rat bone marrow stromal cell (RBM) culture was used to evaluate novel bioactive calcium phosphate ceramics. Three rapidly resorbable, glassy crystalline materials with the main crystalline phase Ca2KNa(PO4)2 were investigated (sample code GB 1a, GB 14, GB 9). These materials were designed to exhibit a higher degree of biodegradability than tricalcium phosphate. Additionally, a bioactive glass ceramic of low biodegradability was examined (sample code AP 40). RBM cells were cultured on the disc-shaped test substrata for 14 d. The culture medium was changed and calcium and phosphate concentrations of the medium were determined daily. Specimens were evaluated using light microscopy and morphometry of the cell-covered substrate surface, scanning electron microscopy and energy dispersive X-ray analysis. Except for GB 1a, the rat bone marrow cells attached and grew on all substrate surfaces. Of the different calcium phosphate ceramics tested, AP 40 facilitated osteoblast growth and the elaboration of the extracellular matrix to the highest degree followed by GB 9 and GB 14. The inhibition of cell growth encountered with GB 1a seemed to be related to its high phosphate ion release. PMID:15348877

Knabe, C; Ostapowicz, W; Radlanski, R J; Gildenhaar, R; Berger, G; Fitzner, R; Gross, U



Demonstration of phosphates in calcium deposits: A modification of von Kossa's reaction  

Microsoft Academic Search

It has been suggested that in von Kóss'as technic silver cations replace calcium bound to phosphate or carbonate groups and are then reduced to black metallic silver during exposure to light. However, in test tube experiments silver phosphate retains its yellow color for days. These differences between reactions of pure calcium phosphates and calcium deposits in tissues were emphasized already

Holde Puchtler; Susan N. Meloan



Short-term implantation effects of a DCPD-based calcium phosphate cement  

Microsoft Academic Search

Calcium phosphate cements can be handled in paste form and set in a wet medium after precipitation of calcium phosphate crystals in the implantation site. Depending on the products entering into the chemical reaction leading to the precipitation of calcium phosphates, different phases can be obtained with different mechanical properties, setting times and injectability. We tested a cement composed of

Patrick Frayssinet; Laurent Gineste; Philippe Conte; Jacques Fages; Nicole Rouquet





... lead levels. Calcium carbonate is used as an antacid for “heartburn.” Calcium carbonate and calcium acetate are ... when given intravenously (by IV). Use as an antacid as calcium carbonate. Reducing phosphate levels in people ...


Prediction of the Setting Properties of Calcium Phosphate Bone Cement  

PubMed Central

Setting properties of bone substitutes are improved using an injectable system. The injectable bone graft substitutes can be molded to the shape of the bone cavity and set in situ when injected. Such system is useful for surgical operation. The powder part of the injectable bone cement is included of ?-tricalcium phosphate, calcium carbonate, and dicalcium phosphate and the liquid part contains poly ethylene glycol solution with different concentrations. In this way, prediction of the mechanical properties, setting times, and injectability helps to optimize the calcium phosphate bone cement properties. The objective of this study is development of three different adaptive neurofuzzy inference systems (ANFISs) for estimation of compression strength, setting time, and injectability using the data generated based on experimental observations. The input parameters of models are polyethylene glycol percent and liquid/powder ratio. Comparison of the predicted values and measured data indicates that the ANFIS model has an acceptable performance to the estimation of calcium phosphate bone cement properties. PMID:22919372

Rabiee, Seyed Mahmud; Baseri, Hamid



Morphological evaluation of osteoblasts cultured on different calcium phosphate ceramics.  


The objective of these investigations was to develop an in vitro test system for evaluating novel rapidly resorbable calcium phosphate ceramics of varying composition. Rat bone marrow cells were cultured on the disc-shaped test substrates for 14 days. Five calcium phosphates were examined: R1 CaNaPO4; R1/M2, composed of CaNaPO4 and MgNaPO4; R1/2, composed of CaNaPO4 and Mg2SiO4; R1 + 9% SiO2 consisting of CaNaPO4 and 9% SiO2 (wt%) and R17, Ca2KNa(PO4)2. Two studies were performed. In study I cultures were re-fed every two to three days. In study II the medium was changed daily, and calcium and phosphate concentrations of the medium were determined daily. Specimens were prepared for light microscopy and morphometric evaluation of the cell-covered substrate area, scanning electron microscopy and energy-dispersive X-ray analysis. With all materials tested except for R1/2, an increase of cellular growth was observed after changing the medium daily. Of the different calcium phosphate ceramics tested, R17 and R1/M2 facilitated osteoblast growth and elaboration of extracellular matrix to the highest degree. The inhibition of cell growth encountered with R1 in study I and R1/2 in both studies seemed to be related to a high phosphate-ion release from these materials. PMID:9363333

Knabe, C; Gildenhaar, R; Berger, G; Ostapowicz, W; Fitzner, R; Radlanski, R J; Gross, U



Reference intervals of serum calcium, ionized calcium, phosphate and alkaline phosphatase in healthy Indian school children and adolescents  

Microsoft Academic Search

ObjectiveTo develop age- and sex-specific reference interval of serum total calcium, ionized calcium, inorganic phosphates and alkaline phosphatase in healthy Indian children in the age group of 6–17years.

R. K. Marwaha; R. Khadgawat; N. Tandon; R. Kanwar; A. Narang; A. Sastry; K. Bhadra; M. Kalaivani



Formation of a calcium phosphate-rich layer on absorbable calcium carbonate bone graft substitutes  

Microsoft Academic Search

The use of natural coral as a bone graft substitute is common in Europe. However, the bone-coral bonding mechanism remains elusive. A rat subcutaneous model was used to demonstrate changes at the surface of resorbable calcium carbonate in the form of natural coral. Histological results indicated in vivo formation of a calcium phosphate (CaP)-rich layer on the surface of the

C. J. Damien; J. L. Ricci; P. Christel; H. Alexander; J.-L. Patat



Sphingosine 1Phosphate Mobilizes Sequestered Calcium, Activates Calcium Entry, and Stimulates Deoxyribonucleic Acid Synthesis in Thyroid FRTL-5 Cells  

Microsoft Academic Search

Sphingosine 1-phosphate (SPP) potently mobilizes sequestered cal- cium and is a mitogen in several cell types. In the present investi- gation, we have evaluated the effect of SPP on intracellular free calcium concentration ((Ca21)i) and synthesis of DNA in thyroid FRTL-5 cells. SPP rapidly and transiently mobilized sequestered calcium and stimulated entry of extracellular calcium. The entry of calcium, but




Microstructure and properties of polyhydroxybutyrate-calcium phosphate cement composites  

Microsoft Academic Search

The biopolymer (polyhydroxybutyrate) microparticles-calcium phosphate composites were prepared by mechanical mixing of the\\u000a basic composite components with the addition of hardening liquid after ethanol-composite mixture suspension moulding. The\\u000a composite microstructures were more compact than the pure cement samples as confirmed by the lower values of specific areas\\u000a and mesopore volumes. Both the specific areas and mesopore volumes decreased with soaking

?ubomír Medvecky; Radoslava Štulajterová; Sergey Vladimirovich Kutsev


Chemical reactions of calcium phosphate implants after implantation in vivo  

Microsoft Academic Search

Sintered microporous cylinders of hydroxyapatite (OHA), tertiary calcium phosphate (ß-TCP and rhenanite (CaNaPO4) were implanted in the bone of the forehead of the domestic pig (Sus scrofa). Implants together with the surrounding bone were retrieved after 6 and 12 weeks. X-ray diffraction showed that OHA and ß-TCP maintain their crystal structure upon implantation. However, rhenanite is transformed completely into an

F. C. M. Driessens; M. M. A. Ramselaar; H. G. Schaeken; A. L. H. Stols; P. J. Mullem; J. R. Wijn



Fourier transform raman spectroscopy of synthetic and biological calcium phosphates  

Microsoft Academic Search

Fourier-transform (FT) Raman spectroscopy was used to characterize the organic and mineral components of biological and synthetic calcium phosphate minerals. Raman spectroscopy provides information on biological minerals that is complimentary to more widely used infrared methodologies as some infrared-inactive vibrational modes are Raman-active. The application of FT-Raman technology has, for the first time, enabled the problems of high sample fluorescence

G. R. Sauer; W. B. Zunic; J. R. Durig; R. E. Wuthier



Calcium phosphate invert glasses with soda and titania  

Microsoft Academic Search

Calcium phosphate glasses in the pyrophosphate region were obtained by addition of Na2O and TiO2. The glasses with CaO content of ?55 mol% contain pyrophosphate and orthophosphate groups without metaphosphate by Raman and NMR observation. Crystalline phases with bioactivity such as ?-Ca3(PO4)2 and\\/or ?-Ca2P2O7 were precipitated in the glasses at 850°C. Some of the glasses can be sintered at 850°C,

Toshihiro Kasuga; Yoshihiro Abe



Stem Cell-Calcium Phosphate Constructs for Bone Engineering  

Microsoft Academic Search

While human bone-marrow-derived mesenchymal stem cells (hBMSCs) have been investigated, human umbilical cord mesenchymal stem cells (hUCMSCs) are a relatively new cell source. Little has been reported on hUCMSC encapsulation in scaffolds for bone tissue engineering. The objective of this study was to encapsulate hBMSCs and hUCMSCs in calcium phosphate cement (CPC) scaffolds for dental, craniofacial, and orthopedic applications. Stem-cell-encapsulating

H. H. K. Xu; L. Zhao; M. D. Weir



Calcium and phosphate changes after renal transplantation.  


Hypercalcemia and hypophosphatemia are frequently observed in recipients of a kidney transplant (KTx). Hypercalcemia has been reported in up to 66% of KTx patients. Many factors have been suggested as the putative causal factors; however, the persistence of moderate-severe secondary hyperparathyroidism, associated with a change in the set-point of the Ca-controlled parathyroid hormone (PTH) secretion, is considered to play a prominent role. Hypercalcemia can negatively impact on both the graft and patient outcome, increasing the incidence of nephrocalcinosis, which can induce a worse graft outcome, inducing vascular calcifications, and increasing the incidence of pancreatitis. In addition, severe hypercalcemia after KTx often requires parathyroidectomy, which is not universally considered a safe medical solution in this clinical setting. After KTx, phosphate levels often fall below the normal range, with hypophosphatemia being observed in up to 40% of patients. The putative causal factors for this metabolic alteration are persistent hyperparathyroidism, increased levels of FGF-23, tubular damage secondary to the immunological effects, and toxic and vascular effectors. Hypophosphatemia can negatively impact on either skeletal or muscular systems, contributing to the increased incidence of bone fractures in KTx patients. The current therapeutic options should take into account an accurate pretransplant treatment and screening of the waiting-list patient and should also evaluate the efficacy and safety profile of the new pharmacological tools (calcimimetics) in comparison with the classical surgical approach (parathyroidectomy). PMID:21170877

Messa, Piergiorgio; Cafforio, Cosimo; Alfieri, Carlo



Retrieval studies on calcium phosphate-coated implants.  


The search for the improvement of implant fixation in bone resulted several years ago in the introduction of calcium phosphate coatings on orthopaedic (and dental) implants. Since then many animal experiments, especially on hydroxylapatite coatings, have been performed. By now the first promising results from clinical studies are also available. In this review, the plasma-spray process is described and some of the current techniques for the analysis of retrieved implants are discussed. It is now widely understood that the calcium phosphate hydroxylapatite is osteoconductive. Various experimental animal studies revealed the capability of calcium phosphate coatings to enhance implant fixation, especially under specific or less optimal conditions such as a with a porous implant, loose fit, micromotion or experimental arthritis. Clinical studies, including the analysis of retrieved hydroxylapatite coated hip implants, confirmed these promising results and as a consequence, hydroxylapatite coated total joint prostheses are now used on a large scale. Two questions that are closely related with each other are very actual, e.g. the strength of the coating-substrate interface and how stable or crystalline should hydroxylapatite coatings be for a proper clinical function? There does not yet seem to be a consistent answer to these questions. PMID:7877559

Dhert, W J



Development of magnesium calcium phosphate biocement for bone regeneration  

PubMed Central

Magnesium calcium phosphate biocement (MCPB) with rapid-setting characteristics was fabricated by using the mixed powders of magnesium oxide (MgO) and calcium dihydrogen phosphate (Ca(H2PO4)2·H2O). The results revealed that the MCPB hardened after mixing the powders with water for about 7 min, and the compressive strength reached 43 MPa after setting for 1 h, indicating that the MCPB had a short setting time and high initial mechanical strength. After the acid–base reaction of MCPB containing MgO and Ca(H2PO4)2·H2O in a molar ratio of 2 : 1, the final hydrated products were Mg3(PO4)2 and Ca3(PO4)2. The MCPB was degradable in Tris–HCl solution and the degradation ratio was obviously higher than calcium phosphate biocement (CPB) because of its fast dissolution. The attachment and proliferation of the MG63 cells on the MCPB were significantly enhanced in comparison with CPB, and the alkaline phosphatase activity of MG63 cells on the MCPB was significantly higher than on the CPB at 7 and 14 days. The MG63 cells with normal phenotype spread well on the MCPB surfaces, and were attached in close proximity to the substrate, as seen by scanning electron microscopy (SEM). The results demonstrated that the MCPB had a good ability to support cell attachment, proliferation and differentiation, and exhibited good cytocompatibility. PMID:20181560

Jia, Junfeng; Zhou, Huanjun; Wei, Jie; Jiang, Xin; Hua, Hong; Chen, Fangping; Wei, Shicheng; Shin, Jung-Woog; Liu, Changsheng



Epidemiology of calcium pyrophosphate crystal arthritis and basic calcium phosphate crystal arthropathy.  


Calcium pyrophosphate crystal deposition (CPPD) is common and mainly associates with increasing age and osteoarthritis (OA). Recent studies suggest that CPPD occurs as the result of a generalized articular predisposition and may also associate with low cortical bone mineral density. The epidemiology of basic calcium phosphate (BCP) crystal deposition is poorly understood. Although periarticular BCP crystal deposits occurs at all ages and in both sexes, intra-articular BCP crystal deposition tends to associate with increasing age and OA. Calcium pyrophosphate and BCP crystals frequently coexist in joints with OA. PMID:24703342

Abhishek, Abhishek; Doherty, Michael



In-situ mineralization of chitosan\\/calcium phosphate composite and the effect of solvent on the structure  

Microsoft Academic Search

Solvent played an important role in the formation of calcium phosphate phase of the chitosan\\/calcium phosphate composites.\\u000a In this investigation, ethanolacetic acid mixtures were employed as solvents, and various calcium phosphate phases, such as\\u000a brushite, amorphous calcium phosphate, and hydroxyapatite, were introduced into the chitosan\\/calcium phosphate composites\\u000a by using in-situ preparation process. The results showed that the structures of composite

Ling-Hao He; Lu Yao; Rui Xue; Jing Sun; Rui Song



Biomimetic coprecipitation of calcium phosphate and bovine serum albumin on titanium alloy  

Microsoft Academic Search

Titanium alloy implants were precoated biomimetically with a thin and dense layer of calcium phosphate and then incubated either in a supersaturated solution of calcium phosphate or in phosphate-buffered saline, each containing bovine serum albumin (BSA) at various concentrations, under physiological conditions for 48 h. Coated implants then underwent scanning electron microscopy, immunohistochemical evaluation, Fourier transform infrared spectroscopy, and X-ray

Yuelian Liu; Pierre Layrolle; Bruijn de Joost; Blitterswijk van Clemens; Groot de Klaas



Modification of estimation of the urinary ion-activity products of calcium oxalate and calcium phosphate.  


Tiselius proposed simplified estimates of the ion-activity products of calcium oxalate, calcium phosphate, and brushite as the AP(CaOx) index, the AP(CaP) index, and the AP(Bru) index, respectively, which allowed assessment of the urinary saturation levels of these lithogenic substances. A number of urinary variables (calcium, magnesium, oxalate, phosphate, citrate, urine volume, and pH) are necessary to derive these indices. In addition, these three indices have correction factors corresponding to the urinary collection periods, although these periods were originally quite limited. In this study, the factors were shown to vary as a function of time. Therefore, they were incorporated into these indices after proper calculation so as to be usable for any collection period less than 24 hours. This means that the factors will now prove more useful in evaluating the urinary saturation levels after short-term collections. PMID:8322621

Ogawa, Y



Study of the calcium phosphate layer grown on AISI 316 stainless steel from simulated body fluid  

Microsoft Academic Search

A calcium phosphate layer was deposited on the surface of AISI 316 stainless steel by immersion in a solution supersaturated with calcium and phosphorus ions. The substrates were pre-modified by ion implantation of Ca and P, in order to induce nuclei for calcium phosphate growth on the surface. The reactivity of these surfaces towards crystal growth in aqueous solution was

E. Pecheva; L. Pramatarova; M. F. Maitz; M. T. Pham



Characterization of the adsorption of conjugated and unconjugated bile acids to insoluble, amorphous calcium phosphate.  


Recently we showed that supplemental dietary calcium stimulates the intestinal formation of insoluble calcium phosphate and decreases the ratio of dihydroxy to trihydroxy bile acids in human duodenal bile. Because previous in vitro studies indicated that these effects could be due to differential adsorption of bile acids to amorphous calcium phosphate, we characterized the binding of bile acids to calcium phosphate. Freshly formed, amorphous, calcium phosphate bound and thus precipitated glycine-conjugated and unconjugated bile acids, whereas taurine-conjugated bile acids showed little binding. Glycochenodeoxycholic acid hardly adsorbed to other insoluble calcium phosphates, including hydroxyapatite. Adsorption studies using increasing amounts of glycine-conjugated and unconjugated bile acids showed that binding occurred above a bile acid-specific critical minimum concentration, dependent on bile acid hydrophobicity. The simultaneous use of a fluorescent hydrophobic probe indicated that this binding was due to ionic adsorption of monomers of bile acids, followed by their hydrophobic aggregation on the calcium phosphate surface, probably in the form of a bilayer. Finally, using human duodenal bile we found that amorphous calcium phosphate, but not Ca2+, preferentially bound and thus precipitated dihydroxy bile acids. We conclude that freshly formed, amorphous, calcium phosphate is a prerequisite for adsorption of bile acids and that monomers of glycine-conjugated and unconjugated dihydroxy bile acids have a high binding affinity for amorphous calcium phosphate. PMID:8071598

Govers, M J; Termont, D S; Van Aken, G A; Van der Meer, R



Polymerizable nanoparticulate silica-reinforced calcium phosphate bone cement.  


Bone cements based on calcium phosphate powder and different concentrations of colloidal silica suspensions were developed. Setting time and washout behavior of the cements were recorded and compared with those of a control group prepared by the same powder phase and distilled water as liquid. The phase composition, compressive strength, and morphology of the cements were determined after incubation and soaking in simulated body fluid. Proliferation of osteoblasts seeded on samples was also determined as a function of time. The results showed that the long setting time, poor compressive strength, and undesirable washout behavior of the cement made with distilled water were considerably improved by adding colloidal silica in a dose-dependent manner. On the basis of XRD and SEM results, both control group and nanosilica-added cements composed of nanosized apatite flakes after 7 days soaking, in addition to tetracalcium phosphate residual for the latter. It was found that the rate of hydraulic reactions that are responsible for conversion of the cement reactants to nanostructured apatite was increased by the presence of colloidal silica. Furthermore, the osteoblasts exhibited better proliferation on nanosilica added cements compared to control one. This study suggests better applied properties for nanosilica-added calcium phosphate cement compared to traditional cements. PMID:22706926

Hesaraki, Saeed; Alizadeh, Masoud; Borhan, Shokoufeh; Pourbaghi-Masouleh, Milad



Method of coating a substrate with a calcium phosphate compound  


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.

Gao, Yufei (Kennewick, WA); Campbell, Allison A. (Kennewick, WA)



Calcium phosphate stabilization of fly ash with chloride extraction.  


Municipal solid waste incinerator by products include fly ash and air pollution control residues. In order to transform these incinerator wastes into reusable mineral species, soluble alkali chlorides must be separated and toxic trace elements must be stabilized in insoluble form. We show that alkali chlorides can be extracted efficiently in an aqueous extraction step combining a calcium phosphate gel precipitation. In such a process, sodium and potassium chlorides are obtained free from calcium salts, and the trace metal ions are immobilized in the calcium phosphate matrix. Moderate calcination of the chemically treated fly ash leads to the formation of cristalline hydroxylapatite. Fly ash spiked with copper ions and treated by this process shows improved stability of metal ions. Leaching tests with water or EDTA reveal a significant drop in metal ion dissolution. Hydroxylapatite may trap toxic metals and also prevent their evaporation during thermal treatments. Incinerator fly ash together with air pollution control residues, treated by the combined chloride extraction and hydroxylapatite formation process may be considered safe to use as a mineral filler in value added products such as road base or cement blocks. PMID:12003153

Nzihou, Ange; Sharrock, Patrick



Biomechanical characterization of a biodegradable calcium phosphate hydraulic cement: a comparison with porous biphasic calcium phosphate ceramics.  


Biomechanical properties of a biodegradable calcium phosphate hydraulic cement (CPHC) were tested with rabbits. The cement was composed of beta-tricalcium phosphate (beta-TCP), monocalcium phosphate monohydrate (MCPM), and calcium sulfate hemihydrate (CSH), beta-TCP-MCPM-CSH cement. Cylinders of 4.7 mm in diameter and 10 mm in length were put into bone cavities created in the distal epiphysis of femurs in rabbits. Cylinders of the same size of porous biphasic calcium phosphate ceramics (BCPC, 75% hydroxyapatite and 25% beta-TCP) were implanted as references. Two, 4, 12, and 16 weeks after the operation, the rabbits were sacrificed. Histomorphometry showed that the cement was resorbed, leaving only 7.67 +/- 1.81% of bone cavity after 12 weeks. Newly formed bone occupied 34.59 +/- 4.00% of the cavity. Cylindrical bone-material composites were cut out with a small dental burr. Compressive force was applied to the specimens and compressive strength, elastic modulus, and toughness were calculated. The same tests were performed on cylinders of normal bone from the same site, which served as controls. The compressive strength and the toughness of the cement-bone composite were higher than those of normal bone and porous ceramics 12 weeks after the operation (p < 0.05). At 16 weeks the compressive strength and the toughness returned to the normal bone values. The elastic modulus of the porous ceramic-bone composite was higher than the normal bone at 4, 12, and 16 weeks after surgery (p < 0.05). We found that the beta-TCP-MCPM-CSH cement is replaced by new bone and that the cement-new bone composite has similar or better mechanical properties than normal bone within 16 weeks. This study suggests the usefulness of a particular cement for filling bone defects or for temporary fixation of orthopedic implants. PMID:9511108

Ikenaga, M; Hardouin, P; Lemaître, J; Andrianjatovo, H; Flautre, B



Antibacterial and physical properties of calcium-phosphate and calcium-fluoride nanocomposites with chlorhexidine  

PubMed Central

Objectives Previous studies have developed calcium phosphate and fluoride releasing composites. Other studies have incorporated chlorhexidine (CHX) particles into dental composites. However, CHX has not been incorporated in calcium phosphate and fluoride composites. The objectives of this study were to develop nanocomposites containing amorphous calcium phosphate (ACP) or calcium fluoride (CaF2) nanoparticles and CHX particles, and investigate S. mutans biofilm formation and lactic acid production for the first time. Methods Chlorhexidine was frozen via liquid nitrogen and ground to obtain a particle size of 0.62 µm. Four nanocomposites were fabricated with fillers of: Nano ACP; nano ACP+10% CHX; nano CaF2; nano CaF2+10% CHX. Three commercial materials were tested as controls: A resin-modified glass ionomer, and two composites. S. mutans live/dead assay, colony-forming unit (CFU) counts, biofilm metabolic activity, and lactic acid were measured. Results Adding CHX fillers to ACP and CaF2 nanocomposites greatly increased their antimicrobial capability. ACP and CaF2 nanocomposites with CHX that were inoculated with S. mutans had a growth medium pH > 6.5 after 3 d, while the control commercial composites had a cariogenic pH of 4.2. Nanocomposites with CHX reduced the biofilm metabolic activity by 10–20 folds and reduced the acid production, compared to the controls. CFU on nanocomposites with CHX were three orders of magnitude less than that on commercial composite. Mechanical properties of nanocomposites with CHX matched a commercial composite without fluoride. Significance The novel calcium phosphate and fluoride nanocomposites could be rendered antibacterial with CHX to greatly reduce biofilm formation, acid production, CFU and metabolic activity. The antimicrobial and remineralizing nanocomposites with good mechanical properties may be promising for a wide range of tooth restorations with anti-caries capabilities. PMID:22317794

Cheng, Lei; Weir, Michael D.; Xu, Hockin H. K.; Kraigsley, Alison M.; Lin, Nancy J.; Lin-Gibson, Sheng; Zhou, Xuedong



Effect of strontium ions substitution on gene delivery related properties of calcium phosphate nanoparticles  

Microsoft Academic Search

Gene therapy has been considered a strategy for delivery of therapeutic nucleic acids to a specific site. Calcium phosphates\\u000a are one gene delivery vector group of interest. However, low transfection efficiency has limited the use of calcium phosphate\\u000a in gene delivery applications. Present work aims at studying the fabrication of strontium substituted calcium phosphate nanoparticles\\u000a with improved gene delivery related

A. HanifiM; M. H. Fathi; H. Mir Mohammad Sadeghi



Kinetic reactions of calcium, phosphate, and fluoride ions at the enamel surface-solution interface  

Microsoft Academic Search

Surfaces of tooth enamel were interfaced with recirculating solutions containing calcium and phosphate. The kinetic interfacial reactions of calcium, phosphate, fluoride, and hydrogen ions were determined in solutions of constant fluoride ion concentrations (0.012, 0.025, 0.050, 0.250, or 0.500 mM\\/l) and \\/or constant pH (6.8, 7.0, 7.2, or 7.4). The rates of the calcium, phosphate, fluoride, and hydrogen ion reactions

F. F. Feagin; M. Gonzalez; B. G. Jeansonne



Renal phosphate leak in patients with idiopathic hypercalciuria and calcium nephrolithiasis  

Microsoft Academic Search

Although urine phosphate loss has been associated with hypercalciuria, it is debated how frequently renal phosphate leak is present in hypercalciuric patients. We reviewed the records of 100 consecutive adult patients who were diagnosed with idiopathic hypercalciuria and calcium urolithiasis, searching for the presence of renal phosphate leak. The renal phosphate threshold, normalized for the glomerular filtration rate (TmPO4\\/GFR), of

ArmandoLuis Negri; Rodolfo Spivacow; Elisa Del Valle; Erich Fradinger; Alicia Marino; JoseRuben Zanchetta



Ab initio modelling of calcium phosphate clusters and their vibrational spectra  

Microsoft Academic Search

Calcium phosphate and hydroxylcalcium phosphate clusters that model amorphous phase elementary unit cells as well as their vibrational spectra were calculated by ab initio quantum chemical method using GAMESS code. Normal coordinate analysis was accomplished for phosphate anion, tricalcium phosphate and hydrox- ylapatite. Calculated IR-spectra and spectra of inelastic neutron scattering were defined in comparison with experimental data. It was

I. E. Boldeskul; L. F. Sukhodub; A. N. Kalinkevich; V. D. Khavryutchenko



Thermokineticanalysis of the hydration process of calcium phosphate cement  

Microsoft Academic Search

A microcalorimeter (Setaram c-80) was used\\u000a to study the thermokinetics of the hydration process of calcium phosphate\\u000a cement (CPC), a biocompatible biomaterial used in bone repair. The hydration\\u000a enthalpy was determined to be 35.8 J g–1\\u000a at 37.0°C when up to 80 mg CPC was dissolved in 2 mL of citric buffer.\\u000a In the present study, parameters related to time

W. Y. Gao; Y. W. Wang; L. M. Dong



Biomimetic layer-by-layer templates for calcium phosphate biomineralization.  


Carboxylated, sulfated and/or phosphorylated surfaces are admitted as potential optimal templates for biomimetic deposition of calcium phosphate (CaP) coatings in view of improving implants' osseointegration. Layer-by-layer films were built up consisting of anionic chondroitin sulfate (ChS), a biological carboxylated and sulfated polysaccharide and cationic poly(l-lysine) (PLL). The films were used as soft matrices to immobilize a model phosphoprotein, phosvitin (PhV). The respective roles of ChS, PLL and PhV terminal layers on the heterogeneous nucleation kinetics and the structure of CaP deposits obtained from supersaturated solutions were inspected. Critical supersaturation ratios and induction times preceding heterogeneous nucleation were precisely determined and interpreted within the framework of classical nucleation theory in order to derive the effective interfacial energies of CaP crystals. It was found that the potency of terminal layers toward CaP nucleation increased in the order: PLLcalcium bridging. Promisingly, all films templated the deposition of thin (a few micrometer thick) uniform coatings of octacalcium phosphate and possibly hydroxyapatite, the two most relevant biological phases of CaP. PMID:22683877

Abdelkebir, K; Morin-Grognet, S; Gaudière, F; Coquerel, G; Labat, B; Atmani, H; Ladam, G



Nucleation, growth and evolution of calcium phosphate films on calcite.  


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. PMID:25233226

Naidu, Sonia; Scherer, George W



Geometrically structured implants for cranial reconstruction made of biodegradable polyesters and calcium phosphate/calcium carbonate.  


The aim of this study was the development of a processing pathway for manufacturing of biodegradable skull implants with individual geometry. The implants on the basis of polylactide and calcium phosphate/calcium carbonate were prepared by a combination of hot pressing and gas foaming. On the inside, the implant consists of a macroporous and faster degradable material (poly(D,L-lactide)+CaCO3) to allow the ingrowth of bone cells. The pore size is in the range of 200-400 microm. On the outside, the implant consists of a compact and slower biodegradable material (poly(L-lactide) and calcium phosphate) to ensure mechanical stability and protection. To overcome problems like inflammatory reactions caused by acidic degradation products of polylactide, the polyester was combined with basic filling materials (calcium salts). The filler neutralises the lactic acid produced during polymer degradation and increases the bioactivity of the material. The stabilised pH was demonstrated by long-term in vitro pH studies. Over a time period of 250 d in demineralised water, the pH was in the physiological range. The in vitro biocompatibility was shown by cell cultures with human osteoblasts. A good proliferation of the cells was observed over the whole test period of 4 weeks. PMID:14643598

Schiller, Carsten; Rasche, Christian; Wehmöller, Michael; Beckmann, Felix; Eufinger, Harald; Epple, Matthias; Weihe, Stephan



[Chondrocalcinosis. Clinical impact of intra-articular calcium phosphate crystals].  


Calcium pyrophosphate dihydrate (CPPD) crystals are known to cause acute attacks of pseudogout in joints but crystal deposition has also been reported to be associated with osteoarthritis (OA). Aside from CPPD crystals, basic calcium phosphates (BCPs), consisting of carbonate-substituted hydroxyapatite (HA), tricalcium phosphate and octacalcium phosphate, have been found in synovial fluid, synovium and cartilage of patients with OA. Although CPPD crystals have been found to be associated with OA and are an important factor in joint disease, this has also recently been associated with a genetic defect. However, according to the most recent findings, the association of BCP crystals, such as apatite with OA is much stronger, as their presence significantly correlates with the severity of cartilage degeneration. Identification of BCP crystals in OA joints remains problematic due to a lack of simple and reliable methods of detection. The clinical and pathological relevance of cartilage mineralization in patients with OA is not completely understood. It is well established that mineralization of articular cartilage is often found close to hypertrophic chondrocytes. A significant correlation between the expression of type X collagen, a marker for chondrocyte hypertrophy and cartilage mineralization was observed. In the process of endochondral ossification, the link between hypertrophy and matrix mineralization is particularly well described. Hypertrophic chondrocytes in OA cartilage and at the growth line share certain features, not only hypertrophy but also a capability to mineralize the matrix. Recent data indicate that chondrocyte hypertrophy is a key factor in articular cartilage mineralization strongly linked to OA and does not characterize a specific subset of OA patients, which has important consequences for therapeutic strategies for OA. PMID:24924727

Fuerst, M



Interaction between calcium and phosphate adsorption on goethite.  


Quantitatively, little is known about the ion interaction processes that are responsible for the binding of phosphate in soil, water, and sediment, which determine the bioavailability and mobility of phosphate. Studies have shown that metal hydroxides are often responsible for the binding of PO4 in soils and sediments, but the binding behavior of PO4 in these systems often differs significantly from adsorption studies on metal hydroxides in laboratory. The interaction between PO4 and Ca adsorption was studied on goethite because Ca can influence the PO4 adsorption equilibria. Since adsorption interactions are very difficult to discriminate from precipitation reactions, conditions were chosen to prevent precipitation of Ca-PO4 solids. Adsorption experiments of PO4 and Ca, individually and in combination, show a strong interaction between adsorbed Ca and PO4 on goethite for conditions below the saturation index of apatite. It is shown that it is possible to predict the adsorption and interaction of PO4 and Ca on electrostatic arguments using the model parameter values derived from the single-ion systems and without invoking ternary complex formation or precipitation. The model enables the prediction of the Ca-PO4 interaction for environmentally relevant calcium and phosphate concentrations. PMID:11529579

Rietra, R P; Hiemstra, T; van Riemsdijk, W H



Structure and properties of gadolinium loaded calcium phosphate glasses  

NASA Astrophysics Data System (ADS)

The glass samples with composition xGd2O3-(50 - x)CaO-50P2O5 (0 ? x ? 9 mol%) were prepared by the conventional melt quench method. The structure and properties of gadolinium loaded in calcium phosphate glasses were investigated using XRD, SEM, DTA, IR and Raman spectroscopy. The XRD and SEM analysis for the samples show that the majority of samples are amorphous, and crystallization occurs when the content of Gd2O3 containing is up to 6 mol%. Two main crystalline phases, Ca2P2O7 and Gd3(P2O7)3, are embedded in an amorphous matrix. IR and Raman data indicate that glass structure consists of predominantly metaphosphate (Q2) units and the depolymerization of phosphate network with the addition of Gd2O3. Both the chemical durability and the glass transition temperature (Tg) are improved with the increase of Gd2O3, which suggests that the Gd acts a role of strengthening the cross-links between the phosphate chains of the glass.

Wang, Cuiling; Liang, Xiaofeng; Li, Haijian; Yu, Huijun; Li, Zhen; Yang, Shiyuan



Development of artificial seed crystal for crystallization of calcium phosphate.  


An artifical seed crystal material consisting of calcium silicate hydrate (5CaO x 6SiO2 x 5H2O : tobermorite crystals) applicable for phosphorus removal by crystallization was developed. Card-house shaped tobermorite crystals were developed on the seed material where orthophosphate crystallized as a calcium phosphate. The seed material can be manufactured by mixing siliceous and calcareous raw materials, pelletizing and subsequent autoclaving. Laboratory experiments were conducted to apply the new developed seed crystal material in the phosphorus recovery from sludge sidestreams of a wastewater treatment plant. In this crystallization process, the performance the carbon dioxide degassingprocess usually carried out when applying crystallization was not necessary, the hydroxyapatite was able to crystallize at a pH of 8.0 to 8.5 without precipitation of calcium carbonates. In the treatment of a sidestream with orthophosphate concentrations of 50 mgl(-1) and COD concentrations between 200 to 400 mgl(-1), phosphorus removal efficiencies ranging from 75 to 85% were observed. The seed crystal material was collected after the laboratory experiments and the chemical estimation and the germination test for agricultural reuse were performed. As a result, it was shown that the hydroxyapatite precipitated on the seed material had a 100% fusibility to soil and had characteristics to be a good nutrient source as a fertilizer for plants. PMID:11804345

Moriyama, K; Kojima, T; Minawa, Y; Matsumoto, S; Nakamachi, K



Characterization of a novel calcium phosphate/sulphate bone cement.  


Apatitic cements have shown excellent biocompatibility and adequate mechanical properties but have slow resorption in the human body. To assure that new bone tissue grows into the bone defect, a certain porosity is necessary although hard to achieve in injectable cements with suitable mechanical properties. An attempt was made by mixing alpha-tricalcium phosphate (alpha-TCP), calcium sulphate hemihydrate (CSH) and an aqueous solution containing 2.5 wt% of Na(2)HPO(4). The aim was to obtain a material containing two phases: a) one apatitic phase (calcium-deficient hydroxyapatite; CDHA) and b) one resorbable phase (calcium sulphate dihydrate; CSD). alpha-TCP and CSH mixtures were produced at relative intervals of 20 wt%. The liquid-to-powder (L/P) ratio to obtain a paste was 0.32 mLg(-1). The highest compressive strength (34 MPa) was obtained for the pure alpha-TCP sample. The strength was, in a first approximation, directly correlated to the weight proportions of the powders. X-ray diffraction analysis showed that the relative intensity for CDHA increased linearly, and the one for CSD decreased exponentially, when the amount of alpha-TCP increased. Thus, CSH ceased to transform to CSD when the amount of alpha-TCP increased. Observations in environmental scanning electron microscopy confirmed the X-ray diffraction results. CSH-crystals (100 microm) were embedded in the HA-matrix permitting gradual porosity in the material when resorbed. PMID:12115450

Nilsson, M; Fernández, E; Sarda, S; Lidgren, L; Planell, J A



The flame photometric determination of calcium in phosphate, carbonate, and silicate rocks  

USGS Publications Warehouse

A flame photometric method of determining calcium in phosphate, carbonate, and silicate locks has been developed Aluminum and phosphate interference was overcome by the addition of a large excess of magnesium. The method is rapid and suitable for routine analysis Results obtained are within ?? 2% of the calcium oxide content. ?? 1957.

Kramer, H.



Calcium phosphate deposition from simulated milk ultrafiltrate on different stainless steel-based surfaces  

Microsoft Academic Search

In order to reduce the fouling caused by milk during heat treatment, it is important to know more about the precipitation process of calcium phosphate, the main mineral component of milk deposits. This work was mainly focused on the relationship between calcium phosphate fouling behaviour and the surface properties of the materials used as metallic substrata. The foulant solution used

Roxane Rosmaninho; Luís F. Melo



Calcium Phosphate Phase Identification Using XPS and Time-of-Flight Cluster SIMS  

E-print Network

Calcium Phosphate Phase Identification Using XPS and Time-of-Flight Cluster SIMS Charles C. Chusuei Characterization and Analysis, Texas A&M University, College Station, Texas 77843-3144 Reproducible time-of-flight cluster static secondary ion mass spectra (ToF-SSIMS) were obtained for various standard calcium phosphate

Goodman, Wayne


Acute kidney injury in a patient with sarcoidosis: hypercalciuria and hypercalcemia leading to calcium phosphate deposition.  


Sarcoidosis can affect kidney function through many different mechanisms. We present a patient with sarcoidosis who developed acute kidney injury (AKI). He had a high 1,25-OH vitamin D level and hypercalciuria. As his renal function declined he developed hypercalcemia. A kidney biopsy showed acute tubular necrosis (ATN) with giant cell formation around calcium phosphate crystals. Calcium phosphate deposition is uncommon in sarcoid. We speculate that early interstitial calcium phosphate deposition may in time lead to the development of Randall's plaques and to the more typical calcium oxalate nephrolithiasis seen in sarcoidosis. PMID:23845267

Manjunath, Veena; Moeckel, Gilbert; Dahl, Neera K



Simulations of Inositol Phosphate Metabolism and Its Interaction with InsP3-Mediated Calcium Release  

E-print Network

Simulations of Inositol Phosphate Metabolism and Its Interaction with InsP3-Mediated Calcium 560065, India ABSTRACT Inositol phosphates function as second messengers for a variety of extracellular and kinases. These enzymes generate a range of inositol phosphate derivatives, many of which have signaling

Bhalla, Upinder S.


Fabrication of calcium phosphate-calcium sulfate injectable bone substitute using chitosan and citric acid.  


In this study, an injectable bone substitute (IBS) consisting of citric acid, chitosan solution as the liquid phase and tetra calcium phosphate (TTCP), dicalcium phosphate anhydrous (DCPA) and calcium sulfate hemihydrate (CSH) powders as the solid phase was prepared. Four groups containing different percentages (0-30%) of calcium sulfate hemihydrate (CSH, CaSO(4) . 0.5H(2)O) were investigated. Initial setting times for IBS with CSH were longer than those without CSH. The setting times for all compositions were in the range of 25-45 min. The injectability was improved by the addition of CSH in the present system. Scanning electron microscopy images showed that fiber-like crystallization appeared in the cements. The enhancement of crystallinity was confirmed by XRD profiles where the peak intensity of HAp increased with incubation time and the addition of CSH. Also, the compressive strength increased with the addition of CSH. The maximum compressive strength obtained for IBS was with 20% CSH after 28-day incubation in 100% humidity at 37 degrees C. PMID:19052849

Song, Ho-Yeon; Esfakur Rahman, A H M; Lee, Byong-Taek



Novel microwave synthesis of amorphous calcium phosphate nanospheres.  


Amorphous calcium phosphate (ACP) is an important precursor phase in tissue mineralization. It shows high solubility and excellent remineralization ability. Commercially viable techniques for producing ACP are high-cost/low-efficiency process. This article describes a novel microwave (MW)-assisted ACP synthesis route as an alternative to current ACP synthesis methods. An important feature of the process is the use of supersaturated biomimetic fluids (SBFs), which are based on Kokubo-like simulated body fluids. However, our present compositions are substantially different in that they no longer simulate the body fluid compositions. The effects of solution composition and processing parameters were studied. The mechanism of ACP synthesis under MW irradiation process is also discussed. The as-synthesized ACP nanospheres were characterized and showed good reactivity and biocompatibility. These as-synthesized nanoparticles can be potential candidates for biomedical applications and remineralization mechanism study. PMID:22331618

Zhou, Huan; Bhaduri, Sarit



Surgical results of lumbar interbody fusion using calcium phosphate cement.  


Clinical and radiological outcomes of lumbar interbody fusion using artificial fusion cages filled with calcium phosphate cements (CPCs) were retrospectively reviewed. Between 2002 and 2011, 25 patients underwent lumbar interbody fusion at Tokushima University Hospital, and 22 patients were enrolled in this study. Of these, 5 patients received autologous local bone grafts and 17 received CPC. Japan Orthopedic Association (JOA) score was used for clinical outcome assessments. Lumbar radiography and computed tomography (CT) were performed at 12, 24 months and last follow-up period to assess bony fusion. The mean JOA score of all patients improved from 9.3 before surgery to 21.0 at 24 months after surgery. Fusion had occurred in 5 of 5 patients in the local bone graft group and in 16 of 17 patients in CPC group at 24 months postoperatively. No surgically related complication was occurred in both groups. CPC is a useful and safe graft material for lumbar interbody fusion. PMID:25169138

Hirasawa, Motohiro; Mure, Hideo; Toi, Hiroyuki; Nagahiro, Shinji



The thermophysical properties of calcium and barium zirconium phosphate  

NASA Astrophysics Data System (ADS)

The thermophysical and structural properties of calcium and barium zirconium phosphate ceramics (CZP and BZP) have been investigated for their potential candidacy as actinide hosts for inert matrix fuels (IMF) in nuclear reactors. These phosphate ceramics, which can accommodate minor actinides as well as the resulting fission products, are found to be thermally stable to 1600 °C in air, however they begin to decompose in an inert atmosphere above approximately 1400 °C. The heat capacity, thermal conductivity and bulk thermal-expansion were measured from room temperature up to 1200 °C. Structural changes in this temperature region as well as the anisotropic thermal-expansion behaviour were studied using high-temperature X-ray diffraction. A phase change from R-3 to R-3c was identified for Ba0.5Zr2(PO4)3 near 880 °C. The thermal conductivity for these ceramics at 1000 °C was found to be 1.0 W m-1 K-1, a relatively low thermal conductivity that was increased to 5.0 W m-1 K-1 at 1000 °C for BZP:Ni (25:75 mass ratio) cermet composites.

Gregg, Daniel J.; Karatchevtseva, Inna; Triani, Gerry; Lumpkin, Gregory R.; Vance, Eric R.



Type IIc sodium-dependent phosphate transporter regulates calcium metabolism.  


Primary renal inorganic phosphate (Pi) wasting leads to hypophosphatemia, which is associated with skeletal mineralization defects. In humans, mutations in the gene encoding the type IIc sodium-dependent phosphate transporter lead to hereditary hypophophatemic rickets with hypercalciuria, but whether Pi wasting directly causes the bone disorder is unknown. Here, we generated Npt2c-null mice to define the contribution of Npt2c to Pi homeostasis and to bone abnormalities. Homozygous mutants (Npt2c(-/-)) exhibited hypercalcemia, hypercalciuria, and elevated plasma 1,25-dihydroxyvitamin D(3) levels, but they did not develop hypophosphatemia, hyperphosphaturia, renal calcification, rickets, or osteomalacia. The increased levels of 1,25-dihydroxyvitamin D(3) in Npt2c(-/-) mice compared with age-matched Npt2c(+/+) mice may be the result of reduced catabolism, because we observed significantly reduced expression of renal 25-hydroxyvitamin D-24-hydroxylase mRNA but no change in 1alpha-hydroxylase mRNA levels. Enhanced intestinal absorption of calcium (Ca) contributed to the hypercalcemia and increased urinary Ca excretion. Furthermore, plasma levels of the phosphaturic protein fibroblast growth factor 23 were significantly decreased in Npt2c(-/-) mice. Sodium-dependent Pi co-transport at the renal brush border membrane, however, was not different among Npt2c(+/+), Npt2c(+/-), and Npt2c(-/-) mice. In summary, these data suggest that Npt2c maintains normal Ca metabolism, in part by modulating the vitamin D/fibroblast growth factor 23 axis. PMID:19056871

Segawa, Hiroko; Onitsuka, Akemi; Kuwahata, Masashi; Hanabusa, Etsuyo; Furutani, Junya; Kaneko, Ichiro; Tomoe, Yuka; Aranami, Fumito; Matsumoto, Natsuki; Ito, Mikiko; Matsumoto, Mitsuru; Li, Minqi; Amizuka, Norio; Miyamoto, Ken-Ichi



Autophagy induced by calcium phosphate precipitates targets damaged endosomes.  


Calcium phosphate precipitates (CPPs) form complexes with DNA, which enter cells via endocytosis. Under this condition CPPs induce autophagy via the canonic autophagy machinery. Here we showed that CPP-induced autophagy was also dependent on endocytosis as the process was significantly inhibited by methyl-?-cyclodextrin and dynasore, which suppress clathrin-dependent endocytosis. Consistently, CPP treatment triggered the formation of filipin-positive intracellular vesicles whose membranes are rich in cholesterol. Unexpectedly, these vesicles were also positive for galectin 3, suggesting that they were damaged and the membrane glycans became accessible to galectins to bind. Endosome damage was caused by endocytosis of CPPs and was reversed by calcium chelators or by endocytosis inhibitors. Notably, CPP-induced LC3-positive autophagosomes were colocalized with galectin 3, ubiquitin, and p62/SQSTM1. Inhibition of galectin 3 reduced p62 puncta and autophagosome formation. Knockdown of p62 additionally inhibited the colocalization of autophagosomes with galectins. Furthermore, most of the galectin 3-positive vesicles were colocalized with Rab7 or LAMP1. Agents that affect endosome/lysosome maturation and function, such as bafilomycin A1, also significantly affected CPP-induced tubulovesicular autophagosome formation. These findings thus indicate that endocytosed CPPs caused endosome damage and recruitment of galectins, particularly at the later endosome stage, which led to the interaction of the autophagosomal membranes with the damaged endosome in the presence of p62. PMID:24619419

Chen, Xi; Khambu, Bilon; Zhang, Hao; Gao, Wentao; Li, Min; Chen, Xiaoyun; Yoshimori, Tamotsu; Yin, Xiao-Ming



Osteoregenerative capacities of dicalcium phosphate-rich calcium phosphate bone cement.  


Calcium phosphate cement (CPC) is a widely used bone substitute. However, CPC application is limited by poor bioresorption, which is attributed to apatite, the stable product. This study aims to systematically survey the biological performance of dicalcium phosphate (DCP)-rich CPC. DCP-rich CPC exhibited a twofold, surface-modified DCP anhydrous (DCPA)-to-tetracalcium phosphate (TTCP) molar ratio, whereas conventional CPC (c-CPC) showed a onefold, surface unmodified DCPA-to-TTCP molar ratio. Cell adhesion, morphology, viability, and alkaline phosphatase (ALP) activity in the two CPCs were examined with bone cell progenitor D1 cultured in vitro. Microcomputed tomography and histological observation were conducted after CPC implantation in vivo to analyze the residual implant ratio and new bone formation rate. D1 cells cultured on DCP-rich CPC surfaces exhibited higher cell viability, ALP activity, and ALP quantity than c-CPC. Histological evaluation indicated that DCP-rich CPC showed lesser residual implant and higher new bone formation rate than c-CPC. Therefore, DCP-rich CPC can improve bioresorption. The newly developed DCP-rich CPC exhibited potential therapeutic applications for bone reconstruction. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 203-210, 2015. PMID:24639027

Ko, Chia-Ling; Chen, Jian-Chih; Tien, Yin-Chun; Hung, Chun-Cheng; Wang, Jen-Chyan; Chen, Wen-Cheng



Polymeric additives to enhance the functional properties of calcium phosphate cements  

PubMed Central

The vast majority of materials used in bone tissue engineering and regenerative medicine are based on calcium phosphates due to their similarity with the mineral phase of natural bone. Among them, calcium phosphate cements, which are composed of a powder and a liquid that are mixed to obtain a moldable paste, are widely used. These calcium phosphate cement pastes can be injected using minimally invasive surgery and adapt to the shape of the defect, resulting in an entangled network of calcium phosphate crystals. Adding an organic phase to the calcium phosphate cement formulation is a very powerful strategy to enhance some of the properties of these materials. Adding some water-soluble biocompatible polymers in the calcium phosphate cement liquid or powder phase improves physicochemical and mechanical properties, such as injectability, cohesion, and toughness. Moreover, adding specific polymers can enhance the biological response and the resorption rate of the material. The goal of this study is to overview the most relevant advances in this field, focusing on the different types of polymers that have been used to enhance specific calcium phosphate cement properties. PMID:22511991

Perez, Roman A; Kim, Hae-Won



Synthesis and application of nanostructured calcium phosphate ceramics for bone regeneration.  


In the past two decades, nanotechnology has entered the field of regenerative medicine, resulting in the development of a novel generation of instructive, nanostructured biomaterials that are able to orchestrate cellular behavior by presenting specific morphological and biological cues. Using nanotechnology, materials containing nanosized features (e.g., pores, patterns, textures, grain sizes) can be obtained that exhibit properties that are considerably altered compared with micron-structured materials. Inspired by the hierarchical nanostructure of bone, the application of nanostructured materials for bone regeneration is gaining increasing interest in the field of biomaterials research. Because crystallographic and chemical studies have shown that synthetic hydroxyapatite closely resembles the inorganic phase found in bone and teeth, synthesis and applications of nanostructured calcium phosphate ceramics have been reviewed. Synthesis techniques for the preparation of calcium phosphate nanoparticles include precipitation, sol-gel, and hydrothermal processes, whereas four main biomedical applications of nanostructured calcium phosphate ceramics in bone regeneration have been addressed in more detail, that is, (1) polymer/calcium phosphate nanocomposites, (2) nanostructured monophasic calcium phosphate bone fillers, (3) nanostructured precursor phases for calcium phosphate cements, and (4) nanostructured calcium phosphate coatings. PMID:23015272

Alves Cardoso, D; Jansen, J A; Leeuwenburgh, S C G



Calcium phosphate granulation in anaerobic treatment of black water: a new approach to phosphorus recovery.  


Recovery of phosphorus from wastewater as calcium phosphate could diminish the need for mining of scarce phosphate rock resources. This study introduces a novel approach to phosphorus recovery by precipitation of calcium phosphate granules in anaerobic treatment of black water. The granules formed in the Upflow Anaerobic Sludge Blanket (UASB) reactor at lab- and demonstration-scale were analyzed for chemical composition and mineralogy by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES), Electron microprobe (EMP), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and micro X-ray Diffraction (XRD). The granules had a diameter of 1-2 mm, organic content of 33 wt%, and phosphorus content of 11-13 wt%. Three calcium phosphate phases were identified in the granules: hydroxyapatite, calcium phosphate hydrate and carbonated hydroxyapatite. Without any addition of chemicals, 7 gP/person/year can be recovered with the calcium phosphate granules, representing 2% of the incoming phosphorus in the UASB reactor. As the heavy metal content was lower compared to other phosphorus recovery products, phosphate rock and phosphorus fertilizer, the calcium phosphate granules could be considered as a new phosphorus product. PMID:24183558

Tervahauta, Taina; van der Weijden, Renata D; Flemming, Roberta L; Hernández Leal, Lucía; Zeeman, Grietje; Buisman, Cees J N



Inorganic-organic hybrid nanoparticles with biocompatible calcium phosphate thin shells for fluorescence enhancement.  


Polymeric micelles consisting of asymmetric triblock copolymers were successfully used for fabrication of robust hybrid nanoparticles with highly biocompatible calcium phosphate shells. The hydrophobic polystyrene core encapsulates hydrophobic fluorescent dyes such as Nile red. The anionic polyacrylic acid provides the site for the mineralization reaction of calcium phosphate. The polyethylene glycol corona stabilizes the hybrid nanoparticles. Fluorescent dyes can be used as imaging agents for determining the location of the nanoparticles and to give an observable indication of drug delivery, while the calcium phosphate shell can enhance the fluorescence of the encapsulated dye. PMID:23526653

Bastakoti, Bishnu Prasad; Hsu, Yin-Chu; Liao, Shih-Hsiang; Wu, Kevin C-W; Inoue, Masamichi; Yusa, Shin-ichi; Nakashima, Kenichi; Yamauchi, Yusuke



Structure, properties and animal study of a calcium phosphate/calcium sulfate composite cement.  


In-vitro and in-vivo studies have been conducted on an in-house-developed tetracalcium phosphate (TTCP)/dicalcium phosphate anhydrous (DCPA)/calcium sulfate hemihydrate (CSH)-derived composite cement. Unlike most commercial calcium-based cement pastes, the investigated cement paste can be directly injected into water and harden without dispersion. The viability value of cells incubated with a conditioned medium of cement extraction is >90% that of Al2O3 control and >80% that of blank medium. Histological examination reveals excellent bonding between host bone and cement without interposition of fibrous tissues. At 12 weeks-post implantation, significant remodeling activities are found and a new bone network is developed within the femoral defect. The 26-week samples show that the newly formed bone becomes more mature, while the interface between residual cement and the new bone appears less identifiable. Image analysis indicates that the resorption rate of the present cement is much higher than that of TTCP or TTCP/DCPA-derived cement under similar implantation conditions. PMID:24582223

Chen, Wei-Luen; Chen, Chang-Keng; Lee, Jing-Wei; Lee, Yu-Ling; Ju, Chien-Ping; Lin, Jiin-Huey Chern



Preparation of in situ hardening composite microcarriers: calcium phosphate cement combined with alginate for bone regeneration.  


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 ?-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

Park, Jung-Hui; Lee, Eun-Jung; Knowles, Jonathan C; Kim, Hae-Won



Polyelectrolyte multilayer-calcium phosphate composite coatings for metal implants.  


The preparation of organic-inorganic composite coatings with the purpose to increase the bioactivity of bioinert metal implants was investigated. As substrates, glass plates and rough titanium surfaces (Ti-SLA) were employed. The method comprises the deposition of polyelectrolyte multilayers (PEMLs) followed by immersion of the coated substrate into a calcifying solution of low supersaturation (MCS). Single or mixed PEMLs were constructed from poly-l-lysine (PLL) alternating with poly-l-glutamate, (PGA), poly-l-aspartate (PAA), and/or chondroitin sulfate (CS). ATR-FTIR spectra reveal that (PLL/PGA)10 multilayers and mixed multilayers with a (PLL/PGA)5 base contain intermolecular ?-sheet structures, which are absent in pure (PLL/PAA)10 and (PLL/CS)10 assemblies. All PEML coatings had a grainy topography with aggregate sizes and size distributions increasing in the order: (PLL/PGA)n < (PLL/PAA)n < (PLL/CS)n. In mixed multilayers with a (PLL/PGA)n base and a (PLL/PAA)n or (PLL/CS)n top, the aggregate sizes were greatly reduced. The PEMLs promoted calcium phosphate nucleation and early crystal growth, the intensity of the effect depending on the composition of the terminal layer(s) of the polymer. In contrast, crystal morphology and structure depended on the supersaturation, pH, and ionic strength of the MCS, rather than on the composition of the organic matrix. Crystals grown on both uncoated and coated substrates were mostly platelets of calcium deficient carbonate apatite, with the Ca/P ratio depending on the precipitation conditions. PMID:25105729

Elyada, Alon; Garti, Nissim; Füredi-Milhofer, Helga



TEM studies of calcium phosphates for the understanding of biomineralization  

NASA Astrophysics Data System (ADS)

Calcium phosphate (Ca-P) formation and bone minerals have been the focus of research for several decades because achievements in these areas could provide valuable insights into the understanding of biomineralization. In this thesis work, Ca-P formation, octacalcium phosphate (OCP) to hydroxyapatite (HA) transformation and bone minerals were systematically studied by transmission electron microscopy (TEM) techniques. Ca-P formations on various bioceramics in simulated body fluid and in rabbit muscle sites were investigated. The bioceramics included sintered bioglass RTM, A-W glass-ceramics, HA, alpha-tricalcium phosphate (TCP), beta-TCP and HA-TCP. The comparative studies showed that OCP formation occurred on all types of bioceramic surfaces in vitro and in vivo, except on beta-TCP; however HA formation did not occur on every type of bioceramics; it less likely occurred on the surfaces of HA and alpha-TCP. These findings were contradicted to the common statements in literatures. OCP to HA transformations in vitro and in vivo were observed by high-resolution TEM (HRTEM). The in vitro transformation was induced by electron beam irradiations of in situ TEM on synthetic OCP crystals. The in vivo transformation was revealed on rod-like HA precipitates formed in dog muscle sites. Based on HRTEM examinations and image simulations, OCP/HA crystallographic orientations were determined to be OCP (010) // HA (01¯0) and OCP (001) // HA (001¯), which differed from a well known model proposed by Brown et al. The minerals of cortical bone were extracted from human tibiae and rat femurs using 10% neutral ethylenediamine tetraacetic acid (EDTA) solution. TEM examinations showed that the dominance of bone minerals was plate-like and a few were needle-like. The length of most plate-like minerals ranged from 50 to 150 nm but could be up to 200 nm. To the author's knowledge, OCP structure was for the first time, identified in a number of plate-like bone minerals by selected area electron diffraction (SAED) and HRTEM.

Xin, Renlong


Quartz crystal microbalance for comparison of calcium phosphate precipitation on planar and rough phospholipid bilayers.  


The planar and rough phospholipid bilayers at the surfaces of quartz crystal and titania-modified quartz crystal were fabricated via the surface modification, respectively, and characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), cyclic voltammetry (CV) and piezoelectric measurement. The formation of calcium phosphate on planar and rough phospholipid bilayers was investigated in detail using in situ quartz crystal microbalance (QCM) and X-ray diffraction (XRD) techniques. The obtained results showed that the calcium phosphate precipitation was closely related to the roughness and surface potential of phospholipid bilayers. Compared with planar phospholipid bilayers, the rough phospholipid bilayers exhibited a higher deposition rate of calcium phosphate. The presence of anionic phosphatidylserine (PS) in phosphatidylcholine (PC)/PS phospholipid induced PC/PS surface with negative charge, thus showing significantly enhanced calcium phosphate precipitation. PMID:24495457

Yang, Zhengpeng; Zhang, Chunjing; Huang, Lina



ili G d C l i h hFertilizer Grade Calcium Phosphate RecoveryFertilizerGrade Calcium Phosphate RecoveryFertilizer Grade Calcium Phosphate Recovery Phillip Barak, PhDAmanda Boyce, MSc Phillip Barak, PhDAmanda Boyce, MSc  

E-print Network

to test synthetic cmHeight 62.7 100 INTRODUCTION solution (schematic and INTRODUCTION ( photo) T l cmID cm thickened filtrate through the addition of Mg(OH)2. This study precipitation from synthetic OA solution endeavored to improve on this recovery system by producing calcium phosphates from p p y fl idi d b d t i d

Barak, Phillip


Antibacterial property expressed by a novel calcium phosphate glass.  


We have developed a calcium phosphate glass (CPG) doped with Zn(2+) or F(-) or combined Zn(2+) and F(-) ions, which are naturally found in the human body and play a dual role in bone formation and antibacterial activity. Previously, we have demonstrated that this family of CPGs has superior osteoconductive and resorbable properties in vivo. This study aimed to investigate the antibacterial property of CPGs incorporating Zn(2+) and/or F(-) . We used Streptococcus mutans as a model organism because it is one of the major human oral pathogens and an early colonizer, and it has been associated with several oral infections, such as dental caries, periodontitis, and peri-implantitis. CPGs of 0.01 and 0.05 g were incubated with S. mutans for 0, 2, 4, and 6 h. Serial dilutions were plated in triplicate and colony forming units were determined. The antimicrobial effect of CPG incorporating Zn(2+) or F(-) was greater than CPG incorporating both these ions. CPG without doping produced a moderate antimicrobial effect. This family of CPGs, previously shown to promote new bone formation in vivo, is demonstrated to have superior bactericidal properties. PMID:24039127

Liu, Lela; Pushalkar, Smruti; Saxena, Deepak; LeGeros, Racquel Z; Zhang, Yu



Antibacterial nanocomposite with calcium phosphate and quaternary ammonium.  


Secondary caries is a frequent reason for restoration failure, resulting from acidogenic bacteria and their biofilms. The objectives of this study were to: (1) develop a novel nanocomposite containing nanoparticles of amorphous calcium phosphate (NACP) and quaternary ammonium dimethacrylate (QADM); and (2) investigate its mechanical and antibacterial durability. A spray-drying technique yielded NACP with particle size of 116 nm. The nanocomposite contained NACP and reinforcement glass fillers, with QADM in the resin. Two commercial composites were tested as controls. Composites were inoculated with Streptococcus mutans. After 180-day water-aging, NACP+QADM nanocomposite had flexural strength and elastic modulus matching those of commercial controls (p > 0.1). NACP+QADM nanocomposite reduced the biofilm colony-forming units (CFU) by 3-fold, compared with commercial composites (p < 0.05). Metabolic activity and lactic acid production of biofilms on NACP+QADM were much less than those on commercial composites (p < 0.05). The antibacterial properties of NACP+QADM were maintained after water-aging for 30, 90, and 180 d (p > 0.05). In conclusion, the novel NACP-QADM nanocomposite greatly decreased biofilm metabolic activity, CFU, and lactic acid, while matching the load-bearing capability of commercial composites without antibacterial properties. The NACP-QADM nanocomposite with strong and durable antibacterial properties, together with its previously reported Ca-PO(4) release capability, may render it useful for caries-inhibiting restorations. PMID:22403412

Cheng, L; Weir, M D; Zhang, K; Xu, S M; Chen, Q; Zhou, X; Xu, H H K



Antibacterial Nanocomposite with Calcium Phosphate and Quaternary Ammonium  

PubMed Central

Secondary caries is a frequent reason for restoration failure, resulting from acidogenic bacteria and their biofilms. The objectives of this study were to: (1) develop a novel nanocomposite containing nanoparticles of amorphous calcium phosphate (NACP) and quaternary ammonium dimethacrylate (QADM); and (2) investigate its mechanical and antibacterial durability. A spray-drying technique yielded NACP with particle size of 116 nm. The nanocomposite contained NACP and reinforcement glass fillers, with QADM in the resin. Two commercial composites were tested as controls. Composites were inoculated with Streptococcus mutans. After 180-day water-aging, NACP+QADM nanocomposite had flexural strength and elastic modulus matching those of commercial controls (p > 0.1). NACP+QADM nanocomposite reduced the biofilm colony-forming units (CFU) by 3-fold, compared with commercial composites (p < 0.05). Metabolic activity and lactic acid production of biofilms on NACP+QADM were much less than those on commercial composites (p < 0.05). The antibacterial properties of NACP+QADM were maintained after water-aging for 30, 90, and 180 d (p > 0.05). In conclusion, the novel NACP-QADM nanocomposite greatly decreased biofilm metabolic activity, CFU, and lactic acid, while matching the load-bearing capability of commercial composites without antibacterial properties. The NACP-QADM nanocomposite with strong and durable antibacterial properties, together with its previously reported Ca-PO4 release capability, may render it useful for caries-inhibiting restorations. PMID:22403412

Cheng, L.; Weir, M.D.; Zhang, K.; Xu, S.M.; Chen, Q.; Zhou, X.; Xu, H.H.K.



Transfecting mammalian cells: optimization of critical parameters affecting calcium-phosphate precipitate formation  

Microsoft Academic Search

DNA-calcium phosphate co-precipitates arise spontaneously in supersaturated solutions. Highly effective precipitates for transfection purposes, however, can be generated only in a very narrow range of physico-chemical conditions that control the initiation and growth of precipitate complexes. The concentrations of calcium and phosphate are the main factors influencing characteristics of the precipitate complex, but other parameters, such as temperature, DNA concentration

Martin Jordan; Annette Schallhorn; Florian M. Wurm



Calcium phosphate cement enhances primary stability of open-wedge high-tibial osteotomies  

Microsoft Academic Search

We investigated if injectable calcium phosphate cement improves primary stability in open-wedge high-tibial osteotomy. A 10 mm\\u000a open-wedge osteotomy was performed on eight pairs of preserved cadaver tibiae and seven pairs of composite (Sawbone) left\\u000a tibiae. Osteosynthesis was performed with the Dynafix plate system. The gap resulting from surgery either was filled with\\u000a 15 g injectable calcium phosphate cement in half the

Thomas Lind-Hansen; Poul Torben Nielsen; Juozas Petruskevicius; Benny Endelt; Karl Brian Nielsen; Ivan Hvid; Martin Lind



Calcium phosphate: an alternative calcium compound for dietary prevention of colon cancer? A study on intestinal and faecal parameters in healthy volunteers.  


In an effort to reduce the risk of colorectal cancer development, oral calcium carbonate supplementation has been used in previous studies for the precipitation of cytotoxic bile acids and fatty acids. In human intervention trials its effect on mucosal hyperproliferation in the colorectum has not always been satisfactory. Because the complexation of calcium and bile acids requires the formation of calcium phosphate, we performed an intervention study in 14 healthy volunteers, giving them 1,500 mg calcium as Ca3(PO4)2 for 1 week. The effects of tricalcium phosphate on luminal and faecal parameters of cytolytic activity were evaluated before, during, and after calcium phosphate supplementation. The cytolytic activity of faecal water and intestinal alkaline phosphatase activity in faecal water were not affected by supplemental calcium phosphate. In duodenal bile, the proportion of cholic acid tended to increase, whereas that of chenodeoxycholic acid tended to decrease during calcium phosphate supplementation. Neither concentrations of total and individual faecal bile acids, nor that of faecal fat were affected during calcium phosphate supplementation. It is suggested that, although phosphate is involved in bile acid precipitation, phosphate competes for calcium in the binding of fatty acids. This might possibly explain the unchanged cytolytic potency of faecal water, and therefore does not make tricalcium phosphate a suitable calcium compound for dietary intervention. PMID:8401176

Cats, A; Mulder, N H; de Vries, E G; Oremus, E T; Kreumer, W M; Kleibeuker, J H



RBS and XPS analyses of the composite calcium phosphate coatings for biomedical applications  

NASA Astrophysics Data System (ADS)

The calcium phosphate coatings on metallic implants are widely used for biomedical applications. The calcium phosphate coatings require mechanical strength, strong adhesion to the metallic implants, chemical stability and low dissolution into the human body fluid for stable functioning in the corrosive environment of the human body. In this study, a novel approach for improving the calcium phosphate coatings is utilized by adding trace metallic element into the coatings. We focused on teeth enamel, which is the hardest calcium phosphate tissue in the human body. Zn concentration increases exponentially from the interior to the surface of the enamel. As the Zn concentration increases, so the local hardness increases. Our previous studies suggest that Zn has influence on the hardness and other properties of enamel, calcium phosphate tissue. Calcium phosphate coatings doped with Zn was fabricated and characterized. The atomic composition and chemical state were investigated by using Rutherford backscattering spectroscopy (RBS) and X-ray photoelectron spectrometer (XPS), respectively. Scratch test was also carried out for measuring the adhesion of the coatings.

Ide-Ektessabi, Ari; Yamaguchi, Tetsuro; Tanaka, Yoshikazu



Calcium-phosphate microprecipitates mimic microparticles when examined with flow cytometry  

PubMed Central

There are increased levels of circulating microparticles in several disease states. Flow cytometry is a common method to examine microparticles, but their small size necessitates the use of markers to specifically distinguish microparticles from artifact. Annexin V, which binds phosphatidylserine, is a commonly used marker for microparticle detection. Annexin V requires millimolar calcium ion for optimum binding. Ca++ can precipitate with phosphate in phosphate-buffered saline (PBS). Calcium-phosphate microprecipitates were formed by titrating Ca++ into PBS and examined using flow cytometry. Calcium-phosphate microprecipitates were compared with microparticles derived from aged donor blood units. Microprecipitates were approximately 0.7–0.9 ?m in diameter compared to standard beads of known size. The microprecipitates disappeared with the addition of Ca++ chelator. When we added fluorescently-labeled antibodies to microprecipitates, the median fluorescent signal increased with increasing Ca++ concentration regardless of specificity of the antibody. When repeated with a biological sample, there was an apparent increase in the fluorescent signal that returned to baseline after Ca++ chelation. The flow cytometry signal of calcium-phosphate microprecipitates overlaps with the microparticle signal. Since Ca++ is essential for annexin V binding, it is essential to avoid artifacts from calcium-phosphate microprecipitates when using any buffer or biological fluid containing phosphate. This also highlights the potential utility of flow cytometry for the analysis of crystals in biological fluids. PMID:23125136

Larson, Michael C.; Luthi, Maia R.; Hogg, Neil; Hillery, Cheryl A.



Hydrated sites in biogenic amorphous calcium phosphates: An infrared, Raman, and inelastic neutron scattering study  

Microsoft Academic Search

Amorphous minerals are widely distributed in biology, and occur as carbonates, phosphates, and silica. Calcium and magnesium are the major cations in the phosphate deposits, but in addition, there is usually an organic component, and the minerals are hydrated with up to 20% water. Such deposits are found as intracellular granules in a variety of invertebrates such as the shore

P. C. H. Mitchell; S. F. Parker; J. Simkiss; Jane Simmons; Marina G. Taylor



Low temperature preparation of calcium phosphate structure via phosphorization of 3D-printed calcium sulfate hemihydrate based material  

Microsoft Academic Search

The conversion of newly developed three dimensionally printed calcium sulfate hemihydrate (70–90% wt\\/wt CaSO4·0.5·H2O) based materials to calcium phosphate bioceramics by phosphorization in di-sodium hydrogen phosphate solution at 80°C for\\u000a 4, 8, 16 and 24 h was studied. It was found that transformation rate, phase composition and mechanical properties were influenced\\u000a by porosity in the fabricated samples and by the duration of

J. Suwanprateeb; W. Suvannapruk; K. Wasoontararat



Electrochemical deposition mechanism of calcium phosphate coating in dilute Ca–P electrolyte system  

Microsoft Academic Search

In this work, the electrochemical deposition behavior of calcium phosphate coating from an aqueous electrolyte containing very dilute calcium and phosphorus species (Ca–P) was studied. The effects of three process parameters, i.e. temperature, current density and duration, were systematically investigated and the underlying mechanism was thoroughly analyzed. It was observed that the coating is mainly composed of hydroxyapatite (HA) in

Ren Hu; Changjian Lin; Haiyan Shi; Hui Wang



Highly enantioselective electrophilic ?-bromination of enecarbamates: chiral phosphoric acid and calcium phosphate salt catalysts.  


Metal-free chiral phosphoric acids and chiral calcium phosphates both catalyze highly enantio- and diastereoselective electrophilic ?-bromination of enecarbamates to provide an atom-economical synthesis of enantioenriched vicinal haloamines. Either enantiomer can be formed in good yield with excellent diastereo- and enantioselectivity simply by switching the catalyst from a phosphoric acid to its calcium salt. PMID:22686436

Alix, Aurélien; Lalli, Claudia; Retailleau, Pascal; Masson, Géraldine



Abstract No Hung0356 A P-XANES Study of Phosphate Sorption to Gibbsite and Calcium Carbonate  

E-print Network

Abstract No Hung0356 A P-XANES Study of Phosphate Sorption to Gibbsite and Calcium Carbonate S solution and freeze-dried. Samples of phosphate sorbed to calcium carbonate were prepared in a similar sorbed to calcium carbonate at pH 8 (Fig. 1) show 2.14 2.16 2.18 2.20 normalizedabsorbance

Sparks, Donald L.


An ultrastructural study of calcium phosphate formation in multilamellar liposome suspensions  

Microsoft Academic Search

Summary  Calcium phosphate precipitation can be induced within liposomes containing buffered inorganic phosphate by the ionophore-mediated\\u000a loading of calcium ions. Negative staining, positive staining for thin sectioning, and freeze-fracture electron microscopy\\u000a were used to characterize these synthetic vesicles and to evaluate the liposome-mineral interactions resulting from apatite\\u000a formation. Suspensions of phosphate (0–50 mM KH2PO4)-encapsulated liposomes were prepared from mixtures of phosphatidylcholine,

Brigid R. Heywood; Edward D. Eanes



Proteoglycan inhibition of calcium phosphate precipitation in liposomal suspensions.  


The major proteoglycan in cartilage (aggrecan) is a complex macromolecule with numerous chondroitin sulphate, keratan sulphate, and oligosaccharide substituents. It has been proposed that this macromolecule has an important role in regulating mineralization in this tissue, a process which is initiated by the deposition of apatite in matrix vesicles. We have used a liposome-centred endogenous precipitation method as a model for matrix vesicle mineralization to study the effect of the rat chondrosarcoma aggrecan and its chondroitin sulphate and core protein components on apatite formation from solution. Precipitation was initiated by encapsulating buffered (pH 7.4) 50 mmol/l KH2PO4 solutions in the aqueous centres of 7:2:1 phosphatidylcholine:dicetylphosphate:cholesterol liposomes, adding 2.25-2.65 mmol/l Ca2+ and 1.5 mmol/l total inorganic phosphate (PO4) to the suspending medium (pH 7.4, 22 degrees C), then making the intervening lipid membranes permeable to the Ca2+ ions with the calcium ionophore X-537A. Aggrecan (0.5%) in the suspending medium had no effect on intraliposomal precipitation, but severely reduced (approximately 70% reduction at 24 h) its subsequent spread into the medium. The chondroitin sulphate and core protein were similarly inhibitory. The degree to which aggrecan and its constituent parts inhibited precipitation correlated with their capacity to bind Ca2+ ions. These findings suggest that functional groups in aggrecan blocked apatite growth by linking via Ca2+ bridges to growth sites on the crystal surfaces. Similar Ca-mediated interactions may well have a critical regulatory role in cartilage mineralization. PMID:1472764

Eanes, E D; Hailer, A W; Midura, R J; Hascall, V C



Application of calcium phosphate as a controlled-release device.  


Calcium phosphate (CaP)-based compounds are biocompatible and have been accepted as promising candidates for novel drug-releasing devices. CaP is biodegradable and can be utilized as a durable drug release reservoir. We developed an injectable self-setting apatite cement. When a plasmid DNA complex containing CaP was injected into tumor-bearing mice, it solidified in the body and slowly released the DNA complex, inducing durable gene expression and high therapeutic effect on solid tumors. Encapsulation of a drug by CaP acts as a protective capsule for the unstable contents and improves biocompatibility. CaP nanocapsules encapsulating a plasmid DNA complex or drug-involved micelle were prepared, and they showed high stability against enzyme and protein degradation. CaP also showed high potential as a durable acid pH buffer. Aqueous alginate solution was found to form a soft gel in the body and was investigated as a drug-releasing device. However, degradation of the alginate gel is sometimes too rapid in an acidic environment such as the area around osteoporotic bones. We found that amorphous CaP powder added to the alginate gel could control the dissociation rate, buffering the pH inside the gel. Alginate gel including CaP powder and a drug for osteoporosis allowed sustained release of the drug under acidic conditions, and a good therapeutic effect was achieved in osteoporosis model rats. CaP could thus be a valuable material for drug-delivery systems as a slow-releasing drug reservoir, a protective coating, or a pH buffer. PMID:24189411

Ito, Tomoko; Otsuka, Makoto



Rheological properties of concentrated aqueous injectable calcium phosphate cement slurry.  


In this paper, the steady and dynamic rheological properties of concentrated aqueous injectable calcium phosphate cement (CPC) slurry were investigated. The results indicate that the concentrated aqueous injectable CPC showed both plastic and thixotropic behavior. As the setting process progressed, the yield stress of CPC slurry was raised, the area of the thixotropic hysteresis loop was enlarged, indicating that the strength of the net structure of the slurry had increased. The results of dynamic rheological behavior indicate that the slurry presented the structure similar to viscoelastic body and the property of shear thinning at the beginning. During the setting process, the slurry was transformed from a flocculent structure to a net structure, and the strength increased. Different factors had diverse effects on the rheological properties of the CPC slurry in the setting process, a reflection of the flowing properties (or injection), and the microstructure development of this concentrated suspension. Raising the powder-to-liquid ratio decreased the distance among the particles, increased the initial strength, and shortened the setting time. In addition, raising the temperature improved the initial strength, increased the order of reaction, and shortened the setting time, which was favorable to the setting process. The particle size of the raw material had much to do with the strength of original structure and setting time. The storage module G' of CPC slurry during the setting process followed the rule of power law function G'=A exp(Bt), which could be applied to forecast the setting time, and the calculated results thereafter are in agreement with the experimental data. PMID:16787661

Liu, Changsheng; Shao, Huifang; Chen, Feiyue; Zheng, Haiyan



Photophysics of Cy3-Encapsulated Calcium Phosphate Nanoparticles  

PubMed Central

Progress towards clinical application of biodegradable fluorescent calcium phosphate (CP) nanoparticles as a bioimaging agent requires detailed knowledge of chromophore interaction with CP. As readouts of this cargo-matrix interaction, we determined the principle photophysical properties of Cy3 encapsulated in CP nanparticles (CPNPs) using steady-state and time-resolved fluorescence spectroscopy. Fluorescence correlation spectroscopy (FCS)-determined diffusion coefficients and associated hydrodynamic radii confirmed the presence of highly monodisperse CPNPs with radii ranging from 7 to 10 nm. Single CP nanoparticles were 20 times brighter than free dye molecules because of a CP-induced 5-fold increase in quantum efficiency and encapsulation of 4 dye molecules per particle. Solvatochromic shifts resulting from hydrogen bonding between free dye and solvent or restricted intramolecular mobility by solvent viscosity were absent when Cy3 was encapsulated in CP. Encapsulation-mediated increases in radiative decay rates and decreases in non-radiative decay rates resulting in longer fluorescence lifetimes of Cy3 were attributed to solvent and CP-related local refractive indices and restricted flexibility of dye by rigid CP. Enhanced brightness of CPNPs enabled imaging of single nanoparticles under epi-fluorescence using both standard and total internal reflection fluorescence (TIRF) modes with camera exposure times on the order of 10s of ms. These enhanced photophysical properties together with excellent biocompatibility make CPNPs ideal for bioimaging applications ranging from single-molecule tracking to in vivo tumor detection and offer the possibility of timed co-delivery of drugs to control cell function. PMID:19260707

Muddana, Hari S.; Morgan, Thomas T.; Adair, James H.; Butler, Peter J.



Discrimination between biologically relevant calcium phosphate phases by surface-analytical techniques  

NASA Astrophysics Data System (ADS)

The spatially resolved phase identification of biologically relevant calcium phosphate phases (CPPs) in bone tissue is essential for the elucidation of bone remodeling mechanisms and for the diagnosis of bone diseases. Analytical methods with high spatial resolution for the discrimination between chemically quite close phases are rare. Therefore the applicability of state-of-the-art ToF-SIMS, XPS and EDX as chemically specific techniques was investigated. The eight CPPs hydroxyapatite (HAP), ?-tricalcium phosphate (?-TCP), ?-tricalcium phosphate (?-TCP), octacalcium phosphate (OCP), dicalcium phosphate dihydrate (DCPD), dicalcium phosphate (DCP), monocalcium phosphate (MCP) and amorphous calcium phosphate (ACP) were either commercial materials in high purity or synthesized by ourselves. The phase purity was proven by XRD analysis. All of the eight CPPs show different mass spectra and the phases can be discriminated by applying the principal component analysis method to the mass spectrometric data. The Ca/P ratios of all phosphates were determined by XPS and EDX. With both methods some CPPs can be distinguished, but the obtained Ca/P ratios deviate systematically from their theoretical values. It is necessary in any case to determine a calibration curve, respectively the ZAF values, from appropriate standards. In XPS also the O(1s)-satellite signals are correlated to the CPPs composition. Angle resolved and long-term XPS measurements of HAP clearly prove that there is no phosphate excess at the surface. Decomposition due to X-ray irradiation has not been observed.

Kleine-Boymann, Matthias; Rohnke, Marcus; Henss, Anja; Peppler, Klaus; Sann, Joachim; Janek, Juergen



Templating route for mesostructured calcium phosphates with carboxylic acid- and amine-type surfactants.  


Mesostructured calcium phosphates constructed by ionic frameworks were synthesized using carboxylic acid- and amine-type surfactants in mixed solvent systems of ethanol and water. A lamellar mesostructured calcium phosphate was prepared using palmitic acid as an anionic surfactant, as in the case using n-alkylamines. A wormhole-like mesostructured calcium phosphate can be obtained using dicarboxyl N-lauroyl- l-glutamic acid, whose headgroup is larger than that of palmitic acid. Similar mesostructured product was obtained using 4-dodecyldiethylenetriamine with a large headgroup containing two primary amine groups. Interactions of carboxyl and primary amino groups in the surfactant molecules with inorganic species are quite important for the formation of mesostructured calcium phosphates. The Ca/P molar ratio of mesostructured calcium phosphates was strongly affected by the molecular structure of surfactants containing carboxyl and primary amino groups. Ca-rich materials can be obtained using carboxylic acid-type surfactants (Ca/P approximately 1.7) rather than amine-type surfactants (Ca/P approximately 1.0). PMID:18947246

Ikawa, Nobuaki; Hori, Hideki; Kimura, Tatsuo; Oumi, Yasunori; Sano, Tsuneji



Formation of hydroxyapatite in soils using calcium citrate and sodium phosphate for control of strontium migration.  

SciTech Connect

{sup 90}Sr contamination is a major problem at several U.S. sites. At some sites, {sup 90}Sr has migrated deep underground making site remediation difficult. In this paper, we describe a novel method for precipitation of hydroxyapatite, a strong sorbent for {sup 90}Sr, in soil. The method is based on mixing a solution of calcium citrate and sodium phosphate in soil. As the indigenous soil microorganisms mineralize the citrate, the calcium is released and forms hydroxyapatite. Soil, taken from the Albuquerque desert, was treated with a sodium phosphate solution or a sodium phosphate/calcium citrate solution. TEM and EDS were used to identify hydroxyapatite with CO{sub 3}{sup 2-} substitutions, with a formula of (Ca{sub 4.8}Na{sub 0.2})[(PO{sub 4}){sub 2.8}(CO{sub 3}){sub 0.2}](OH), in the soil treated with the sodium phosphate/calcium citrate solution. Untreated and treated soils were used in batch sorption experiments for Sr uptake. Average Sr uptake was 19.5, 77.0 and 94.7% for the untreated soil, soil treated with sodium phosphate, and soil with apatite, respectively. In desorption experiments, the untreated soil, phosphate treated soil and apatite treated soil released an average of 34.2, 28.8 and 4.8% respectively. The results indicate the potential of forming apatite in soil using soluble reagents for retardation of radionuclide migration.

Moore, Robert Charles; Hasan, Ahmed Ali Mohamed; Sanchez, Charles Anthony (University of Arizona, Yuma, AZ); Zhao, Hongting; Salas, Fred Manuel; Hasan, Mahmoud A. (Egyptian Atomic Energy Authority, Cairo, Egypt); Holt, Kathleen Caroline



Ossification vesicles with calcium phosphate in the eyes of the insect Copium teucrii (Hemiptera: Tingidae).  


Arthropod eyes are built of repeating units named ommatidia. Each single ommatidium unit contains a cluster of photoreceptor cells surrounded by support cells and pigment cells. The insect Copium eye ommatidia include additional calcium-phosphate deposits, not described in insects to date, which can be examined today using a combined set of modern microscopy and spectroscopy techniques. Teucrium gnaphalodes L'Her plants, growing in central Spain, develop galls induced by Copium insects. A survey of C. teucrii adult specimens resulted in surprising environmental scanning electron microscopy (ESEM) images, showing that their bright red eyes contain a calcium-phosphate mineralization. A complete survey of Copium eye specimens was performed by ESEM using energy-dispersive spectroscopy, backscattered electron detector and cathodoluminescence (CL) probes, field emission scanning electron microscopy, micro-Raman spectroscopy, and confocal laser scanning microscopy in order to learn ommatidia features, such as chemical composition, molecular structure, cell membrane, and internal ommatidium eye fluids and calcium-phosphate distribution deposits. The CL panchromatic images distinguish between the calcium-phosphate ommatidium and calcium-phosphate setae, which are more apatite rich. They show Raman bands attributable to bone tissue apatite biomaterials, such as bone, collagen, lipids, and blood, i.e., peptides, amide-S, amide-II, amide-III, and cytochrome P-450 scc. The chemical composition of both galls and leaves of T. gnaphalodes was determined by gas chromatography-mass spectrometry (GC-MS) of their extracts. The spectrometric and microscopic images reveal that the calcium-phosphate mineralization is formed and constrained to Copium ommatidia, which are both matrix vesicles generating mixtures of apatite collagen and operational compound eyes of the insect. PMID:21258761

Garcia-Guinea, Javier C; Jorge, Alberto C; Tormo, Laura; Furio, Marta; Crespo-Feo, Elena; Correcher, Virgilio; Prado-Herrero, Pedro; Soria, Ana C; Sanz, Jesus; Nieves-Aldrey, Jose L



Optimization of the mineral content in polymeric gels: The effect of calcium to phosphate molar ratio  

Microsoft Academic Search

The influence of calcium to phosphate (Ca\\/P) molar ratio on the extent of mineralization in a model (poly)acrylamide gel was investigated under simulated physiological conditions. We hypothesized that the optimal growth of hydroxyapatite crystals will take place at the stoichiometric Ca\\/P molar ratio of 1.67. Phosphate ions were incorporated during the polymerization of the gel and mineralization was initiated by

Prasenjit Das; Ozan Akkus; Abdul-Majeed Azad



Mg2+ substituted calcium phosphate nano particles synthesis for non viral gene delivery application.  


Gene therapy provides a unique approach to medicine as it can be adapted towards the treatment of both inherited and acquired diseases. Recently, calcium phosphate vectors as a new generation of the non viral gene delivery nano carriers have been studied because of their biocompatibility and DNA condensation and gene transfer ability. Substituting cations, like magnesium, affects physical and chemical properties of calcium phosphate nano particles. In this study, Mg(2+) substituted calcium phosphate nano particles have been prepared using the simple sol gel method. X-ray diffraction analysis, Fourier transform infra red spectroscopy, transmission electron microscopy, specific surface area analysis, zeta potential measurement and ion release evaluation were used for characterization of the samples. It was concluded that presence of Mg ions decrease particle size and crystallinity of the samples and increase positive surface charge as well as beta tricalcium phosphate fraction in chemical composition of calcium phosphate. These properties result in increasing the DNA condensation ability, specific surface area and dissolution rate of the samples which make them suitable particles for gene delivery application. PMID:20464457

Hanifi, A; Fathi, M H; Sadeghi, H Mir Mohammad; Varshosaz, J



Enzymatic pH control for biomimetic deposition of calcium phosphate coatings.  


The current study examines the enzymatic decomposition of urea into carbon dioxide and ammonia as a means to increase the pH during biomimetic deposition of calcium phosphate (CaP) onto implant surfaces. The kinetics of the enzymatically induced pH increase were studied by monitoring pH, calcium concentration and conductivity of the aqueous solutions as a function of time, urease concentration and initial concentrations of calcium and phosphate ions. Cryogenic transmission electron microscopy was used to study the process of homogeneous CaP precipitation in solution, whereas CaP deposition on conventional acid-etched titanium and micropatterned polystyrene (PS) surfaces was studied using scanning electron microscopy. The data presented in this study confirm that the substrate-enzyme combination urea-urease offers strong control over the rate of pH increase by varying the concentrations of precursor salts and urease. Formation of biomimetic CaP coatings was shown to proceed via formation of ionic polymeric assemblies of prenucleation complexes. The process of deposition and corresponding coating morphology was strongly dependent on the concentration of calcium, phosphate and urease. Finally, it was shown that the substrate-enzyme combination urea-urease allowed for spatial distribution of CaP crystals along the grooves of micropatterned PS surfaces at low concentrations of calcium, phosphate and urease, stressing the sensitivity of the presented method. PMID:24095783

Nijhuis, Arnold W G; Nejadnik, M Reza; Nudelman, Fabio; Walboomers, X Frank; te Riet, Joost; Habibovic, Pamela; Tahmasebi Birgani, Zeinab; Li, Yubao; Bomans, Paul H H; Jansen, John A; Sommerdijk, Nico A J M; Leeuwenburgh, Sander C G



Raman spectroscopy of calcium phosphate glasses with varying CaO modifier concentrations  

Microsoft Academic Search

Raman spectroscopy has been performed on a series of calcium phosphate glasses prepared from calcium dihydrogenphosphate and CaO in which the CaO content is varied from that of the metaphosphate stoichiometry, in which the mole ratio of CaO to PâOâ is 1.00, to a stoichiometry in which the mole ratio is 1.49. Investigation of the vibrational behavior provides insight into

J. E. Pemberton; L. Latifzadeh; J. P. Fletcher; S. H. Risbud



Dense fine-grained biphasic calcium phosphate (BCP) bioceramics designed by two-step sintering  

Microsoft Academic Search

In this study, dense, fine-grained biphasic calcium phosphate bioceramics were designed via the two-step sintering method. The starting powder was nanosized calcium-deficient hydroxyapatite, whose phase composition, average particle size and morphology were characterized by XRD, FTIR, Raman spectroscopy, laser diffraction and FE-SEM. The phase transformations of the initial powder during heating up to 1200°C were examined using TG\\/DSC. At first,

M. Luki?; Z. Stojanovi?; S. D. Škapin; M. Ma?ek-Kržmanc; M. Mitri?; S. Markovi?; D. Uskokovi?



Surface modification of porous polycaprolactone/biphasic calcium phosphate scaffolds for bone regeneration in rat calvaria defect.  


In this study, polycaprolactone scaffolds fabricated by a salt-leaching process were loaded with biphasic calcium phosphate successfully to improve the osteoconductivity in bone regeneration. The surface of polycaprolactone/biphasic calcium phosphate scaffolds was aminolyzed by 1,6-hexamethylenediamine to introduce amino groups onto the surface, which was verified qualitatively by ninhyrin staining. Collagen was further immobilized on the aminolyzed porous polycaprolactone via N-ethyl-N'-(3-dimethylaminopropy) carbodiimide hydrochloride/hydroxy-2,5-dioxopyrolidine-3-sulfonic acid sodium cross-linking. The pore size of polycaprolactone/biphasic calcium phosphate-collagen scaffolds was 200-300?µm, which was suitable for bone in-growth. The X-ray photoelectron spectroscopy confirmed the coupling of collagen immobilized on the surface of polycaprolactone/biphasic calcium phosphate. In vitro results demonstrated that the spreading and viability of MC3T3-E1 cells were remarkably improved in the polycaprolactone/biphasic calcium phosphate-collagen scaffolds. The in vivo study was carried out by implanting the porous polycaprolactone, polycaprolactone/biphasic calcium phosphate, and polycaprolactone/biphasic calcium phosphate-collagen to the skulls of rats. Although the addition of biphasic calcium phosphate particles in the polycaprolactone scaffolds does not have a strong effect on the new bone formation, the immobilization of collagen on the polycaprolactone/biphasic calcium phosphate scaffolds significantly improved the bone regeneration even though the implantation time was short, 6 weeks. The present results provide more evidence that functionalizing polycaprolactone with biphasic calcium phosphate and collagen may be a feasible way to improve the osteoconduction in bone regeneration. PMID:24939961

Kim, Ji-Hyun; Linh, Nguyen Tb; Min, Young K; Lee, Byong-Taek



Low temperature preparation of calcium phosphate structure via phosphorization of 3D-printed calcium sulfate hemihydrate based material.  


The conversion of newly developed three dimensionally printed calcium sulfate hemihydrate (70-90% wt/wt CaSO(4).0.5.H(2)O) based materials to calcium phosphate bioceramics by phosphorization in di-sodium hydrogen phosphate solution at 80 degrees C for 4, 8, 16 and 24 h was studied. It was found that transformation rate, phase composition and mechanical properties were influenced by porosity in the fabricated samples and by the duration of the phosphorization treatment. Formulation with 85% CaSO(4).0.5 H(2)O showed the fastest transformation rate and resulted in the highest flexural modulus and strength. Depending on the materials formulation, XRD, FT-IR and EDS revealed that calcium deficient hydroxyapatite (CDHA) or a mixture of CDHA and dicalcium phosphate anhydrous (DCPA) were the resulting phases in the transformed samples. After cell culturing for 14 and 21 days, human osteoblast cells were observed to attach to and attain normal morphology on the surface of the transformed sample containing 85% CaSO(4).0.5 H(2)O. Various sizes and shapes of mineralized nodules were also found after 21 days. PMID:19784760

Suwanprateeb, J; Suvannapruk, W; Wasoontararat, K



RenaGel®, a nonabsorbed calcium- and aluminum-free phosphate binder, lowers serum phosphorus and parathyroid hormone  

Microsoft Academic Search

RenaGel®, a nonabsorbed calcium- and aluminum-free phosphate binder, lowers serum phosphorus and parathyroid hormone.Background.This multicenter, open-label, dose-titration study assessed the safety and efficacy of RenaGel®, a nonabsorbed calcium- and aluminum-free phosphate binder, in lowering serum phosphorus. Secondary outcomes were its effects on serum intact parathyroid hormone (iPTH) and serum lipids.Methods.Phosphate binders were discontinued during a two-week washout period. Patients whose




The determination of calcium in phosphate, carbonate, and silicate rocks by flame photometer  

USGS Publications Warehouse

A method has been developed for the determination of calcium in phosphate, carbonate, and silicate rocks using the Beckman flame photometer, with photomultiplier attachement. The sample is dissolved in hydrofluoric, nitric, and perchloric acids, the hydrofluoric and nitric acids are expelled, a radiation buffer consisting of aluminum, magnesium, iron, sodium, potassium, phosphoric acid, and nitric acid is added, and the solution is atomized in an oxy-hydrogen flame with an instrument setting of 554 mµ. Measurements are made by comparison against calcium standards, prepared in the same manner, in the 0 to 50 ppm range. The suppression of calcium emission by aluminum and phosphate was overcome by the addition of a large excess of magnesium. This addition almost completely restores the standard curve obtained from a solution of calcium nitrate. Interference was noted when the iron concentration in the aspirated solution (including the iron from the buffer) exceeded 100 ppm iron. Other common rock-forming elements did not interfere. The results obtained by this procedure are within ± 2 percent of the calcium oxide values obtained by other methods in the range 1 to 95 percent calcium oxide. In the 0 to 1 percent calcium oxide range the method compares favorably with standard methods.

Kramer, Henry



In vitro degradation behavior of porous calcium phosphates under diametral compression loading  

Microsoft Academic Search

Four different types of porous calcium phosphates were made on addition of a pore-forming compound (PVA) by sinter processing. Mechanical properties, morphology, and weight change with immersion time in Hanks’ physiological solution were evaluated. The in vitro fatigue test was also performed. Experimental results showed the pore microstructure of the as-sintered bodies to be made up of the macropores and

Shinn-Jyh Ding; Chien-Wen Wang; David Chan-Hen Chen; Hsien-Chang Chang



The use of thermal printing to control the properties of calcium phosphate deposits  

Microsoft Academic Search

The objective of this work was to characterize the deposits of calcium phosphate produced by thermal printing in terms of structure, topography and mechanical properties. Hydroxyapatite was molten and directed to (a) a titanium target in relative motion and (b) stationary titanium substrates preheated to 100°C and 350°C. Scanning electron microscopy showed round-like deposits, but high resolution profilometry measured the

Saeed Saber-Samandari; K?rlis A. Gross



Inhomogeneity of calcium phosphate coatings deposited by laser ablation at high deposition rate  

Microsoft Academic Search

Calcium phosphate coatings were deposited with a KrF excimer laser onto titanium alloy to study their homogeneity. Deposition was performed at a high deposition rate under a water vapour atmosphere of 45 Pa and at a substrate temperature of 575 °C. Samples were also submitted to annealing under the same conditions of deposition for different times just after deposition. The

J. M. Fernández-Pradas; G. Sardin; J. L. Morenza



The role of prenucleation clusters in surface-induced calcium phosphate crystallization  

NASA Astrophysics Data System (ADS)

Unravelling the processes of calcium phosphate formation is important in our understanding of both bone and tooth formation, and also of pathological mineralization, for example in cardiovascular disease. Serum is a metastable solution from which calcium phosphate precipitates in the presence of calcifiable templates such as collagen, elastin and cell debris. A pathological deficiency of inhibitors leads to the uncontrolled deposition of calcium phosphate. In bone and teeth the formation of apatite crystals is preceded by an amorphous calcium phosphate (ACP) precursor phase. ACP formation is thought to proceed through prenucleation clusters-stable clusters that are present in solution already before nucleation-as was recently demonstrated for CaCO3 (refs 15,16). However, the role of such nanometre-sized clusters as building blocks for ACP has been debated for many years. Here we demonstrate that the surface-induced formation of apatite from simulated body fluid starts with the aggregation of prenucleation clusters leading to the nucleation of ACP before the development of oriented apatite crystals.

Dey, Archan; Bomans, Paul H. H.; Müller, Frank A.; Will, Julia; Frederik, Peter M.; de With, Gijsbertus; Sommerdijk, Nico A. J. M.



Effect of milk solids concentration on the pH, soluble calcium and soluble phosphate levels  

E-print Network

Note Effect of milk solids concentration on the pH, soluble calcium and soluble phosphate levels, the level of Casol and Psol, as mmol·kg-1 , increased and the pH decreased as the milk concentration as the milk concentration was increased. At any given milk concentration, the level of Casol, Psol and milk pH

Boyer, Edmond


Influence of polymer addition on the mechanical properties of a premixed calcium phosphate cement  

PubMed Central

Premixed calcium phosphate cements can reduce handling complications that are associated with the mixing of cements in the operating room. However, to extend the clinical indication of ceramic cements their mechanical properties need to be further improved. The incorporation of a polymeric material with intrinsically high tensile properties could possibly assist in increasing the mechanical properties of calcium phosphate cement. In this study polymer microparticles made from poly(lactid-co-glycolide) plasticised with poly(ethylene glycol) 400 (PLGA/PEG microparticles) were added in amounts of up to 5 wt% to a premixed acidic calcium phosphate cement. The PLGA/PEG microparticles added undergo a shape transformation at 37 °C, which could give a better integration between polymer microparticles and ceramic cement compared with polymer microparticles lacking this property. The results showed that the incorporation of 1.25 wt% PLGA/PEG microparticles increased the compressive strength by approximately 20% up to 15.1 MPa while the diametral tensile strength was kept constant. The incorporation of PLGA/PEG microparticles increased the brushite to monetite ratio after setting compared with pure ceramic cements. In conclusion, small amounts of PLGA/PEG microparticles can be incorporated into premixed acidic calcium phosphate cement and increase their mechanical properties, which could lead to increased future applications. PMID:24270588

Engstrand, Johanna; Persson, Cecilia; Engqvist, Håkan



Calcium phosphate coatings: A comparative study between simultaneous vapor deposition and electron beam deposition techniques  

Microsoft Academic Search

A comparative study on calcium phosphate coatings produced by two different physical vapor deposition techniques namely, simultaneous vapor deposition (SVD) and electron beam deposition (EBD), has been carried out. All the as-deposited films were annealed at various temperature levels to achieve crystalline structure. The films produced were studied using X-ray diffraction and Rutherford backscattering spectroscopy. Surface morphological studies were conducted

M. Hamdi; Ari-Ide Ektessabi



Phosphorus-31 NMR Studies of Cell Wall-Associated Calcium-Phosphates in Ulva lactuca1  

PubMed Central

Phosphate concentrations in the range 0.1 to 2.0 millimolar induced the formation of extracellular amorphous calcium-phosphates in the cell wall of the marine macro algae Ulva lactuca when they were cultivated in light in seawater at 20°C. A broad resonance representing these compounds as well as resonances for extracellular orthophosphate and polyphosphates could be followed by 31P-nuclear magnetic resonance spectroscopy. The presence of the calcium-phosphate made the cells brittle and it inhibited the growth of the macro algae and caused mortality within 1 week. The formation of the calcium-phosphates was influenced by the external phosphate concentration, the extracellular pH and the nature and concentration of the external nitrogen source. Furthermore, no formation of these compounds was observed when Ulva lactuca was cultivated in the dark, at low temperatures (5°C) or in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea. The complex could be removed through washes with ethylenediaminetetraacetate; this treatment did not alter the intracellular pH or the orthophosphate and polyphosphate pools and it restored growth. Images Figure 2 PMID:16666741

Weich, Rainer G.; Lundberg, Peter; Vogel, Hans J.; Jensen, Paul



Inhomogeneity of calcium phosphate coatings deposited by laser ablation at high deposition rate  

NASA Astrophysics Data System (ADS)

Calcium phosphate coatings were deposited with a KrF excimer laser onto titanium alloy to study their homogeneity. Deposition was performed at a high deposition rate under a water vapour atmosphere of 45 Pa and at a substrate temperature of 575 °C. Samples were also submitted to annealing under the same conditions of deposition for different times just after deposition. The effects of the annealing were also investigated. The morphology of the coatings was studied by scanning electron microscopy. Their structure and phase distribution was analysed by X-ray diffractometry and infrared and micro-Raman spectroscopies. Besides the non-uniform thickness, the results reveal an inhomogeneity in the spatial distribution of calcium phosphate phases in the coatings. The phase distribution can be almost completely correlated with the deposition rate. High deposition rates (0.5 nm/pulse) occurring in the centre of deposition results in the formation of amorphous calcium phosphate, while lower deposition rates favour the presence of hydroxyapatite and alpha tricalcium phosphate. At intermediate deposition rates, beta tricalcium phosphate is found, probably because the superimposed effect of energetic particles bombardment. The annealing process promotes the crystallisation of the amorphous material. The importance of the deposition rate in the phases obtained is stated after comparing these results with a previous work where homogeneous hydroxyapatite coatings were obtained under the same conditions of laser fluence, temperature and pressure, but at lower deposition rates.

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


Calcium pyrophosphate dihydrate and basic calcium phosphate crystal-induced arthropathies: update on pathogenesis, clinical features, and therapy.  


Calcium-containing crystals are the most common class for the osteoarthritic joint. They are responsible for acute periarthritis and destructive arthropathies, and for tissue deposits mimicking tumor-like masses. These crystals encompassed mainly calcium pyrophosphate dihydrate and basic calcium phosphate crystals, with the latter being related to hydroxyapatite, carbonate-substituted apatite, and octacalcium phosphate. Calcification deposit mechanisms will be reviewed with respect to extracellular inorganic pyrophosphate dysregulation mainly caused by modulation of specific membrane channel disorders. Genetic defects have been extensively studied and identified mutation of specific genes such as ANKH and COL. Pathogenesis of crystal-induced inflammation is related to synovial tissue and direct cartilage activation. Besides classical knee or wrist pseudogout attacks or Milwaukee shoulder arthropathies, clinicians should be aware of other specific common presentations, such as erosive calcifications, spinal cord compression by intraspinal masses, ligamentum flavum calcification, or atypical calcified tophus. Promising clinical results for preventing calcium crystal deposits and cartilage degradation are lacking. Practical imaging tools are needed to monitor reduction of calcification of fibrocartilage and articular cartilage as markers of drug efficacy. PMID:15134602

Ea, Hang-Korng; Lioté, Frédéric



Determination of calcium phosphate inhibitor activity. Critical assessment of the methodology.  


A method is described which determines the amount of calcium phosphate inhibitor activity in solutions with ionic compositions similar to that of undiluted plasma or serum. Constant supersaturations were obtained for the inhibitor analysis by equilibrating an aliquot of sample with dicalcium phosphate dihydrate (DCPD) and it was shown that the ion activity product of the equilibrated solutions was similar to the solubility product of DCPD. The amount of inhibitor activity in solution is assessed by determining the amount of hydroxylapatite seed needed for a predetermined rate of crystal growth. It was shown that the Langmuir adsorption isotherm is an appropriate model for describing the inhibitor data and provides a convenient linear-regression means for computing inhibitor activities. When tested at its normal physiological concentrations in plasma, albumin was the most important of the known calcium phosphate inhibitors. PMID:6087103

Meyer, J L; Fleisch, H



A construction of novel iron-foam-based calcium phosphate/chitosan coating biodegradable scaffold material.  


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. PMID:23827538

Wen, Zhaohui; Zhang, Liming; Chen, Chao; Liu, Yibo; Wu, Changjun; Dai, Changsong



Modelling biological and chemically induced precipitation of calcium phosphate in enhanced biological phosphorus removal systems.  


The biologically induced precipitation processes can be important in wastewater treatment, in particular treating raw wastewater with high calcium concentration combined with Enhanced Biological Phosphorus Removal. Currently, there is little information and experience in modelling jointly biological and chemical processes. This paper presents a calcium phosphate precipitation model and its inclusion in the Activated Sludge Model No 2d (ASM2d). The proposed precipitation model considers that aqueous phase reactions quickly achieve the chemical equilibrium and that aqueous-solid change is kinetically governed. The model was calibrated using data from four experiments in a Sequencing Batch Reactor (SBR) operated for EBPR and finally validated with two experiments. The precipitation model proposed was able to reproduce the dynamics of amorphous calcium phosphate (ACP) formation and later crystallization to hydroxyapatite (HAP) under different scenarios. The model successfully characterised the EBPR performance of the SBR, including the biological, physical and chemical processes. PMID:21565382

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



Structure and properties of calcium iron phosphate glasses  

NASA Astrophysics Data System (ADS)

The structural properties of xCaO-(100 - x) (0.4Fe2O3-0.6P2O5) (x = 0, 10, 20, 30, 40, 50 mol%) glasses have been investigated by XRD, DTA, IR and Raman spectroscopy. XRD analysis has confirmed that the majority of samples are X-ray amorphous, and EDS analysis indicates that the glass matrix can accommodate ?30 mol% CaO. IR and Raman spectra show that the glass structure consists predominantly of pyrophosphate (Q1) units. IR spectra indicate that the phosphate network is depolymerized with the addition of CaO content. The density and glass transition temperature (Tg) increase with increasing CaO content for the glasses. This behavior indicates that the addition of CaO improves the strength of the cross-links between the phosphate chains of the glass.

Qian, Bin; Liang, Xiaofeng; Wang, Cuiling; Yang, Shiyuan



Formation of calcium-deficient hydroxyapatite from ?-tricalcium phosphate  

Microsoft Academic Search

This study investigated the factors influencing the kinetics of Ca9HPO4(PO4)5OH (calcium deficient hydroxyapatite or CDHAp) formation from ?-Ca3(PO4)2 (?-TCP). The kinetics of CDHAp formation were investigated by isothermal calorimetry at constant temperatures ranging between 30 and 75°C and by changes in pH at 37.4 and 70°C. The calorimetric curves were characterized by two reaction peaks. Activation energies were calculated for

Kevor S. TenHuisen; Paul W. Brown



Calcium Phosphate Phase Transformation Produced by the Interaction of the Portland Cement Component of White Mineral Trioxide Aggregate with a Phosphate-containing Fluid  

Microsoft Academic Search

The bioactivity of mineral trioxide aggregate (MTA) has been attributed to its ability to produce hydroxyapatite in the presence of phosphate-containing fluids. It is known that stoichiometric hydroxyapatites do not exist in biological systems and do not contribute to the osteogenic potential of calcium phosphate–based biomaterials. Because Portland cement is the active ingredient in white MTA, we have characterized the

Franklin R. Tay; David H. Pashley; Frederick A. Rueggeberg; Robert J. Loushine; R. Norman Weller



Structural characterization of anion-calcium-humate complexes in phosphate-based fertilizers.  


Fertilizers based on phosphate-metal-humate complexes are a new family of compounds that represents a more sustainable and bioavailable phosphorus source. The characterization of this type of complex by using solid (31)P NMR in several fertilizers, based on single superphosphate (SSP) and triple superphosphate (TSP) matrices, yielded surprising and unexpected trends in the intensity and fine structure of the (31)P NMR peaks. Computational chemistry methods allowed the characterization of phosphate-calcium-humate complexes in both SSP and TSP matrices, but also predicted the formation of a stable sulfate-calcium-humate complex in the SSP fertilizers, which has not been described previously. The stability of this complex has been confirmed by using ultrafiltration techniques. Preference towards the humic substance for the sulfate-metal phase in SSP allowed the explanation of the opposing trends that were observed in the experimental (31)P NMR spectra of SSP and TSP samples. Additionally, computational chemistry has provided an assignment of the (31)P NMR signals to different phosphate ligands as well as valuable information about the relative strength of the phosphate-calcium interactions within the crystals. PMID:23670945

Baigorri, Roberto; Urrutia, Oscar; Erro, Javier; Mandado, Marcos; Pérez-Juste, Ignacio; Garcia-Mina, José María



Ectopic Osteoid and Bone Formation by Three Calcium-Phosphate Ceramics in Rats, Rabbits and Dogs  

PubMed Central

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 (?-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

Wang, Liao; Zhang, Bi; Bao, Chongyun; Habibovic, Pamela; Hu, Jing; Zhang, Xingdong



Complexation/encapsulation of green tea polyphenols in mixed calcium carbonate and phosphate micro-particles.  


We used a double-jet mixer to encapsulate water-soluble polyphenols, green tea extract (GTE), with calcium-based inorganic materials. The device mixed calcium chloride solutions with a solution of carbonate and phosphate in the presence of a GTE solution, and formed micro-particles which capture the GTE molecules. The micro-particles were analysed by liquid chromatography coupled to tandem mass spectroscopy to determine the encapsulation yield and loading of the different GTE components. We established correlations between (1) the efficiency of the GTE encapsulation and the composition of the mixed anion solutions and (2) the protonation degree of the ions and the molar ratio of calcium cations and carbonate/phosphate anions. An optimal and reproducible GTE loading of about 40% with an encapsulation yield of 65% was observed for a carbonate/phosphate molar composition of 4?:?1. In addition, our experimental results showed that the process is selective and favours the encapsulation of gallated species which form stronger complexes with calcium cations. PMID:20945969

Elabbadi, Amal; Jeckelmann, Nicolas; Haefliger, Olivier P; Ouali, Lahoussine



Laminin Coating Promotes Calcium Phosphate Precipitation on Titanium Discs in vitro  

PubMed Central

ABSTRACT Objectives The objective of this study was to investigate the effect of a laminin coating on calcium phosphate precipitation on three potentially bioactive titanium surfaces in simulated body fluid. Material and Methods Blasted titanium discs were prepared by alkali and heat treatment (AH), anodic oxidation (AO) or hydroxyapatite coating (HA) and subsequently coated with laminin. A laminin coated blasted surface (B) served as a positive control while a blasted non coated (B-) served as a negative control. Surface morphology was examined by Scanning Electron Microscopy (SEM). The analysis of the precipitated calcium and phosphorous was performed by Energy Dispersive X-ray Spectroscopy (EDX). Results The thickness of the laminin coating was estimated at 26 Å by ellipsometry. Interferometry revealed that the coating process did not affect any of the tested topographical parameters on µm level when comparing B to B-. After 2 weeks of incubation in SBF, the alkali-heat treated discs displayed the highest calcium phosphate deposition and the B group showed higher levels of calcium phosphate than the B- group. Conclusions Our results suggest that laminin may have the potential to be used as a coating agent in order to enhance the osseoinductive performance of biomaterial surfaces, with the protein molecules possibly functioning as nucleation centres for apatite formation. Nevertheless, in vivo studies are required in order to clarify the longevity of the coating and its performance in the complex biological environment. PMID:24422002

Stenport, Victoria Franke; Currie, Fredrik; Wennerberg, Ann



Synthesis of some calcium phosphate crystals using the useful biomass for immobilization of microorganisms  

NASA Astrophysics Data System (ADS)

Three sources of biomass generated by primary industry were used as the raw material for the synthesis of calcium phosphate crystals. Phosphoric acid was extracted from burned rice chaff using a 30% nitric acid solution, while scallop shells and gypsum of plasterboard were used as calcium sources. The calcium phosphate crystals were synthesized by a method involving homogeneous precipitation, and the relationship between the composition and shape of the crystals and the pH at the time of the precipitation was investigated. Monetite crystals in a petal form with a diameter ranging from 0.1 to 2 ?m were precipitated at pH 2.0, while granular apatite crystals with a mean diameter of 1 ?m were precipitated at pH 6.0. We also investigated the ability of the synthesized calcium phosphate crystals to immobilize lactic acid bacteria for practical use in industrial bioreactor. It was determined that monetite crystals with a diameter of 2 ?m had the highest ability to fix lactic acid bacteria. The population of lactic acid bacteria was estimated to exceed 1,300 bacteria per crystal surface of 50 ?m2 suggesting that these crystals may be of practical use in industrial fermenters.

Kohiruimaki, T.



Precipitation of calcium phosphates from electrolyte solutions. V. The influence of citrate ions.  


The influence of citrate ions on the precipitation of crystalline apatitic precipitates with low Ca/P molar ratios [octacalcium phosphate (OCP) and calcium-deficient apatites (DA) (system A)] and of the intercrystalline mixtures of calcium hydrogen phosphate dihydrate (DCPD) and DA (system B) was investigated. Samples were prepared by direct mixing of calcium chloride solutions (A, 6.10(-3) mol dm-3; B, 1.10(-1) mol dm-3) and sodium phosphate solutions (A, 6.10(-3) mol dm-3; B, 2.10(-2) mol dm-3) containing citrate (0-2.10(-3) mol dm-3) and preadjusted to pH 7.4. In the presence of citrate ions: (a) crystal growth of OCP and DA was slowed down; (b) habit modification of DCPD crystals occurred; and (c) equilibration in intercrystalline mixtures of DCPD and DA's was slowed down. All phenomena were caused by surface adsorption of negatively charged ions, most probably CaC6H5O7-, which is the prevalent calcium citrate species under the given experimental conditions. Habit modification of DCPD was induced by preferential adsorption at the (001) crystal plane. PMID:116729

Brecevi?, L; Füredi-Milhofer, H



Effect of the Intravenous Lipid Emulsions on the Availability of Calcium when using Organic Phosphate in TPN Admixtures  

Microsoft Academic Search

Purpose  The addition of high amounts of calcium remains a pharmaceutical concern due to its precipitation with phosphate in total\\u000a parenteral nutrient (TPN) admixtures, compromising also the stability of the lipid emulsion.\\u000a \\u000a \\u000a \\u000a Materials and Methods  Calcium-phosphate solubility was compared when using binary PN solutions versus all-in-one TPN (admixtures with lipid emulsions) in three formulas using organic calcium gluconate and gulcose-1-phosphate.\\u000a \\u000a \\u000a \\u000a Results  It was

Jean Claude Chaumeil; Sami Jebnoun; Naima Khrouf; Abderrazek Hedhili; Souad Sfar



Characterization of calcium phosphate powders originating from Phyllacanthus imperialis and Trochidae Infundibulum concavus marine shells.  


The study reports the preparation and characterization of powders consisting of the different phases of calcium phosphates that were obtained from the naturally derived raw materials of sea-shell origins reacted with H3PO4. Species of sea origin, such as corals and nacres, attracted a special interest in bone tissue engineering area. Nacre shells are built up of calcium carbonate in aragonite form crystallized in an organic matrix. In this work two natural marine origin materials (shells of echinoderm Sputnik sea urchin - Phyllacanthus imperialis and Trochidae Infundibulum concavus mollusk) were involved in the developing powders of calcium phosphate based biomaterials (as raw materials for bone-scaffolds) by hotplate and ultrasound methods. Thermal analyses of the as-prepared materials were made for an assessment of the thermal behavior and heat treatment temperatures. Samples from both sea shells each of them prepared by the above mentioned methods were subjected to thermal treatments at 450 °C and 850 °C in order to evaluate the crystalline transformations of the calcium phosphate structures in the heating process. By X-ray diffraction analyses various calcium phosphate phases were identified. In Sputnik sea urchins originated samples were found predominantly brushite and calcite as a small secondary phase, while in Trochidae I. concavus samples mainly monetite and HA phases were identified. Thermal treatment at 850 °C resulted flat-plate whitlockite crystals - ?-MgTCP [(Ca, Mg)3 (PO4)2] for both samples regardless the preparation method (ultrasound or hotplate) or the targeted Ca/P molar ratio according with XRD patterns. Scanning electron microscopy and Fourier transformed infrared spectroscopy were involved more in the characterization of these materials and the good correlations of the results of these methods were made. PMID:23623070

T?m??an, M; Ozyegin, L S; Oktar, F N; Simon, V



On the Pressure-Induced Loss of Crystallinity in Zinc- and Calcium-Phosphates  

SciTech Connect

A recently suggested mechanism for the stress memory of various metal phosphates is investigated experimentally. Based on first-principles simulations [N. J. Mosey et al., Science 307, 1612 (2005)], it had been argued that atoms with flexible coordination, such as zinc or heavy-metal cations, act as network-forming agents, undergoing irreversible pressure-induced changes in bonding that lead to increased connectivity between phosphate anions. In the present study, orthophosphates of zinc and calcium were exposed to high pressures on surfaces and in diamond anvil cells. An additional set of first-principles simulations was accomplished on ?-orthophosphate of zinc, which suggested that this material was already cross-linked before compression but that it nevertheless underwent a reversible coordination change under pressure in agreement with the experimental results presented here. Raman spectra indicate an irreversible, pressure-induced loss of long-range crystallinity. The pressures required to induce these changes are around 7 GPa for the zinc phosphates, while they are close to 21 GPa for the calcium phosphates. Hydrogenation of the metal phosphate lowers the threshold pressure by approximately 2-3 GPa in both cases. Moreover, ?-orthophosphate of zinc could be partially amorphisized under nonisotropic pressure on copper foils.

Shakhvorostov, D.; Mosey, N; Munoz-Paniagua, D; Pereira, G; Song, Y; Kasrai, M; Norton, P; Müser, M



Sonoelectrochemical deposition of calcium phosphates on carbon materials: effect of current density  

Microsoft Academic Search

Calcium phosphate (CaP) coatings on carbon fabric substrate were produced by sonoelectrodeposition at different current densities\\u000a (5, 8, 13, 20 and 34 mA\\/cm2). The surface morphology and chemical composition of the coatings were characterized by SEM, Raman and FTIR spectra. The\\u000a results showed that at 5 mA\\/cm2 current density, the coating exhibits plate-like morphology, indicating an octacalcium phosphate (OCP) phase was pre-formed

H. M. Han; G. J. Phillips; S. V. Mikhalovsky; S. FitzGerald; A. W. Lloyd



In vitro degradation of electrodeposited calcium phosphate coatings by osteoclast-like cells.  


The aim of this study is to investigate the in vitro degradation of electrolytically deposited calcium phosphate coatings in the presence of osteoclast-like cells. Titanium alloy plates electrolytically coated with calcium phosphate with or without chitosan were incubated with RAW264.7 cells for 14 days. The TRAP activity was measured and the cell attachment and proliferation capacity were analyzed. The calcium ion concentrations in the culture medium before and after incubation were calculated. Both coatings were observed with scanning electron microscopy and characterized through an x-ray diffractometer and Fourier transform infrared spectrum. The RAW264.7 cells differentiated into TRAP-positive osteoclast-like cells on both coatings after 7 days. Although presenting different cell attachment pattern, the RAW264.7 cells demonstrated the similar TRAP activity and proliferation capacity. It was found that the calcium ion concentrations in the medium decreased at the beginning, but increased after 11 and 14 days. The chitosan containing coatings had higher Ca(2+) concentration in the medium compared to that without chitosan. Besides, the incubation of coatings with cells induced higher calcium ion concentrations than those without cells at day 11 and day 14. Despite the structural changes of dissolution pits and osteoclastic resorption lacunae present on both coatings, the x-ray diffractometer and Fourier transform infrared spectrum showed few alternations in their chemical compositions. Both electrodeposited calcium phosphate coatings can be resorbed by osteoclast-like RAW264.7 cells and dissolved in the culture medium in vitro. The degradation brings little change to the chemical compositions of both coatings. PMID:22652553

Long, Tian; Hong, Feng; Shen, Shiqian; Wang, Lina; Wang, Yining; Wang, Jiawei



Structural aspects of calcium iron phosphate glass containing neodymium oxide  

NASA Astrophysics Data System (ADS)

Homogeneous glasses of the xNd2O3sbnd (100 - x)(12CaOsbnd 20Fe2O3sbnd 68P2O5) system were obtained within the 0 ? x ? 10 mol% composition range. The density and molar volume measurements helped to understand the structural changes occurring in these glasses. Vickers-hardness results showed that addition of Nd2O3 strengthened the crosslinking of the glass network. Spectra analysis indicated that Nd2O3 enters in the structure of the phosphate glasses as a network modifier. The depolymerization of the glass network by the addition of Nd2O3 is characterized by the increase in the concentration of pyrophosphate. The decrease of the Q1 terminal oxygen with increasing Nd2O3 content indicated that Psbnd Osbnd Nd bonds participated in the pyrophosphate glass structure, determined from the Raman spectra.

Li, Haijian; Liang, Xiaofeng; Wang, Cuiling; Yu, Huijun; Li, Zhen; Yang, Shiyuan



Identification and quantitive analysis of calcium phosphate microparticles in intestinal tissue by nuclear microscopy  

NASA Astrophysics Data System (ADS)

Microscopic particles (0.5-2 ?m diameter), rich in calcium and phosphorus, are found in the lumen of the mid-distal gut of all mammals investigated, including humans, and these may play a role in immuno-surveillance and immune regulation of antigens from food and symbiotic bacteria that are contained in the gut. Whether these particles can cross in to tissue of the intestinal mucosa is unclear. If so, characterising their morphology and chemical composition is an important task in elucidating their function. The analysis of calcium phosphate in biological tissues has been approached in several ways including optical microscopy, scanning electron microscopy and, most recently in this work, with nuclear microscopy. In this paper, we describe the use of microPIXE and microRBS to locate these particles and to determine, accurately, the ratio of phosphorus to calcium using the information on sample thickness obtained from RBS to allow the PIXE ratios to be corrected. A commercial sample of hydroxy apatite was used to demonstrate accuracy and precision of the technique. Then, in a pilot study on intestinal tissue of mice, we demonstrated the presence of calcium phosphate microparticles, consistent with confocal microscopy observations, and we identified the average molar P:Ca molar ratio as 1.0. Further work will confirm the exact chemical speciation of these particles and will examine the influence of differing calcium containing diets on the formation of these microparticles.

Gomez-Morilla, Inmaculada; Thoree, Vinay; Powell, Jonathan J.; Kirkby, Karen J.; Grime, Geoffrey W.



Preparation and Properties of Nanoparticles of Calcium Phosphates With Various Ca/P Ratios  

PubMed Central

This study aimed at preparing and studying the properties of nanoparticles of calcium phosphate (nCaP) with Ca/P ratios ranging from 1.0 to 1.67 using a spray-drying technique. Micro-structural analyses suggested that the nCaPs with Ca/P ratios of 1.67 to 1.33 were nano-sized amorphous calcium phosphate (ACP) containing varying amounts of acid phosphate and carbonate. The nCaP with Ca/P ratio of 1 contained only nano-sized low crystalline dicalcium phosphate (DCP). BET measurements of the nCaPs showed specific surface areas of (12 ± 2 to 50 ± 1) m2/g, corresponding to estimated equivalent spherical diameters of (38 to 172) nm. However, dynamic light scattering measurements revealed much larger particles of (380 ± 49 to 768 ± 111) nm, owing to agglomeration of the smaller primary nano particles as revealed by Scanning Electron Microscopy (SEM). Thermodynamic solubility measurements showed that the nCaPs with Ca/P ratio of 1.33 – 1.67 all have similar solubility behavior. The materials were more soluble than the crystalline hydroxyapatite (HA) at pH greater than about 4.7, and more soluble than ?-tricalcium phosphate (?-TCP), octacalcium phosphate (OCP) and DCP at pH above 5.5. Their solubility approached that of ?-tricalcium phosphate (?-TCP) at about pH 7. These nCaPs, which cannot be readily prepared by other currently available methods for nanoparticle preparation, have potential biomedical applications. PMID:21037948

Sun, Limin; Chow, Laurence C.; Frukhtbeyn, Stanislav A.; Bonevich, John E.



Biphasic calcium phosphate/hydrosoluble polymer composites: a new concept for bone and dental substitution biomaterials.  


Calcium phosphate materials have been increasingly employed in orthopedic and dental applications in recent years and are now being developed for use in noninvasive surgery or as carriers for drug delivery systems. We developed an injectable bone substitute (IBS) constituted of biphasic calcium phosphate and a hydrosoluble polymer as a carrier. In vivo biocompatibility and biofunctionality of IBS were tested in rabbits using implants in osseous and nonosseous areas. The results obtained demonstrated that the concept of IBS, a filler without initial mechanical properties but able to be rapidly resorbed and replaced by newly formed bone, can be applied to new surgical applications in orthopedic surgery, maxillofacial surgery, and dentistry for pulp capping and root filling. PMID:10458277

Daculsi, G; Weiss, P; Bouler, J M; Gauthier, O; Millot, F; Aguado, E



Preparation of polyelectrolyte/calcium phosphate hybrids for drug delivery application.  


Biocompatible and biodegradable polyelectrolyte complex consisting of carboxylmethyl cellulose (CMC) and chitosan (CHI) were studied as a template for calcium phosphate biomimetic mineralization. CMC/CHI/calcium phosphate hybrids were prepared using different concentrations of simulated body fluid (2, 5 and 10×SBF) for producing hybrids with different organic/inorganic ratio. These hybrids were characterized using X-ray diffraction (XRD), infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The equilibrium swelling extents of the hybrids were found to be dependent on the inorganic % in the hybrids. The release profile of bovine serum albumin as a model drug in simulated intestine solution (pH 7.4) during 24h has established the efficiency of the hybrids as a sustained delivery system. The hybrids developed in this contribution exhibit a great potential in bone tissue engineering and drug delivery applications. PMID:25256512

Salama, Ahmed; El-Sakhawy, Mohamed



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

PubMed Central

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

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



Stabilization/solidification of mercury-contaminated waste ash using calcium sodium phosphate (CNP) and magnesium potassium phosphate (MKP) processes.  


This study examined the stabilization and solidification (S/S) of mercury (Hg)-contaminated waste ash generated from an industrial waste incinerator using chemically bonded phosphate ceramic (CBPC) technology. A magnesium potassium phosphate (MKP; MgKPO4 · 6H2O) ceramic, fabricated from MgO and KH2PO4, and a calcium sodium phosphate (CNP; CaNaPO4) ceramic, fabricated from CaO and Na2HPO4, were used as solidification binders in the CBPC process, and Na2S or FeS was added to each solidification binder to stabilize the Hg-contaminated waste ash. The S/S processes were conducted under various operating conditions (based on the solidification binder and stabilization reagent, stabilization reagent dosage, and waste loading ratio), and the performance characteristics of the S/S sample under each operating condition were compared, including the Hg leaching value and compressive strength. The Hg leaching value of untreated Hg-contaminated waste ash was 231.3 ?g/L, whereas the S/S samples treated using the MKP and CNP processes exhibited Hg leaching values below the universal treatment standard (UTS) limit (25 ?g/L). Although the compressive strengths of the S/S samples decreased as the sulfide dosage and waste loading ratio were increased, most of the S/S samples fabricated by the MKP and CNP processes exhibited good mechanical properties. PMID:24997263

Cho, Jae Han; Eom, Yujin; Lee, Tai Gyu



Calcium Phosphate Transfection Works very well for 293 cells (up to 95% transfection efficiencies). Grow cells in  

E-print Network

Calcium Phosphate Transfection Works very well for 293 cells (up to 95% transfection efficiencies to transfection. This gives them enough time to settle back down. 2. Thaw 2X HBS at room temperature (37°C

Lamond, Angus I.


Preparation and Sustained-Release Property of Triblock Copolymer/Calcium Phosphate Nanocomposite as Nanocarrier for Hydrophobic Drug  

NASA Astrophysics Data System (ADS)

The P123/ACP nanocomposite with sizes less than 100 nm consisting of triblock copolymer P123 and amorphous calcium phosphate (ACP) has been prepared by using an aqueous solution containing CaCl2, (NH4)3PO4, and P123 at room temperature. The P123/ACP nanocomposite is used as the nanocarrier for hydrophobic drug ibuprofen, based on the combined advantages of both amphiphilic block copolymer and calcium phosphate delivery system. The P123/ACP nanocomposite has a much higher ibuprofen loading capacity (148 mg/g) than the single-phase calcium phosphate nanostructures. The drug release percentage of the P123/ACP nanocomposite in simulated body fluid reaches about 100% in a period of 156 h, which is much slower than that of single-phase calcium phosphate nanostructures. It is expected that the P123/ACP nanocomposite is promising for the application in the controlled delivery of hydrophobic drugs.

Cao, Shao-Wen; Zhu, Ying-Jie; Wu, Jin; Wang, Ke-Wei; Tang, Qi-Li



Mg 2+ substituted calcium phosphate nano particles synthesis for non viral gene delivery application  

Microsoft Academic Search

Gene therapy provides a unique approach to medicine as it can be adapted towards the treatment of both inherited and acquired\\u000a diseases. Recently, calcium phosphate vectors as a new generation of the non viral gene delivery nano carriers have been studied\\u000a because of their biocompatibility and DNA condensation and gene transfer ability. Substituting cations, like magnesium, affects\\u000a physical and chemical

A. HanifiM; M. H. Fathi; H. Mir Mohammad Sadeghi; J. Varshosaz



Chemoradiotherapy of ME180 Tumors with an Intratumoral Cisplatin\\/Calcium Phosphate Drug Delivery System  

Microsoft Academic Search

Drug delivery systems are able to concentrate cancer drugs in a localized region, thereby increasing drug effectiveness. Side effects are decreased due to reduced systemic drug exposure. This in vivo study investigates the use of a calcium phosphate (CaP) crystal drug delivery system to deliver cisplatin (CDDP) into murine ME-180 tumors. Forty-two athymic Ner-nu\\/nu mice were put into six groups:

Felix Santiago; Stacha Campbell; Robert Dowsett; Liisa Kuhn



Calcium phosphate-containing precipitate and the carcinogenicity of sodium salts in rats.  


Sodium saccharin, ascorbate and other sodium salts fed at high doses to rats produce urinary bladder urothelial cytotoxicity with consequent regenerative hyperplasia. For sodium salts that have been tested, tumor activity is enhanced when administered either alone or after a brief exposure to a known genotoxic bladder carcinogen. These sodium salts alter urinary composition of rats resulting in formation of an amorphous precipitate. We examined the precipitate to ascertain its composition and further delineate the basis for its formation in rat urine. Using scanning electron microscopy with attached X-ray energy dispersive spectroscopy, the principal elements present were calcium, phosphorus, minor amounts of silicon and sulfur. Smaller elements are not detectable by this method. Infrared analyses demonstrated that calcium phosphate was in the tribasic form and silicon was most likely in the form of silica. Small amounts of saccharin were present in the precipitate from rats fed sodium saccharin (<5%), but ascorbate was not detectable in the precipitate from rats fed similar doses of sodium ascorbate. Large amounts of urea and mucopolysaccharide, apparently chondroitin sulfate, were detected in the precipitate by infrared analysis. Chemical analyses confirmed the presence of large amounts of calcium phosphate with variably small amounts of magnesium, possibly present as magnesium ammonium phosphate crystals, present in urine even in controls. Small amounts of protein, including albumin and alpha(2u)-globulin, were also detected (<5% of the precipitate). Calcium phosphate is an essential ingredient of the medium for tissue culture of epithelial cells, but when present at high concentrations (>5 mM) it precipitates and becomes cytotoxic. The nature of the precipitate reflects the unique composition of rat urine and helps to explain the basis for the species specificity of the cytotoxic and proliferative effects of high doses of these sodium salts. PMID:10753216

Cohen, S M; Arnold, L L; Cano, M; Ito, M; Garland, E M; Shaw, R A



Laser pulse dependent micro textured calcium phosphate coatings for improved wettability and cell compatibility  

Microsoft Academic Search

Surface wettability of an implant material is an important criterion in biological response as it controls the adsorption\\u000a of proteins followed by attachment of cells to its surface. Hence, micro-textured calcium phosphate coatings with four length\\u000a scales were synthesized on Ti–6Al–4V substrates by a laser cladding technique and their effects on wettability and cell adhesion\\u000a were systematically evaluated. Microstructure and

Sameer R. Paital; Wei He; Narendra B. Dahotre



Endothelial cells stimulate osteogenic differentiation of mesenchymal stem cells on calcium phosphate scaffolds.  


The interaction of mesenchymal stem cells (MSCs) with endothelium in vivo is significant for regenerative processes in organisms. To design concepts for tissue engineering for bone regeneration based on this interaction, the osteogenic differentiation of human bone marrow-derived MSCs in a co-culture with human dermal microvascular endothelial cells (HDMECs) was studied. The experiments were focussed on the regulation of MSCs in a co-culture with HDMECs on different calcium phosphate scaffolds. Alkaline phosphatase (ALP) activity and mRNA expression of various osteogenic markers increased significantly when cells were co-cultured on materials with calcium phosphate scaffolds compared to tissue culture polystyrene or when MSCs were cultured alone. In addition, it was observed that the expression of osteopontin and osteocalcin was highly sensitive to the substrate for cell adhesion. Whereas these late osteogenic markers were down-regulated in co-cultures on polystyrene, they were up-regulated on calcium phosphate and moreover, were differentially expressed on the three calcium phosphate scaffolds tested. To enhance the osteogenic differentiation of MSCs in a co-culture, direct cell-cell interactions were required. Concerning molecular mechanisms in the interactions between both cell types, it was found that connexin 43 was expressed in contact sites and more apparently, endothelial cells grew over the MSCs, which facilitated direct cellular interactions mediated by various adhesion receptors. This study revealed significant findings for the design of implant materials suitable for regeneration of bone by stimulating the functional interaction of MSCs with endothelial cells. Copyright © 2012 John Wiley & Sons, Ltd. PMID:23038605

Bulnheim, Ulrike; Müller, Petra; Neumann, Hans-Georg; Peters, Kirsten; Unger, Ronald E; Kirkpatrick, C James; Rychly, Joachim



Perfusion electrodeposition of calcium phosphate on additive manufactured titanium scaffolds for bone engineering  

Microsoft Academic Search

A perfusion electrodeposition (P-ELD) system was reported to functionalize additive manufactured Ti6Al4V scaffolds with a calcium phosphate (CaP) coating in a controlled and reproducible manner. The effects and interactions of four main process parameters – current density (I), deposition time (t), flow rate (f) and process temperature (T) – on the properties of the CaP coating were investigated. The results

Yoke Chin Chai; Silvia Truscello; Simon Van Bael; Frank P. Luyten; Jozef Vleugels; Jan Schrooten



Rapid prototyped porous titanium coated with calcium phosphate as a scaffold for bone tissue engineering  

Microsoft Academic Search

High strength porous scaffolds and mesenchymal stem cells are required for bone tissue engineering applications. Porous titanium scaffolds (TiS) with a regular array of interconnected pores of 1000?m in diameter and a porosity of 50% were produced using a rapid prototyping technique. A calcium phosphate (CaP) coating was applied to these titanium (Ti) scaffolds with an electrodeposition method. Raman spectroscopy

Marco A. Lopez-Heredia; Jerome Sohier; Cedric Gaillard; Sophie Quillard; Michel Dorget; Pierre Layrolle



Vibration spectroscopy study of hydrolyzed precursors for sintering calcium phosphate bio-ceramics  

Microsoft Academic Search

Diffuse reflectance infrared Fourier transform and Raman spectroscopy is applied to investigate the structure of hydrolyzed CaHPO4 · 2H2O (DCPD) processed to non-stoichiometric apatite to be used as starting material for preparing sintered calcium phosphate materials. The spectra of hydrolyzed DCPD samples, obtained under differing experimental conditions, are analyzed to check how the sintered phase composition correlates with the structure

B. Mihailova; B. Kolev; C. Balarew; E. Dyulgerova; L. Konstantinov



Inhomogeneity of calcium phosphate coatings deposited by laser ablation at high deposition rate  

Microsoft Academic Search

.   Calcium phosphate coatings were deposited with a KrF excimer laser onto titanium alloy to study their homogeneity. Deposition\\u000a was performed at a high deposition rate under a water vapour atmosphere of 45 Pa and at a substrate temperature of 575 C.\\u000a Samples were also submitted to annealing under the same conditions of deposition for different times just after deposition.\\u000a The effects

J. M. Fernández-Pradas; G. Sardin; J. L. Morenza



Induction of calcium phosphate on IBED-TiO x -coated carbon–carbon composite  

Microsoft Academic Search

Carbon–carbon composite has mechanical properties similar to human bone, as well as good biocompatibility, but without bioactivity. TiOx film was deposited onto carbon–carbon composite by ion beam-enhanced deposition (IBED) technique, and a porous network was formed on the TiOx film after alkali treatment. The network induced the deposition of calcium phosphate layers with different morphologies and compositions from simulated body

Tao Fu; Yong Han; Ke-Wei Xu; Jin-Yong Li; Zhong-Xiao Song



Electrochemically assisted co-deposition of calcium phosphate\\/collagen coatings on carbon\\/carbon composites  

Microsoft Academic Search

Calcium phosphate (CaP)\\/collagen coatings were prepared on the surface of carbon\\/carbon (C\\/C) composites by electrochemically assisted co-deposition technique. The effects of collagen concentration in the electrolyte on morphology, structure and composition of the coatings were systematically investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The adhesive strength of the

Xueni Zhao; Tao Hu; Hejun Li; Mengdi Chen; Sheng Cao; Leilei Zhang; Xianghui Hou



Synthesis, formulation and evaluation of novel zinc-calcium phosphate-based adhesive resin composite cement  

Microsoft Academic Search

Three novel adhesive oligomers having carboxylic acid and methacrylate groups were synthesized, characterized and used to formulate composite bone cements with newly synthesized zinc-calcium-silicate phosphate. The optimal formulation was determined based on types of oligomer, oligomer\\/diluent ratio, initiator concentration, and filler level using compressive strength (CS) and curing time (CT) as screening tools. Shrinkage, exotherm and aging of the formed

Dong Xie; IL-Doo Chung; Guigui Wang; Dingsong Feng; Jimmy Mays



Biomimetic calcium phosphate coating on Ti wires versus flat substrates: structure and mechanism of formation  

Microsoft Academic Search

Biomimetic calcium phosphate (Ca–P) coatings improve the osteoconductivity of orthopedic implants and show promise as slow\\u000a delivery systems for growth factors. This paper compares the structure and composition of biomimetic coatings on flat titanium\\u000a coupons and on Ti wires\\/thin pins that are often used as model implants in small animal in vivo models. Ca–P coatings were\\u000a grown on alkali-treated Ti substrates

Tal Reiner; Irena Gotman



Morphology and composition of nanograde calcium phosphate needle-like crystals formed by simple hydrothermal treatment  

Microsoft Academic Search

Nanograde calcium phosphate needle-like crystals are prepared from wet synthesized Ca-P precipitates by simple hydrothermal treatment at 140°C and 0.3 MPa for 2 h. The morphology of these crystals is observed by transmission electron microscopy (TEM). The phase composition is tested through X-ray diffractometer (XRD) and infrared spectroscopy (IR). It is found that the morphology of these crystals is related

Li Yubao; K. DE GROOT; J. Wijn; C. P. A. T. Klein; S. V. D. Meer



Calcium phosphate coupled Newcastle disease vaccine elicits humoral and cell mediated immune responses in chickens  

Microsoft Academic Search

Calcium phosphate (CaP) particles were coupled with inactivated Newcastle disease virus (NDV) vaccine. The surface morphology of CaP particles coupled to NDV was found to be spherical, smooth and with a tendency to agglomerate. The mean (± SE) size of CaP particles was found 557.44±18.62nm. The mean percent encapsulation efficiency of CaP particles coupled to NDV assessed based on total

Sanganagouda Koppad; G. Dhinakar Raj; V. P. Gopinath; J. John Kirubaharan; A. Thangavelu; V. Thiagarajan



Calcium phosphate stones produced by Madin-Darby canine kidney (MDCK) cells inoculated in nude mice  

Microsoft Academic Search

The canine renal distal tubular cell line Madin-Darby canine kidney (MDCK) forms calcium phosphate microliths during a long-term\\u000a culture in vitro. We identified osteopontin (OPN) and calprotectin (CPT) from a urinary stone matrix. We recently also detected\\u000a the expression of OPN and CPT in MDCK cells. The relationship between the mechanism of the stone formation and these stone\\u000a matrix proteins

Takeshi Sakakura; Keiji Fujita; Takahiro Yasui; Shoich Sasaki; Yoshio Mabuchi; Masanori Iguchi; Kenjiro Kohri



The role of sphingosine-1-phosphate and ceramide-1-phosphate in calcium homeostasis.  


During the last several years, sphingolipids have been identified as a source of important signaling molecules. Particularly, the understanding of the distinct biological roles of ceramide, sphingosine-1-phosphate (S1P), ceramide-1-phosphate (C1P) and lyso-sphingomyelin in the regulation of cell growth, death, senescence, adhesion, migration, inflammation, angiogenesis and intracellular trafficking has rapidly expanded. Additional studies have elucidated the biological roles of sphingolipids in maintaining a homeostatic environment in cells, as well as in regulating numerous cellular responses to environmental stimuli. This review focuses on the role of S1P and C1P in maintaining Ca2+ homeostasis. By studying changes in the metabolism of S1P and C1P in pathological conditions, it is hoped that altered sphingolipid-metabolizing enzymes and their metabolites can be used as therapeutic targets. PMID:18951299

Hinkovska-Galcheva, Vania; VanWay, Susan M; Shanley, Thomas P; Kunkel, Robin G



Development of a calcium phosphate nanocomposite for fast fluorogenic detection of bacteria.  


Current procedures for the detection and identification of bacterial infections are laborious, time-consuming, and require a high workload and well-equipped laboratories. Therefore the work presented herein developed a simple, fast, and low cost method for bacterial detection based on hydroxyapatite nanoparticles with a nutritive mixture and the fluorogenic substrate. Calcium phosphate ceramic nanoparticles were characterized and integrated with a nutritive mixture for the early detection of bacteria by visual as well as fluorescence spectroscopy techniques. The composite was obtained by combining calcium phosphate nanoparticles (Ca:P ratio, 1.33:1) with a nutritive mixture of protein hydrolysates and carbon sources, which promote fast bacterial multiplication, and the fluorogenic substrate 4-methylumbellipheryl-?-D-glucuronide (MUG). The composite had an average particle size of 173.2 nm and did not show antibacterial activity against Gram-negative or Gram-positive bacteria. After an Escherichia coli suspension was in contact with the composite for 60-90 min, fluorescence detected under UV light or by fluorescence spectrophotometer indicated the presence of bacteria. Intense fluorescence was observed after incubation for a maximum of 90 min. Thus, this calcium phosphate nanocomposite system may be useful as a model for the development of other nanoparticle composites for detection of early bacterial adhesion. PMID:25197932

Martínez, Claudio R; Rodríguez, Tamara L; Zhurbenko, Raisa; Valdés, Ivonne A; Gontijo, Sávio M L; Gomes, Alinne D M; Suarez, Diego F; Sinisterra, Rubén D; Cortés, Maria E



Europium-doped amorphous calcium phosphate porous nanospheres: preparation and application as luminescent drug carriers  

NASA Astrophysics Data System (ADS)

Calcium phosphate is the most important inorganic constituent of biological tissues, and synthetic calcium phosphate has been widely used as biomaterials. In this study, a facile method has been developed for the fabrication of amorphous calcium phosphate (ACP)/polylactide-block-monomethoxy(polyethyleneglycol) hybrid nanoparticles and ACP porous nanospheres. Europium-doping is performed to enable photoluminescence (PL) function of ACP porous nanospheres. A high specific surface area of the europium-doped ACP (Eu3+:ACP) porous nanospheres is achieved (126.7 m2/g). PL properties of Eu3+:ACP porous nanospheres are investigated, and the most intense peak at 612 nm is observed at 5 mol% Eu3+ doping. In vitro cytotoxicity experiments indicate that the as-prepared Eu3+:ACP porous nanospheres are biocompatible. In vitro drug release experiments indicate that the ibuprofen-loaded Eu3+:ACP porous nanospheres show a slow and sustained drug release in simulated body fluid. We have found that the cumulative amount of released drug has a linear relationship with the natural logarithm of release time ( ln( t)). The Eu3+:ACP porous nanospheres are bioactive, and can transform to hydroxyapatite during drug release. The PL properties of drug-loaded nanocarriers before and after drug release are also investigated.

Chen, Feng; Zhu, Ying-Jie; Zhang, Kui-Hua; Wu, Jin; Wang, Ke-Wei; Tang, Qi-Li; Mo, Xiu-Mei



Influence of anodization on the adhesion of calcium phosphate coatings on titanium substrates.  


Electrochemical deposition is an attractive technique for the deposition of calcium phosphate, especially hydroxyapatite, on titanium implants. However, the adhesion of these coatings to the titanium substrates needs to be improved for clinical use. It is demonstrated that anodization of a titanium alloy does marginally increase the adhesion of calcium phosphate coatings. Although scratch test measurements on coatings deposited at a constant potential appear to suggest that adhesion improves with increased thickness of the anodized layer, when a constant current is used to deposit the coatings their adhesion becomes independent of the thickness of the anodized layer. This apparent contradiction is explained by the thicker oxides acting as larger series resistors that reduce the magnitude of the current density when deposition is conducted at a constant potential. The resulting lower current density is responsible for increased adhesion of the calcium phosphate coating. It was also observed that surface roughness affects the interfacial adhesion strength between the coating and the titanium substrate, with a more adherent coating being formed over a rough surface. However, adhesion becomes independent of surface finish at levels smoother than 600 grit, suggesting that mechanical interlocking is not the sole force at play. PMID:20014290

Blackwood, Daniel J; Seah, Kar Heng W



Analysis of the interface between a pulsed laser deposited calcium phosphate coating and a titanium alloy substrate  

Microsoft Academic Search

Calcium phosphate coatings deposited on titanium alloy are intended to add a bioactive surface to medical implants. This work presents the characterisation of the interface between Ti-6Al-4V and a crystalline calcium phosphate coating obtained by pulsed laser deposition, with a KrF excimer laser, at 575 °C and under a 45 Pa water-vapour atmosphere. The coating–substrate system was studied by secondary-ion mass spectrometry,

J. M. Fernández-Pradas; M. V. García-Cuenca; J. L. Morenza



Analysis of the interface between a pulsed laser deposited calcium phosphate coating and a titanium alloy substrate  

Microsoft Academic Search

Calcium phosphate coatings deposited on titanium alloy are intended to add a bioactive surface to medical implants. This work presents the characterisation of the interface between Ti-6Al-4V and a crystalline calcium phosphate coating obtained by pulsed laser deposition, with a KrF excimer laser, at 575 °C and under a 45 Pa water-vapour atmosphere. The coating substrate system was studied by

J. M. Fernández-Pradas; M. V. García-Cuenca; J. L. Morenza



Effect of calcium phosphate and vitamin D3 supplementation on bone remodelling and metabolism of calcium, phosphorus, magnesium and iron  

PubMed Central

Background The aim of the present study was to determine the effect of calcium phosphate and/or vitamin D3 on bone and mineral metabolism. Methods Sixty omnivorous healthy subjects participated in the double-blind, placebo-controlled parallel designed study. Supplements were tricalcium phosphate (CaP) and cholecalciferol (vitamin D3). At the beginning of the study (baseline), all subjects documented their normal nutritional habits in a dietary record for three successive days. After baseline, subjects were allocated to three intervention groups: CaP (additional 1 g calcium/d), vitamin D3 (additional 10 ?g/d) and CaP?+?vitamin D3. In the first two weeks, all groups consumed placebo bread, and afterwards, for eight weeks, the test bread according to the intervention group. In the last week of each study period (baseline, placebo, after four and eight weeks of intervention), a faecal (three days) and a urine (24 h) collection and a fasting blood sampling took place. Calcium, phosphorus, magnesium and iron were determined in faeces, urine and blood. Bone formation and resorption markers were analysed in blood and urine. Results After four and eight weeks, CaP and CaP?+?vitamin D3 supplementations increased faecal excretion of calcium and phosphorus significantly compared to placebo. Due to the vitamin D3 supplementations (vitamin D3, CaP?+?vitamin D3), the plasma 25-(OH)D concentration significantly increased after eight weeks compared to placebo. The additional application of CaP led to a significant increase of the 25-(OH)D concentration already after four weeks. Bone resorption and bone formation markers were not influenced by any intervention. Conclusions Supplementation with daily 10 ?g vitamin D3 significantly increases plasma 25-(OH)D concentration. The combination with daily 1 g calcium (as CaP) has a further increasing effect on the 25-(OH)D concentration. Both CaP alone and in combination with vitamin D3 have no beneficial effect on bone remodelling markers and on the metabolism of calcium, phosphorus, magnesium and iron. Trial registration NCT01297023 PMID:24438153



Biomimetic synthesis of modified calcium phosphate fine powders and their in vitro studies  

SciTech Connect

Biomimetic approach and subsequent high-temperature treatment were used to synthesize ion modified calcium phosphate fine powders. Thus, using Simulated Body Fluid (SBF) as an ion modifier, a bi-phase mixture of ion modified ?-tricalcium phosphate and hydroxyapatite (?-TCP + HA) was prepared. The use of SBF electrolyte solution enriched with Mg{sup 2+} or Zn{sup 2+} yielded monophase ?-tricalcium phosphate additionally modified with Mg{sup 2+} or Zn{sup 2+} (Mg-?-TCP or Zn-?-TCP). The in vitro behavior of the prepared powders on cell viability and proliferation of murine BALB/c 3T3 fibroblasts and of human Lep 3 cells was studied by MTT test assays and Mosmann method after 72 h incubation. The relative cell viability was calculated.

Gergulova, R., E-mail:; Tepavitcharova, S., E-mail:; Rabadjieva, D., E-mail:; Sezanova, K., E-mail:; Ilieva, R., E-mail: [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 11, 1113 Sofia (Bulgaria); Alexandrova, R.; Andonova-Lilova, B. [Institute of Experimental Morphology, Pathology and Anthropology with Museum, BAS, Acad. G. Bonchev Str., Bl. 25, Sofia (Bulgaria)



Effect of polydopamine on the biomimetic mineralization of mussel-inspired calcium phosphate cement in vitro.  


Inspired by the excellent adhesive property of mussel adhesive protein, we added polydopamine (PDA) to calcium phosphate cement (PDA-CPC) to enhance its compressive strength previously. The mineralization and mechanism on PDA-CPC were investigated by soaking it in simulated body fluid in this study. The results indicated that PDA promoted the conversion of dicalcium phosphate dihydrate and ?-tricalcium phosphate to hydroxyapatite (HA) in the early stage but inhibited this conversion subsequently. PDA promoted the rapid mineralization on PDA-CPC to form a layer of nanoscale calcium phosphate (CaP) whereas there was no CaP formation on the control-CPC after 1d of soaking. This layer of nanoscale CaP was similar to that of natural bone, which was always observed during soaking. X-ray photoelectron spectroscopy showed that the peak of CO of PDA existed in the newly formed CaP on PDA-CPC, indicating the co-precipitation of CaP with PDA. Furthermore, the newly formed CaP on PDA-CPC was HA confirmed by transmission electron microscopy, which the newly formed HA was in association with PDA. Therefore, PDA increased the capacity of mineralization of CPC and induced the formation of nanoscale bone-like apatite on PDA-CPC. Thus, this provides the feasible route for surface modification on CPC. PMID:25280678

Liu, Zongguang; Qu, Shuxin; Zheng, Xiaotong; Xiong, Xiong; Fu, Rong; Tang, Kuangyun; Zhong, Zhendong; Weng, Jie



Fabrication of freeform bone-filling calcium phosphate ceramics by gypsum 3D printing method.  


Transformation of gypsum model fabricated by three-dimensional printing (3DP) into hydroxyapatite (HA) by treating in ammonium phosphate solution is possible. However, 3DP powder supplied by the manufacturer contains unknown additives which may be questionable for biomaterials. Accordingly, pure plaster of Paris (POP) powder was used for fabrication in the present study. For accurate fabrication, reduction of supplied binder ink to 80% of standard amount for 3DP powder supplied by the manufacturer was found to be the optimal condition for POP fabrication. Transformation from POP to HA was done by immersing into 1 mol/L ammonium phosphate solution. However, preheating of fabricated POP specimen at 200 degrees C for 30 min to change from calcium sulfate dihydrate into calcium sulfate hemihydrate could accelerate the transformation into HA effectively. To increase compressive strength, HA transformed specimen was sintering at 1150 degrees C for 3 h. The compressive strength increased four times comparing with as transformed HA specimen. However, crystal structure was transformed to beta-TCP due to the chemical reaction between the transformed HA and remained phosphate from ammonium phosphate solution at the sintering temperature. A sophisticated application of the present 3DP method to fabricate the freeform bioceramic for osseous defect was attempted, and jaw bone defect filling biomaterial of beta-TCP and scaffold with macroporous structures could be fabricated. Present 3DP method has possibility to fabricate freeform bioceramic for osseous defect or scaffold. PMID:19145633

Lowmunkong, Rungnapa; Sohmura, Taiji; Suzuki, Yumiko; Matsuya, Shigeki; Ishikawa, Kunio



Fabrication of calcium phosphate-calcium sulfate injectable bone substitute using hydroxy-propyl-methyl-cellulose and citric acid  

PubMed Central

In this study, an injectable bone substitute (IBS) consisting of citric acid, chitosan, and hydroxyl propyl methyl cellulose (HPMC) as the liquid phase and tetra calcium phosphate (TTCP), dicalcium phosphate dihydrate (DCPD) and calcium sulfate dehydrate (CSD, CaSO4·2H2O) powders as the solid phase, were fabricated. Two groups were classified based on the percent of citric acid in the liquid phase (20, 40 wt%). In each groups, the HPMC percentage was 0, 2, and 4 wt%. An increase in compressive strength due to changes in morphology was confirmed by scanning electron microscopy images. A good conversion rate of HAp at 20% citric acid was observed in the XRD profiles. In addition, HPMC was not obviously affected by apatite formation. However, both HPMC and citric acid increased the compressive strength of IBS. The maximum compressive strength for IBS was with 40% citric acid and 4% HPMC after 14 days of incubation in 100% humidity at 37°C. PMID:20333539

Thai, Van Viet



Collagen immobilization on 316L stainless steel surface with cathodic deposition of calcium phosphate  

NASA Astrophysics Data System (ADS)

Collagen fibril/(calcium phosphate and carbonate) composite coatings on 316L stainless steel were developed with a cathodic deposition technique. The response of SaOS-2 osteoblast-like cells to the collagen/calcium salt-coated 316L steel was investigated. The collagen fibrils were self-assembled on the 316L steel surface and immobilized by their partial incorporation into a calcium salt layer electrodeposited cathodically in Hanks' solution. The amount of calcium salt depended on the applied cathodic potential. The mineralization of collagen fibrils was observed. The collagen coverage localized and the composition of calcium salts varied on the same specimen. Such non-uniform surfaces affected the cell response. The observed outlines of cell bodies and nuclei on the thin collagen coating were clearer than those on the thick collagen coating in most cases. The collagen coating did not significantly influence the mean viability of cells on the whole specimen surface. Interestingly, the alkaline phosphatase activity per cell on the collagen/calcium salt-coated specimens was higher than that on the as-received specimen. It was revealed that cathodic deposition is an effective technique to immobilize collagen fibrils on a 316L steel surface.

Roguska, Agata; Hiromoto, Sachiko; Yamamoto, Akiko; Wo?niak, Micha? Jerzy; Pisarek, Marcin; Lewandowska, Ma?gorzata



Scaffolds with a standardized macro-architecture fabricated from several calcium phosphate ceramics using an indirect rapid prototyping technique  

PubMed Central

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

Wilson, C. E.; van Blitterswijk, C. A.; Verbout, A. J.; de Bruijn, J. D.



Pulsed electrodeposition for the synthesis of strontium-substituted calcium phosphate coatings with improved dissolution properties.  


Strontium-substituted calcium phosphate coatings are synthesized by pulsed electrodeposition on titanium alloy (Ti6Al4V) substrates. Experimental conditions of the process are optimized in order to obtain a coating with a 5% atomic substitution of calcium by strontium which corresponds to the best observations on the osteoblast cells activity and on the osteoclast cells proliferation. The physical and chemical characterizations of the obtained coating are carried out by scanning electron microscopy associated to energy dispersive X-ray spectroscopy (EDXS) for X-ray microanalysis and the structural characterization of the coating is carried out by X-ray diffraction. The in vitro dissolution/precipitation properties of the coated substrates are investigated by immersion into Dulbecco's Modified Eagle Medium (DMEM) from 1h to 14 days. The calcium, phosphorus and strontium concentrations variations in the biological liquid are assessed by Induced Coupled Plasma - Atomic Emission Spectroscopy for each immersion time. The results show that under specific experimental conditions, the electrodeposition process is suitable to synthesize strontium-substituted calcium phosphate coatings. Moreover, the addition of hydrogen peroxide (H2O2) into the electrolytic solution used in the process allows us to observe a control of the strontium release during the immersion of the prosthetic materials into DMEM. PMID:23910341

Drevet, Richard; Benhayoune, Hicham



Association of serum phosphorus and calcium x phosphate product with mortality risk in chronic hemodialysis patients: A national study  

Microsoft Academic Search

Elevated serum phosphorus is a predictable accompaniment of end-stage renal disease (ESRD) in the absence of dietary phosphate restriction or supplemental phosphate binders. The consequences of hyperphosphatemia include the development and progression of secondary hyperparathyroidism and a predisposition to metastatic calcification when the product of serum calcium and phosphorus (Ca x PO4) is elevated. Both of these conditions may contribute

GA Block; TE Hulbert-Shearon; NW Levin; FK Port



Synthetic Aragonite (CaCO3) as a Potential Additive in Calcium Phosphate Cements: Evaluation in Tris-free SBF at 37C  

E-print Network

apatitic CaP (calcium phosphate) deposits on their sur- faces. Mg-doped (1050 ppm) synthetic aragoniteSynthetic Aragonite (CaCO3) as a Potential Additive in Calcium Phosphate Cements: Evaluation solutions. All three crystalline polymorphs of calcium carbonate (calcite, aragonite and vaterite) have

Tas, A. Cuneyt


Phase composition, mechanical performance and in vitro biocompatibility of hydraulic setting calcium magnesium phosphate cement.  


Brushite (CaHPO(4) x 2H(2)O)-forming calcium phosphate cements are of great interest as bone replacement materials because they are resorbable in physiological conditions. However, their short setting times and low mechanical strengths limit broad clinical application. In this study, we showed that a significant improvement of these properties of brushite cement could be achieved by the use of magnesium-substituted beta-tricalcium phosphate with the general formula Mg(x)Ca((3-x))((PO(4))(2) with 0 < x < 3 as cement reactants. The incorporation of magnesium ions increased the setting times of cements from 2 min for a magnesium-free matrix to 8-11 min for Mg(2.25)Ca(0.75)(PO(4))(2) as reactant. At the same time, the compressive strength of set cements was doubled from 19 MPa to more than 40 MPa after 24h wet storage. Magnesium ions were not only retarding the setting reaction to brushite but were also forming newberyite (MgHPO(4) x 3H(2)O) as a second setting product. The biocompatibility of the material was investigated in vitro using the osteoblast-like cell line MC3T3-E1. A considerable increase of cell proliferation and expression of alkaline phosphatase, indicating an osteoblastic differentiation, could be noticed. Scanning electron microscopy analysis revealed an obvious cell growth on the surface of the scaffolds. Analysis of the culture medium showed minor alterations of pH value within the physiological range. The concentrations of free calcium, magnesium and phosphate ions were altered markedly due to the chemical solubility of the scaffolds. We conclude that the calcium magnesium phosphate (newberyite) cements have a promising potential for their use as bone replacement material since they provide a suitable biocompatibility, an extended workability and improved mechanical performance compared with brushite cements. PMID:19837194

Klammert, Uwe; Reuther, Tobias; Blank, Melanie; Reske, Isabelle; Barralet, Jake E; Grover, Liam M; Kübler, Alexander C; Gbureck, Uwe



Optimization of the mineral content in polymeric gels: The effect of calcium to phosphate molar ratio  

NASA Astrophysics Data System (ADS)

The influence of calcium to phosphate (Ca/P) molar ratio on the extent of mineralization in a model (poly)acrylamide gel was investigated under simulated physiological conditions. We hypothesized that the optimal growth of hydroxyapatite crystals will take place at the stoichiometric Ca/P molar ratio of 1.67. Phosphate ions were incorporated during the polymerization of the gel and mineralization was initiated by submersion of the gel in calcium acetate solution. Ca/P molar ratios were varied in the range of 0.5-5.0. The mineralized gel was characterized by Raman spectroscopy, scanning electron microscopy (SEM) and mineral weight fraction analysis via ashing. Raman spectra captured across the bulk of the gels indicated the presence of mineral at the core section. The phosphate symmetric stretching peak was observed in the range of 955-960 cm -1 which is characteristic of hydroxyapatite. SEM images showed that crystals formed at Ca/P=2.0 were denser and larger in size than at other molar ratios. In agreement with SEM images, the dry weight fraction of mineral reached the maximum at the molar ratio of 2.0 and the extent of mineralization rapidly declined as the molar ratio diverged from 2.0. Also, the crystallinity of the mineral was optimum at the molar ratio of 2.0. Thus it appears that for effective mineralization, the molar ratio of the two ions needs to be in excess of the stoichiometric requirement, suggesting that ions are expended in processes other than the formation and growth of hydroxyapatite crystals. Therefore, the optimal level of mineralization in biomimetic-based growth of calcium phosphate crystals in sol-gel environment requires consideration of a range of molar ratios as opposed to using the molar ratios corresponding to that of the crystal species intended to grow.

Das, Prasenjit; Akkus, Ozan; Azad, Abdul-Majeed



Glucose-6-phosphate reduces calcium accumulation in rat brain endoplasmic reticulum.  


Brain cells expend large amounts of energy sequestering calcium (Ca(2+)), while loss of Ca(2+) compartmentalization leads to cell damage or death. Upon cell entry, glucose is converted to glucose-6-phosphate (G6P), a parent substrate to several metabolic major pathways, including glycolysis. In several tissues, G6P alters the ability of the endoplasmic reticulum (ER) to sequester Ca(2+). This led to the hypothesis that G6P regulates Ca(2+) accumulation by acting as an endogenous ligand for sarco-endoplasmic reticulum calcium ATPase (SERCA). Whole brain ER microsomes were pooled from adult male Sprague-Dawley rats. Using radio-isotopic assays, (45)Ca(2+) accumulation was quantified following incubation with increasing amounts of G6P, in the presence or absence of thapsigargin, a potent SERCA inhibitor. To qualitatively assess SERCA activity, the simultaneous release of inorganic phosphate (Pi) coupled with Ca(2+) accumulation was quantified. Addition of G6P significantly and decreased Ca(2+) accumulation in a dose-dependent fashion (1-10 mM). The reduction in Ca(2+) accumulation was not significantly different that seen with addition of thapsigargin. Addition of glucose-1-phosphate or fructose-6-phosphate, or other glucose metabolic pathway intermediates, had no effect on Ca(2+) accumulation. Further, the release of Pi was markedly decreased, indicating G6P-mediated SERCA inhibition as the responsible mechanism for reduced Ca(2+) uptake. Simultaneous addition of thapsigargin and G6P did decrease inorganic phosphate in comparison to either treatment alone, which suggests that the two treatments have different mechanisms of action. Therefore, G6P may be a novel, endogenous regulator of SERCA activity. Additionally, pathological conditions observed during disease states that disrupt glucose homeostasis, may be attributable to Ca(2+) dystasis caused by altered G6P regulation of SERCA activity. PMID:22529775

Cole, Jeffrey T; Kean, William S; Pollard, Harvey B; Verma, Ajay; Watson, William D



Bone growth on and resorption of calcium phosphate coatings obtained by pulsed laser deposition.  


Three different calcium phosphate coatings of crystalline hydroxyapatite (HA), alpha- and beta-tricalcium phosphate (alpha+beta-TCP), or amorphous calcium phosphate (ACP) obtained by pulsed laser deposition on Ti-6Al-4V were incubated in a potentially osteogenic primary cell culture (rat bone marrow) in order to evaluate the amount and mode of mineralized bone matrix formation after 2 weeks with special emphasis on the type of interfacial structure that was created. Evaluation techniques included fluorescence labeling and scanning electron microscopy. The resistance to cellular resorption by osteoclasts was also studied. Bone matrix delaminated from the ACP coatings, while it remained on the HA and the alpha+beta-TCP coatings even after fracturing. A cementlike line was seen as the immediate contiguous interface with the nondegrading dense HA surface and with the surface of the remaining porous beta-TCP coating. Highly dense and crystalline HA coatings do not dissolve but are capable of establishing a strong bond with the bone matrix grown on top. Chemical and mechanical bonding were considered in this case. Cellular resorption was practically not observed on the HA coatings, but it was observed on the alpha+beta-TCP coatings. Resorption took place as dissolution that was due to the acidic microenvironment. PMID:10559745

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



Biomineralization and Size Control of Stable Calcium Phosphate Core Protein Shell Nanoparticles: Potential for Vaccine Applications  

PubMed Central

Calcium phosphate (CaP) polymorphs are nontoxic, biocompatible and hold promise in applications ranging from hard tissue regeneration to drug delivery and vaccine design. Yet, simple and robust routes for the synthesis of protein-coated CaP nanoparticles in the sub-100 nm size range remain elusive. Here, we used cell surface display to identify disulfide-constrained CaP binding peptides that, when inserted within the active site loop of E. coli Thioredoxin 1 (TrxA), readily and reproducibly drive the production of nanoparticles that are 50–70 nm in hydrodynamic diameter and consist of an approximately 25 nm amorphous calcium phosphate (ACP) core stabilized by the protein shell. Like bone and enamel proteins implicated in biological apatite formation, peptides supporting nanoparticle production were acidic. They also required presentation in a loop for high affinity ACP binding since elimination of the disulfide bridge caused a nearly 3-fold increase in hydrodynamic diameters. When compared to a commercial aluminum phosphate adjuvant, the small core-shell assemblies led to a 3-fold increase in mice anti-TrxA titers three weeks post-injection, suggesting that they might be useful vehicles for adjuvanted antigen delivery to dendritic cells. PMID:22263898

Chiu, David; Zhou, Weibin; Kitayaporn, Sathana; Schwartz, Daniel T.; Murali-Krishna, Kaja; Kavanagh, Terrance J.; Baneyx, Francois



Cytocompatibility evaluation of microwave sintered biphasic calcium phosphate scaffolds synthesized using pH control.  


Compounds belonging to the calcium phosphate (CaP) system are known to be major constituents of bone and are bioactive to different extents in vitro and in vivo. Their chemical similarity makes them prime candidates for implants and bone tissue engineering scaffolds. CaP nanoparticles of amorphous hydroxyapatite (aHA) and dicalcium phosphate dihydrate (DCPD) were synthesized using chemical precipitation. Uniaxially pressed aHA and DCPD powders were subjected to microwave radiation to promote solid state phase transformations resulting in crystalline hydroxyapatite (HA), tricalcium phosphate (TCP) and biphasic compositions: HA/TCP and TCP/calcium pyrophosphate (CPP) and their subsequent densification. Phase composition of microwave sintered compacts was confirmed via X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Solution pH during crystal growth was found to have a profound effect on particle morphology and post-sintered phases, despite constant sintering temperature. Cytocompatibility assessment using 7F2 cells, corresponding to adult mouse osteoblasts, on microwave and conventional, furnace sintered samples demonstrated that manufacturing method does not impact cellular viability after 24 h or proliferation over 7 days. New CaP deposition and extracellular matrix components were observed in vitro via scanning electron microscopy (SEM). PMID:23827628

Wagner, Darcy E; Jones, Andrew D; Zhou, Huan; Bhaduri, Sarit B



Effect of phase composition on protein adsorption and osteoinduction of porous calcium phosphate ceramics in mice.  


The purpose of this study was to investigate the effect of phase compositions of porous calcium phosphate (CaP) ceramics on their protein adsorption behaviors in vitro and osteoinductive potentials in vivo in mice. Under competitive conditions, a high adsorption of bone morphogenetic protein 2 (BMP-2) was observed at a high initial concentration of BMP-2 in the multi-protein solution on all the four types of ceramics, indicating their strong affinity for BMP-2. No significant difference in BMP-2 adsorption between the ceramics was noted, indicating that phase composition could have little influence on BMP-2 adsorption. After implantation into the thigh muscles of mice for 45 and 90 days, the histological and histomorphometric analyses showed that porous biphasic calcium phosphate (BCP) ceramic consisting of 30% hydroxyapatite HA and 70% tricalcium phosphate (?-TCP), i.e. BCP-2 had stronger osteoinductive ability than the other three groups of ceramics. The immunohistochemical staining showed the highest expression of BMP-2 and osteocalcin (OCN) in BCP-2 group. Osteoinduction of porous CaP ceramics might be influenced by the amount of BMP-2 present in the local microenvironment in the implant, which was regulated by the phase composition of the ceramics. BCP-2 promoted the highest expression of BMP-2 and then showed the strongest osteoinduction in mice. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 4234-4243, 2014. PMID:24497384

Wang, Jing; Chen, Ying; Zhu, Xiangdong; Yuan, Tun; Tan, Yanfei; Fan, Yujiang; Zhang, Xingdong



In-Situ Cold Temperature XRD of Calcium Phosphate Produced From Organic Phosphoric Acid  

NASA Astrophysics Data System (ADS)

In this study, we synthesized calcium phosphate from an organic phosphoric acid, diethylhexyl phosphoric acid (DEHPA) and calcium hydroxide solution. The reaction involves a sol-gel process with a whitish gel formed. In-situ XRD analysis was then performed on the sample from room temperature to -140° C. At room the XRD diffractogram shows the sample as an amorphous material and as the temperature was further lowered sharp peaks begins to form indicating that the material had becomes crystalline. The peaks were identified to be that calcium hydrogen phosphate (Ca(H2PO4)2) and this indicates that there is no hydroxyl group removal during the cooling process. The relative crystallinity values obtained for the different cooling temperatures show a slow exponential increase on the initial cooling of 0 to -100° C and at further cooling temperatures resulted fast and linear process. Also unlike the in-situ XRD analysis performs at high temperature no phase transformation occurred at this low temperature.

Yusoff, M. S. Meor; Paulus, Wilfred; Muslimin, Masliana



Effects of 1,25-dihydroxicolecalciferol and dietary calcium-phosphate on distribution of lead to tissues during growth  

SciTech Connect

The susceptibility to the toxic effects of lead (Pb) is mainly mediated by age and nutritional and hormonal status, and children are among the most vulnerable to them. During growth, an increase in calcium, phosphate and vitamin D in diet is recommended to enhance calcium and phosphate intestinal absorption and bone deposit. Calcium and phosphate reduce lead intestinal absorption, and 1,25-dihydroxicolecalciferol (1,25(OH){sub 2}D{sub 3}) (active metabolite of vitamin D) increases both lead and calcium intestinal absorption. However, the effects of 1,25(OH){sub 2}D{sub 3} on lead bone deposit and redistribution to soft tissues are not well known. In this study, we examined the effects of calcium-phosphate diet supplementation and the administration of 1,25(OH){sub 2}D{sub 3} on Pb distribution to soft tissue and bone in growing rats exposed to Pb. Rats (21 days old) were exposed for 28 days to 100 ppm of Pb solution in drinking water. Calcium and phosphate in diet were increased from 1 to 2.5% and from 0.65 to 1.8%, respectively, and 1,25(OH){sub 2}D{sub 3} was administrated by intraperitoneal injection of 7.2 ng/kg every 7 days. Between 21 and 49 days, the body weight increased about 5 times. The results showed that high calcium-phosphate diet led to lower Pb concentration in blood and in bone, but Pb liver and kidney concentrations increased, which indicates that absorption and bone deposit redistribution of Pb decreased. On the other hand, no effect of this diet rich in calcium-phosphate in Pb concentration was observed in brain. Blood and bone Pb concentrations increased even more when the high calcium-phosphate diet included 1,25(OH){sub 2}D{sub 3}. In the rats treated only with 1,25(OH){sub 2}D{sub 3}, blood and bone Pb concentrations were lower. Higher concentrations of lead in the soft organs were observed also in rats treated under a high calcium-phosphate diet plus 1,25(OH){sub 2}D{sub 3} administration. The above mentioned results suggested that 1,25(OH){sub 2}D{sub 3} induces an increased absorption and redistribution of Pb, and therefore, it may enhance systemic damage in Pb-exposed growing animals.

Cortina-Ramirez, G.E. [Department of Biochemistry, Centro de Investigacion y de Estudios Avanzados del IPN, PO Box 14-740, Mexico City 07000 (Mexico); Cerbon-Solorzano, J. [Department of Biochemistry, Centro de Investigacion y de Estudios Avanzados del IPN, PO Box 14-740, Mexico City 07000 (Mexico); Calderon-Salinas, J.V. [Department of Biochemistry, Centro de Investigacion y de Estudios Avanzados del IPN, PO Box 14-740, Mexico City 07000 (Mexico)]. E-mail:



Influence of the use of phosphate binders on serum levels of calcium phosphate in patients with chronic kidney disease undergoing hemodialysis: A retrospective and prospective study  

PubMed Central

Hypercalcemia–hyperphosphatemia is an unavoidable consequence of end-stage chronic kidney disease and common in hemodialytic patients. Calcium carbonate (CaCO3) is one type of phosphate binder used widely and prescribed in patients undergoing hemodialysis, aiming to control the levels of calcium and phosphate. These drugs are most effective if taken with meals. This study aimed to evaluate the use of phosphate binders in hemodialysis patients and the factors that influence the success of phosphate binder therapy by experimental studies with retrospective data collection through the medical records and prospectively through the questionnaire and interviews with patients. The research was conducted in the Unit Hemodialysis building floor 8 of Cipto Mangunkusumo Hospital, Jakarta. The data were collected in a retrospective way for two months (January–February 2013) and a prospective study in March–April 2013. Patients included were stage 5 chronic kidney disease patients who underwent hemodialysis in hemodialysis ward of Cipto Mangunkusumo Hospital. Patients who had data of serum levels at the beginning of the use of calcium phosphate and the final data in 2013 got the phosphate binder therapy. Results Ninety six patients with stage 5 chronic kidney disease who underwent hemodialysis had been using phosphate binder for 3 years in average. Patient evaluation showed that hypocalcemia was obtained in 23%; normokalemia in 42.7% and hypercalcemia in 34.3%. While the percentage of patients with hipofosfatemia14, 6%, normofosfatemia 32.3% and 53.1% hyperphosphatemia. Results obtained by the prospective analysis of factors that affect the success of the use of phosphate binder therapy are related to how the routine use of phosphate binders is made by the patient. Chi square test showed a significance of 0.000 (p < 0.05), the effect of 54%. Conclusion We can conclude there are many events happening such as hyperphosphatemia in hemodialysis patients that use phosphate binders. Monitoring of serum levels of calcium phosphate in patients with chronic kidney disease undergoing hemodialysis should be performed every month. Education and the role of clinical staff required to assist compliance and therapeutic efficacy of phosphate binder are necessary. PMID:25161377

Setiani Agus, Lusi; Effendi, Imam; Abdillah, Syamsudin



Mechanisms for the removal of calcium phosphate deposits in turbulent flow  

SciTech Connect

This work investigates the mechanisms for the removal of calcium phosphate deposits from stainless steel tubing in turbulent flows. Two types of deposits were analyzed: brushite (dicalcium phosphate dihydrate, DCPD) and a mixture of DCPD/hydroxyapatite (HAP). Cleaning studies were carried out at pHs ranging from 2.85 to 10. The data were analyzed by means of a mathematical model that incorporates the effects of interfacial dissolution and mass transfer. The results show that the HAP/DCPD cleaning rate is influenced both by the kinetics of the interfacial dissolution and by mass transfer. Within the same range of experimental conditions, the rate-limiting mechanism for DCPD removal was the abrasion of the solid by shear stresses. In this case, the interfacial dissolution process plays the role of decreasing the structural integrity of the deposit. These findings show that the removal mechanism of the HAP/DCPD mixture differs significantly from the behavior of individual components.

Littlejohn, F.; Grant, C.S.; Saez, A.E.



Effect of amorphous calcium phosphate and silver nanocomposites on dental plaque microcosm biofilms.  


A dental composite containing amorphous calcium phosphate nanoparticles (NACP) was developed that released calcium (Ca) and phosphate (PO(4)) ions and possessed acid-neutralization capability. There has been little study on incorporation of antibacterial agents into calcium phosphate composites. The objective of this study was to investigate the effect of silver nanoparticle (NAg) mass fraction in NACP nanocomposite on mechanical properties and dental plaque microcosm biofilm for the first time. NACP nanoparticles of 116 nm were synthesized via a spray-drying technique. NAg nanoparticles were synthesized using Ag 2-ethylhexanoate and 2-(tert-butylamino)ethyl methacrylate, yielding NAg of particle size of 2.7 nm that were well-dispersed in the resin. Five NACP nanocomposites were fabricated with NAg mass fractions of 0, 0.028, 0.042, 0.088, and 0.175%, respectively. Mechanical properties of NACP nanocomposites containing 0-0.042% of NAg matched those of a commercial composite without antibacterial activity. Live/dead assay of dental plaque microcosm biofilms showed complete coverage with live bacteria on commercial composite. However, there were increasingly more dead bacteria with higher NAg content in the NACP nanocomposite. Colony-forming unit (CFU) counts for total microorganisms, total streptococci, and mutans streptococci for NACP nanocomposite with 0.042% NAg were about 1/4 those of commercial composite. Lactic acid production on NACP nanocomposite with 0.042% NAg was 1/3 that on commercial composite. In conclusion, novel NACP-NAg nanocomposites were developed which possessed good mechanical properties and potent antibacterial properties, with substantially reduced biofilm viability and lactic acid production. Hence, the NACP-NAg nanocomposites are promising for dental restorations with remineralizing and antibacterial capabilities. PMID:22566464

Cheng, Lei; Weir, Michael D; Xu, Hockin H K; Antonucci, Joseph M; Lin, Nancy J; Lin-Gibson, Sheng; Xu, Sarah M; Zhou, Xuedong



Polymeric-Calcium Phosphate Cement Composites-Material Properties: In Vitro and In Vivo Investigations  

PubMed Central

New polymeric calcium phosphate cement composites (CPCs) were developed. Cement powder consisting of 60?wt% tetracalcium phosphate, 30?wt% dicalcium phosphate dihydrate, and 10?wt% tricalcium phosphate was combined with either 35%?w/w poly methyl vinyl ether maleic acid or polyacrylic acid to obtain CPC-1 and CPC-2. The setting time and compressive and diametral tensile strength of the CPCs were evaluated and compared with that of a commercial hydroxyapatite cement. In vitro cytotoxicity and in vivo biocompatibility of the two CPCs and hydroxyapatite cement were assessed. The setting time of the cements was 5–15?min. CPC-1 and CPC-2 showed significantly higher compressive and diametral strength values compared to hydroxyapatite cement. CPC-1 and CPC-2 were equivalent to Teflon controls after 1 week. CPC-1, CPC-2, and hydroxyapatite cement elicited a moderate to intense inflammatory reaction at 7 days which decreased over time. CPC-1 and CPC-2 show promise for orthopedic applications. PMID:20811498

Khashaba, Rania M.; Moussa, Mervet M.; Mettenburg, Donald J.; Rueggeberg, Frederick A.; Chutkan, Norman B.; Borke, James L.



Low temperature fabrication of high strength porous calcium phosphate and the evaluation of the osteoconductivity  

Microsoft Academic Search

Porous NaO2–MgO–CaO–P2O5 bioglass doped beta-tri-calcium phosphate (?-TCP) bioceramic possessing high mechanical properties and well pore structure\\u000a with high porosity and high pore connectivity has been prepared through dipping method with the porous polyurethane as the\\u000a pore forming template. The sintering mechanism and the mechanical properties of the bioglass doped ?-TCP scaffold have been\\u000a investigated by the X-ray diffraction (XRD) analysis,

Xianzhu Yu; Shu Cai; Guohua Xu; Wei Zhou; Dongmei Wang



Bioactivity and Surface Reactivity of RF-sputtered Calcium Phosphate Thin Films  

Microsoft Academic Search

Calcium phosphates (CaP) are known to be bioactive, i.e. able to bond\\u000ato bone. This makes CaPs very suitable to be aplied as thin coatings\\u000aon bone-implants. In this work we studied the physicochemical\\u000abehaviour of CaP coatings applied with radio frequency (RF) magnetron\\u000asputtering, a deposition technique that can produce thin (~100 nm),\\u000ahomogeneous, and well-adhereing coatings. As-deposited CaP

Edwin van der Wal



Ionic liquid-assisted formation of cellulose/calcium phosphate hybrid materials  

PubMed Central

Summary Cellulose/calcium phosphate hybrid materials were synthesized via an ionic liquid-assisted route. Scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis/differential thermal analysis show that, depending on the reaction conditions, cellulose/hydroxyapatite, cellulose/chlorapatite, or cellulose/monetite composites form. Preliminary studies with MC3T3-E1 pre-osteoblasts show that the cells proliferate on the hybrid materials suggesting that the ionic liquid-based process yields materials that are potentially useful as scaffolds for regenerative therapies.

Salama, Ahmed; Neumann, Mike; Gunter, Christina



Remodeling potentials of biphasic calcium phosphate granules in open wedge high tibial osteotomy  

Microsoft Academic Search

Introduction  Biphasic calcium phosphate (BCP) has proved to be an effective bone substitute, but it’s effectiveness and remodeling potential\\u000a in open wedge high tibial osteotomy (OWHTO) has not been analyzed yet. This study sought to evaluate the bone healing and\\u000a remodeling potentials of BCP granules using a radiographic rating system in biplanar OWHTO.\\u000a \\u000a \\u000a \\u000a Materials and methods  Fifteen patients (15 knees) underwent biplanar

Metin Ozalay; Orcun Sahin; Sercan Akpinar; Gurkan Ozkoc; Murat Cinar; Necip Cesur



The mineral phase in the cuticles of two species of Crustacea consists of magnesium calcite, amorphous calcium carbonate, and amorphous calcium phosphate.  


The cuticules (shells) of the woodlice Porcellio scaber and Armadillidium vulgare were analysed with respect to their content of inorganic material. It was found that the cuticles consist of crystalline magnesium calcite, amorphous calcium carbonate (ACC), and amorphous calcium phosphate (ACP), besides small amounts of water and an organic matrix. It is concluded that the cuticle, which constitutes a mineralized protective organ, is chemically adapted to the biological requirements by this combination of different materials. PMID:15877152

Becker, Alexander; Ziegler, Andreas; Epple, Matthias



Fabrication of multilayer ZrO?-biphasic calcium phosphate-poly-caprolactone unidirectional channeled scaffold for bone tissue formation.  


We developed a continuously porous scaffold with laminated matrix and bone-like microstructure by a multi-pass extrusion process. In this scaffold, tetragonal ZrO?, biphasic calcium phosphate and poly-caprolactone layers were arranged in a co-axially laminated unit cell with a channel in the center. The entire matrix phase had a laminated microstructure of alternate lamina of tetragonal ZrO?, biphasic calcium phosphate and poly-caprolactone--biphasic calcium phosphate with optimized designed thickness and channeled porosity. Each of the continuous pores was coaxially encircled by the poly-caprolactone--biphasic calcium phosphate layer, biphasic calcium phosphate layer and finally tetragonal ZrO? layer, one after the other. Before extrusion, 5?vol% graphite powder was mixed with tetragonal ZrO? to ensure pores in the outer layer and connectivity among the lamellas. The design strategy is aimed to incorporate a lamellar microstructure like the natural bone in the macro-scaled ceramic body to investigate the strengthening phenomenon and pave the way for fabricating complex microstructure of natural bone could be applied for whole bone replacement. The final fabricated scaffold had a compressive strength of 12.7?MPa and porosity of 78?vol% with excellent cell viability, cell attachment and osteocalcin and collagen expression from cultured MG63 cells on scaffold. PMID:23064831

Mondal, Dibakar; So-Ra, Son; Sarkar, Swapan Kumar; Min, Young Ki; Yang, Hun Mo; Lee, Byong Taek



Effects of phosphates on microstructure and bioactivity of micro-arc oxidized calcium phosphate coatings on Mg-Zn-Zr magnesium alloy.  


Calcium phosphate (CaP) coatings were prepared on Mg-Zn-Zr magnesium alloy by micro-arc oxidation (MAO) in electrolyte containing calcium acetate monohydrate (CH3COO)2Ca·H2O) and different phosphates (i.e. disodium hydrogen phosphate dodecahydrate (Na2HPO4·12H2O), sodium phosphate (Na3PO4·H2O) and sodium hexametaphosphate((NaPO3)6)). Scanning electron microscope (SEM), energy-dispersive X-ray spectrometry (EDS) and X-ray diffractometer (XRD) were employed to characterize the microstructure, elemental distribution and phase composition of the CaP coatings. Simulated body fluid (SBF) immersion test was used to evaluate the coating bioactivity and degradability. Systemic toxicity test was used to evaluate the coating biocompatibility. Fluoride ion selective electrode (ISE) was used to measure F(-) ions concentration during 30 days SBF immersion. The CaP coatings effectively reduced the corrosion rate and the surfaces of CaP coatings were covered by a new layer formed of numerous needle-like and scale-like apatites. The formation of these calcium phosphate apatites indicates that the coatings have excellent bioactivity. The coatings formed in (NaPO3)6-containging electrolyte exhibit thicker thickness, higher adhesive strength, slower degradation rate, better apatite-inducing ability and biocompatibility. PMID:23603036

Pan, Y K; Chen, C Z; Wang, D G; Zhao, T G



Biomaterial Co-Cr-Mo Alloys Nano Coating Calcium Phosphate Orthopedic Treatment  

NASA Astrophysics Data System (ADS)

The modem study a thermal martensitic transformation of biomedical Co-Cr-Mo alloys and ultimately offers large elongation to failure while maintaining high strength. In the future study, structural evolution and dislocation slip as an elementary process in the martensitic transformation in Co-Cr-Mo alloys were investigated to reveal the origin of their enhanced phase stability due to nitrogen addition and coating of calcium phosphate specimens with and without nitrogen addition were prepared. The N-doped alloys had a single-phase matrix, whereas the N-free alloys had a duplex microstructure. Irrespective of the nitrogen content, dislocations frequently dissociated into Shockley partial dislocations with stacking faults. The Nano range coating of calcium phosphate function as obstacles to the glide of partial dislocations and consequently significantly affect the kinetics of the martensitic transformation. As a result, the formation of marten site plays a crucial role in plastic deformation and wear behavior, the developed nanostructures modification associated with nitrogen addition must be a promising strategy for highly durable orthopedic implants.

Palaniappan, N.; Inwati, Gajendra Kumar; Singh, Man



Remineralization of early enamel lesions using casein phosphopeptide amorphous calcium Phosphate: An ex-vivo study  

PubMed Central

Objective: This study aimed at qualitatively evaluating the remineralization potential of casein phosphopeptide amorphous calcium phosphate on artificial early enamel lesions in an ex-vivo scenario by observing the treated tooth surface using a scanning electron microscope (SEM). Materials and Methods: This randomized study was conducted on 10 subjects undergoing orthodontic treatment with premolar extraction as part of their treatment. Artificial white lesions were created with the application of 37% phosphoric acid for 20 mins. Teeth were then divided into two groups: one experimental and the other control. Customised orthodontic band with a window was luted with intermediate restorative material in the experimental group whereas in the control group, band without a window was luted. The casein phosphopeptide amorphous calcium phosphate (GC TOOTH MOUSSE) paste was then applied on the window region of the experimental group for 3 mins thrice daily after meals for 14 days, whereas no paste was applied in the control group. After 14 days, teeth were extracted and viewed under an SEM. Results: The study groups showed remineralization of the lesions as compared with the control group in most of the samples. Conclusion: Casein phophopeptide could significantly remineralize the artificial enamel lesions in vivo. PMID:22114422

Vashisht, Ruchi; Kumar, Anil; Indira, R.; Srinivasan, M.R.; Ramachandran, S.



siRNA transfection with calcium phosphate nanoparticles stabilized with PEGylated chelators.  


Despite the enormous therapeutic potential of siRNAs, their delivery is still problematic due to unfavorable biodistribution profiles and poor intracellular bioavailability. Calcium phosphate co-precipitate has been used for nearly 40 years for in vitro transfection due to its non-toxic nature and simplicity of preparation. However, rapid particle growth has largely prevented the translation of this method for in vivo purposes. It has recently been shown that bisphosphonate derivatives can physically stabilize calcium phosphate nanoparticles while still allowing for efficient cell transfection with plasmid DNA. Herein, two novel PEGylated chelating agents (PEG-alendronate and PEG-inositolpentakisphosphate) with enhanced stabilizing properties are introduced, and it is demonstrated that the bisphosphonate-stabilized nanoparticles can efficiently deliver siRNA in vitro. The nanoparticles are mainly taken up by clathrin-dependent endocytosis, and acidification of the endosomal compartment is required to release the entrapped siRNA into the cytosol. Furthermore, particle uptake enhances the inhibition of the mevalonate pathway by the bisphosphonate in macrophages. PMID:23184402

Giger, Elisabeth V; Castagner, Bastien; Räikkönen, Johanna; Mönkkönen, Jukka; Leroux, Jean-Christophe



Morphological modifications of electrodeposited calcium phosphate coatings under amino acids effect  

NASA Astrophysics Data System (ADS)

Calcium phosphate coatings are synthesized on titanium alloy (Ti6Al4V) substrates by pulsed electrodeposition. This work aims to observe the morphological modifications of the coating when an amino acid is added to the electrolytic solution used in the process. The effects of two amino acids (glutamic acid and aspartic acid) are studied at a low and a high concentration. The coating morphology is observed at a nanometer scale by field emission gun-scanning electron microscopy (FEG-SEM). The structural characterization of the coating is performed by Fourier transformed infrared spectroscopy (FT-IR), Raman spectroscopy and X-ray diffraction (XRD). Moreover, corrosion measurements of the prosthetic surfaces are carried out by potentiodynamic polarization experiments in a physiological solution named Dulbecco's modified eagle medium (DMEM). The results show that the addition of an amino acid to the electrolytic solution leads to the decrease of the size of the crystallites which compose the prosthetic calcium phosphate coating that becomes denser and less porous than the coatings obtained without amino acid. Consequently, the corrosion behavior of the prosthetic material immersed in DMEM is improved.

Drevet, R.; Lemelle, A.; Untereiner, V.; Manfait, M.; Sockalingum, G. D.; Benhayoune, H.



Computational study of dimethyl phosphate anion and its complexes with water, magnesium, and calcium  

NASA Astrophysics Data System (ADS)

Dimethyl phosphate anion (DMP-) is often used to simulate the properties of the phosphate group, an important structural fragment of nucleic acids and phospholipids. Besides its functional importance, DMP- has a strong affinity for metal cations and is often considered to be their binding site. In this study we reevaluate the binding properties of DMP- with water molecules and with explicitly hydrated magnesium and calcium cations in the presence of a polar continuum solvent. We analyze the stability of the DMP- in different conformations that represent possible inner- and outer-sphere binding modes. Our previous work (Petrov et al. J Phys Chem B 2004) has shown that electrostatic calculations, particularly those using a point-charge model, are wholly inadequate for this purpose. Calculations were performed at the B3LYP/6-31G(d,p) level of theory within the framework of the COSMO polarized continuum model (CPCM). Our data indicate that magnesium prefers outer-sphere coordination with DMP-, whereas calcium binds directly. The effect of cation binding on vibrational infrared and Raman spectra are also discussed. We found that the inclusion of polar solvent in the computations improves the agreement between calculated spectral data and experimental results.

Petrov, Anton S.; Funseth-Smotzer, Joni; Pack, George R.


Stability of radiofrequency magnetron sputtered calcium phosphate coatings under cyclically loaded conditions.  


The stability of radiofrequency (RF) magnetron sputtered calcium phosphate was studied under cyclically loaded conditions. The coatings were deposited on titanium bars and tested in either dry or wet conditions X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis and Fourier transform infrared (FTIR) spectroscopy were used to characterize the as-sputtered and tested coatings. XRD demonstrated that the amorphous structure after annealing at 650 C changed into a crystalline apatite structure. The residual stresses were determined by the XRD cos 2 i/i method. These residual film stresses were influenced by the coating conditions and the crystalline sputtered coating showed the presence of compressive stresses. SEM demonstrated that, after cyclic loading conditions in air, the crystalline sputter-coated Ti-6A1-4V bars showed a partial coating loss. Furthermore, in wet conditions (simulated body fluid) only the heat-treated sputter-coated bars appeared to be stable. On the other hand, the amorphous coating only showed signs of delamination in the more highly stressed regions, while in the less stressed regions a Ca-P precipitate was formed. On the basis of these results we conclude that calcium phosphate coatings subjected to cyclic loading conditions show an important difference in fatigue behaviour when tested in either dry or wet conditions. PMID:9111952

Wolke, J G; van der Waerden, J P; de Groot, K; Jansen, J A



Bioactive calcium sulfate/magnesium phosphate cement for bone substitute applications.  


A novel calcium sulfate/magnesium phosphate cement (CSMPC) composite was prepared and studied in the present work. The physical properties including the phases, the microstructures, the setting properties and the compressive strengths of the CSMPCs were studied. The bio-performances of the CSMPCs were comprehensively evaluated using in vitro simulated body fluid (SBF) method and in vitro cell culture. The dependence of the physical and chemical properties of the CSMPC on its composition and microstructure was studied in detail. It is found that the CSMPC composites exhibited mediate setting times (6-12 min) compared to the calcium sulfate (CS) and the magnesium phosphate cement (MPC). They showed an encapsulation structure in which the unconverted hexagonal prism CSH particles were embedded in the xerogel-like MPC matrix. The phase compositions and the mechanical properties of the CSMPCs were closely related to the content of MPC and the hardening process. The CSMPCs exhibited excellent bioactivity and good biocompatibility to support the cells to attach and proliferate on the surface. The CSMPC composite has the potential to serve as bone grafts for the bone regeneration. PMID:24411353

Yang, Guangyong; Liu, Jianli; Li, Fan; Pan, Zongyou; Ni, Xiao; Shen, Yue; Xu, Huazi; Huang, Qing



Amorphous calcium phosphate/urethane methacrylate resin composites. I. Physicochemical characterization.  


Urethane dimethacrylate (UDMA), an oligomeric poly(ethylene glycol) extended UDMA (PEG-U) and a blend of UDMA/PEG-U were chosen as model systems for introducing both hydrophobic and hydrophilic segments and a range of compliances in their derived polymers. Experimental composites based on these three resins with amorphous calcium phosphate (ACP) as the filler phase were polymerized and evaluated for mechanical strength and ion release profiles in different aqueous media. Strength of all composites decreased upon immersion in saline (pH = 7.4). Both polymer matrix composition and the pH of the liquid environment strongly affected the ion release kinetics. In saline, the UDMA/PEG-U composite showed a sustained release for at least 350 h. The initially high ion release of the PEG-U composites decreased after 72 h, seemingly due to the mineral re-deposition at the composite surface. Internal conversion from ACP to poorly crystallized apatite could be observed by X-ray diffraction. In various lactic acid (LA) environments (initial pH = 5.1) ion release kinetics was much more complex. In LA medium without thymol and/or carboxymethylcellulose, as a result of unfavorable changes in the internal calcium/phosphate ion stoichiometry, the ion release rate greatly increased but without observable conversion of ACP to apatite. PMID:17619969

Regnault, William F; Icenogle, Tonya B; Antonucci, Joseph M; Skrtic, Drago



Dry mechanochemical synthesis of hydroxyapatites from dicalcium phosphate dihydrate and calcium oxide: a kinetic study.  


Calcium phosphate ceramics have been used successfully as synthetic bone substitutes in orthopedics, dentistry, and maxillofacial surgery. One way of preparing these ceramics is the sintering of a calcium-deficient hydroxyapatite (CDHA), which can be obtained in different ways. Mechanochemistry is one possible means of synthesizing CDHA, with an expected molar calcium-to-phosphate (Ca/P) ratio +/- 0.005. The grinding can be carried out under dry or wet conditions. To optimize the experimental conditions of CDHA preparation by dry mechanosynthesis and for a better understanding of the DCPD/CaO mechanochemical reaction, we performed a kinetic study in which some of the experimental parameters were varied. Carried out with two different vertical rotating ball mills, this kinetic study showed that (1) experiments are reproducible and give as a final product a hydroxyapatite powder, formed of nano-sized crystals of around 20 nm, with a controlled Ca/P ratio; (2) the time for complete disappearance of DCPD and the time for complete reaction are in direct proportion to the mass of the ground powder; but (3) the time for complete disappearance of DCPD is independent of the Ca/P ratio while the time for complete reaction increases exponentially with the Ca/P ratio; and (4) the time for complete disappearance of DCPD corresponds to the time for complete reaction solely for Ca/P = 1.5. These observations suggest a reaction mechanism in two well differentiated stages: (First stage) CaO reacts with DCPD to give first an amorphous calcium phosphate (ACP) with a low Ca/P ratio that transforms into CDHA when its Ca/P ratio reaches 1.5. At the same time, CaO is hydrated into Ca(OH)(2) by the water produced by the reaction. (Second stage) If the Ca/P > 1.5 in the initial mixture, the excess Ca(OH)(2) is added to CDHA 1.5 by reacting with the HPO(4) group of CDHA until its Ca/P ratio reaches the expected value. The slower the reaction, the higher the Ca/P in the initial mixture. PMID:14613241

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



Improved sugar cane juice clarification by understanding calcium oxide-phosphate-sucrose systems.  


It is accepted that the efficiency of sugar cane clarification is closely linked with sugar juice composition (including suspended or insoluble impurities), the inorganic phosphate content, the liming condition and type, and the interactions between the juice components. These interactions are not well understood, particularly those between calcium, phosphate, and sucrose in sugar cane juice. Studies have been conducted on calcium oxide (CaO)/phosphate/sucrose systems in both synthetic and factory juices to provide further information on the defecation process (i.e., simple liming to effect impurity removal) and to identify an effective clarification process that would result in reduced scaling of sugar factory evaporators, pans, and centrifugals. Results have shown that a two-stage process involving the addition of lime saccharate to a set juice pH followed by the addition of sodium hydroxide to a final juice pH or a similar two-stage process where the order of addition of the alkalis is reversed prior to clarification reduces the impurity loading of the clarified juice compared to that of the clarified juice obtained by the conventional defecation process. The treatment process showed reductions in CaO (27% to 50%) and MgO (up to 20%) in clarified juices with no apparent loss in juice clarity or increase in residence time of the mud particles compared to those in the conventional process. There was also a reduction in the SiO2 content. However, the disadvantage of this process is the significant increase in the Na2O content. PMID:21322558

Doherty, William O S



Development of a new calcium phosphate powder-binder system for the 3D printing of patient specific implants  

Microsoft Academic Search

A key requirement for three-dimensional printing (3-DP) of medical implants is the availability of printable and biocompatible\\u000a powder-binder systems. In this study we developed a powder mixture comprising tetracalcium phosphate (TTCP) as reactive component\\u000a and ?-tricalcium phosphate (?-TCP) or calcium sulfate as biodegradable fillers, which can be printed with an aqueous citric\\u000a acid solution. The potential of this material combination

Alaadien Khalyfa; Sebastian Vogt; Jürgen Weisser; Gabriele Grimm; Annett Rechtenbach; Wolfgang Meyer; Matthias Schnabelrauch



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


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 (CO?-HA) with ?5?wt% substituted carbonate content (sample 7.5CO?-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 7.5CO?-HA. For silicate-substituted hydroxyapatite (SiO?-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 SiO?-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

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



Rapid screening of mineralization capacity of biomaterials by means of quantification of enzymatically deposited calcium phosphate.  


The current study focused on the development of a rapid, straightforward quantification method based on the use of enzymatic decomposition of urea using urease to assess the mineralization capacity of a wide range of biomaterials for bone regeneration. Urea-containing mineralizing solutions (MSs) (containing: Na2HPO4, CaCl2, and NaCl at 37°C and pH 6.0) were used in the mineralization experiments. Urease was added to these solutions to induce enzymatic decomposition of urea resulting in increased pH and deposition of calcium phosphate. By optimizing the ionic and urease concentrations in these MSs, it was shown that the proposed system could mineralize titanium substrates with six different pretreatments, as opposed to normal simulated body fluid that mineralized only two of them. It was possible to rank the mineralization capacity of these substrates by measuring the amount of calcium deposited. Furthermore, the ranking of (i) various polymeric substrates and (ii) hydrogels with and without functionalization with calcium-binding bisphosphonate groups was also possible. These results confirm that the proposed testing system has a broad applicability in the field of biomaterials due to its inherent versatility and discriminative power. PMID:24650236

Nijhuis, Arnold W G; Takemoto, Shinji; Nejadnik, M Reza; Li, Yubao; Yang, Xia; Ossipov, Dmitri A; Hilborn, Jons; Mikos, Antonios G; Yoshinari, Masao; Jansen, John A; Leeuwenburgh, Sander C G



Electrolytic deposition of calcium phosphate\\/chitosan coating on titanium alloy: Growth kinetics and influence of current density, acetic acid, and chitosan  

Microsoft Academic Search

Electrolytically deposited calcium phosphate\\/chitosan coating demonstrated good bone marrow stromal cell attachment. The aim of this study was to understand the coating's growth kinetics as well as the effects of current density, acetic acid, and chitosan on the coating's formation. The scanning electron micrographs found that calcium phosphate crystals homogeneously distributed into chitosan aggregates as early as 30 min. X-ray

Jiawei Wang; Apeldoorn van Aart; Groot de Klaas



Observation of calcium phosphate powder mixed with an adhesive monomer experimentally developed for direct pulp capping and as a bonding agent  

Microsoft Academic Search

In this study, morphological shape, elemental distribution and elution properties of Ca, P, Mg in four types of calcium phosphate powder were investigated using SEM, EPMA and ICP-AES. Calcium phosphate powder: OHAp, DCPD, ?-TCP and OCP were observed in the white powder form and in the photopolymerized adhesive monomer they scattered like dispersed fillers in resin composite. In elemental analysis,

Yoshiroh KATOH; Masaya SUZUKI; Chikage KATO; Koichi SHINKAI; Masaaki OGAWA; Junichi YAMAUCHI



High phosphate reduces host ability to develop arbuscular mycorrhizal symbiosis without affecting root calcium spiking responses to the fungus.  


The arbuscular mycorrhizal symbiosis associates soil fungi with the roots of the majority of plants species and represents a major source of soil phosphorus acquisition. Mycorrhizal interactions begin with an exchange of molecular signals between the two partners. A root signaling pathway is recruited, for which the perception of fungal signals triggers oscillations of intracellular calcium concentration. High phosphate availability is known to inhibit the establishment and/or persistence of this symbiosis, thereby favoring the direct, non-symbiotic uptake of phosphorus by the root system. In this study, Medicago truncatula plants were used to investigate the effects of phosphate supply on the early stages of the interaction. When plants were supplied with high phosphate fungal attachment to the roots was drastically reduced. An experimental system was designed to individually study the effects of phosphate supply on the fungus, on the roots, and on root exudates. These experiments revealed that the most important effects of high phosphate supply were on the roots themselves, which became unable to host mycorrhizal fungi even when these had been appropriately stimulated. The ability of the roots to perceive their fungal partner was then investigated by monitoring nuclear calcium spiking in response to fungal signals. This response did not appear to be affected by high phosphate supply. In conclusion, high levels of phosphate predominantly impact the plant host, but apparently not in its ability to perceive the fungal partner. PMID:24194742

Balzergue, Coline; Chabaud, Mireille; Barker, David G; Bécard, Guillaume; Rochange, Soizic F



Interaction between hydroxypropyl methylcellulose and biphasic calcium phosphate after steam sterilisation  

E-print Network

phosphate w/w). After separation of the organic and mineral phases, capillary gas chromatography (GC were then derived from monosaccharides and phosphates by trimethylsilylation, which separates similar molecules and transforms mineral phosphate into organic phosphate detectable by flame ionisation

Boyer, Edmond


Preparation and characterization of calcium phosphate ceramics and composites as bone substitutes  

NASA Astrophysics Data System (ADS)

Marine CaCO3 skeletons have tailored architectures created by nature, which give them structural support and other functions. For example, seashells have dense lamellar structures, while coral, cuttlebone and sea urchin spines have interconnected porous structures. In our experiments, seashells, coral and cuttlebone were hydrothermally converted to hydroxyapatite (HAP), and sea urchin spines were converted to Mg-substituted tricalcium phosphate (beta-TCMP), while maintaining their original structures. Partially converted shell samples have mechanical strength, which is close to that of compact human bone. After implantation of converted shell and spine samples in rat femoral defects for 6 weeks, there was newly formed bone growth up to and around the implants. Some new bone was found to migrate through the pores of converted spine samples and grow inward. These results show good bioactivity and osteoconductivity of the implants, indicating the converted shell and spine samples can be used as bone defect fillers. Calcium phosphate powders were prepared through different synthesis methods. Micro-size HAP rods were synthesized by hydrothermal method through a nucleation-growth mechanism. On the other hand, HAP particles, which have good crystallinity, were prepared by wet precipitation with further hydrothermal treatment. beta-TCP or beta-TCMP powders were prepared by a two-step process: wet precipitation of apatitic tricalcium phosphate ('precursor') and calcination of the precursor at 800°C for 3 hours. beta-TCMP or beta-TCP powders were also prepared by solid-state reactions from CaHPO4 and CaCO 3 with/without MgO. Biphasic calcium phosphate, which is mixture of HAP and beta-TCP, can be prepared though mechanical mixing of HAP and beta-TCP powders synthesized as above. Dense beta-TCP and beta-TCMP ceramics can be produced by pressing green bodies at 100MPa and further sintering above 1100°C for 2 hours. beta-TCMP ceramics ˜99.4% relative dense were prepared by this method. Dense beta-TCP ceramics have average strength up to 540MPa. Macroporous beta-TCMP ceramics were produced with sucrose as the porogen following a two-step pressing method. Porous beta-TCMP ceramics were also prepared by replication of polyurethane sponge. beta-TCMP ceramics with porous structures in the center surrounded by dense structures were created. The outside dense structures give the scaffold mechanical strength, while the central porous structures enable cells migration and vascular infiltration, and finally in-growth of new bone into the scaffold.

Zhang, Xing


Comparison of human bone marrow stromal cells seeded on calcium-deficient hydroxyapatite, ?-tricalcium phosphate and demineralized bone matrix  

Microsoft Academic Search

The aim of this study was to compare three resorbable biomaterials regarding seeding efficacy with human bone marrow stromal cells (BMSCs), cell penetration into the matrix, cell proliferation and osteogenic differentiation. Calcium-deficient hydroxyapatite (CDHA), ?-tricalcium phosphate (?-TCP), and demineralized bone matrix (DBM) were seeded with human BMSCs and kept in human serum and osteogenic supplements for 3 weeks. Morphologic and

P. Kasten; R. Luginbühl; M. van Griensven; T. Barkhausen; C. Krettek; M. Bohner; U. Bosch



Preparation and characterization of electrodeposited calcium phosphate/chitosan coating on Ti6Al4V plates.  


Electrolytically deposited carbonate apatite coating demonstrates higher strength but weaker support for bone marrow stromal cell attachment than do biomimetically deposited coatings. It is hypothesized that the incorporation of chitosan will increase the biocompatibility of electrolytic coating while maintaining its original strength. To verify this hypothesis, we formed a hybrid calcium phosphate/chitosan coating through electrodeposition. We found that the incorporation of chitosan influenced calcium phosphate formation and crystallization. Moreover, coating thickness and surface roughness decreased with increasing chitosan concentration. Hybrid coating exhibited an increased dissolution rate in both acidic and neutral simulated physiologic solution, whereas no significant difference on adhesive strength was found between the hybrid and original coatings (P > 0.05). Most importantly, the calcium phosphate/chitosan coating proved to be a more favorable surface for goat bone marrow stromal cell attachment than an unincorporated coating (P < 0.01). Considering its economic and simple production, a hybrid calcium phosphate/chitosan coating is thought to be an attractive candidate for future applications. PMID:15044502

Wang, J; de Boer, J; de Groot, K



In vivo biological performance of composites combining micro-macroporous biphasic calcium phosphate granules and fibrin sealant  

Microsoft Academic Search

Introduction Fibrin glues are currently used by surgeons and can facilitate the handling of biomaterials. Combining fibrin glue with calcium phosphate bioce- ramics gives a mouldable composite that cements the granules into the implantation site. In addition to the mechanical aspect of the composite, it has been sug- gested that the mixture also promotes wound healing. These human blood derivatives

Franck Jegoux; Eric Goyenvalle; Maurice Bagot D’arc; Eric Aguado; Guy Daculsi



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

Microsoft Academic Search

Calcium phosphate coatings were deposited by pulsed laser ablation with a radiation of 355nm 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

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



Aluminum diffusion in Oxisols as influenced by soil water matric potential, ph, lime, gypsum, potassium chloride, and calcium phosphate  

Microsoft Academic Search

Plant root exposure to soil aluminum (Al) depends on the soil solution Al concentration and transport to the root by diffusion. Changes in Al diffusive flux for two Oxisols was measured under laboratory conditions as a function of pH, water matric potential, and applications of gypsum, potassium chloride, and calcium phosphate. Double?faced cation exchange resin sheets served as sinks for

F. H. T. Oliveira; R. F. Novais; T. J. Smyth; J. C. L. Neves



Characterization of the bone-like apatite precipitated on high velocity oxy-fuel (HVOF) sprayed calcium phosphate deposits  

Microsoft Academic Search

Bone-like apatite was precipitated on the surface of thermal sprayed calcium phosphate coatings following in vitro incubation in a simulated body fluid. The coatings were initially deposited on titanium alloy substrates by the high velocity oxy-fuel (HVOF) spray technique. Structural characterization and mechanical evaluation of the precipitated apatite layer were conducted. Results showed that the precipitation rate was directly influenced

K. A Khor; H Li; P Cheang



Clinical, radiological and histological evaluation of biphasic calcium phosphate bioceramic wedges filling medial high tibial valgisation osteotomies  

Microsoft Academic Search

We report clinical, radiological and histological findings following high tibial valgisation osteotomy (HTVO) using micro–macroporous biphasic calcium phosphate wedges fixed with a plate and locking screws. From 1999 to 2002, 43 knees were operated on and studied prospectively. All underwent clinical and radiological follow-up at days 1, 90, and 365 to evaluate consolidation and bone substitute interfaces. Additionally, biopsies were

J. L. Rouvillain; F. Lavallé; H. Pascal-Mousselard; Y. Catonné; G. Daculsi



Basic calcium phosphate crystal-induced Egr-1 expression stimulates mitogenesis in human fibroblasts  

SciTech Connect

Previously, we have reported that basic calcium phosphate (BCP) crystals stimulate mitogenesis and synthesis of matrix metalloproteinases in cultured human foreskin and synovial fibroblasts. However, the detailed mechanisms involved are still unclear. In the present study, using RT-PCR and Egr-1 promoter analysis we showed that BCP crystals could stimulate early growth response gene Egr-1 transcription through a PKC{alpha}-dependent p44/p42 MAPK pathway. Using a retrovirus gene expression system (Clontech) to overexpress Egr-1 in human fibroblast BJ-1 cells resulted in promotion of mitogenesis measured either by MTT cell proliferation analysis or by direct cell counting. The results demonstrate that Egr-1 may play a key role in mediating BCP crystal-induced synovial fibroblast mitogenesis.

Zeng, Xiao R. [Department of Biomedical Engineering, University of Miami, Coral Gablek, FL 33146 (United States); Sun Yubo [Division of Rheumatology and Immunology, Department of Medicine, University of Miami School of Medicine, Miami, FL 33101 (United States); Wenger, Leonor [Department of Biomedical Engineering, University of Miami, Coral Gablek, FL 33146 (United States); Cheung, Herman S. [Department of Biomedical Engineering, University of Miami, Coral Gablek, FL 33146 (United States) and Division of Rheumatology and Immunology, Department of Medicine, University of Miami School of Medicine, Miami, FL 33101 (United States) and Research Service and the Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Miami, FL 33125 (United States)]. E-mail:



Treatment of toxic metal aqueous solutions: encapsulation in a phosphate-calcium aluminate matrix.  


Polyphosphate-modified calcium aluminate cement matrices were prepared by using aqueous solutions polluted with toxic metals as mixing water to obtain waste-containing solid blocks with improved management and disposal. Synthetically contaminated waters containing either Pb or Cu or Zn were incorporated into phosphoaluminate cement mortars and the effects of the metal's presence on setting time and mechanical performance were assessed. Sorption and leaching tests were also executed and both retention and release patterns were investigated. For all three metals, high uptake capacities as well as percentages of retention larger than 99.9% were measured. Both Pb and Cu were seen to be largely compatible with this cementitious matrix, rendering the obtained blocks suitable for landfilling or for building purposes. However, Zn spoilt the compressive strength values because of its reaction with hydrogen phosphate anions, hindering the development of the binding matrix. PMID:24721638

Fernández, J M; Navarro-Blasco, I; Duran, A; Sirera, R; Alvarez, J I



Mechanism of the uptake of cationic and anionic calcium phosphate nanoparticles by cells.  


The uptake of calcium phosphate nanoparticles (diameter 120nm) with different charge by HeLa cells was studied by flow cytometry. The amount of uptaken nanoparticles increased with increasing concentration of nanoparticles in the cell culture medium. Several inhibitors of endocytosis and macropinocytosis were applied to elucidate the uptake mechanism of nanoparticles into HeLa cells: wortmannin, LY294002, nocodazole, chlorpromazine and nystatin. Wortmannin and LY294002 strongly reduced the uptake of anionic nanoparticles, which indicates macropinocytosis as uptake mechanism. For cationic nanoparticles, the uptake was reduced to a lesser extent, indicating a different uptake mechanism. The localization of nanoparticles inside the cells was investigated by conjugating them with the pH-sensitive dye SNARF-1. The nanoparticles were localized in lysosomes after 3h of incubation. PMID:23454056

Sokolova, Viktoriya; Kozlova, Diana; Knuschke, Torben; Buer, Jan; Westendorf, Astrid M; Epple, Matthias



Preparation and properties of ?-calcium sulphate hemihydrate and ?-tricalcium phosphate bone substitute.  


Autogenous bone graft carries the risk of complications. In contrast, artificial bone graft provides initial strength and allows new bone ingrowth. In this study, we examined methods of preparation of ?-calcium sulphate hemihydrate (?-CSH) and ?-tricalcium phosphate (?-TCP), and a composite of the two materials. Characterization of the materials was determined with X-ray diffraction, differential thermal analysis (DTA), scanning electron microscopy (SEM), and porosity analysis. ?-TCP exhibited the spatial structure and porosity of normal bone with a macropore size of 50-400 ?m and some 1 ?m micropores. ?-CSH exhibited a regular crystal structure. A combined material was prepared in a 1:1 weight ratio, and in a rabbit model, the rate of new bone mineralization was similar to that of autogenous bone graft. The combined material of ?-TCP and ?-CSH in this study may provide similar efficacy as autogenous bone graft. PMID:23629533

Mao, Keya; Zhou, Feihu; Cui, Fuzai; Li, Jiangtao; Hou, Xijun; Li, Peng; Du, Mingkui; Liang, Maohua; Wang, Yan



Adjuvant effects of chitosan and calcium phosphate particles in an inactivated Newcastle disease vaccine.  


The adjuvant activity of chitosan (CS) and calcium phosphate (CAP) particles was studied following intranasal (mucosal) administration to commercial chickens with inactivated Newcastle disease virus (NDV) vaccine. After three vaccinations with inactivated NDV in combination with CS or CAP an increase in antibody titers in blood and mucosal samples in chickens was observed when compared with the administration of NDV antigen only. A lower level of humoral immunity was observed in broiler chickens compared to layer-type birds. The CS-based vaccine demonstrated higher antigenic and protective activity following lethal challenge than the vaccine containing CAP. Because CS particles efficiently changed mucosal and humoral immunity and protective activity, CS may in the future be considered for use as a potential adjuvant for production of vaccines for poultry. PMID:24758112

Volkova, Marina A; Irza, Anna V; Chvala, Irina A; Frolov, Sergy F; Drygin, Vladimir V; Kapczynski, Darrell R



Trace element doping in calcium phosphate ceramics to Understand osteogenesis and angiogenesis  

PubMed Central

The general trends in synthetic bone grafting materials are shifting towards approaches that can illicit osteoinductive properties. Pharmacologics and biologics have been used in combination with calcium phosphate (CaP) ceramics, however, recently have become the target of scrutiny over the safety. The importance of trace elements in natural bone health is well documented. Ions, e.g. lithium, zinc, magnesium, manganese, silicon, strontium etc. have shown to increase osteogenesis and neovascularization. Incorporation of dopants into CaPs can provide a platform for safe and efficient delivery in clinical applications where increased bone healing is favorable. This review highlights use of trace elements in CaP biomaterials, and offers an insight into the mechanisms of how metal ions can enhance both osteogenesis and angiogenesis. PMID:24012308

Bose, Susmita; Fielding, Gary; Tarafder, Solaiman; Bandyopadhyay, Amit



Electrochemical characteristics of calcium-phosphatized AZ31 magnesium alloy in 0.9 % NaCl solution.  


Magnesium alloys suffer from their high reactivity in common environments. Protective layers are widely created on the surface of magnesium alloys to improve their corrosion resistance. This article evaluates the influence of a calcium-phosphate layer on the electrochemical characteristics of AZ31 magnesium alloy in 0.9 % NaCl solution. The calcium phosphate (CaP) layer was electrochemically deposited in a solution containing 0.1 M Ca(NO3)2, 0.06 M NH4H2PO4 and 10 ml l(-1) of H2O2. The formed surface layer was composed mainly of brushite [(dicalcium phosphate dihidrate (DCPD)] as proved by energy-dispersive X-ray analysis. The surface morphology was observed by scanning electron microscopy. Immersion test was performed in order to observe degradation of the calcium phosphatized surfaces. The influence of the phosphate layer on the electrochemical characteristics of AZ31, in 0.9 % NaCl solution, was evaluated by potentiodynamic measurements and electrochemical impedance spectroscopy. The obtained results were analysed by the Tafel-extrapolation method and equivalent circuits method. The results showed that the polarization resistance of the DCPD-coated surface is about 25 times higher than that of non-coated surface. The CaP electro-deposition process increased the activation energy of corrosion process. PMID:24477876

Hadzima, Branislav; Mhaede, Mansour; Pastorek, Filip



Long-term mechanical durability of dental nanocomposites containing amorphous calcium phosphate nanoparticles  

PubMed Central

Half of all dental restorations fail within 10 years, with secondary caries and restoration fracture being the main reasons. Calcium phosphate (CaP) composites can release Ca and PO4 ions and remineralize tooth lesions. However, there has been no report on their long-term mechanical durability. The objective of this study was to investigate the wear, thermal-cycling, and water-aging of composites containing amorphous calcium phosphate nanoparticles (NACP). NACP of 112-nm and glass particles were used to fabricate four composites: (1) 0% NACP+75% glass; (2) 10% NACP+65% glass; (3) 15% NACP+60% glass; and (4) 20% NACP+50% glass. Flexural strength and elastic modulus of NACP nanocomposites were not degraded by thermal-cycling. Wear depth increased with increasing NACP filler level. Wear depths of NACP nanocomposites after 4 × 105 cycles were within the range for commercial controls. Mechanical properties of all the tested materials decreased with water-aging time. After 2 years, the strengths of NACP nanocomposites were moderately higher than the control composite, and much higher than the resin-modified glass ionomers. The mechanism of strength loss for resin-modified glass ionomer was identified as microcracking and air-bubbles. NACP nanocomposites and control composite were generally free of microcracks and air-bubbles. In conclusion, combining NACP nanoparticles with reinforcement glass particles resulted in novel nanocomposites with long-term mechanical properties higher than those of commercial controls, and wear within the range of commercial controls. These strong long-term properties, plus the Ca-PO4 ion release and acid-neutralization capability reported earlier, suggest that the new NACP nanocomposites may be promising for stress-bearing and caries-inhibiting restorations. PMID:22514160

Moreau, Jennifer L.; Weir, Michael D.; Giuseppetti, Anthony A.; Chow, Laurence C.; Antonucci, Joseph M.; Xu, Hockin H. K.



Mechanical and acid neutralizing properties and bacteria inhibition of amorphous calcium phosphate dental nanocomposite  

PubMed Central

Dental composites do not hinder bacteria colonization and plaque formation. Caries at the restoration margins is a frequent reason for replacement of existing restorations, which accounts for 50 to 70% of all restorations. The objectives of this study were to examine the filler level effect on nanocomposite containing nanoparticles of amorphous calcium phosphate (NACP) and investigate the load-bearing and acid-neutralizing properties and bacteria inhibition. NACP with 116-nm particle size were synthesized via a spray-drying technique and incorporated into a resin. Flexural strength of nanocomposite with 10 to 30% NACP fillers matched the strength of a commercial hybrid composite (p > 0.1). Nanocomposite with 40% NACP matched the strength of a microfill composite, which was 2-fold that of a resin-modified glass ionomer. Nanocomposite with 40% NACP neutralized a lactic acid solution of pH 4 by rapidly increasing the pH to 5.69 in 10 min. In contrast, the commercial controls had pH staying at near 4. Using Streptoccocus mutans, an agar disk-diffusion test showed no inhibition zone for commercial controls. In contrast, the inhibition zone was (2.5 ± 0.7) mm for nanocomposite with 40% NACP. Crystal violet staining showed that S. mutans coverage on nanocomposite was 1/4 that on commercial composite. In conclusion, novel calcium–phosphate nanocomposite matched the mechanical properties of commercial composite and rapidly neutralized lactic acid of pH 4. The nanocomposite appeared to moderately reduce the S. mutans growth, and further study is needed to obtain strong antimicrobial properties. The new nanocomposite may have potential to reduce secondary caries and restoration fracture, two main challenges facing tooth cavity restorations. PMID:21504057

Moreau, Jennifer L.; Sun, Limin; Chow, Laurence C.; Xu, Hockin H. K.



Effects of calcium phosphate composition in sputter coatings on in vitro and in vivo performance.  


Calcium phosphate (CaP) ceramic coatings have been used to enhance the biocompatibility and osteoconductive properties of metallic implants. The chemical composition of these ceramic coatings is an important parameter, which can influence the final bone performance of the implant. In this study, the effect of phase composition of CaP-sputtered coatings was investigated on in vitro dissolution behavior and in vivo bone response. Coatings were prepared by a radio frequency (RF) magnetron sputtering technique; three types of CaP target materials were used to obtain coatings with different stoichiometry and calcium to phosphate ratios (hydroxyapatite (HA), ?-tricalciumphosphate (?-TCP), and tetracalciumphosphate (TTCP)) were compared with non-coated titanium controls. The applied ceramic coatings were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and inductively coupled plasma optical emission spectroscopy. The in vitro dissolution/precipitation of the CaP coatings was evaluated using immersion tests in simulated body fluid (SBF). To mimic the in vivo situation, identical CaP coatings were also evaluated in a femoral condyle rabbit model. TCPH and TTCPH showed morphological changes during 4-week immersion in SBF. The results of bone implant contact (BIC) and peri-implant bone volume (BV) showed a similar response for all experimental coatings. An apparent increase in tartrate resistant acid phosphatase (TRAP) positive staining was observed in the peri-implant region with decreasing coating stability. In conclusion, the experimental groups showed different coating properties when tested in vitro and an apparent increase in bone remodeling with increasing coating dissolution in vivo. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 300-310, 2015. PMID:24659523

Urquia Edreira, Eva R; Wolke, Joop G C; Aldosari, Abdullah AlFarraj; Al-Johany, Sulieman S; Anil, Sukumaran; Jansen, John A; van den Beucken, Jeroen J J P



Porous calcium phosphate ceramic granules and their behaviour in differently loaded areas of skeleton.  


Two kinds of calcium phosphate ceramic (CPC) granules of high porosity (50 +/- 5%) and improved (for such materials) compressive strength (10-25 MPa) consisted of hydroxyapatite (PHA) and a mixture of hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP) in 60 HA/40 beta-TCP composition (PCPC) were developed. A comparative study of in vivo behavior of the materials implanted into an almost unloaded (greater trochanter of femur) and loaded (distal methaphysis of femur) zones in the skeleton of rabbits was performed. Significant activating influence of loading on the processes of new bone formation and reconstruction in macropores of both materials during all periods of implantation (up to 6 months) was observed. The role of relevant cells in the processes in the unsoluble PHA and the degradable PCPC (in which the processes was observed to intensify due to dissolution of the material) was studied and is discussed. Great disturbance in pore structure of the BCPC was revealed in more late periods of implantation. After 6 months, presence of large composite fragments located in intertrabecula spaces of greater trochanter was a characteristic feature of the PCPC crushing. The developed CPC materials seems to have good perspective for using in bone defect plasty in some loaded areas of the skeleton. PMID:18049875

Zyman, Z; Glushko, V; Dedukh, N; Malyshkina, S; Ashukina, N



Phosphorus removal and recovery from wastewater by tobermorite-seeded crystallisation of calcium phosphate.  


Investigations were focused on the development of a technology for phosphorus (P) recovery straight from wastewater. Facing the finiteness of the natural resources of this essential nutrient, the declared goal must be the sustainable use of available phosphorus sinks such as wastewater treatment plants (WWTP) for the generation of P rock substitutes. A feasible method for simultaneous elimination and recovery of phosphorus from wastewater proved to be the P-RoC process - the phosphorus recovery from wastewater by induced crystallisation of calcium phosphate, applying tobermorite-rich waste compounds of the construction industry. The experiments were performed in fixed bed-, stirred- and expanded bed reactors in laboratory--as well as in pilot-scale experiments. The efficiency and longevity of the P-RoC process was determined by the supply of Ca ions and the initial P concentration. Total P (P-tot) contents in the generated crystallisation products of up to 13% P-tot (30% P2O5) were achieved. Mineralogical investigations proved the formation of a hydroxy-apatite-(HAP)-like coating onto the seed material's surface. Reuse options for the generated crystallisation products, such as substitute for phosphate rock or as new fertiliser, were assessed. PMID:16605025

Berg, U; Donnert, D; Weidler, P G; Kaschka, E; Knoll, G; Nüesch, R



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


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 (?-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. PMID:21207950

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



Calcium phosphate ceramic systems in growth factor and drug delivery for bone tissue engineering: A review  

PubMed Central

Calcium phosphates (CaPs) are the most widely used bone substitutes in bone tissue engineering due to their compositional similarities to bone mineral and excellent biocompatibility. In recent years, CaPs, especially hydroxyapatite and tricalcium phosphate, have attracted significant interest in simultaneous use as bone substitute and drug delivery vehicle, adding a new dimension to their application. CaPs are more biocompatible than many other ceramic and inorganic nanoparticles. Their biocompatibility and variable stoichiometry, thus surface charge density, functionality, and dissolution properties, make them suitable for both drug and growth factor delivery. CaP matrices and scaffolds have been reported to act as delivery vehicles for growth factors and drugs in bone tissue engineering. Local drug delivery in musculoskeletal disorder treatments can address some of the critical issues more effectively and efficiently than the systemic delivery. CaPs are used as coatings on metallic implants, CaP cements, and custom designed scaffolds to treat musculoskeletal disorders. This review highlights some of the current drug and growth factor delivery approaches and critical issues using CaP particles, coatings, cements, and scaffolds towards orthopedic and dental applications. PMID:22127225

Bose, Susmita; Tarafder, Solaiman



Thermal spraying of functionally graded calcium phosphate coatings for biomedical implants  

NASA Astrophysics Data System (ADS)

Biomedical requirements in a prosthesis are often complex and diverse in nature. Biomaterials for implants have to display a wide range of adaptability to suit the various stages of the bio-integration process of any foreign material into the human body. Often, a combination of materials is needed. The preparation of a functionally graded bioceramic coating composed of essentially calcium phosphate compounds is explored. The coating is graded in accordance to adhesive strength, bioactivity, and bioresorbability. The bond coat on the Ti-6Al-4V stub is deposited with a particle range of the hydroxyapatite (HA) that will provide a high adhesive strength and bioactivity but have poor bioresorption properties. The top coat, however, is composed of predominantly ?-tricalcium phosphate (?-TCP) that is highly bioresorbable. This arrangement has the propensity of allowing accelerated bio-integration of the coating by the body tissues as the top layer is rapidly resorbed, leaving the more bioactive intermediate layer to facilitate the much needed bioactive properties for proper osteoconduction. The processing steps and problems are highlighted, as well as the results of post-spray heat treatment.

Wang, Y.; Khor, K. A.; Cheang, P.



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

NASA Astrophysics Data System (ADS)

In this study, Mg doped hydroxyapatite [(Ca, Mg)10(PO4)6(OH)2] and ?-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 (?-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.

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


Highly sensitive amperometric biosensor based on a biocompatible calcium phosphate cement.  


Brushite is a biocompatible calcium phosphate mineral with properties of solid electrolyte. In this study we take advantage of this characteristic to develop an enzymatic amperometric biosensor based on brushite cement. The biosensor was prepared by immobilizing tyrosinase (PPO) on a brushite cement layer which was subsequently cross-linked with glutaraldehyde (GA) on the surface of a glassy carbon electrode. The system was optimized for the detection of phenolic compounds in both aqueous and non-aqueous solutions. Several variables involved in the enzyme immobilization method such as glutaraldehyde cross-linking time, PPO/brushite ratio and thickness of the brushite film were investigated. Furthermore, the effects of the pH, temperature and applied potential on the biosensor performance were also optimized. On the other hand, the biosensor analytical properties were studied in presence of different organic solvents: dioxane, acetonitrile and ethanol. In both, phosphate buffer solution (PBS) and acetonitrile/PBS solution, the biosensor exhibits a rapid response (12 s); a wide linear range (0.001-3 microM and 0.007-2 microM respectively); low detection limit (1 and 2 nM respectively); and high sensitivity (46.6 and 28.6 A M(-1) cm(-2) respectively). The performance of the biosensor in the analysis of phenols in real samples was successful. PMID:19211238

Sánchez-Paniagua López, M; Tamimi, F; López-Cabarcos, E; López-Ruiz, B



Influence of Mg-substitution on the physicochemical properties of calcium phosphate powders  

SciTech Connect

Tricalcium phosphate based ceramics (TCP) are bioresorbable and thereby considered to be promising bone replacement materials. The differences in crystal structure between {alpha} and {beta}-TCP phases gives rise for different dissolution rates in vitro and in vivo, which may alter the bioresorbable behavior of TCP ceramics. It is suggested that the addition of magnesium ions, which are also present in biological tissues, stabilizes {beta}-phase to higher temperatures and thus enables the sintering of {beta}-TCP at elevated temperatures compared to Mg free TCP. In this paper, Mg-substituted TCP, with the general formula (Ca{sub 1-x}Mg {sub x}){sub 3}(PO{sub 4}){sub 2} and 0.01 {<=} x {<=} 0.045, were produced by wet chemical synthesis from Ca(OH){sub 2}, H{sub 3}PO{sub 4} and MgO, after calcinations at three different temperatures between 750 and 1050 deg. C. The influence of different amounts of Mg substitution on the physical properties, microstructure, and sintering behavior of calcium phosphate powders was evaluated. Thermal analytical techniques, together with X-ray diffraction analysis, were successfully combined in order to characterize the occurring phase transformations during annealing of the powders. The results show that the addition of small amounts of Mg (up to 1.5 mol%) are adequate to postpone the {beta}-{alpha} TCP phase transformation to 1330 deg. C and to accelerate the densification process during sintering of {beta}-TCP ceramics.

Marchi, J. [University of Erlangen-Nuernberg, Department of Materials Science-Biomaterials, Henkestr. 91, D-91052 Erlangen (Germany); Institute of Energetic and Nuclear Research (IPEN), Centre of Science and Materials Technology, Department of Ceramics, Av. Prof. Lineu Prestes, 2242, 05508-000 Sao Paulo, SP (Brazil); Dantas, A.C.S. [University of Erlangen-Nuernberg, Department of Materials Science-Biomaterials, Henkestr. 91, D-91052 Erlangen (Germany); Greil, P. [University of Erlangen-Nuernberg, Department of Materials Science-Biomaterials, Henkestr. 91, D-91052 Erlangen (Germany); Bressiani, J.C. [Institute of Energetic and Nuclear Research (IPEN), Centre of Science and Materials Technology, Department of Ceramics, Av. Prof. Lineu Prestes, 2242, 05508-000 Sao Paulo, SP (Brazil); Bressiani, A.H.A. [Institute of Energetic and Nuclear Research (IPEN), Centre of Science and Materials Technology, Department of Ceramics, Av. Prof. Lineu Prestes, 2242, 05508-000 Sao Paulo, SP (Brazil); Mueller, F.A. [University of Erlangen-Nuernberg, Department of Materials Science-Biomaterials, Henkestr. 91, D-91052 Erlangen (Germany)]. E-mail:



Incorporation of active ions into calcium phosphate coatings, their release behavior and mechanism.  


The dissolution and release of active ions from ion-doped apatites is currently gaining interest due to indications of a beneficial biologic response. The release of ions from apatite coatings is important because it influences the biological effect of these types of materials. In this study the ion release from three different ion-doped apatite coatings (iHA coatings), SrCaP, SiHA and FHA, has been studied. The coatings were prepared by a mineralization method based on immersion in modified PBS solutions containing additions of Sr, Si or F. The kinetics of ion release from the iHA coatings were studied in two different media with and without calcium and phosphate ions (phosphate buffer saline solution (PBS) and Tris-HCl). The amount of cumulative release of Sr, Si and F ions from the iHA coatings was SrCaP>SiHA>FHA in Tris-HCl, which could be also be related to the solubility for these iHA coatings. According to analysis using the Korsmeyer-Peppas model, the release of ions from the coatings was in most cases controlled by a combination of Fickian diffusion and dissolution of the coatings. The morphologies of the iHA coatings were not markedly changed after immersion in Tris-HCl. In the phosphate buffer solution, there was a concurrent redeposition of new apatite crystals on the surface of all of the iHA coatings, which means there were both a dissolution and a remineralization process acting, ultimately controlling the ion release rate. PMID:22736143

Lindahl, Carl; Xia, Wei; Lausmaa, Jukka; Engqvist, Håkan



Calcium Carbonate Phosphate Binding Ion Exchange Filtration and Accelerated Denitrification Improve Public Health Standards and Combat Eutrophication in Aquatic Ecosystems  

PubMed Central

Cultural eutrophication, the process by which a lake becomes rich in dissolved nutrients as a result of point and nonpoint pollutant sources, is a major cause of the loss of natural lake ecosystems throughout the world. The process occurs naturally in all lakes, but phosphate-rich nutrient runoff from sources such as storm drains and agricultural runoff is a major cause of excess phosphate-induced eutrophication. Especially in Madrona Marsh, one of the last remaining vernal marshes in the greater Los Angeles area, California, cultural eutrophication has become a major problem. In this study, calcium carbonate was found to be an excellent phosphate binder, reducing up to 70% of the phosphates in a given sample of water, and it posed relatively negligent ecological repercussions. This study involved the testing of this principle in both the laboratory and the real ecosystem. A calcium carbonate lacing procedure was first carried out to determine its efficacy in Madrona Marsh. Through this, ammonia was found to interfere with the solubility of calcium carbonate and therefore to be a hindrance to the reduction of phosphate. Therefore, various approaches for reduction of ammonia were tested, including aeration, use of fiber growth media, and plants, mainly Caulerpa verticellata, chosen for it hardiness, primarily in an attempt to increase population of Nitrobacter and Nitrosomonas. All were successful in moderately reducing ammonia levels. In addition, soil sampling, sediment analysis, microscopic plant analysis, microorganism and macroinvertebrate identification, and rate law formulations were conducted. The effect of phosphate and ammonia reduction on the populations of enterobacteria was also an important focus of this experiment. Varying concentrations of phosphate, ammonia, and calcium carbonate in conjunction with phosphate were tested in Madrona Marsh to determine their effects on the populations of enteropathogens on nonspecific blood agar, MacConkey agar, and Hektoen agar. Initial analyses suggest a strong correlation between phosphate concentrations and bacterial populations; a 66% decrease in phosphate resulted in a 35% reduction in bacterial populations and a 45% reduction in enteropathogenic populations. Likewise, a strong correlation was shown between calcium carbonate concentrations and bacterial reduction greater than that which can be attributed to the phosphate reduction alone. This was followed by the construction of various phosphate binding calcium carbonate filters, which used the ion exchange principle, including a spring loading filter, PVC pipe filter, and a galvanized filter. All were tested with the aid of Stoke's law formulation. The experiment was extremely successful in designing a working phosphate-binding and ammonia-reducing filter, and a large-scale agitator-clarifier filter system is currently being planned for construction in Madrona Marsh; this filter will reduce phosphate and ammonia levels substantially in the following years, bringing ecological, economical, and health-related improvements to the overall ecosystem and habitat. PMID:16381147

Yanamadala, Vijay




PubMed Central

The hepatopancreas of the adult male blue crab Callinectes sapidus in intermolt was found to contain substantial amounts of calcium, magnesium, and inorganic phosphorus, averaging about 260, 20, and 250 µg-atoms per g wet tissue, respectively, accounting for over 10% of the tissue dry weight. Electron microscopy of the intact tissue showed three qualitatively different granular structures having electron densities suggestive of high mineral content. After fractionation of the tissue using centrifugal techniques, almost 95% of the total mineral was found to reside in a heavy, nonmitochondrial particulate fraction(s). The bulk of the low-speed pellet consisted of relatively dense, roughly spherical granules 1–5 µm in diameter, which could be considerably purified by repeated suspension in water and low-speed sedimentation. In the electron microscope the isolated granules appeared basically similar to one of the three characteristic types of electron-dense granules seen in the intact tissue. Although the freshly isolated granules lost approximately 50% of their wet weight when dried at 105°C, only 10% more was lost upon dry ashing at 450°C, suggesting a fairly low content of organic material. Chemical analysis revealed calcium, magnesium, and inorganic phosphate at 5.7, 2.1, and 4.4 µg-atoms per mg dried granules, respectively, accounting for 69% of the dry weight of the fraction. By specific enzymatic assays, the freshly isolated granules were found to contain ATP, ADP, and AMP at levels of 0.13, 0.03, and 0.01 µmol/mg, or 8% of their total dry weight. The remainder of the total phosphorus contributed an additional 3%, whereas carbonate, citrate, oxalate, and protein each constituted no more than 1%. The mineral granules of the crab hepatopancreas appear to function as storage forms of calcium and phosphate during the intermolt period. This tissue appears promising as a model for study of the cellular events associated with biological calcification, since conventional biochemical techniques can be employed. Furthermore, the major mineralized component of the tissue can be obtained in large amounts for direct study by a simple fractionation procedure. PMID:4827907

Becker, Gerald L.; Chen, Chung-Ho; Greenawalt, John W.; Lehninger, Albert L.



Ceramide 1-phosphate enhances calcium entry through voltage-operated calcium channels by a protein kinase C-dependent mechanism in GH4C1 rat pituitary cells.  

PubMed Central

Sphingomyelin derivatives modulate a multitude of cellular processes, including the regulation of [Ca2+]i (the intracellular free calcium concentration). Previous studies have shown that these metabolites often inhibit calcium entry through VOCCs (voltage-operated calcium channels). In the present study, we show that, in pituitary GH4C1 cells, C1P (C2-ceramide 1-phosphate) enhances calcium entry in a dose-dependent manner. The phospholipase C inhibitor U73122 attenuated the response. C1P invoked a small, but significant, increase in the formation of inositol phosphates. Pre-treatment of the cells with pertussis toxin was without an effect on the C1P-evoked increase in [Ca2+]i. The effect of C1P was critically dependent on extracellular calcium, since no increase in [Ca2+]i was observed when cells in a calcium-free buffer were stimulated with C1P. Furthermore, if the cells were retreated with 300 nM of the VOCC inhibitor nimodipine, the effect of C1P was almost totally abolished. In addition, ceramide C8-1-phosphate evoked an increase in [Ca2+]i, but the onset of the response was slow compared with that of C1P. In cells treated with 1 mM thapsigargin for 15 min, C1P still evoked an increase in [Ca2+]i. In patch-clamp experiments in the whole-cell mode, C1P enhanced calcium entry through the VOCCs compared with vehicle-treated cells. Dialysis of the cells with C1P did not enhance the calcium current. On-cell patch-clamp experiments showed an enhanced probability of the VOCCs being open (P(open)) in the presence of C1P. Inhibition of PKC (protein kinase C) with GF109203X and down-regulation of PKC with PMA attenuated the C1P-evoked increase in [Ca2+]i. Furthermore, down-regulation of PKC abolished the effect of C1P on P(open). This is the first report showing that a sphingomyelin derivative enhances calcium entry through VOCCs. PMID:15018614

Tornquist, Kid; Blom, Tomas; Shariatmadari, Ramin; Pasternack, Michael



Effect of hydroxyapatite, octacalcium phosphate and calcium phosphate on the auto-flocculation of the microalgae in a high-rate algal pond.  


Recovering microalgae is one of the main technological and economic concerns in a high-rate algal pond (HRAP) because of their small size and their low density. This paper emphasizes the characterization (identification and assessment of potential flocculation) of chemical compounds involved in microalgae auto-flocculation in a HRAP. First, thermodynamic simulations were performed, using two models (i.e. Visual Minteq and a simplified thermodynamic model) in order to determine the chemical compounds of interest. Experimental tests were then carried out with these compounds for assessing their flocculation ability. Both models revealed that precipitates of calcium phosphates and their substituted forms were the compounds involved in the auto-flocculation. Moreover, experimental tests showed that the stoichiometric neutralization of algal charges by calcium phosphates (i.e. hydroxyapatite (Ca5(PO4)3OH), octacalcium phosphate (Ca4H(PO4)3) and amorphous calcium phosphate (Ca3(PO4)2)), at a pH within the range 7-10 yields 70-82% recovered algal biomass. The optimum ratio required for algae auto-flocculation was 0.33 Ca5(PO4)3OH/g DM(algae) at pH 10, 0.11 Ca4H(PO4)3/g DM(algae) at pH 7 and 0.23 g Ca3(PO4)2/g DM(algae) at pH 9. Auto-flocculation appears as a simple, sustainable and promising method for efficient harvesting of microalgae in a HRAP. PMID:24350497

Baya, D T; Effebi, K R; Tangou, T T; Keffala, C; Vasel, J L



Basic Calcium Phosphate Crystals Activate c-fos Expression Through a Ras/ERK Dependent Signaling Mechanism  

PubMed Central

Diseases caused by calcium pyrophosphate dihydrate (CPPD) and basic calcium phosphate (BCP) crystals occur frequently in osteoarthritic joints. Both crystals induce mitogenesis, metalloproteinase synthesis and secretion by fibroblasts and chondrocytes, promoting degradation of articular tissue. We investigated the mechanism by which BCP activates the c-fos proto-oncogene, which has been shown to activate various matrix metalloproteinases (MMPs). We demonstrate that BCP crystals induce c-fos expression primarily through a Ras/ERK dependent signaling mechanism targeting two highly conserved regulatory binding sites, the serum response element (SRE) and the cAMP response element (CRE). These results establish a calcium crystal induced, calcium/Calmodulin independent, signaling pathway in which BCP crystals activate Ras/MAPK, which can directly target an SRF-containing transcription factor complex, to induce fibroblasts to secrete metalloproteinases. PMID:17307136

Major, Michael L.; Cheung, Herman S.; Misra, Ravi P.



Alpha-TCP improves the apatite-formation ability of calcium-silicate hydraulic cement soaked in phosphate solutions  

Microsoft Academic Search

The in vitro apatite-forming ability of experimental calcium-silicate hydraulic cements designed for dentistry was investigated.Two cements containing di- and tricalcium-silicate (wTC and wTC-TCP, i.e. wTC added with alpha-TCP) were soaked in different phosphate-containing solutions, namely Dulbecco's Phosphate Buffered Saline (DPBS) or Hank's Balanced Salt Solution (HBSS), at 37°C and investigated over time (from 24h to 6months) by SEM\\/EDX, micro-Raman and

Maria Giovanna Gandolfi; Paola Taddei; Anna Tinti; Elettra De Stefano Dorigo; Carlo Prati



Performance of fuel cell using calcium phosphate hydrogel membrane prepared from waste incineration fly ash and chicken bone powder.  


Waste incineration fly ash and bone powder could be successfully recycled to calcium phosphate hydrogel, a type of fast proton conductor. The electric conductivity of the crystallized hydrogel from them was compared with that from calcium carbonate reagent. It was found that the conductivity of the hydrogel from bone powder is almost equal to that from calcium carbonate reagent, which is higher than that from incineration fly ash. Because the crystallized hydrogel from incineration ash has a lower crystallinity than that from bone powder and calcium carbonate reagent. However, the difference of the conductivity among them can be hardly observed above 100 degrees C. The fuel cell with membrane electrode assembly (MEA) using the calcium phosphate hydrogel membrane prepared from incineration fly ash and bone powder was observed to generate electricity. The performance of fuel cells having the hydrogel membrane obtained from all raw materials increases with the cell temperature, and the fuel cell containing the hydrogel membrane from incineration fly ash has the highest dependence of the fuel cell performance. For this reason, the difference in the cell performance among them can be hardly observed above 120 degrees C. This tendency agrees with the change in the electric conductivity with the temperature. Further, the performance of all fuel cells with the hydrogel membrane is superior to that of the fuel cell with perfluorosulfonic polymer membrane at temperatures greater than approximately 85 degrees C. PMID:19328627

Fukui, Kunihiro; Arimitsu, Naoki; Jikihara, Kenji; Yamamoto, Tetsuya; Yoshida, Hideto



Physical properties and cellular responses to calcium phosphate coating produced by laser rapid forming on titanium.  


In order to improve the surface bioactivity of titanium implants, CaCO? and CaHPO?·2H?O powder was used to fabricate a calcium phosphate (CaP) coating using laser rapid forming (LRF) technology. The surface characterization showed that a porous and beta-tricalcium phosphate (beta-TCP) layer with small amount of alpha-TCP was formed on commercial pure titanium (Ti). The bonding strength between the coating and the Ti substrate was above 40.17 MPa measured by the means of pull-off test. The elastic modulus and the average microhardness of the coating were 117.61 GPa and 431.2 HV?.?, respectively. Through the static immersion test, it was proved that the coating could not only prevent the corrosion of Ti but also promote the redeposition of beta-TCP in artificial saliva. Osteoblasts possessed good attachment performance and strong proliferation ability on the surface of LRF coating (p < 0.05) in our cell experiments. This result demonstrated that the LRF coating could improve the surface cytocompatibility of titanium. Using scanning electron microscopy observation, it was found that osteoblasts grown on LRF coating formed multiple layers in pours. The result of reverse transcription PCR analysis demonstrated that the expressions of ITG?1 and BMP-2 were significantly (p < 0.05) upregulated on the LRF coating in a time-dependent manner, compared with uncoated Ti. These findings suggested that the LRF technology might be a promising potential treatment for fabricating CaP coatings on titanium implants. PMID:23139072

Gao, Y; Hu, J; Guan, T H; Wu, J; Zhang, C B; Gao, B



Short-term in vivo evaluation of zinc-containing calcium phosphate using a normalized procedure.  


The effect of zinc-substituted calcium phosphate (CaP) on bone osteogenesis was evaluated using an in vivo normalized ISO 10993-6 protocol. Zinc-containing hydroxyapatite (ZnHA) powder with 0.3% by wt zinc (experimental group) and stoichiometric hydroxyapatite (control group) were shaped into cylindrical implants (2×6 mm) and were sintered at 1000 °C. Thermal treatment transformed the ZnHA cylinder into a biphasic implant that was composed of Zn-substituted HA and Zn-substituted ?-tricalcium phosphate (ZnHA/?ZnTCP); the hydroxyapatite cylinder was a highly crystalline and poorly soluble HA implant. In vivo tests were performed in New Zealand White rabbits by implanting two cylinders of ZnHA/?ZnTCP in the left tibia and two cylinders of HA in the right tibia for 7, 14 and 28 days. Incorporation of 0.3% by wt zinc into CaP increased the rate of Zn release to the biological medium. Microfluorescence analyses (?XRF-SR) using synchrotron radiation suggested that some of the Zn released from the biomaterial was incorporated into new bone near the implanted region. In contrast with previous studies, histomorphometric analysis did not show significant differences between the newly formed bone around ZnHA/?ZnTCP and HA due to the dissolution profile of Zn-doped CaP. Despite the great potential of Zn-containing CaP matrices for future use in bone regeneration, additional in vivo studies must be conducted to explain the mobility of zinc at the CaP surface and its interactions with a biological medium. PMID:24907765

Calasans-Maia, Monica; Calasans-Maia, José; Santos, Silvia; Mavropoulos, Elena; Farina, Marcos; Lima, Inayá; Lopes, Ricardo Tadeu; Rossi, Alexandre; Granjeiro, José Mauro



Novel calcium phosphate nanocomposite with caries-inhibition in a human in situ model  

PubMed Central

Objectives Secondary caries at the restoration margins remains the main reason for failure. Although calcium phosphate (CaP) composites are promising for caries inhibition, there has been no report of CaP composite to inhibit caries in situ. The objectives of this study were to investigate the caries-inhibition effect of nanocomposite containing nanoparticles of amorphous calcium phosphate (NACP) in a human in situ model for the first time, and to determine colony-forming units (CFU) and Ca and P ion concentrations of biofilms on the composite restorations. Methods NACP with a mean particle size of 116 nm were synthesized via a spray-drying technique. Two composites were fabricated: NACP nanocomposite, and control composite filled with glass particles. Twenty-five volunteers wore palatal devices containing bovine enamel slabs with cavities restored with NACP or control composite. After 14 days, the adherent biofilms were collected for analyses. Transverse microradiography determined the enamel mineral profiles at the margins, and the enamel mineral loss ! Z was measured. Results NACP nanocomposite released Ca and P ions and the release significantly increased at cariogenic low pH (p < 0.05). Biofilms on NACP nanocomposite contained higher Ca (p = 0.007) and P ions (p = 0.005) than those of control (n = 25). There was no significant difference in biofilm CFU between the two composites (p > 0.1). Microradiographs showed typical subsurface lesions in enamel next to control composite, but much less lesion around NACP nanocomposite. Enamel mineral loss ! Z (mean ± sd; n = 25) around NACP nanocomposite was 13.8 ± 9.3 ?m, much less than 33.5 ± 19.0 ?m of the control (p = 0.001). Significance Novel NACP nanocomposite substantially reduced caries formation in a human in situ model for the first time. Enamel mineral loss at the margins around NACP nanocomposite was less than half of the mineral loss around control composite. Therefore, the Ca and P ion-releasing NACP nanocomposite is promising for caries-inhibiting restorations. PMID:23140916

Melo, Mary Anne S.; Weir, Michael D.; Rodrigues, Lidiany K.A.; Xu, Hockin H.K.



Synovial fluid inorganic pyrophosphate concentration and nucleotide pyrophosphohydrolase activity in basic calcium phosphate deposition arthropathy and Milwaukee shoulder syndrome.  


Synovial fluid (SF) inorganic pyrophosphate (PPi) concentration is elevated in calcium pyrophosphate dihydrate (CPPD) crystal deposition arthropathy. Since CPPD and basic calcium phosphate (BCP) crystals often are present in the same joints, we determined [PPi] and activity of the PPi-generating enzyme, nucleotide pyrophosphohydrolase (NPPH), in SF from the joints of patients with various arthropathies, including those with BCP crystals. We found elevated SF [PPi] in joints with BCP crystals, as well as in joints with CPPD crystals. The presence of BCP crystals in synovial fluids was also predictive of elevated NPPH activity. PMID:2833903

Rachow, J W; Ryan, L M; McCarty, D J; Halverson, P C




SciTech Connect

Citric acid added as set retarder significantly contributed to enhancing the setting temperature and to extending the thickening time of a calcium aluminate phosphate (CaP) geothermal cement slurry consisting of calcium aluminate cement (CAC) as the base reactant and sodium polyphosphate (NaP) solution as the acid reactant. The set-retarding activity of citric acid was due to the uptake of Ca{sup 2+} ions from the CAC by carboxylic acid groups within the citric acid. This uptake led to the precipitation of a Ca-complexed carboxylate compound as a set-retarding barrier layer on the CAC grains' surfaces. However, this barrier layer was vulnerable to disintegration by the attack of free Ca{sup 2+} ions from CAC, and also to degradation at elevated temperature, thereby promoting the generation of exothermic energy from acid-base reactions between the CAC and NaP after the barrier was broken. The exothermic reaction energy that was promoted in this way minimized the loss in strength of the citric acid-retarded cement. The phase composition assembled in both retarded and non-retarded cements after autoclaving at 180 C encompassed three reaction products, hydroxyapatite (HOAp), hydrogrossular and boehmite, which are responsible for strengthening the autoclaved cement. The first two reaction products were susceptible to reactions with sulfuric acid and sodium sulfate to form crystalline bassanite scale as the corrosion product. The boehmite phase possessed a great resistance to acid and sulfate. Although the bassanite scales clinging to the cement's surfaces were the major factor governing the loss in weight, they served in protecting the cement from further acid- and sulfate-corrosion until their spallation eventually occurred. Nevertheless, the repetitive processes of HOAp and hydrogrossular {yields} bassanite {yields} spallation played an important role in extending the useful lifetime of CaP cement in a low pH environment at 180 C.




Calcium phosphate coupled Newcastle disease vaccine elicits humoral and cell mediated immune responses in chickens.  


Calcium phosphate (CaP) particles were coupled with inactivated Newcastle disease virus (NDV) vaccine. The surface morphology of CaP particles coupled to NDV was found to be spherical, smooth and with a tendency to agglomerate. The mean (± SE) size of CaP particles was found 557.44 ± 18.62 nm. The mean percent encapsulation efficiency of CaP particles coupled to NDV assessed based on total protein content and haemagglutination (HA) activity in eluate was found to be 10.72 ± 0.89 and 12.50 ± 2.09, respectively. The humoral and cell mediated immune responses induced by CaP coupled NDV vaccine were assessed in comparison to a commercial live vaccine (RDV 'F'). CaP coupled NDV vaccine elicited prolonged haemagglutination inhibition (HI) and enzyme linked immunosorbent assay (ELISA) titres in the serum even at fourth and fifth week post-vaccination (PV), unlike RDV 'F' inoculated chickens whose titres declined to insignificant levels by this time. CaP coupled NDV vaccine could stimulate HI antibodies in tracheal washings and tears from second and first week PV, respectively. IgA ELISA antibodies were also seen in tracheal washings of these birds from third week PV and in tears from second week PV. CaP coupled NDV vaccine elicited cell mediated immune responses (CMI) from two to four weeks PV. The stimulation indices obtained after stimulation with specific antigen was not significantly different between CaP coupled antigen and live NDV virus except on first week PV. However, CaP coupled antigen did not cause suppression of lympo proliferation as indicated by statistically similar responses to mitogen, concanavalin A between the two groups. Overall, CaP coupled NDV vaccine elicited stronger and prolonged immune responses in comparison to the commercial live vaccine. No increase in the serum calcium and phosphorous levels were seen in CaP coupled NDV vaccine inoculated chickens. PMID:20951398

Koppad, Sanganagouda; Raj, G Dhinakar; Gopinath, V P; Kirubaharan, J John; Thangavelu, A; Thiagarajan, V



Alpha-tricalcium phosphate (?-TCP): solid state synthesis from different calcium precursors and the hydraulic reactivity.  


The effects of solid state synthesis process parameters and primary calcium precursor on the cement-type hydration efficiency (at 37 °C) of ?-tricalcium phosphate (Ca(3)(PO(4))(2) or ?-TCP) into hydroxyapatite (Ca(10-x)HPO(4)(PO(4))(6-x)(OH)(2-x) x = 0-1, or HAp) have been investigated. ?-TCP was synthesized by firing of stoichiometric amount of calcium carbonate (CaCO(3)) and monetite (CaHPO(4)) at 1150-1350 °C for 2 h. Three commercial grade CaCO(3) powders of different purity were used as the starting material and the resultant ?-TCP products for all synthesis routes were compared in terms of the material properties and the reactivity. The reactant CaHPO(4) was also custom synthesized from the respective CaCO(3) source. A low firing temperature in the range of 1150-1350°C promoted formation of ?-polymorph as a second phase in the resultant TCP. Meanwhile, higher firing temperatures resulted in phase pure ?-TCP with poor hydraulic reactivity. The extension of firing operation also led to a decrease in the reactivity. It was found that identical synthesis history, morphology, particle size and crystallinity match between the ?-TCPs produced from different CaCO(3) sources do not essentially culminate in products exhibiting similar hydraulic reactivity. The changes in reactivity are arising from differences in the trace amount of impurities found in the CaCO(3) precursors. In this regard, a correlation between the observed hydraulic reactivities and the impurity content of the CaCO(3) powders--as determined by inductively coupled plasma mass spectrometry--has been established. A high level of magnesium impurity in the CaCO(3) almost completely hampers the hydration of ?-TCP. This impurity also favors formation of ?- instead of ?-polymorph in the product of TCP upon firing. PMID:21445656

Cicek, Gulcin; Aksoy, Eda Ayse; Durucan, Caner; Hasirci, Nesrin



[Raman spectrum study of the calcium phosphate glass structure affected by the addition of TiO2].  


Calcium phosphate glasses in which part of CaO was replaced by TiO2 were prepared by the conventional melt quench method. The structures and their thermal properties were studied by XRD, Raman and DSC techniques. The results show that, TiO2 and calcium phosphate form homogeneous glass with the amount of the additive less than 3 mol%. The glasses matrix generates a Ca2P2O7 and CaTi4 (PO4)6 crystal phase with the amount of the additives in the range of 6-12 mol%. With the addition of TiO2, the structural changes of the glass system are from metaphosphate to pyrophosphate and orthophosphate. With the TiO2 less than 3 mol%, the cohesion of the glasses structure and the glasses thermal stability is enhanced, and the glasses transition temperature is gradually increased. PMID:21942025

Liang, Xiao-feng; Yin, Guang-fu; Yang, Shi-yuan; Wang, Jun-xia



Observation of calcium phosphate powder mixed with an adhesive monomer experimentally developed for direct pulp capping and as a bonding agent.  


In this study, morphological shape, elemental distribution and elution properties of Ca, P, Mg in four types of calcium phosphate powder were investigated using SEM, EPMA and ICP-AES. Calcium phosphate powder: OHAp, DCPD, beta-TCP and OCP were observed in the white powder form and in the photopolymerized adhesive monomer they scattered like dispersed fillers in resin composite. In elemental analysis, CaKalpha showed a relatively high concentration in relation to PKalpha. In elution analysis, each calcium phosphate showed different elution of Ca and P. But Mg was almost equal to the detection limit of ICP-AES. Namely it was suggested that reparative dentin formation was effectively promoted under the following conditions: a calcification promoting effect by direct contact of the calcium phosphate powder, an ionic effect of Ca and P eluted from the powder located in the vicinity of the exposed pulp and environmental pH change of the surface in exposed pulp. PMID:20379007

Katoh, Yoshiroh; Suzuki, Masaya; Kato, Chikage; Shinkai, Koichi; Ogawa, Masaaki; Yamauchi, Junichi



Structural studies of calcium phosphate doped with titanium and zirconium obtained by high-energy mechanical alloying  

NASA Astrophysics Data System (ADS)

In this paper, we present a new variation of the solid-state procedure on the synthesis of bioceramics with titanium (CapTi) and zirconium (CapZr), considering that zirconium (ZrO2) and titanium oxide (TiO2) are strengthening agents, due to their superb force and fracture toughness. The high efficiency of the calcination process opens a new way of producing commercial amounts of nanocrystalline bioceramics. In this work, a new variation of the solid-state procedure method was used to produce nanocrystalline powders of titanium and zirconium, using two different experimental chemical routes: CapTi: Ca(H2PO4)2+TiO2 and CapZr: Ca(H2PO4)2+ZrO2. The powders were submitted to calcination processes (CapTic and CapZrc) at 800, 900 and 1000 °C. The calcium titanium phosphate phase, CaTi4P6O24, was obtained in the CapTic reaction and the calcium zirconium phosphate, CaZr4P6O24, was obtained in the CapZrc reaction. The obtained ceramics were characterized by x-ray powder diffraction (XRD), infrared (IR) spectroscopy, Raman scattering spectroscopy (RSS) and scanning electron microscopy (SEM) analysis. This method was compared with the milling process (CapTim and CapZrm), where in the last process the melting is not necessary and the powder obtained is nanocrystalline. The calcium titanium phosphate phase, CaTi4P6O24, was obtained in the reaction CapTim, but in CapZrm the formation of any calcium phosphate phase even after 15 h of dry mechanical alloying was not observed.

Silva, C. C.; Sombra, A. S. B.



The role of surface functional groups in calcium phosphate nucleation on titanium foil: a self-assembled monolayer technique  

Microsoft Academic Search

Surface functional groups play important roles in nucleating calcium phosphate deposition on surgical titanium implants. In this study, various functional groups were introduced onto the surface of commercially pure titanium foils using a self-assembled monolayer (SAM) technique. An organic silane, 7-oct-1-enyltrichlorosilane (OETS) was used and ?OH, ?PO4H2, ?COOH groups were derived from its unsaturated double bond. Ti foils were first

Qing Liu; Jiang Ding; Francis K Mante; Stephanie L Wunder; George R Baran



Mechanistic studies of electrodeposition for bioceramic coatings of calcium phosphates by an in situ pH-microsensor technique  

Microsoft Academic Search

A pH-microsensor technique was developed to measure in-situ the pH value at the titanium alloy?solution interface for the first time during the electrodeposition process of calcium phosphate coatings. Electrochemically prepared iridium oxide was used as a pH sensitive material, which is of a good response behavior in the measured solutions. The pH response slope was ?70.2 mV\\/pH at 60°C. The

J. M Zhang; C. J Lin; Z. D Feng; Z. W Tian



A new approach in biomimetic synthesis of calcium phosphate coatings using lactic acid–Na lactate buffered body fluid solution  

Microsoft Academic Search

The main objective of this study was to investigate calcium phosphate (CaP) coatings on Ti6Al4V substrates by using the biomimetic technique. To this purpose, a new solution was developed to coat CaP on Ti6Al4V alloy substrates. The newly formulated body fluid (Lac-SBF) contained appropriate amounts of sodium lactate (NaL) and lactic acid (HL), as well as all the other ionic

Ahmet Pasinli; Mithat Yuksel; Erdal Celik; Sevil Sener; A. Cuneyt Tas



Sintering and Properties of Dense Manganese-Doped Calcium Phosphate Bioceramics Prepared Using Sol-Gel Derived Nanopowders  

Microsoft Academic Search

Dense manganese-doped biphasic calcium phosphate (Mn-BCP) ceramics were fabricated via uniaxial pressing using the sol-gel derived powders. The compacted discs were sintered in ambient atmosphere with temperatures ranging from 800°C to 1400°C. Manganese (Mn) level was varied in the range of 0.6, 1.9, 4.3, and 11.9 mol%, and its effect on physical and mechanical properties of the dense samples were investigated.

I. Sopyan; N. A. Nawawi; Q. H. Shah; S. Ramesh; C. Y. Tan; M. Hamdi



Remineralization of Enamel Subsurface Lesions by Sugar-free Chewing Gum Containing Casein Phosphopeptide-Amorphous Calcium Phosphate  

Microsoft Academic Search

Casein phosphopeptide-amorphous calcium phosphate nanocomplexes (CPP-ACP) exhibit anticariogenic potential in laboratory, animal, and human in situ experiments. The aim of this study was to determine the ability of CPP-ACP in sugar-free chewing gum to remineralize enamel subsurface lesions in a human in situ model. Thirty subjects in randomized, cross-over, double-blind studies wore removable palatal appliances with six human-enamel half-slabs inset

P. Shen; F. Cai; A. Nowicki; J. Vincent; E. C. Reynolds



Effects of blood on bone cement made of calcium phosphate: problems and advantages.  


In recent years, calcium phosphate cements (CPCs) have frequently been used as bone substitutes in the field of orthopedic surgery. When CPC is used as a bone substitute in vivo, blood contamination is unavoidable. To date, however, no detailed study has been conducted focusing on how the physical properties of CPCs would change under the influence of blood. In this study, the effects of blood contamination on Biopex-R (BPR, PENTAX, Tokyo) are examined in vitro and in vivo. The compressive strength of BPR after setting decreased depending on the amount of contaminating blood. The BPR, which has set in vivo, not only has a fragile surface due to the contamination by blood, but also has a propensity to shorten and be destroyed during the early postoperative stage, especially in the bone exposed to loads. On the other hand, radiographic and histological features in vivo indicated that the absorption and the bone replacement of BPR were stimulated by blood contamination. In the clinical evaluation, the patient's own peripheral venous blood was added to the BPR. One year after the surgery, the absorption was noted around the hardened BPR. To advance CPCs (including BPR) as bioabsorbable bone replaceable materials, it is essential to utilize the patient's own blood in combination with the CPC. PMID:19924692

Musha, Yoshiro; Umeda, Tomohiro; Yoshizawa, Sayuri; Shigemitsu, Toshio; Mizutani, Kazuhiro; Itatani, Kiyoshi



Comparison of three dissolution apparatuses for testing calcium phosphate pellets used as ibuprofen delivery systems.  


Porous calcium phosphate pellets were produced according to two granulation processes (low and high shear wet granulations) and drug loaded with five ibuprofen contents (1.75%, 7%, 12.5%, 22%, and 36%) in order to ensure both bone defect filling and local drug delivery. The drug-release kinetics from the two types of pellets was studied using three dissolution apparatuses: paddle apparatus, reciprocating cylinder, and flow-through cell. The paper compared the three dissolution methods and considered the effect of the granulation process on the ibuprofen-release kinetics. Dissolution data were analyzed using the Weibull function as well as the difference (f1) and similarity (f2) factors. Dissolution kinetics was not influenced by the granulation process, regardless of the dissolution apparatus and of the drug content. The comparison of the three dissolution devices indicated that ibuprofen was released faster from granules loaded with 36% of drug content with the reciprocating apparatus, due to the disintegration of the granules occurring during the dissolution test. For the other drug contents, dissolution profiles were not significantly different from one apparatus to another. However, the flow-through cell seemed to be more suitable for the drug-release study of implantable materials. PMID:19440841

Chevalier, Emilie; Viana, Marylène; Artaud, Aymeric; Chomette, Lisette; Haddouchi, Samir; Devidts, Gille; Chulia, Dominique



A clinically relevant model of osteoinduction: a process requiring calcium phosphate and BMP/Wnt signalling.  


In this study, we investigated a clinically relevant model of in vivo ectopic bone formation utilizing human periosteum derived cells (HPDCs) seeded in a Collagraft carrier and explored the mechanisms by which this process is driven. Bone formation occurred after eight weeks when a minimum of one million HPDCs was loaded on Collagraft carriers and implanted subcutaneously in NMRI nu/nu mice. De novo bone matrix, mainly secreted by the HPDCs, was found juxta-proximal of the calcium phosphate (CaP) granules suggesting that CaP may have triggered the 'osteoinductive program'. Indeed, removal of the CaP granules by ethylenediaminetetraacetic acid decalcification prior to cell seeding and implantation resulted in loss of bone formation. In addition, inhibition of endogenous bone morphogenetic protein and Wnt signalling by overexpression of the secreted antagonists Noggin and Frzb, respectively, also abrogated osteoinduction. Proliferation of the engrafted HPDCs was strongly reduced in the decalcified scaffolds or when seeded with adenovirus-Noggin/Frzb transduced HPDCs indicating that cell division of the engrafted HPDCs is required for the direct bone formation cascade. These data suggest that this model of bone formation is similar to that observed during physiological intramembranous bone development and may be of importance when investigating tissue engineering strategies. PMID:19538476

Eyckmans, J; Roberts, S J; Schrooten, J; Luyten, F P



Improving the packing density of calcium phosphate coating on a magnesium alloy for enhanced degradation resistance.  


In this study, an attempt was made to improve the packing density of calcium phosphate (CaP) coating on a magnesium alloy by tailoring the coating solution for enhanced degradation resistance of the alloy for implant applications. An organic solvent, ethanol, was added to the coating solution to decrease the conductivity of the coating solution so that hydrogen bubble formation/bursting reduces during the CaP coating process. Experimental results confirmed that ethanol addition to the coating solution reduces the conductivity of the solution and also decreases the hydrogen evolution/bubble bursting. In vitro electrochemical experiments, that is, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization showed that CaP coating produced in 30% (v/v) ethanol containing coating solution (3E) exhibits significantly higher degradation resistance (i.e., ~50% higher polarization resistance and ~60% lower corrosion current) than the aqueous solution coating. Scanning electron microscope (SEM) analysis of the coatings revealed that the packing of 3E coating was denser than that of aqueous coating, which can be attributed to the lower hydrogen evolution in the former than in the latter. Further increase in the ethanol content in the coating solution was not beneficial; in fact, the coating produced in 70% (v/v) ethanol containing solution (7E) showed degradation resistance much inferior to that of the aqueous coating, which is due to low thickness of 7E coating. PMID:23008190

Kannan, M Bobby



The effect of magnetic field on electrochemically deposited calcium phosphate/collagen coatings.  


Nanostructured calcium phosphate/collagen (CaP/COL) coatings were deposited on the carbon/carbon (C/C) composites through electrochemical deposition (ECD) under magnetic field. The effect of magnetic fields with different orientations on the morphology and composition was investigated. Both the morphology and composition of the coatings could be altered by superimposed magnetic field. Under zero magnetic field and magnetic field, three-dimensional network structure consisting of collagen fibers and CaP were formed on the C/C substrate. The applied magnetic field in the electric field helped to form nanostructured and plate-like CaP on collagen fibers. For the ECD under magnetic field, the Ca/P molar ratio of the coatings was lower than the one under B=0. This may be contributed to the decreased electrical resistance or the increased electrical conductivity of electrolyte solutions under magnetic field. The nanosized CaP/COL coatings exhibited the similar morphology to the human bone and could present excellent cell bioactivity and osteoblast functions. PMID:25201398

Zhao, Xueni; He, Jianpeng; Zhang, Jing; Wang, Xudong; Wang, Wanying



Electrospun gelatin/poly(?-caprolactone) fibrous scaffold modified with calcium phosphate for bone tissue engineering.  


In this study gelatin (Gel) modified with calcium phosphate nanoparticles (SG5) and polycaprolactone (PCL) were used to prepare a 3D bi-layer scaffold by collecting electrospun PCL and gelatin/SG5 fibers separately in the same collector. The objective of this study was to combine the desired properties of PCL and Gel/SG5 in the same scaffold in order to enhance mineralization, thus improving the ability of the scaffold to bond to the bone tissue. The scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and the wide angle X-ray diffraction (WAXD) measurements confirmed that SG5 nanoparticles were successfully incorporated into the fibrous gelatin matrix. The composite Gel/SG5/PCL scaffold exhibited more enhanced mechanical properties than individual Gel and Gel/SG5 scaffolds. The presence of SG5 nanoparticles accelerated the nucleation and growth of apatite crystals on the surface of the composite Gel/SG5/PCL scaffold in simulated body fluid (SBF). The osteoblast response in vitro to developed electrospun scaffolds (PCL and Gel/SG5/PCL) was investigated by using normal human primary NHOst cell lines. NHOst cell culture studies showed that higher alkaline phosphatase (ALP) activity and better mineralization were obtained in the case of composite materials than in pure PCL scaffolds. The mechanically strong PCL scaffold served as a skeleton, while the Gel/SG5 fibers facilitated cell spreading and mineralization of the scaffold. PMID:25280695

Rajzer, Izabella; Menaszek, El?bieta; Kwiatkowski, Ryszard; Planell, Josep A; Castano, Oscar



Attachment, Proliferation, and Chondroinduction of Mesenchymal Stem Cells on Porous Chitosan-Calcium Phosphate Scaffolds  

PubMed Central

Symptomatic osteochondral lesions occur frequently, but relatively few treatment options are currently available. The purpose of this study was to conduct a preliminary investigation into a new tissue engineering approach to osteochondral regeneration. The concept is a biphasic construct consisting of a porous, osteoconductive chitosan-calcium phosphate scaffold supporting a layer of neocartilage formed by marrow-derived mesenchymal stem cells. Two experiments were conducted to assess the feasibility of this approach. The first experiment characterized the attachment efficiency and proliferation of primary human marrow-derived mesenchymal stem cells seeded relatively sparely onto the scaffold’s surface. The second experiment compared two different methods of creating a biphasic construct using a much higher density of primary porcine marrow stromal cells. About 40% of the sparsely seeded human cells attached and proliferated rapidly. Constructs formed by one of the two experimental techniques exhibited a layer of cartilaginous tissue which only partially covered the scaffold’s surface due to inadequate adhesion between the cells and the scaffold. This study demonstrates some potential for the approach to yield an implantable biphasic construct, but further development is required to improve cell-scaffold adhesion. PMID:23986794

Elder, Steven; Gottipati, Anuhya; Zelenka, Hilary; Bumgardner, Joel



The Role of Carboxydothermus hydrogenoformans in the Conversion of Calcium Phosphate from Amorphous to Crystalline State  

PubMed Central

Two previously unknown modes of biomineralization observed in the presence of Carboxydothermus hydrogenoformans are presented. Following the addition of NaHCO3 and the formation of an amorphous calcium phosphate precipitate in a DSMZ medium inoculated with C. hydrogenoformans, two distinct crystalline solids were recovered after 15 and 30 days of incubation. The first of these solids occurred as micrometric clusters of blocky, angular crystals, which were associated with bacterial biofilm. The second solid occurred as 30–50 nm nanorods that were found scattered among the organic products of bacterial lysis. The biphasic mixture of solids was clearly dominated by the first phase. The X-ray diffractometry (XRD) peaks and Fourier transform infrared spectroscopy (FTIR) spectrum of this biphasic material consistently showed features characteristic of Mg-whitlockite. No organic content or protein could be identified by dissolving the solids. In both cases, the mode of biomineralization appears to be biologically induced rather than biologically controlled. Since Mg is known to be a strong inhibitor of the nucleation and growth of CaP, C. hydrogenoformans may act by providing sites that chelate Mg or form complexes with it, thus decreasing its activity as nucleation and crystal growth inhibitor. The synthesis of whitlockite and nano-HAP-like material by C. hydrogenoformans demonstrates the versatility of this organism also known for its ability to perform the water-gas shift reaction, and may have applications in bacterially mediated synthesis of CaP materials, as an environmentally friendly alternative process. PMID:24586811

Haddad, Mathieu; Vali, Hojatollah; Paquette, Jeanne; Guiot, Serge R.



Bi-layered calcium phosphate cement-based composite scaffold mimicking natural bone structure  

NASA Astrophysics Data System (ADS)

In this study, a core/shell bi-layered calcium phosphate cement (CPC)-based composite scaffold with adjustable compressive strength, which mimicked the structure of natural cortical/cancellous bone, was fabricated. The dense tubular CPC shell was prepared by isostatic pressing CPC powder with a specially designed mould. A porous CPC core with unidirectional lamellar pore structure was fabricated inside the cavity of dense tubular CPC shell by unidirectional freeze casting, followed by infiltration of poly(lactic-co-glycolic acid) and immobilization of collagen. The compressive strength of bi-layered CPC-based composite scaffold can be controlled by varying thickness ratio of dense layer to porous layer. Compared to the scaffold without dense shell, the pore interconnection of bi-layered scaffold was not obviously compromised because of its high unidirectional interconnectivity but poor three dimensional interconnectivity. The in vitro results showed that the rat bone marrow stromal cells attached and proliferated well on the bi-layered CPC-based composite scaffold. This novel bi-layered CPC-based composite scaffold is promising for bone repair.

He, Fupo; Ye, Jiandong



Physicochemical Evaluation of Bioactive Polymeric Composites Based on Hybrid Amorphous Calcium Phosphates  

NSDL National Science Digital Library

Amorphous calcium phosphate (ACP)-filled methacrylate composites were recently found to effectively remineralize in vitro caries-like enamel lesions. Their inferior mechanical properties compared to glass-filled composites, however, limit their use as a dental restorative material. In this study, the feasibility of introducing glass-forming elements (tetraethoxysilane or zirconyl chloride) during the low-temperature synthesis of ACP was investigated. Composites based on such hybrid fillers (mass fraction, 40%) were evaluated to establish whether hybridization strengthened the composites via improved interfacial interactions with the polymer phase without compromising the release of the mineral ions. Two types of visible-light cured resins were prepared: BTHZ resin from 2,2-bis[p-(2â-hydroxy-3â- methacryloxypropoxy)phenyl]propane (BisGMA), triethylene glycol dimethacrylate (TEGDMA), 2-hydroxyethyl methacrylate (HEMA) and zirconyl methacrylate (ZrM), and TP resin from TEGDMA and pyromellitic glycerol dimethacrylate (PMGDM). Hybridized fillers and BTHZ- and TP-based composites were characterized by the IR spectroscopy, X-ray diffraction, dissolution/transformation kinetic studies, and biaxial flexure strength (BFS) testing before and after immersion in buffered saline solutions. The feasibility of improving the BFS via hybridization, while retaining, if not enhancing the remineralizing potential was demonstrated for BTHZ-based composites. Both BFS and remineralizing ability of the TPcomposites, however, deteriorated upon their exposure to an aqueous environment. Therefore, hybridized ACP-filled BTHZ composites have a potential for utilization in more demanding restorative, sealant, and adhesive applications.

Skrtic, D.; Antonucci, J. M.; Eanes, E. D.; Eichmiller, F. C.; Schumacher, G. E.



Collagen scaffolds with in situ-grown calcium phosphate for osteogenic differentiation of Wharton's jelly and menstrual blood stem cells.  


The aim of this research was to investigate the osteogenic differentiation potential of non-invasively obtained human stem cells on collagen nanocomposite scaffolds with in situ-grown calcium phosphate crystals. The foams had 70% porosity and pore sizes varying in the range 50-200 µm. The elastic modulus and compressive strength of the calcium phosphate containing collagen scaffolds were determined to be 234.5 kPa and 127.1 kPa, respectively, prior to in vitro studies. Mesenchymal stem cells (MSCs) obtained from Wharton's jelly and menstrual blood were seeded on the collagen scaffolds and proliferation and osteogenic differentiation capacities of these cells from two different sources were compared. The cells on the composite scaffold showed the highest alkaline phosphatase activity compared to the controls, cells on tissue culture polystyrene and cells on collagen scaffolds without in situ-formed calcium phosphate. MSCs isolated from both Wharton's jelly and menstrual blood showed a significant level of osteogenic activity, but those from Wharton's jelly performed better. In this study it was shown that collagen nanocomposite scaffolds seeded with cells obtained non-invasively from human tissues could represent a potential construct to be used in bone tissue engineering. PMID:22744919

Karadas, Ozge; Yucel, Deniz; Kenar, Halime; Torun Kose, Gamze; Hasirci, Vasif



Analysis of the interface between a pulsed laser deposited calcium phosphate coating and a titanium alloy substrate  

NASA Astrophysics Data System (ADS)

Calcium phosphate coatings deposited on titanium alloy are intended to add a bioactive surface to medical implants. This work presents the characterisation of the interface between Ti-6Al-4V and a crystalline calcium phosphate coating obtained by pulsed laser deposition, with a KrF excimer laser, at 575 °C and under a 45 Pa water-vapour atmosphere. The coating substrate system was studied by secondary-ion mass spectrometry, scanning electron microscopy, X-ray diffractometry, Raman spectroscopy and X-ray photoelectron spectroscopy. The results show that the deposition process promotes the interdiffusion of substrate elements into the coating and coating elements into the substrate oxide layer. Thus, a graded layer of mixed calcium phosphate and amorphous titanium oxide is formed. For the substrate, a hydroxyapatite coating acts more as a barrier for oxygen incoming from a gas than as an oxygen source during deposition. Moreover, oxygen diffusion into the substrate occurs. Thus, the content of oxygen of this oxide layer diminishes with depth. When the oxygen concentration is low enough it is incorporated in solid solution in the titanium alloy.

Fernández-Pradas, J. M.; García-Cuenca, M. V.; Morenza, J. L.



Formation of a FGF-2 and calcium phosphate composite layer on a hydroxyapatite ceramic for promoting bone formation.  


Fibroblast growth factor-2 (FGF-2) was immobilized on a hydroxyapatite (HAP) ceramic in supersaturated calcium phosphate solution prepared using solutions corresponding to clinically approved infusion fluids. To avoid the risk of FGF-2 denaturation, FGF-2 immobilization was carried out at 25 degrees C. FGF-2 was successfully immobilized on HAP ceramic surfaces by deposition with calcium phosphate to form a FGF-2 and calcium phosphate composite layer. A maximum of 2.72 +/- 0.01 microg cm(-2) of FGF-2 was immobilized in the composite layer formed on the HAP ceramic under the optimum condition. A FGF-2-immobilized HAP ceramic is likely to have the ability to release a sufficient amount of FGF-2 to promote bone formation. FGF-2 released from a FGF-2-immobilized HAP ceramic maintained its biological activity, since the proliferation of fibroblastic NIH3T3 was promoted. Therefore, the FGF-2-immobilized HAP ceramic is expected to be a useful material for promoting new bone formation. PMID:18458464

Sogo, Yu; Ito, Atsuo; Onoguchi, Masahiro; Oyane, Ayako; Tsurushima, Hideo; Ichinose, Noboru



Development of a calcium phosphate co-precipitate\\/poly(lactide- co-glycolide) DNA delivery system: release kinetics and cellular transfection studies  

Microsoft Academic Search

One of the most common non-viral methods for the introduction of foreign deoxyribonucleic acid (DNA) into cultured cells is calcium phosphate co-precipitate transfection. This technique involves the encapsulation of DNA within a calcium phosphate co-precipitate, particulate addition to in vitro cell culture, endocytosis of the co-precipitate, and exogenous DNA expression by the transfected cell. In this study, we fabricated a

Michelle D. Kofron; Cato T. Laurencin



In situ thermal and structural characterization of bioactive calcium phosphate glass ceramics containing TiO 2 and MgO oxides: High temperature – XRD studies  

Microsoft Academic Search

This study aims to develop glass ceramics in the calcium phosphate system that exhibit suitable properties to be used for biomedical applications. Calcium phosphate glasses with the incorporation of small additions of MgO and TiO2 oxides were prepared in the pyro-and orthophosphate regions. The glass ceramics were prepared by a controlled powder sintering process through heat-treatment at different temperatures, as

A. G. Dias; J. M. S. Skakle; I. R. Gibson; M. A. Lopes; J. D. Santos



In vivo bone regeneration with injectable calcium phosphate biomaterial: A three-dimensional micro-computed tomographic, biomechanical and SEM study  

Microsoft Academic Search

This in vivo study investigated the efficiency of an injectable calcium phosphate bone substitute (IBS) for bone regenerative procedures through non-destructive three-dimensional (3D) micro-tomographic (?CT) imaging, biomechanical testing with a non-destructive micro-indentation technique and 2D scanning electron microscopy (SEM) analysis. The injectable biomaterial was obtained by mixing a biphasic calcium phosphate (BCP) ceramic mineral phase and a cellulosic polymer. The

Olivier Gauthier; Ralph Müller; Dietrich von Stechow; Bernard Lamy; Pierre Weiss; Jean-Michel Bouler; Eric Aguado; Guy Daculsi



The Effect of Calcium Phosphate Particle Shape and Size on their Antibacterial and Osteogenic Activity in the Delivery of Antibiotics in vitro  

PubMed Central

Powders composed of four morphologically different calcium phosphate particles were prepared by precipitation from aqueous solutions: flaky, brick-like, elongated orthogonal, and spherical. The particles were then loaded with either clindamycin phosphate as the antibiotic of choice, or fluorescein, a model molecule used to assess the drug release properties. A comparison was carried out of the comparative effect of such antibiotic-releasing materials on: sustained drug release profiles; Staphylococcus aureus growth inhibition; and osteogenic propensities in vitro. Raman spectroscopic analysis indicated the presence of various calcium phosphate phases, including monetite (flaky and elongated orthogonal particles), octacalcium phosphate (brick-shaped particles) and hydroxyapatite (spherical particles). Testing the antibiotic-loaded calcium phosphate powders for bacterial growth inhibition demonstrated satisfying antibacterial properties both in broths and on agar plates. All four calcium-phosphate-fluorescein powders exhibited sustained drug release over 21 days. The calcium phosphate sample with the highest specific surface area and the smallest, spherical particle size was the most effective in both drug loading and release, consequently having the highest antibacterial efficiency. Moreover, the highest cell viability, the largest gene expression upregulation of three different osteogenic markers – osteocalcin, osteopontin and Runx2 - as well as the least disrupted cell cytoskeleton and cell morphologies were also noticed for the calcium phosphate powder composed of smallest, spherical nanosized particles. Still, all four powders exerted a viable effect on osteoblastic MC3T3-E1 cells in vitro, as evidenced by both morphological assessments on fluorescently stained cells and measurements of their mitochondrial activity. The obtained results suggest that the nanoscale particle size and the corresponding coarseness of the surface of particle conglomerates as the cell attachment points may present a favorable starting point for the development of calcium-phosphate-based osteogenic drug delivery devices. PMID:23484624

Uskokovic, Vuk; Batarni, Samir Shariff; Schweicher, Julien; King, Andrew; Desai, Tejal A.



Effect of calcium phosphate particle shape and size on their antibacterial and osteogenic activity in the delivery of antibiotics in vitro.  


Powders composed of four morphologically different calcium phosphate particles were prepared by precipitation from aqueous solutions: flaky, brick-like, elongated orthogonal, and spherical. The particles were then loaded with either clindamycin phosphate as the antibiotic of choice or fluorescein, a model molecule used to assess the drug release properties. A comparison was carried out of the effect of such antibiotic-releasing materials on: sustained drug release profiles; Staphylococcus aureus growth inhibition; and osteogenic propensities in vitro. Raman spectroscopic analysis indicated the presence of various calcium phosphate phases, including monetite (flaky and elongated orthogonal particles), octacalcium phosphate (brick-shaped particles), and hydroxyapatite (spherical particles). Testing the antibiotic-loaded calcium phosphate powders for bacterial growth inhibition demonstrated satisfying antibacterial properties both in broths and on agar plates. All four calcium-phosphate-fluorescein powders exhibited sustained drug release over 21 days. The calcium phosphate sample with the highest specific surface area and the smallest, spherical particle size was the most effective in both drug loading and release, consequently having the highest antibacterial efficiency. Moreover, the highest cell viability, the largest gene expression upregulation of three different osteogenic markers--osteocalcin, osteopontin, and Runx2--as well as the least disrupted cell cytoskeleton and cell morphologies were also noticed for the calcium phosphate powder composed of the smallest, spherical nanosized particles. Still, all four powders exerted a viable effect on osteoblastic MC3T3-E1 cells in vitro, as evidenced by both morphological assessments on fluorescently stained cells and measurements of their mitochondrial activity. The obtained results suggest that the nanoscale particle size and the corresponding coarseness of the surface of particle conglomerates as the cell attachment points may present a favorable starting point for the development of calcium-phosphate-based osteogenic drug delivery devices. PMID:23484624

Uskokovi?, Vuk; Batarni, Samir Shariff; Schweicher, Julien; King, Andrew; Desai, Tejal A



Can. J. Fish. Aquat. Sci. (2013) Prepublication Draft Page 1 Modeling the Calcium and Phosphate Mineralization  

E-print Network

, model building, biomineralization, ab initio, carbonate apatite, calcite, amorphous calcium carbonate content, fig 1 (Kunkel et al. 2012; Kunkel and Jercinovic 2013). Calcium carbonate is the dominant calcium of the general cuticle that assumes a uniform matrix of amorphous calcium carbonate (ACC). While a complete

Kunkel, Joseph G.


Reciprocal regulation of calcium-/phosphate-regulating hormones in cyclists during the Giro d'Italia 3-week stage race.  


Calcium and phosphate are essential for cell functions, and their serum concentrations result from the balance between intestinal absorption, bony storage, and urinary excretion. Fibroblast growth factor 23 (FGF23), expressed by osteocytes and osteoblasts, acts in the kidney, leading to hypophosphatemia and low 1,25-dihydroxycholecalciferol synthesis, but suppresses parathyroid function. The aim of this study was to explore the effects of a high-energy demanding cycling race on this bone-kidney-parathyroid axis. We studied nine cyclists during the 2011 Giro d'Italia stage race. Pre-analytical and analytical phases followed academic and anti-doping recommendations. Serum parathyroid hormone (PTH), 25(OH)D, total calcium, inorganic phosphorus, and plasma FGF23 were measured on days -1, 12, and 22 and corrected for changes in plasma volume. Dietary calcium and phosphorus, anthropometric parameters (height, weight, and body mass index) and indexes of metabolic effort (net energy expenditure, power output) were recorded. Dietary calcium and phosphorus intakes were kept at the same levels throughout the race. Twenty-five (OH)D, PTH, and calcium concentrations remained stable. FGF23 increased 50% with a positive correlation with the indexes of metabolic effort and, consequently, phosphorous decreased, although only in the first half. The strong metabolic effort acts on the bone-kidney-parathyroid system, and the rise in FGF23 plasma concentration might be aimed at maintaining calcium and phosphorus homeostasis. PMID:23647316

Lombardi, G; Corsetti, R; Lanteri, P; Grasso, D; Vianello, E; Marazzi, M G; Graziani, R; Colombini, A; Galliera, E; Corsi Romanelli, M M; Banfi, G





... when taken with food. Some over-the-counter antacid products, such as Tums® and Rolaids®, contain calcium ... calcium excretion and thereby lower blood calcium levels. Antacids containing aluminum or magnesium increase calcium loss in ...


Inhibitory effects of phytic acid and other inositol phosphates on zinc and calcium absorption in suckling rats.  


While it is known that phytic acid, inositol hexaphosphate, has a negative effect on zinc and calcium absorption, the effects of inositol which is phosphorylated to a lesser extent are less known. We have prepared inositol triphosphate (IP-3), tetraphosphate (IP-4), pentaphosphate (IP-5) and hexaphosphate (IP-6) by hydrolysis of sodium phytate and separation by ion-exchange chromatography and have studied their effect on zinc and calcium absorption. Using a suckling rat pup model, we found that liver uptake of 65Zn after 6 h was 5% of the total dose from solutions of IP-6, 19% from IP-5, 28% from IP-4, 29% from IP-3 and 31% from ZnCl2 (control). Non-absorbed calcium was 17%, 1.4%, 0.5%, 0.5% and 0.5% of the given dose of 45Ca, respectively. Thus, at a high degree of phosphorylation (IP-6, IP-5), zinc and calcium uptake was inhibited, while no effect was observed for the other phosphates. Consequently, total "phytate" analysis, which includes inositol phosphates with varying degrees of phosphorylation, can give misleading information with regard to mineral availability. In addition, even limited dephosphorylation of inositol hexaphosphate can have a positive effect on mineral absorption. PMID:2918393

Lönnerdal, B; Sandberg, A S; Sandström, B; Kunz, C



A novel strategy for preparing nanoporous biphasic calcium phosphate of controlled composition via a modified nanoparticle-assembly method.  


Biphasic calcium phosphate (BCP) consisting of hydroxyapatite (HAp) and ?-tricalcium phosphate is usually prepared by thermal decomposition of calcium-deficient HAp (CDHAp). However, the calcium deficiency and morphology of CDHAp are difficult to manipulate in parallel. In this study, we report a novel strategy for controlling the composition of nanoporous BCP by using only CDHAp nanoparticles with specific properties (Ca/P molar ratio, 1.61; particle size, 50 nm) as a building block and by adjusting the calcium deficiency of the nanoparticle-assembled CDHAp (Ca/P molar ratio, 1.50-1.67; pore size, 8 nm) with the addition of water-soluble Ca(NO3)2 or (NH4)2HPO4. After thermal treatment at 1000 °C, the composition of BCP could be predictably controlled by adjusting the Ca/P ratio of the nanoparticle-assembled CDHAp. Changes in the Ca/P ratio did not significantly affect the surface morphology of BCP, but the grain size (210-300 nm) and pore size (140-170 nm) tended to increase slightly as the Ca/P ratio decreased. The porosity significantly decreased upon the addition of Ca salts (porosity, 20%) or PO4 salts (porosity, 14%) compared with that of the sample without additives (porosity, 53%). In vitro tests demonstrated enhanced cell adhesion on nanoporous BCP compared with densely sintered pure HAp, and cell differentiation was promoted on the nanoporous pure HAp. PMID:24411377

Fujiwara, Keiko; Okada, Masahiro; Takeda, Shoji; Matsumoto, Naoyuki



Changes in calcium phosphate on bone surfaces and in lining cells after the administration of parathyroid hormone or calcitonin  

SciTech Connect

Small doses of parathyroid hormone and calcitonin were injected into thyroparathyroidectomized newborn rats to investigate the histological and chemical changes in bone surfaces and in mitochondrial granules of bone lining cells. Nondecalcified tissue specimens were observed under transmission electron microscope, electron probe X-ray microanalyzer, and microdiffraction after freeze substitution preparation of tibia shafts. Amorphous calcium phosphate, which appears as clusters and globules by this freeze substitution preparation, appears on the bone surfaces in a short time after the administration of a small dose of calcitonin. The Ca:PO4 ratio in the mitochondria of bone lining cells rises slightly with a small dose of parathyroid hormone and is reduced with a small dose of calcitonin. These data support the postulate that both parathyroid hormone and calcitonin act directly on bone lining cells in the process of influencing calcium concentrations of blood and temporarily storing calcium at bone surfaces.

Norimatsu, H.; Yamamoto, T.; Ozawa, H.; Talmage, R.V.



Chemical, modulus and cell attachment studies of reactive calcium phosphate filler-containing fast photo-curing, surface-degrading, polymeric bone adhesives  

Microsoft Academic Search

The initial structure, setting and degradation processes of a poly(lactide-co-propylene glycol-co-lactide) dimethacrylate adhesive filled with 50, 60 or 70wt.% reactive calcium phosphates (monocalcium phosphate monohydrate (MCPM)\\/?-tricalcium phosphate (?-TCP)) have been assessed using nuclear magnetic resonance, Fourier transform infrared spectroscopy, Raman, X-ray powder diffraction and gravimetric studies. Filler incorporation reduced the rapid light-activated monomer polymerization rates slightly, but not the final

E. A. Abou Neel; G. Palmer; J. C. Knowles; V. Salih; A. M. Young



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)

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.

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



Enhanced sintering ability of biphasic calcium phosphate by polymers used for bone scaffold fabrication.  


Biphasic calcium phosphate (BCP), which is composed of hydroxyapatite [HAP, Ca10(PO4)6(OH)2] and ?-tricalcium phosphate [?-TCP, ?-Ca3(PO4)2], is usually difficult to densify into a solid state with selective laser sintering (SLS) due to the short sintering time. In this study, the sintering ability of BCP ceramics was significantly improved by adding a small amount of polymers, by which a liquid phase was introduced during the sintering process. The effects of the polymer content, laser power and HAP/?-TCP ratios on the microstructure, chemical composition and mechanical properties of the BCP scaffolds were investigated. The results showed that the BCP scaffolds became increasingly more compact with the increase of the poly(l-lactic acid) (PLLA) content (0-1 wt.%) and laser power (6-10 W). The fracture toughness and micro-hardness of the sintered scaffolds were also improved. Moreover, PLLA could be gradually decomposed in the late sintering stages and eliminated from the final BCP scaffolds if the PLLA content was below a certain value (approximately 1 wt.% in this case). The added PLLA could not be completely eliminated when its content was further increased to 1.5 wt.% or higher because an unexpected carbon phase was detected in the sintered scaffolds. Furthermore, many pores were observed due to the removal of PLLA. Micro-cracks and micro-pores occurred when the laser power was too high (12 W). These defects resulted in a deterioration of the mechanical properties. The hardness and fracture toughness reached maximum values of 490.3±10 HV and 1.72±0.10 MPa m(1/2), respectively, with a PLLA content of approximately 1 wt.% and laser power of approximately 10 W. Poly(l-lactic-co-glycolic acid) (PLGA) showed similar effects on the sintering process of BCP ceramics. Rectangular, porous BCP scaffolds were fabricated based on the optimum values of the polymer content and laser power. This work may provide an experimental basis for improving the mechanical properties of BCP bone scaffolds fabricated with SLS. PMID:23910280

Gao, Chengde; Yang, Bo; Hu, Huanlong; Liu, Jinglin; Shuai, Cijun; Peng, Shuping



Microstructure, corrosion properties and bio-compatibility of calcium zinc phosphate coating on pure iron for biomedical application.  


In order to improve the biocompatibility and the corrosion resistance in the initial stage of implantation, a phosphate (CaZn2(PO4)2·2H2O) coating was obtained on the surface of pure iron by a chemical reaction method. The anti-corrosion property, the blood compatibility and the cell toxicity of the coated pure iron specimens were investigated. The coating was composed of some fine phosphate crystals and the surface of coating was flat and dense enough. The electrochemical data indicated that the corrosion resistance of the coated pure iron was improved with the increase of phosphating time. When the specimen was phosphated for 30min, the corrosion resistance (Rp) increased to 8006 ?. Compared with that of the naked pure iron, the anti-hemolysis property and cell compatibility of the coated specimen was improved significantly, while the anti-coagulant property became slightly worse due to the existence of element calcium. It was thought that phosphating treatment might be an effective method to improve the biocompatibility of pure iron for biomedical application. PMID:24268250

Chen, Haiyan; Zhang, Erlin; Yang, Ke



Calcium phosphate/porous silicon biocomposites prepared by cyclic deposition methods: spin coating vs electrochemical activation.  


Porous silicon (PSi) provides an excellent platform for bioengineering applications due to its biocompatibility, biodegradability, and bioresorbability. However, to promote its application as bone engineering scaffold, deposition of calcium phosphate (CaP) ceramics in its hydroxyapatite (HAP) phase is in progress. In that sense, this work focuses on the synthesis of CaP/PSi composites by means of two different techniques for CaP deposition on PSi: Cyclic Spin Coating (CSC) and Cyclic Electrochemical Activation (CEA). Both techniques CSC and CEA consisted on alternate Ca and P deposition steps on PSi. Each technique produced specific morphologies and CaP phases using the same independent Ca and P stem-solutions at neutral pH and at room temperature. The brushite (BRU) phase was favored with the CSC technique and the hydroxyapatite (HAP) phase was better synthesized using the CEA technique. Analyses by elastic backscattering spectroscopy (EBS) on CaP/PSi structures synthesized by CEA supported that, by controlling the CEA parameters, an HAP coating with the required Ca/P atomic ratio of 1.67 can be promoted. Biocompatibility was evaluated by bone-derived progenitor cells, which grew onto CaP/PSi prepared by CSC technique with a long-shaped actin cytoskeleton. The density of adhered cells was higher on CaP/PSi prepared by CEA, where cells presented a normal morphological appearance and active mitosis. These results can be used for the design and optimization of CaP/PSi composites with enhanced biocompatibility for bone-tissue engineering. PMID:24268256

Hernandez-Montelongo, J; Gallach, D; Naveas, N; Torres-Costa, V; Climent-Font, A; García-Ruiz, J P; Manso-Silvan, M



Strontium calcium phosphate for the repair of leporine (Oryctolagus cuniculus) ulna segmental defect.  


Scaffolds to aid in repair, replacement, or regeneration of bony tissues have been developed using a wide spectra of materials. Under clinical conditions, assessment of healing and implant placement is guided radiographically. In this context, strontium's role in osteostimulation and its relevance in radio-opacity are known. Therefore to aid in assessment and to ensure tissue regeneration, a bone mimetic porous strontium calcium phosphate (SrCaPO(4) ) was synthesized in-house, which was non-cytotoxic (ISO 10993 (Part V) and subsequently characterized for its crystallinity, functional groups, and 3D porous topography. Furthermore, to assess the feasibility of the bioactive ceramic scaffolds in bone repair, SrCaPO(4) and hydroxyapatite (HA-Control) scaffolds were implanted in the segmental ulna bone critical-sized defect (1.5 cm) of New Zealand White Rabbits (leporine model-Oryctolagus cuniculus) for a period of 4 and 12 weeks, respectively. Healing of the defects was uneventful without any inflammation or infection. Radio-opacity of SrCaPO(4) within the defect site enabled easy assessment of implant placement and osteointegration. Again, histological evaluation coupled with micro-CT and histomorphometrical analysis indicated that SrCaPO(4) favored significant de novo bone formation in par with material degradation at 4 and 12 weeks post-implantation compared to HA at 4 and 12 weeks. Investigations on this radio-opaque SrCaPO(4) established its role in the repair of critical-sized segmental defects, proposing it as a suitable bone substitute for clinical reconstructive surgery with easy radiographic evaluation. PMID:22941787

Mohan, Beena G; Shenoy, Sachin J; Babu, Suresh S; Varma, H K; John, Annie



In vitro degradation rate of apatitic calcium phosphate cement with incorporated PLGA microspheres.  


Calcium phosphate cements (CPCs) are frequently used as bone substitute material. Despite their superior clinical handling and excellent biocompatibility, they exhibit poor degradability, which limits bone ingrowth into the implant. Microspheres were prepared from poly(d,l-lactic-co-glycolic acid) (PLGA) and included in injectable CPCs as porogens in order to enhance its macroporosity after the polymeric microspheres had degraded. Upon degradation of the PLGA microspheres, acid is produced that enhances the dissolution rate of the CPC. However, the effect of the characteristics of PLGA microspheres on the degradation rate of CPCs has never been studied before. Therefore, the purpose of the current study was to investigate the dependence of CPC degradation on the chemical and morphological characteristics of incorporated PLGA microspheres. With respect to the chemical characteristics of the PLGA microspheres, the effects of both PLGA molecular weight (5, 17 and 44kDa) and end-group functionalization (acid-terminated or end-capped) were studied. In addition, two types of PLGA microspheres, differing in morphology (hollow vs. dense), were tested. The results revealed that, although both chemical parameters clearly affected the polymer degradation rate when embedded as hollow microspheres in CPC, the PLGA and CPC degradation rates were mainly dependent on the end-group functionalization. Moreover, it was concluded that dense microspheres were more efficient porogens than hollow ones by increasing the CPC macroporosity during in vitro incubation. By combining all test parameters, it was concluded that dense PLGA microspheres consisting of acid-terminated PLGA of 17kDa exhibited the highest and fastest acid-producing capacity and correspondingly the highest and fastest amount of porosity. In conclusion, the data presented here indicate that the combination of dense, acid-terminated PLGA microspheres with CPC emerges as a successful combination to achieve enhanced apatitic CPC degradation. PMID:21689794

Félix Lanao, R P; Leeuwenburgh, S C G; Wolke, J G C; Jansen, J A



Volume effect on biological properties of a calcium phosphate hydraulic cement: experimental study in sheep.  


Injectable calcium phosphate hydraulic cements (CPHC) are a new family of bone substitutes within the class of bone reconstruction biomaterials. In this work, CPHC were tested in two consistencies (preset blocks or liquid paste) in an experimental model of cancellous bone defect in sheep. The defects were eight times larger than those investigated previously in rabbits. Three delays (12, 24, and 52 weeks) were used. Before death, a double label of oxytetracycline and alizarine was made intravenously. The distribution of implants was randomized, histomorphometric evaluation was performed and compared with micrographic observation, and optical microscopy of stained sections was performed either under visible, ultraviolet, or polarized light. The results were compared with spontaneous healing of empty defects and with a control group of normal cancellous bone from sheeps of the same age. No significant difference has been observed between premolded and injected implants. In the sheep model, the degradation and new bone formation rates are three times slower, compared with those observed previously in rabbits. New bone formation increased from 5.9% (12 weeks) up to 11.0% (24 weeks) in the empty defect group. In the cement groups, 28.3% new bone was obtained at 12 weeks, which seemed then to level off (27.8% new bone at 24 weeks). Cement residues appear as radio-opaque cylinders on microradiographs. In all cases, a radiolucent layer was observed at the cement/bone interface at 24 weeks. Stained sections showed the formation of a fibroconnective capsule around the residual cement, which presumably slows down new bone formation. Nevertheless, quantitative bone remodeling was accelerated in the cement group; mineral apposition as well as adjusted apposition rates were higher, and the formation period as well as the mineralization of osteoid tissue were faster compared with empty cavities and controls. These results point to higher osteoblast activity and better exchange with surrounding tissues in the defects filled with cement. PMID:10458272

Flautre, B; Delecourt, C; Blary, M C; Van Landuyt, P; Lemaître, J; Hardouin, P



Elucidation of real-time hardening mechanisms of two novel high-strength calcium phosphate bone cements.  


Despite the numerous literature data available in the field of calcium phosphate bone cements, the mechanism and kinetics of their hardening, both of which are of great importance for cements application, in most cases, is unknown. In this work, the mechanism and kinetics of hardening of two novel high-strength calcium phosphate bone cements were studied using the energy dispersive X-ray diffraction technique, which allows rapid collection of the patterns. The phase transformations occurring on the setting and hardening processes were monitored in situ. Containing minimal quantity of components, whose mixing leads to the formation of cements with pH close to neutral, the cements under study are simple in handling. The main component of both formulations is tetracalcium phosphate. In both cements, the effect of the addition of high- and low-molecular weight chitosan on phase development and kinetics was investigated in detail. One of the cements has the compressive strength of about 70 MPa, whereas the strength of the other, containing Ca(3)Al(2)O(6), is much higher, about 100 MPa. This latter cement could be regarded as an alternative to the common low-strength bioresorbable brushite cements. PMID:20024971

Smirnov, Valery V; Rau, Julietta V; Generosi, Amanda; Albertini, Valerio Rossi; Ferro, Daniela; Barinov, Sergey M



XPS, EDX and FTIR analysis of pulsed laser deposited calcium phosphate bioceramic coatings: the effects of various process parameters.  


Many techniques have been used to produce calcium phosphate, especially hydroxyapatite (HA), coatings on metallic implant surfaces for improved biocompatibility. Although some techniques have produced coatings used clinically, the long-term stability of the coating/implant is still questionable. As a new technique for making HA coatings, pulsed laser deposition (PLD) shows some advantages in controlling the coatings' crystal structure and composition. In this study, three types of HA target and two wavelengths of laser were used to produce calcium phosphate coatings. Despite PLDs ability to improve the crystal structure by incorporating water vapor into the deposition process, the characterization with EDX and XPS showed that coatings had different Ca/P ratios from that of the pure HA targets, which almost assured the presence of non-HA phases. FTIR spectra also showed differences in phosphate bands of coatings and targets although the difference in data collecting modes might have been a factor. The observed differences might be related to the differences between the surface and bulk chemistries of the coatings. Nevertheless, when evaluating the suitability of the PLD technique for making HA coatings, the possibility of the formation of non-HA phases cannot be excluded, although it may not necessarily be a negative factor. PMID:10619675

Zeng, H; Lacefield, W R



Development of a calcium phosphate-gelatin composite as a bone substitute and its use in drug release.  


This study was carried out to develop a calcium phosphate-gelatin composite implant that would mimic the structure and function of bone for use in filling voids or gaps and to release bioactive compounds like drugs, growth hormones into the implant site to assist healing. XDS analysis of the synthesized calcium phosphate revealed a calcium to phosphorus molar ratio of ca. 2.30, implying a less erodible material than hydroxyapatite (1.67). Release of the antibiotic gentamicin from the implant was with a burst, whether in situ or in vivo, followed by an almost constant release for about three months. It was found that the release rate could be decreased by increasing the density of the gelatin membrane. Upon implantation into rabbit tibia the release duration was substantially shortened (to about 4 weeks) with respect to the in situ tests basically due to the degradation of gelatin. In vivo studies with rabbits confirmed this degradation. The composite was perfectly biocompatible as shown by the histological studies. It, thus, has a great potential as a bone substitute material. PMID:10353654

Yaylao?lu, M B; Korkusuz, P; Ors, U; Korkusuz, F; Hasirci, V



Novel layered crystalline organic polymer-inorganic hybrid material comprising calcium phosphate with unique architectures for superior performance catalyst support.  


An organic copolymer-inorganic hybrid material, calcium phosphonate-phosphate (CaPS-PVPA), is fabricated under mild conditions. In particular, CaPS-PVPA is not prepared with traditional methods such as a hydrothermal one, but with amorphous reactions for a simple, fast, cost-effective and environmentally benign approach. Characterization shows that CaPS-PVPA is a layered crystalline mesoporous material, and could be readily used as a catalytic support. A catalyst with immobilization of chiral salen Mn(iii) onto CaPS-PVPA demonstrate a superior catalytic disposition (conv. > 99% and ee > 99%), which offers great potential for industry scale applications. PMID:25340324

Huang, Jing; Tang, Mei; Li, Xin; Zhong, Guo Zhen; Li, Chang Ming



Synthesis and characterization of strontium–calcium phosphate ?-Ca 3? x Sr x (PO 4) 2 (0 ? x ? 2)  

Microsoft Academic Search

The solid solutions of strontium–calcium phosphate, ?-Ca3?xSrx(PO4)2 (0?x?2), have been synthesized under high-pressure and high-temperature conditions. The products were well characterized by powder X-ray diffraction measurements and Micro-Raman spectroscopy. All the products are isostructural and belong to R-3m space group. With the increasing content of Sr in ?-Ca3?xSrx(PO4)2, the unit cell parameters (a, c, c\\/a, V) linearly increase, and the

Shuangmeng Zhai; Masami Kanzaki; Tomoo Katsura; Eiji Ito



Culture Human Mesenchymal Stem Cells With Calcium Phosphate Cement Scaffolds for Bone Repair  

PubMed Central

Because of its moldability and excellent osteoconductivity, calcium phosphate cement (CPC) is highly promising for craniofacial and orthopedic applications. The objectives of this study were to investigate the response of human mesenchymal stem cells (hMSCs) to a high-strength CPC-chitosan scaffold and to examine cell proliferation and osteogenic differentiation. hMSCs were seeded onto CPC-chitosan composite, CPC control, and tissue culture polystyrene (TCPS). Alkaline phosphatase activity (ALP) and mineralization of hMSCs were measured. CPC-chitosan had a flexural strength (mean ± SD; n = 5) of (19.5 ± 1.4) MPa, higher than (8.0 ± 1.4) MPa of CPC control (p < 0.05). The percentage of live hMSCs on CPC-chitosan was (90.5 ± 1.3)% at 8 days, matching (90.7 ± 3.8)% of CPC control (p > 0.1). The CPC-chitosan surface area covered by the attached hMSCs increased from (51 ± 11)% at 1 day to (90 ± 4)% at 8 days (p < 0.05), matching those of CPC control (p > 0.1). Hence, the CPC strength was significantly increased via chitosan without compromising the hMSC response. At 8 days, there was a significant increase in ALP of cells in osteogenic media (10.99 ± 0.93) [(mM pNpp/min)/(?g DNA)] versus control media (3.62 ± 0.40) (p < 0.05). hMSCs in osteogenic media exhibited greater mineralization area of (47.5 ± 19.7)% compared with (6.1 ± 2.3)% in control medium on TCPS (p < 0.05). In conclusion, hMSCs showed excellent attachment and viability on the strong and tough CPC-chitosan scaffold, matching the hMSC response on CPC control. hMSCs were successfully differentiated down the osteogenic lineage. Hence, the strong, in situ hardening CPC-chitosan scaffold may be useful as a moderate load-bearing vehicle to deliver hMSCs for maxillofacial and orthopedic bone tissue engineering. PMID:20091907

Weir, Michael D.; Xu, Hockin H. K.



Mesenchymal stem cell proliferation and differentiation on an injectable calcium phosphate - chitosan composite scaffold  

PubMed Central

Calcium phosphate cement (CPC) can be molded or injected to form a scaffold in situ, has excellent osteoconductivity, and can be resorbed and replaced by new bone. However, its low strength limits CPC to non-stress-bearing repairs. Chitosan could be used to reinforce CPC, but mesenchymal stem cell (MSC) interactions with CPC-chitosan scaffold have not been examined. The objective of this study was to investigate MSC proliferation and osteogenic differentiation on high-strength CPC-chitosan scaffold. MSCs were harvested from rat bone marrow. At CPC powder/liquid (P/L) mass ratio of 2, flexural strength (mean ± sd; n = 5) was (10.0 ± 1.1) MPa for CPC-chitosan, higher than (3.7 ± 0.6) MPa for CPC (p < 0.05). At P/L of 3, strength was (15.7 ± 1.7) MPa for CPC-chitosan, higher than (10.2 ± 1.8) MPa for CPC (p < 0.05). Percentage of live MSCs attaching to scaffolds increased from 85% at 1 day to 99% at 14 days. There were (180 ± 37) cells/mm2 on scaffold at 1 day; cells proliferated to (1808 ± 317) cells/mm2 at 14 days. SEM showed MSCs with healthy spreading and anchored on nano-apatite crystals via cytoplasmic processes. Alkaline phosphatase activity (ALP) was (557 ± 171) (pNPP mM/min)/(?g DNA) for MSCs on CPC-chitosan, higher than (159 ± 47) on CPC (p < 0.05). Both were higher than (35 ± 32) of baseline ALP for undifferentiated MSCs on tissue-culture plastic (p < 0.05). In summary, CPC-chitosan scaffold had higher strength than CPC. MSC proliferation on CPC-chitosan matched that of the FDA-approved CPC control. MSCs on the scaffolds differentiated down the osteogenic lineage and expressed high levels of bone marker ALP. Hence, the stronger CPC-chitosan scaffold may be useful for stem cell-based bone regeneration in moderate load-bearing maxillofacial and orthopedic applications. PMID:19187958

Moreau, Jennifer L.; Xu, Hockin H.K.



Advances in synthesis of calcium phosphate crystals with controlled size and shape.  


Calcium phosphate (CaP) materials have a wide range of applications, including biomaterials, adsorbents, chemical engineering materials, catalysts and catalyst supports and mechanical reinforcements. The size and shape of CaP crystals and aggregates play critical roles in their applications. The main inorganic building blocks of human bones and teeth are nanocrystalline CaPs; recently, much progress has been made in the application of CaP nanocrystals and their composites for clinical repair of damaged bone and tooth. For example, CaPs with special micro- and nanostructures can better imitate the biomimetic features of human bone and tooth, and this offers significantly enhanced biological performances. Therefore, the design of CaP nano-/microcrystals, and the shape and hierarchical structures of CaPs, have great potential to revolutionize the field of hard tissue engineering, starting from bone/tooth repair and augmentation to controlled drug delivery devices. Previously, a number of reviews have reported the synthesis and properties of CaP materials, especially for hydroxyapatite (HAp). However, most of them mainly focused on the characterizations and physicochemical and biological properties of HAp particles. There are few reviews about the control of particle size and size distribution of CaPs, and in particular the control of nano-/microstructures on bulk CaP ceramic surfaces, which is a big challenge technically and may have great potential in tissue engineering applications. This review summarizes the current state of the art for the synthesis of CaP crystals with controlled sizes from the nano- to the macroscale, and the diverse shapes including the zero-dimensional shapes of particles and spheres, the one-dimensional shapes of rods, fibers, wires and whiskers, the two-dimensional shapes of sheets, disks, plates, belts, ribbons and flakes and the three-dimensional (3-D) shapes of porous, hollow, and biomimetic structures similar to biological bone and tooth. In addition, this review will also summarize studies on the controlled formation of nano-/microstructures on the surface of bulk ceramics, and the preparation of macroscopical bone grafts with 3-D architecture nano-/microstructured surfaces. Moreover, the possible directions of future research and development in this field, such as the detailed mechanisms behind the size and shape control in various strategies, the importance of theoretical simulation, self-assembly, biomineralization and sacrificial precursor strategies in the fabrication of biomimetic bone-like and enamel-like CaP materials are proposed. PMID:24954909

Lin, Kaili; Wu, Chengtie; Chang, Jiang



Design and application of chitosan/biphasic calcium phosphate porous scaffolds for bone tissue engineering  

NASA Astrophysics Data System (ADS)

For the restoration of maxillofacial bone tissue, design of novel tissue engineering scaffolds capable of inducing bone remodeling through the delivery of mesenchymal stem cells (MSCs) and an angiogenic growth factor, directly at the site of the defect was investigated in order to replace autogenous cancellous bone grafts with synthetic materials. Porous, three dimensional scaffolds were fabricated by a freeze drying method. In culture media, biphasic calcium phosphate particles within chitosan produced a surface reprecipitate of a composition similar to natural apatite that led to a uniform distribution of cells and mineralized ECM through chemotaxis. Further, the reprecipitation regulated the differentiation pathway and phenotype commitment of stem cells by altering the initial cell attachment morphology and actin cytoskeleton organization. In order to induce neovascularization after implantation, constructs were designed to be loaded with gelatin microspheres that delivered basic fibroblast growth factor (bFGF), a potent angiogenic factor. In vitro proliferation tests performed on fibroblastic cells showed no detectible loss of bFGF activity when delivered through enzymatic degradation of gelatin. Laser scanning confocal microscopy was used to demonstrate that gelatin microspheres can be injected evenly into cell-scaffold constructs owing to the spongy characteristics of the scaffold. To examine the binding interactions of bFGF with surface bound gelatin, a label free biosensor system, Biomolecular INteraction Detection sensor (BIND) was used. Results confirm that the principal interaction that takes place between bFGF and gelatin is electrostatic. Cell loaded tissue engineered constructs were produced in vitro at clinically relevant sizes and implanted with and without bFGF into a porcine mandibular defect model. Tissue engineered constructs facilitated the healing of mandibular defects only if combined with delivery of bFGF via gelatin microspheres. bFGF release from the constructs improved neovascularization in the defect area and subsequently enhanced new bone formation. Although the rate and extent of bone formation was similar in bFGF group to those in empty defects for the period of the study, existence of woven bone in bFGF group suggests that bone formation is continuing while the lamellar structure in empty defects indicates that bone formation in that group was finalized.

Sendemir-Urkmez, Aylin


Gene Expression Responses to Mechanical Stimulation of Mesenchymal Stem Cells Seeded on Calcium Phosphate Cement  

PubMed Central

Introduction The aim of the study reported here was to investigate the molecular responses of human mesenchymal stem cells (MSC) to loading with a model that attempts to closely mimic the physiological mechanical loading of bone, using monetite calcium phosphate (CaP) scaffolds to mimic the biomechanical properties of bone and a bioreactor to induce appropriate load and strain. Methods Human MSCs were seeded onto CaP scaffolds and subjected to a pulsating compressive force of 5.5±4.5?N at a frequency of 0.1?Hz. Early molecular responses to mechanical loading were assessed by microarray and quantitative reverse transcription-polymerase chain reaction and activation of signal transduction cascades was evaluated by western blotting analysis. Results The maximum mechanical strain on cell/scaffolds was calculated at around 0.4%. After 2?h of loading, a total of 100 genes were differentially expressed. The largest cluster of genes activated with 2?h stimulation was the regulator of transcription, and it included FOSB. There were also changes in genes involved in cell cycle and regulation of protein kinase cascades. When cells were rested for 6?h after mechanical stimulation, gene expression returned to normal. Further resting for a total of 22?h induced upregulation of 63 totally distinct genes that were mainly involved in cell surface receptor signal transduction and regulation of metabolic and cell division processes. In addition, the osteogenic transcription factor RUNX-2 was upregulated. Twenty-four hours of persistent loading also markedly induced osterix expression. Mechanical loading resulted in upregulation of Erk1/2 phosphorylation and the gene expression study identified a number of possible genes (SPRY2, RIPK1, SPRED2, SERTAD1, TRIB1, and RAPGEF2) that may regulate this process. Conclusion The results suggest that mechanical loading activates a small number of immediate-early response genes that are mainly associated with transcriptional regulation, which subsequently results in activation of a wider group of genes including those associated with osteoblast proliferation and differentiation. The results provide a valuable insight into molecular events and signal transduction pathways involved in the regulation of MSC osteogenic differentiation in response to a physiological level of mechanical stimulation. PMID:23968499

Gharibi, Borzo; Cama, Giuseppe; Capurro, Marco; Thompson, Ian; Deb, Sanjukta; Di Silvio, Lucy



Silica- and Zirconia-Hybridized Amorphous Calcium Phosphate: Effect on Transformation to Hydroxyapatite  

NSDL National Science Digital Library

The goal of this study was to determine the effect that silica and zirconia have on the stability of bioactive amorphous calcium phosphate (ACP) mineral, i.e., in retarding its transformation to hydroxyapatite (HAP). The glassforming agents, tetraethoxysilane and zirconyl chloride, were introduced individually during the low-temperature preparation of ACP. These hybrid ACPs (Si-ACP and Zr-ACP, respectively) as well as the control, unhybridized ACP (u-ACP), were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, specific surface area measurements, and chemical analysis (Ca/PO4 ratio of the solids) before being dispersed in one of the following four test solutions: N-2-hydroxyethylpiperazine- N8-2-ethanesulfonic acid (HEPES)-buffered (pH = 7.40) saline solutions with 0 mg/g fluoride (test solution A1), 1 mg/g fluoride (test solution A2), and 10 mg/g fluoride (test solution A3), or a lactic acid-containing solution (pH = 5.10, adjusted with NaOH; test solution B). Aliquots were taken at predetermined time intervals for solution Ca and PO4 analysis. Solids isolated after 30 and 90 min exposure to solution B as well as the final dissolution/transformation products from all four solution experiments were analyzed by Fourier transform infrared spectroscopy and X-ray diffraction. Regardless of the type of experimental solution used, slower conversion to HAP was observed with the hybrid ACPs compared with u-ACP. The retarding effect of the Si or Zr species in the hybridized ACPs is probably due to these ions specifically blocking, by adsorption, potential sites for HAP nucleation and growth. The stability of ACP toward HAP conversion increased in the following order: u-ACP < Si-ACP < Zr-ACP. Hybrid ACP fillers, especially Zr-ACP, could be utilized in applications in which it is desired to enhance performance of composites, sealants, and/or adhesives in preventing demineralization or actively promoting remineralization.

Skrtic, D.; Antonucci, J. M.; Eanes, E. D.; Brunworth, R. T.



Biphasic calcium phosphate loading on polycaprolactone/poly(lacto-co-glycolic acid) membranes for improved tensile strength, in vitro biocompatibility, and in vivo tissue regeneration.  


Electrospun polycaprolactone and poly(lacto-co-glycolide) membranes were loaded with biphasic calcium phosphate powder to facilitate osteoconductivity. Different concentrations of biphasic calcium phosphate powder were added to the polymer solution, and successful loading was confirmed by X-ray diffraction analysis, transmission electron microscope, and scanning electron microscope with energy-dispersive spectroscopy visualization. The effect of the added biphasic calcium phosphate on the polymer membrane was investigated in terms of the material's tensile strength and strain, in vitro cytocompatibility, and in vivo tissue regeneration. It was observed that the tensile strength of the membranes increased with the addition of the biphasic calcium phosphate powder. Immersion in simulated body fluid solution for seven days leads to the formation of apatite-like deposits in the fibers, which further improved the mechanical stability. Moreover, proliferation and adhesion of osteoblast-like cells were more apparent upon the addition of the biphasic calcium phosphate powder as seen with the increasing cell density from (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and micrographs from scanning electron microscope and confocal microscopy. Sample membranes were also implanted to investigate the membrane's ability to regenerate bone in a rat calvarium. Histological staining and micro-CT histomorphometric analyses showed neo-bone formation in the implanted rat skull. PMID:24014247

Franco, Rose Ann; Sadiasa, Alexander; Seo, Hyung Seok; Lee, Byong-Taek



Quantitative determination of the composition of multi-shell calcium phosphate-oligonucleotide nanoparticles and their application for the activation of dendritic cells.  


Biodegradable calcium phosphate nanoparticles as carriers for the immunoactive toll-like receptor ligands CpG and polyinosinic-polycytidylic acid for the activation of dendritic cells (DC) combined with the viral antigen hemagglutinin (HA) were prepared. A purification method based on ultracentrifugation and ultrasonication was developed to separate the nanoparticles from dissolved biomolecules. The number of biomolecules, i.e., oligonucleotides and peptide, incorporated into the nanoparticles was quantitatively determined by UV-spectroscopy, using fluorescent derivatives of the biomolecules. The immunostimulatory effects of purified calcium phosphate nanoparticles on DC were studied, i.e., cytokine production and activation of the cells in terms of the upregulation of surface molecules. Purified calcium phosphate nanoparticles, i.e., without dissolved biomolecules, are capable of inducing adaptive immunity by activation of DC. Immunostimulatory effects of purified calcium phosphate nanoparticles on DC were demonstrated by increased expression of co-stimulatory molecules and MHC II and by cytokine secretion. In addition, DC treated with purified functionalized calcium phosphate nanoparticles induced an antigen-specific T-cell response in vitro. PMID:21784177

Sokolova, V; Knuschke, T; Buer, J; Westendorf, A M; Epple, M



In vitro Evaluation of Calcium Phosphate Precipitation on Possibly Bioactive Titanium Surfaces in the Presence of Laminin  

PubMed Central

ABSTRACT Objectives The aim of the present study was to evaluate calcium phosphate precipitation and the amount of precipitated protein on three potentially bioactive surfaces when adding laminin in simulated body fluid. Material and Methods Blasted titanium discs were prepared by three different techniques claimed to provide bioactivity: alkali and heat treatment (AH), anodic oxidation (AO) or hydroxyapatite coating (HA). A blasted surface incubated in laminin-containing simulated body fuid served as a positive control (B) while a blasted surface incubated in non laminin-containing simulated body fuid served as a negative control (B-). The immersion time was 1 hour, 24 hours, 72 hours and 1 week. Surface topography was investigated by interferometry and morphology by Scanning Electron Microscopy (SEM). Analysis of the precipitated calcium and phosphorous was performed by Energy Dispersive X-ray Spectroscopy (EDX) and the adsorbed laminin was quantified by iodine (125I) labeling. Results SEM demonstrated that all specimens except for the negative control were totally covered with calcium phosphate (CaP) after 1 week. EDX revealed that B- demonstrated lower sum of Ca and P levels compared to the other groups after 1 week. Iodine labeling demonstrated that laminin precipitated in a similar manner on the possibly bioactive surfaces as on the positive control surface. Conclusions Our results indicate that laminin precipitates equally on all tested titanium surfaces and may function as a nucleation center thus locally elevating the calcium concentration. Nevertheless further studies are required to clarify the role of laminin in the interaction of biomaterials with the host bone tissue. PMID:24421995

Stenport, Victoria Franke; Currie, Fredrik; Wennerberg, Ann



Effect of calcium, phosphate and nitrogen on cell growth and biosynthesis of cell wall polysaccharides by Silene vulgaris cell culture.  


Medium nutrients such as calcium, phosphorus, nitrogen and nitrate to ammonium ratio have significant influence on the growth, biosynthetic and biochemical characteristics of polysaccharides produced by Silene vulgaris (M.) G. cell culture. Cell growth and production of polysaccharides was limited by an absence of any of these components in the medium. Optimal growth of the callus and production of arabinogalactan were achieved at 1.5-4.5 microM calcium while the optimal production of pectin named silenan was observed at 3.0-4.5 microM. The phosphate contents in the medium in the range of 0.63-3.75 microM were favorable for callus growth. Production of silenan was maximal at 1.25-3.75 microM phosphate. Optimal growth of the callus was achieved at 30-90 microM nitrogen. Maximal production of silenan was observed at 60 microM nitrogen while the optimal production of arabinogalactan was at 90 microM nitrogen (at ratio of NH(4)(+):NO(3)(-) as 1:2). A presence both of nitrate and ammonium is needed for the silenan biosynthesis (the NH(4)(+):NO(3)(-) ratio as 1:1 and 1:2). Yields and volumetric production of arabinogalactan were maximal at deletion of ammonium from the nutrient medium (ratio 0:1). Absence of calcium or nitrogen in the medium leads to a decrease of the galacturonic acid residues in silenan. The galactose residues contents in arabinogalactan were decreased in the absence of nitrogen and calcium in the medium. PMID:15878212

Günter, Elena A; Ovodov, Yury S



Effects of sevelamer and calcium-based phosphate binders on mortality in hemodialysis patients  

Microsoft Academic Search

Elevated serum phosphorus and calcium are associated with arterial calcification and mortality in dialysis patients. Unlike calcium-based binders, sevelamer attenuates arterial calcification but it is unknown whether sevelamer affects mortality or morbidity. In a multicenter, randomized, open-label, parallel design trial we compared sevelamer and calcium-based binders on all-cause and cause-specific mortality (cardiovascular, infection, and other) in prevalent hemodialysis patients. A

W N Suki; R Zabaneh; J L Cangiano; J Reed; D Fischer; L Garrett; B N Ling; S Chasan-Taber; M A Dillon; A T Blair; S K Burke



Vitamin D and Adaptation to Dietary Calcium and Phosphate Deficiencies Increase Intestinal Plasma Membrane Calcium Pump Gene Expression  

Microsoft Academic Search

The effect of vitamin D and other variables on the synthesis of the chicken intestinal plasma membrane calcium pump (PMCA) mRNA was assessed. The DNA probe for Northern analysis was obtained by reverse transcription and PCR with intestinal poly(A)^+ RNA, using two 20-mer oligonucleotide primers homologous to the 3' coding region of the human teratoma PMCA. An EcoRI restriction fragment

Qiang Cai; John S. Chandler; Robert H. Wasserman; Rajiv Kumar; John T. Penniston



The effect of processing on the structural characteristics of vancomycin-loaded amorphous calcium phosphate matrices  

Microsoft Academic Search

Calcium polyphosphate antibiotic delivery matrices were prepared using a unique processing technique involving the exposure of calcium polyphosphate pastes to high humidity for 0, 5, 24 or 48h to induce gelling. Subsequently, samples were dried for a minimum of 24h. The mild conditions associated with matrix fabrication readily allowed for vancomycin incorporation within an environment that did not disrupt antibiotic

Anna Dion; Bob Berno; Gordon Hall; Mark Joseph Filiaggi



Comparison study of biomimetic strontium-doped calcium phosphate coatings by electrochemical deposition and air plasma spray: morphology, composition and bioactive performance.  


In this study, strontium-doped calcium phosphate coatings were deposited by electrochemical deposition and plasma spray under different process parameters to achieve various coating morphologies. The coating composition was investigated by energy dispersive X-ray spectroscopy and X-ray diffraction. The surface morphologies of the coatings were studied through scanning electron microscopy while the cytocompatibility and bioactivity of the strontium-doped calcium phosphate coatings were evaluated using bone cell culture using MC3T3-E1 osteoblast-like cells. The addition of strontium leads to enhanced proliferation suggesting the possible benefits of strontium incorporation in calcium phosphate coatings. The morphology and composition of deposited coatings showed a strong influence on the growth of cells. PMID:22528069

Li, Ling; Lu, Xia; Meng, Yizhi; Weyant, Christopher M



Fabrication of porous scaffolds by three-dimensional plotting of a pasty calcium phosphate bone cement under mild conditions.  


The major advantage of hydroxyapatite (HA)-forming calcium phosphate cements (CPCs) used as bone replacement materials is their setting under physiological conditions without the necessity for thermal treatment that allows the incorporation of biological factors. In the present study, we have combined the biocompatible consolidation of CPCs with the potential of rapid prototyping (RP) techniques to generate calcium phosphate-based scaffolds with defined inner and outer morphology. We demonstrate the application of the RP technique three-dimensional (3D) plotting for the fabrication of HA cement scaffolds. This was realized by utilizing a paste-like CPC (P-CPC) which is stable as a malleable paste and whose setting reaction is initiated only after contact with aqueous solutions. The P-CPC showed good processability in the 3D plotting process and allowed the fabrication of stable?3D structures of different geometries with adequate mechanical stability and compressive strength. The cytocompatibility of the plotted P-CPC scaffolds was demonstrated in a cell culture experiment with human mesenchymal stem cells. The mild conditions during 3D plotting and post-processing and the realization of the whole procedure under sterile conditions make this approach highly attractive for fabrication of individualized implants with respect to patient-specific requirements by simultaneous plotting of biological components. PMID:22933381

Lode, Anja; Meissner, Katrin; Luo, Yongxiang; Sonntag, Frank; Glorius, Stefan; Nies, Berthold; Vater, Corina; Despang, Florian; Hanke, Thomas; Gelinsky, Michael



Preliminary research on a novel bioactive silicon doped calcium phosphate coating on AZ31 magnesium alloy via electrodeposition.  


A silicon doped calcium phosphate coating was obtained successfully on AZ31 alloy substrate via pulse electrodeposition. A novel dual-layer structure was observed with a porous lamellar-like and outer block-like apatite layer. In vitro immersion tests were adopted in simulated body fluid within 28 days of immersion. Slow degradation rate obtained from weight loss was observed for the Si-doped Ca-P coating, which was also consistent with the results of electrochemical experiments showing an enhanced corrosion resistance for the coating. Further formation of an apatite-like layer on the surface after immersion proved better integrity and biomineralization performance of the coating. Biological characterization was carried out for viability, proliferation and differentiation of MG63 osteoblast-like cells. The coating showed a good cell growth and an enhanced cell proliferation. Moreover, an increased activity of osteogenic marker ALP was found. All the results demonstrated that the Si-doped calcium phosphate was perspective to be used as a coating for magnesium alloy implants to control the degradation rate and enhance the bioactivity, which would facilitate the rapidity of bone tissue repair. PMID:24433888

Qiu, Xun; Wan, Peng; Tan, Lili; Fan, Xinmin; Yang, Ke



Cytotoxicity of fecal water is dependent on the type of dietary fat and is reduced by supplemental calcium phosphate in rats.  


The effects of the type of dietary fat (180 g/kg diet) and of calcium phosphate (CaHPO4) supplementation (25 vs. 225 mmol/kg diet) on luminal solubility of fatty acids and bile acids, cytotoxicity of fecal water and intestinal epitheliolysis were studied in rats. In rats fed the low and high calcium phosphate diets, fecal excretion of fatty acids diminished in the order palm oil > milk fat > corn oil. Palm oil also caused the highest concentration of fatty acids measured in fecal water followed by milk fat and corn oil when fed at both calcium phosphate levels. The differences in concentrations of luminal surfactants in fecal water of rats fed the three fat diets resulted in a fat type-dependent cytotoxicity of fecal water, with that of palm oil-fed rats the most cytotoxic. The concentrations of fatty acids as well as bile acids in fecal water were, however, significantly lowered by calcium phosphate supplementation in rats fed all types of dietary fat. This reduction in concentration of fecal water surfactants resulted in a lower cytotoxicity of fecal water. The concentration of surfactants in fecal water and cytotoxicity were correlated by multiple regression analysis (R = 0.89). Intestinal epitheliolysis measured as alkaline phosphatase activity in fecal water was lowered comparably to the reduction in cytotoxicity by supplemental calcium phosphate. Intestinal epitheliolysis and cytotoxicity of fecal water were correlated (r = 0.92, P < 0.001). The type of dietary fat and the amount of dietary calcium phosphate influence the concentrations of surfactants in fecal water and consequently affect cytotoxicity of fecal water and intestinal epitheliolysis.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8463858

Lapré, J A; De Vries, H T; Van der Meer, R



On the Pressure-Induced Loss of Crystallinity in Zinc and Calcium-Phosphates  

Microsoft Academic Search

A recently suggested mechanism for the stress memory of various metal phosphates is investigated experimentally. Based on first-principles simulations [N. J. Mosey et al., Science 307, 1612 (2005)], it had been argued that atoms with flexible coordination, such as zinc or heavy-metal cations, act as network-forming agents, undergoing irreversible pressure-induced changes in bonding that lead to increased connectivity between phosphate

D. Shakhvorostov; N Mosey; D Munoz-Paniagua; G Pereira; Y Song; M Kasrai; P Norton; M Müser



Static and dynamic cultivation of bone marrow stromal cells on biphasic calcium phosphate scaffolds derived from an indirect rapid prototyping technique  

Microsoft Academic Search

The adequate regeneration of large bone defects is still a major problem in orthopaedic surgery. Synthetic bone substitute\\u000a materials have to be biocompatible, biodegradable, osteoconductive and processable into macroporous scaffolds tailored to\\u000a the patient specific defect. Hydroxyapatite (HA) and tricalcium phosphate (TCP) as well as mixtures of both phases, biphasic\\u000a calcium phosphate ceramics (BCP), meet all these requirements and are

M. Schumacher; F. Uhl; R. Detsch; U. Deisinger; G. Ziegler



Effect of TiO2-Ag2O additives on the formation of calcium phosphate based functionally graded bioceramics.  


The combined effect of titanium dioxide and silver oxide on the in situ formation of biphasic calcium phosphate ceramics was investigated. Titania (5-20 mol%) was mixed with pure hydroxyapatite (HA) or HA containing Ag2O (10-20 mol%) and was heated to 900 degrees C for 12 h. The sintered samples were found to contain tricalcium phosphate (beta-TCP) and other phases along with HA depending upon the amount as well as the type of the additives used as evidenced by X-ray powder diffraction (XRD) and fourier transform infrared (FT-IR) spectroscopic studies. Enhanced TCP formation with reduced impurity phases was observed with TiO2-Ag2O addition. In vitro solubility study in phosphate buffer at physiological conditions shows the resorbable nature of these materials. A functionally graded material (FGM) structure was formed by spreading TiO2-Ag2O mixture on the surface of the HA green compact and heating at 900 degrees C. The FGM shows gradient structure of TCP and HA from the surface to the interior of the pellet in addition to titania and silver phases. PMID:10941921

Manjubala, I; Sampath Kumar, T S



Electrolytic deposition of calcium phosphate/chitosan coating on titanium alloy: growth kinetics and influence of current density, acetic acid, and chitosan.  


Electrolytically deposited calcium phosphate/chitosan coating demonstrated good bone marrow stromal cell attachment. The aim of this study was to understand the coating's growth kinetics as well as the effects of current density, acetic acid, and chitosan on the coating's formation. The scanning electron micrographs found that calcium phosphate crystals homogeneously distributed into chitosan aggregates as early as 30 min. X-ray diffraction patterns and Fourier transform infrared spectra demonstrated that the coating experienced a compositional conversion from octacalcium phosphate to carbonate apatite during the deposition process. Electric current influenced the deposition. Higher current density accelerated the process and induced faster and more chitosan deposition. Both acetic acid and chitosan were found to inhibit calcium phosphate deposition. Chitosan was thought to induce stronger effects than acetic acid did. Furthermore, the inhibitive effect related to their concentration in the electrolyte. When chitosan concentration increased to a certain degree, this inhibitive effect not only affected calcium phosphate deposition, but also affected its own deposition. The chitosan content within the hybrid coating was small, which could be verified through Raman spectrum. At the same time, no clear evidence of chemical reactions could be found between these two components. We considered that both components were just naturally wrapped to form as a whole. PMID:16278873

Wang, Jiawei; van Apeldoorn, Aart; de Groot, Klaas



Bioactivity and Surface Reactivity of RF-sputtered Calcium Phosphate Thin Films  

NASA Astrophysics Data System (ADS)

Calcium phosphates (CaP) are known to be bioactive, i.e. able to bond to bone. This makes CaPs very suitable to be aplied as thin coatings on bone-implants. In this work we studied the physicochemical behaviour of CaP coatings applied with radio frequency (RF) magnetron sputtering, a deposition technique that can produce thin ( 100 nm), homogeneous, and well-adhereing coatings. As-deposited CaP coatings are amorphous and can be crystallized by a heat-treatment of 30 minutes at 650C, resulting in a mainly apatitic structure. Firstly, we have studied the behaviour of these CaP coatings in so-called simulated body fluid (SBF or SBF1), an anorganic equivalent of human blood plasma. Amorphous CaP coatings dissolve in SBF and even in SBF with twice the Ca and PO4 concentrations (SBF2). After a heat-treatment CaP coatings remain inert in SBF for days, i.e. coatings do not dissolve and no crystals are formed from the solution on the coating surface. However, formation of crystals is possible in SBF2. At room temperature, the formation of crystals is preceeded by an induction time, in which rod-shaped sediments can be found on the coating surface, but no significant growth is observed. Only after completion of the induction period growth of CaP crystals is allowed. Growth can proceed in solutions with lower concentrations like SBF1. Only within a limited range of Ca over PO4 ratio of the coatings, formation of CaP crystals from SBF2 is possible. In a rat bone marrow (RBM) cell-culture CaP was compared to RF-sputtered coatings of other bioceramics like alumina (Al2O3) and titania (TiO2). Alumina is a known bioinert material. However, there is still discussion on the biocompatibility of titania. It was found that cell behavior on CaP coatings significantly differed from alumina. CaP coatings showed decreased early proliferation, increased differentiation, and increased mature osteoblast activity compared to alumina. Results for titania were intermediate compared to CaP and alumina. That is, early proliferation followed the alumina results, whereas the mature osteoblast activity and the matrix production confirmed the CaP findings. Coinciding with the differentiation of cells towards mature, extracellular matrix forming osteoblasts, both the CaP and titania coatings showed the formation of a directly bonded CaP layer ( 1 micron after 16 days), quite similar to the precipitate grown in simulated body fluids. The directly bonded CaP layer is thought to be indicative of bone-bonding bioactivity. In simulated body fluids we showed that the presence of CaP nuclei, obtained by 40-60 minutes pre-immersion in SBF2, is required to allow growth in SBF1. Therefore, we also studied the effect of pre-immersion in a RBM cell-model. The coatings that were not pre-immersed showed the formation of a directly bonded \\cap layer, again after the start of osteoblast-differentiation. However, the pre-immersed samples allowed the growth of a this layer without an offset. Thus by applying CaP nuclei, the formation of the directly bonded CaP layer has been decoupled from the ECM calcifications.

van der Wal, Edwin



Fibroblast growth factor-23 and calcium phosphate product in young chronic kidney disease patients: a cross-sectional study  

PubMed Central

Background Fibroblast growth factor-23 (FGF-23), a novel marker of bone disease in chronic kidney disease (CKD) has been shown to correlate with vascular calcifications. We aimed to describe the effect of the calcium phosphate product (Ca*P) on FGF-23 concentrations in children and young adults without confounding cardiovascular disease. Methods Pediatric and young adult patients with CKD stages I-V were recruited in this cross sectional study to measure FGF-23, cystatin C, vitamin D-metabolites and other serum markers of bone metabolism. FGF-23 levels were determined with an enzyme-linked immunosorbent assay. The association between FGF-23 and (Ca*P) was assessed using non-parametric methods. Patients were divided into two age groups, less than 13 years of age and greater than 13 years of age. Results This cross-sectional study measured serum FGF-23, in 81 patients (42 females, 51.9%) at London Health Sciences Centre, aged 2 to 25 years, with various stages of CKD (Cystatin C estimated glomerular filtration rate, eGFR=10.7-213.0 ml/min). For the whole entire group of patients, FGF-23 levels were found to correlate significantly with age (Spearman r= 0.26, p=0.0198), Cystatin C eGFR (Spearman r=?0.40 p=0.0002), CKD stage (Spearman r=0.457, p<0.0001), PTH (Spearman r=0.330, p=0.0039), ionized calcium (Spearman r=?0.330, p=0.0049), CysC (Spearman r= 0.404, p=0.0002) and 1,25-dihydroxyvitamin D (Spearman r=?0.345, p=0.0034) concentrations. No significant correlation was found between FGF-23 levels and calcium phosphate product (Spearman r= 0.164, p=0.142). Upon classification of patients into two age groups, less than 13 years of age and more than 13 years of age, correlational results differed significantly. FGF-23 correlated with CysC eGFR( Spearman r= ?0.633, p<0.0001), CKD stage (Spearman r=0.731, p<0.0001), phosphate (Spearman r= 0.557, p<0.0001), calcium phosphate product (Spearman r=0.534, p<0.0001), 125(OH)2 Vit D (Spearman r=?0.631, p<0.0001), PTH (Spearman r= 0.475, p=0.0017) and ionized calcium (Spearman r= ?0.503, p=0.0015) only in the older group. The relationship between FGF-23 and Ca*P for the older group could be expressed by the exponential model FGF-23= 38.15 e0.4625Ca*P. Conclusion Abnormal values of FGF-23 in adolescents and young adults with CKD correlate with Ca* P in the absence of vascular calcifications, and may serve as a biomarker for the risk of cardiovascular calcifications. PMID:23413976



In vitro Phosphate Transport in Chick Ileum: Effect of Cholecalciferol, Calcium, Sodium and Metabolic Inhibitors1  

Microsoft Academic Search

Three parameters of phosphate transport were monitored in everted gut sacs prepared from the ileum of rachitic chicks injected with cholecalciferol 48 hours before use and untreated rachitic chicks by measuring tracer T movement: transfer from the outside ( mucosa) ) compartment to inside ( serosa! ) compartment; total transfer out of mucosa! compartment, i.e., into intestinal tissue plus serosal



Increases in Fluoride, Calcium, and Phosphate in Dental Plaque Resulting from the Use of a Mineralizing Mouthrinse Containing Urea and Monofluorophosphate  

Microsoft Academic Search

A mouthrinse used ten times over a four-day period increased the concentration of acid-extractable fluoride in immature plaque by 320%, calcium by 190%, and phosphate by 97%. Corresponding increases in mature plaque were smaller, yet significant. Diffusion of the ions from plaque was restricted, and hence a prolonged caries-inhibitory effect can be expected.

E. I. F. Pearce; R. G. Schamschula; M. H. Cooper



Fabrication of a calcium phosphate scaffold with a three dimensional channel network and its application to perfusion culture of stem cells  

Microsoft Academic Search

Purpose – The purpose of this paper is to adopt rapid prototyping (RP) technology to fabricate self-hardening calcium phosphate composite (CPC) scaffolds with a controlled internal channel network to facilitate nutrient supplying and cell growth using RP technique and investigate their in vitro performance. Design\\/methodology\\/approach – Porous scaffolds should possess branched channels to ensure uniform cell feeding and even flow

Shanglong Xu; Dichen Li; Bingheng Lu; Yiping Tang; Chaofeng Wang; Zhen Wang



Combinatorial screening of osteoblast response to 3D calcium phosphate/poly(?-caprolactone) scaffolds using gradients and arrays  

PubMed Central

There is a need for combinatorial and high-throughput methods for screening cell–biomaterial interactions to maximize tissue generation in scaffolds. Current methods employ a flat two-dimensional (2D) format even though three-dimensional (3D) scaffolds are more representative of the tissue environment in vivo and cells are responsive to topographical differences of 2D substrates and 3D scaffolds. Thus, combinatorial libraries of 3D porous scaffolds were developed and used to screen the effect of nano-amorphous calcium phosphate (nACP) particles on osteoblast response. Increasing nACP content in poly (?-caprolactone) (PCL) scaffolds promoted osteoblast adhesion and proliferation. The nACP-containing scaffolds released calcium and phosphate ions which are known to activate osteoblast function. Scaffold libraries were fabricated in two formats, gradients and arrays, and the magnitude of the effect of nACP on osteoblast proliferation was greater for arrays than gradients. The enhanced response in arrays can be explained by differences in cell culture designs, diffusional effects and differences in the ratio of “scaffold mass to culture medium”. These results introduce a gradient library approach for screening large pore 3D scaffolds and demonstrate that inclusion of the nACP particles enhances osteoblast proliferation in 3D scaffolds. Further, comparison of gradients and arrays suggests that gradients were more sensitive for detecting effects of scaffold composition on cell adhesion (short time points, 1 day) whereas arrays were more sensitive at detecting effects on cell proliferation (longer time points, 14 day). PMID:21074846

Chatterjee, Kaushik; Sun, Limin; Chow, Laurence C.; Young, Marian F.; Simon, Carl G.



The homing of bone marrow MSCs to non-osseous sites for ectopic bone formation induced by osteoinductive calcium phosphate  

PubMed Central

Osteoinductive biomaterials are promising for bone repair. There is no direct proof that bone marrow mesenchymal stem cells (BMSCs) home to non-osseous sites and participate in ectopic bone formation induced by osteoinductive bioceramics. The objective of this study was to use a sex-mismatched beagle dog model to investigate BMSC homing via blood circulation to participate in ectopic bone formation via osteoinductive biomaterial. BMSCs of male dogs were injected into female femoral marrow cavity. The survival and stable chimerism of donor BMSCs in recipients were confirmed with polymerase chain reaction (PCR) and fluorescence in situ hybridization (FISH). Biphasic calcium phosphate (BCP) granules were implanted in dorsal muscles of female dogs. Y chromosomes were detected in samples harvested from female dogs which had received male BMSCs. At 4 weeks, cells with Y-chromosomes were distributed in the new bone matrix throughout the BCP granule implant. At 6 weeks, cells with Y chromosomes were present in newly mineralized woven bone. TRAP positive osteoclast-like cells were observed in 4-week implants, and the number of such cells decreased from 4 to 6 weeks. These results show that osteoprogenitors were recruited from bone marrow and homed to ectopic site to serve as a cell source for calcium phosphate-induced bone formation. In conclusion, BMSCs were demonstrated to migrate from bone marrow through blood circulation to non-osseous bioceramic implant site to contribute to ectopic bone formation in a canine model. BCP induced new bone in muscles without growth factor delivery, showing excellent osteoinductivity that could be useful for bone tissue engineering. PMID:23298780

Song, Guodong; Habibovic, Pamela; Bao, Chongyun; Hu, Jing; van Blitterswijk, Clemens A.; Yuan, Huipin; Chen, Wenchuan; Xu, Hockin H.K.



The effect of particle size on the osteointegration of injectable silicate-substituted calcium phosphate bone substitute materials  

PubMed Central

Calcium phosphate (CaP) particles as a carrier in an injectable bone filler allows less invasive treatment of bony defects. The effect of changing granule size within a poloxamer filler on the osteointegration of silicate-substituted calcium phosphate (SiCaP) bone substitute materials was investigated in an ovine critical-sized femoral condyle defect model. Treatment group (TG) 1 consisted of SiCaP granules sized 1000–2000 ?m in diameter (100 vol %). TG2 investigated a granule size of 250–500 ?m (75 vol %), TG3 a granule size of 90–125 ?m (75 vol %) and TG4 a granule size of 90–125 ?m (50 vol %). Following a 4 and 8 week in vivo period, bone area, bone-implant contact, and remaining implant area were quantified within each defect. At 4 weeks, significantly increased bone formation was measured in TG2 (13.32% ± 1.38%) when compared with all other groups (p = 0.021 in all cases). Bone in contact with the bone substitute surface was also significantly higher in TG2. At 8 weeks most new bone was associated within defects containing the smallest granule size investigated (at the lower volume) (TG4) (42.78 ± 3.36%) however this group was also associated with higher amounts of fragmented SiCaP. These smaller particles were phagocytosed by macrophages and did not appear to have a negative influence on healing. In conclusion, SiCaP granules of 250–500 ?m in size may be a more suitable scaffold when used as an injectable bone filler and may be a convenient method for treating bony defects. © 2013 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 101B: 902–910, 2013 PMID:23362131

Coathup, Melanie J; Cai, Qian; Campion, Charlie; Buckland, Thomas; Blunn, Gordon W




Microsoft Academic Search

21205 ABSTRACT The hepatopancreas of the adult male blue crab Callinectes sapidusin intermolt was found to contain substantial amounts of calcium, magnesium, and inorganic phosphorus, averaging about 260, 20, and 250 µg-atoms per g wet tissue, respectively, accounting for over 10% of the tissue dry weight . Electron microscopy of the intact tissue showed three qualitatively different granular structures having




Pathophysiology of Calcium and Phosphate Metabolism Impairment in Chronic Kidney Disease  

Microsoft Academic Search

Secondary hyperparathyroidism (SHPT) is a classical feature of chronic kidney disease (CKD). Commonly, hypocalcemia, hyperphosphatemia, and vitamin D deficiency are involved into the pathogenesis of SHPT. Parathyroid (PT) glands are characterized by a low turnover and rarely undergo mitoses. However, in the presence of low calcium, high phosphorus, vitamin D deficiency, and uremia, PT cells leave quiescence. In the last

Mario Cozzolino; Paola Ciceri; Elisa Maria Volpi; Laura Olivi; Pier Giorgio Messa



Hierarchical pore structure of calcium phosphate scaffolds by a combination of gel-casting and multiple tape-casting methods.  


The objective of this work was to design hierarchical pore structure scaffolds with potential applications in bone tissue regeneration. For that purpose, a bioceramic material such as biphasic calcium phosphate, which consists of a mixture of hydroxyapatite and beta-tricalcium phosphate, was selected. Multilayer pieces (MLP) with hierarchical pore structure were developed employing a new technique that combines gel casting and adding porogens, using multiple tape-casting methods. Pieces with functionally graded porosity were fabricated using porogens with different sizes. The porogens used were Porlat K85 and Porlat K86 with diameters <150 microm and 150-300 microm, respectively. Two types of sintered tapes, with different porosity, no cracking and enough interconnection size were selected. MLP with hierarchical pore structure were designed by the multiple tape-casting method. Interconnected pores whose sizes increase from interior tapes (1.6-3.6 microm) towards exterior tapes (20-51.5 microm) and interpenetration between tapes were achieved. Delamination or cracking were not observed after heat treatment. The flexural strength of pieces was investigated by the three-point bending test. This new combination of methods offers the possibility of manufacturing scaffolds with interconnected pore sizes ranging from 1.6 to 51.5 microm. PMID:18346947

Sánchez-Salcedo, S; Werner, J; Vallet-Regí, M



Raman and EPR studies of calcium-phosphate glasses doped with manganese ions  

Microsoft Academic Search

The structure of xMnO·(1-x)[2.5P2O5·CaO] glass system with 1 <= x <= 10 mol% was prepared and investigated by Raman and EPR spectroscopy. The characteristic Raman bands of these glasses due to the stretching and bending vibrations were identified and analyzed by increasing of MnO content. The intensity and frequency variations for the characteristic phosphate group vibrations have been correlated with

Dana Toloman; A. R. Biris; Adriana Popa; Oana Raita; L. M. Giurgiu; I. Ardelean



Proteins incorporated into biomimetically prepared calcium phosphate coatings modulate their mechanical strength and dissolution rate  

Microsoft Academic Search

In a previous investigation, we demonstrated that when bovine serum albumin (BSA) is biomimetically co-precipitated with Ca2+ and PO43? ions upon titanium-alloy implants, it becomes incorporated into the crystal lattice and is not merely deposited on its surface. Moreover, the protein elicited a change in crystal structure from an octacalcium phosphate type to a carbonated apatite one, which bears a

Y Liu; E. B Hunziker; N. X Randall; K de Groot; P Layrolle



3D printing of bone substitute implants using calcium phosphate and bioactive glasses  

Microsoft Academic Search

Customized implants for bone replacement are a great help for a surgeon to remodel maxillofacial or craniofacial defects in an esthetical way, and to significantly reduce operation times. The hypothesis of this study was that a composite of ?-tricalcium phosphate (?-TCP) and a bioactive glass similar to the 45S5 Henchglass® is suitable to manufacture customized implants via 3D-printing process. The

Christian Bergmann; Markus Lindner; Wen Zhang; Karolina Koczur; Armin Kirsten; Rainer Telle; Horst Fischer



Synthesis and thermal behavior of well-crystallized calcium-deficient phosphate apatite  

Microsoft Academic Search

Large crystals (0.5 × 0.5 × 10 mum) of calcium-deficient hydroxyapatites (DAp's) have been synthesized by aqueous precipitation under controlled conditions of pH and temperature. The samples have been characterized using chemical analysis, temperature-programmed dehydration (TPR). X-ray diffraction, IR spectroscopy, and transmission electron microscopy. They show that very well-crystallized DAp's with Ca\\/P close to 1.50 can be obtained under well-selected

Anne Mortier; Jacques Lemaitre; Luc Rodrique; Paul G. Rouxhet



Calcium phosphate apatites with variable Ca\\/P atomic ratio II. Calcination and sintering  

Microsoft Academic Search

The calcination and natural sintering of calcium deficient hydroxyapatite powders Ca10?x(PO4)6?x(HPO4)x(OH)2?x (with 0?x?1) were studied. For temperature below 700°C, particle coalescence occurs without densification. The particle coalescence is associated with a reduction of the specific surface area. This surface decreases all the more as the Ca\\/P molar ratio of the powder is small. The mechanism agrees with a transfer of

S Raynaud; E Champion; D Bernache-Assollant



Ceramide 1-phosphate increases intracellular free calcium concentrations in thyroid FRTL-5 cells: evidence for an effect mediated by inositol 1,4,5-trisphosphate and intracellular sphingosine 1-phosphate.  

PubMed Central

Sphingolipid (SP) derivatives have diverse effects on the regulation of intracellular free calcium concentrations ([Ca2+]i) in a multitude of non-excitable cells. In the present investigation, the effect of C2-ceramide 1-phosphate (C1P) on [Ca2+]i was investigated in thyroid FRTL-5 cells. C1P evoked a concentration-dependent increase in [Ca2+]i, both in a calcium-containing and a calcium-free buffer. A substantial part of the C1P-evoked increase in [Ca2+]i was due to calcium entry. The effect of C1P was attenuated by overnight pretreatment of the cells with pertussis toxin. Similar results were obtained with C8-ceramide 1-phosphate, although the magnitude of the responses was smaller than with C1P. The phospholipase C inhibitor U73122 attenuated the effect of C1P. C1P invoked a small, but significant, increase in inositol 1,4,5-trisphosphate (IP3). However, the effect of C1P on [Ca2+]i was inhibited by neither Xestospongin C, 2-aminoethoxydiphenylborate nor neomycin. C1P mobilized calcium from an IP3-sensitive calcium store, as C1P did not increase [Ca2+]i in cells pretreated with thapsigargin. The effect of C1P on [Ca2+]i was potently attenuated by dihydrosphingosine and dimethylsphingosine, two inhibitors of sphingosine kinase, but not by the inactive SP-derivative N -acetyl sphingosine. Stimulating the cells with C1P evoked an increase in the production of intracellular sphingosine 1-phosphate. C1P did not modulate DNA synthesis or the forskolin-evoked production of cAMP. The results indicate that C1P may be an important SP participating in cellular signalling. PMID:12416995

Hogback, Susanna; Leppimaki, Petra; Rudnas, Britt; Bjorklund, Sonja; Slotte, J Peter; Tornquist, Kid



Synthesis and characterization of calcium phosphate loaded with Ho-166 and Sm-153: a novel biomaterial for treatment of spine metastases.  


Spine metastases are a common and painful complication of cancer. A novel concept of treatment combines the in situ vertebroplasty with radiotherapy employing radioactive bone cement into the human vertebrae. Thus, investigations concerning possible bioactive and radioactive cements become a relevant theme. In this work, we have synthesized calcium phosphate bioceramics incorporated with Ho and Sm nuclides using sol-gel technique. Characterizations were performed using X-ray diffractometry, infrared spectroscopy, scanning electron microscopy, instrumental neutron activation analysis, and gamma spectroscopy. Results showed bioceramics composed by multiphasic calcium phosphates along with holmium and samarium phosphates, with 8.9 and 13.7 % of Sm and Ho in weight, respectively. After neutron activation, the Ho-166 and Sm-153 beta-emitters were identified and quantified on the bioceramics with activities estimated at 32.5 and 14.5 MBq/mg of Sm-153 and Ho-166 bioceramic powder, respectively. These radioactive calcium phosphate bioceramics can compose suitable radioactive cements to radiovertebroplasty. PMID:23912793

Donanzam, B A; Campos, T P R; Dalmázio, I; Valente, E S



Calcium phosphate/chitosan composite coating: Effect of different concentrations of Mg2+ in the m-SBF on its bioactivity  

NASA Astrophysics Data System (ADS)

The purpose of this study was to investigate the effect of different concentration of Mg2+ in a modified simulated body fluid (m-SBF) on the bioactivity of calcium phosphate/chitosan composite coating. Calcium phosphate/chitosan composite coating was prepared on graphite substrate via electrophoretic deposition (EPD) followed by conversion in a phosphate buffer solution (PBS). The obtained samples were soaked in the m-SBF containing different concentration of Mg2+ for different times. And then, the composite coatings were assessed using X-ray diffractometer (XRD), Fourier-transformed infrared spectroscopy (FTIR), Raman spectra, and scanning electron microscope (SEM) with an energy dispersive spectrometer (EDS). The soaking solution was evaluated by inductively coupled plasma optical emission spectrometer (ICP-OES) test. The analytical results showed that hydroxyapatite (HA) and bone-like apatite (HCA) grew on the surface of calcium phosphate/chitosan composite coating after incubation in different m-SBF. With Mg2+ concentration in m-SBF increased from 1× Mg to 10× Mg, HA in the composite coating first presented a dissolving process and then a precipitating one slowly, while HCA presented a growing trend, continuously. The increasing of Mg2+ concentration in the m-SBF inhibited the total growing process of HA and HCA as a whole. The structure of the composite coating changed from spherical into irregular morphology with the concentration of Mg2+ increasing from 1× Mg to 10× Mg. Over all, with the Mg2+ concentration increasing, the bioactivity of calcium phosphate/chitosan composite coating tended to decrease.

Zhang, Jie; Dai, Changsong; Wei, Jie; Wen, Zhaohui; Zhang, Shujuan; Lin, Lemin



Dynamic cell culture on calcium phosphate microcarriers for bone tissue engineering applications  

PubMed Central

Developing appropriate cell culturing techniques to populate scaffolds has become a great challenge in tissue engineering. This work describes the use of spinner flask dynamic cell cultures to populate hydroxyapatite microcarriers for bone tissue engineering. The microcarriers were obtained through the emulsion of a self-setting aqueous ?-tricalcium phosphate slurry in oil. After setting, hydroxyapatite microcarriers were obtained. The incorporation of gelatin in the liquid phase of the ?-tricalcium phosphate slurry allowed obtaining hybrid gelatin/hydroxyapatite-microcarriers. Initial cell attachment on the microcarriers was strongly influenced by the speed of the dynamic culture, achieving higher attachment at low speed (40 r/min) as compared to high speed (80 r/min). Under moderate culture speeds (40 r/min), the number of cells present in the culture as well as the number of microcarrier-containing cells considerably increased after 3 days, particularly in the gelatin-containing microcarriers. At longer culture times in dynamic culture, hydroxyapatite-containing microcarriers formed aggregates containing viable and extracellular matrix proteins, with a significantly higher number of cells compared to static cultures. PMID:25383168

Perez, Roman A; Riccardi, Kiara; Altankov, George



Mechanical properties of zinc and calcium phosphates. Structural insights and relevance to anti-wear functionality  

NASA Astrophysics Data System (ADS)

Recent studies on a variety of metal phosphates (MP) have revealed that MPs tend to be soft at ambient pressure if the coordination on the metal cation is low and the degree of hydration or hydrogenation is high, while they are stiff otherwise. In addition, the softer MPs were found to stiffen dramatically more quickly with increasing pressure than the stiffer MPs. Here we review these findings and support their relevance with new results on the mechanical properties of tribofilms aged in air of relative humidity, which were produced from commercial, zinc phosphate-containing lubricant packages via heating and rubbing. We find that the films can soften quite substantially after having been exposed to humidity, as to be expected from the studies of bulk MPs. Moreover, when the hydrated films are exposed to high loads, the force-distance withdrawal curve becomes identical to that of unaged, non-hydrated films. A straightforward explanation of this observation is that large pressure reverses the hydration of the tribofilms.

Shakhvorostov, D.; Nicholls, M. A.; Norton, P. R.; Müser, M. H.



Calcium phosphate phases integrated in silica/collagen nanocomposite xerogels enhance the bioactivity and ultimately manipulate the osteoblast/osteoclast ratio in a human co-culture model.  


A human co-culture model of osteoblasts and osteoclasts, derived from bone marrow stromal cells and monocytes respectively, was used to characterize the influence of biomaterial modification on the bioactivity and ultimately the ratio of bone-forming to bone-resorbing cells cultivated directly on the surface. Nanocomposites of silica and collagen have been shown to function as skeletal structures in nature and were reproduced in vitro by using a sol-gel approach. The resulting xerogels exhibit a number of features that make it a valuable system for the development of innovative materials for bone substitution applications. In the present study, the incorporation of different calcium phosphate phases in silica/collagen-based gels was demonstrated to enhance the bioactivity of these samples. This ability of the biomaterial to precipitate calcium phosphate on the surface when incubated in simulated body fluids or cell culture medium is generally considered to an advantageous property for bone substitution materials. By co-cultivating human osteoblasts and osteoclasts up to 42 days on the xerogels, we demonstrate that the long-term ratio of these cell types depends on the level of bioactivity of the substrate samples. Biphasic silica/collagen xerogels exhibited comparably low bioactivity but encouraged proliferation of osteoblasts in comparison to osteoclast formation. A balanced ratio of both cell types was detected for moderately bioactive triphasic xerogels with 5% calcium phosphate. However, enhancing the bioactivity of the xerogel samples by increasing the calcium phosphate phase percentage to 20% resulted in a diminished number of osteoblasts in favor of osteoclast formation. Quantitative evaluation was carried out by biochemical methods (calcium, DNA, ALP, TRAP 5b) as well as RT-PCR (ALP, BSP II, OC, RANKL, TRAP, CALCR, VTNR, CTSK), and was supported by confocal laser scanning microscopy (cell nuclei, actin, CD68, TRAP) as well as scanning electron microscopy. PMID:23072829

Heinemann, S; Heinemann, C; Wenisch, S; Alt, V; Worch, H; Hanke, T





... it from: Dairy products. Low-fat milk, yogurt, cheese, and cottage cheese are good sources of calcium. Veggies. You'll ... burritos or wraps. Fill them with eggs and cheese for breakfast; turkey, cheese, lettuce, tomato, and light ...


The effect of amorphous pyrophosphate on calcium phosphate cement resorption and bone generation.  


Pyrophosphate ions are both inhibitors of HA formation and substrates for phosphatase enzymes. Unlike polyphosphates their hydrolysis results simultaneously in the complete loss of mineral formation inhibition and a localised elevation in orthophosphate ion concentration. Despite recent advances in our knowledge of the role of the pyrophosphate ion, very little is known about the effects of pyrophosphate on bone formation and even less is known about its local delivery. In this work we first developed a self setting pyrophosphate based calcium cement system with appropriate handling properties and then compared its in vivo degradation properties with those of a non-pyrophosphate containing control. Contrary to expectation, the presence of the pyrophosphate phase in the cement matrix did not inhibit mineralisation of the healing bone around the implant, but actually appeared to stimulate it. In vitro evidence suggested that enzymatic action accelerated dissolution of the inorganic pyrophosphate ions, causing a simultaneous loss of their mineralisation inhibition and a localised rise in supersaturation with respect to HA. This is thought to be a rare example of a biologically responsive inorganic material and these materials seem to be worthy of further investigation. Bioceramics to date have mainly been limited to orthophosphate, silicate and carbonate salts of calcium, here we report the successful application of a pyrophosphate material as a degradable osteoconductive bone repair cement. PMID:23747007

Grover, Liam M; Wright, Adrian J; Gbureck, Uwe; Bolarinwa, Aminat; Song, Jiangfeng; Liu, Yong; Farrar, David F; Howling, Graeme; Rose, John; Barralet, Jake E



Raman and EPR studies of calcium-phosphate glasses doped with manganese ions  

NASA Astrophysics Data System (ADS)

The structure of xMnO·(1-x)[2.5P2O5·CaO] glass system with 1 <= x <= 10 mol% was prepared and investigated by Raman and EPR spectroscopy. The characteristic Raman bands of these glasses due to the stretching and bending vibrations were identified and analyzed by increasing of MnO content. The intensity and frequency variations for the characteristic phosphate group vibrations have been correlated with the changes of the structural units present in these glasses. All the investigated samples exhibit EPR signals which are characteristic to the Mn2+ ions. The shapes of spectra are also changed with the increasing of manganese ions content.

Toloman, Dana; Biris, A. R.; Popa, Adriana; Raita, Oana; Giurgiu, L. M.; Ardelean, I.



Human embryonic stem cell-encapsulation in alginate microbeads in macroporous calcium phosphate cement for bone tissue engineering  

PubMed Central

Human embryonic stem cells (hESCs) are exciting for regenerative medicine applications because of their strong proliferative ability and multilineage differentiation capability. To date there has been no report on hESC seeding with calcium phosphate cement (CPC). The objective of this study was to investigate hESC-derived mesenchymal stem cell (hESCd-MSC) encapsulation in hydrogel microbeads in macroporous CPC for bone tissue engineering. hESCs were cultured to form embryoid bodies (EBs), and the MSCs were then migrated out of the EBs. hESCd-MSCs had surface markers characteristic of MSCs, with positive alkaline phosphatase (ALP) staining when cultured in osteogenic medium. hESCd-MSCs were encapsulated in alginate at a density of 1 million cells/mL, with an average microbead size of 207 µm. CPC contained mannitol porogen to create a porosity of 64% and macropores with size of 218 µm, with 20% absorbable fibers for additional porosity when the fibers degrade. hESCd-MSCs encapsulated in microbeads in CPC had good viability from 1 to 21 d. ALP gene expression at 21 d was 25-fold that at 1 d. Osteocalcin (OC) at 21 d was two orders of magnitude of that at 1 d. ALP activity in colorimetric p-nitrophenyl phosphate assay at 21 d was 5-fold that at 1 d. Mineral synthesis by the encapsulated hESCd-MSCs at 21 d was 7-fold that at 1 d. Potential benefits of the CPC-stem cell paste include injectability, intimate adaptation to complex-shaped bone defects, ease in contouring to achieve esthetics in maxillofacial repairs, and in situ setting ability. In conclusion, hESCd-MSCs were encapsulated in alginate microbeads in macroporous CPC showing good cell viability, osteogenic differentiation and mineral synthesis for the first time. The hESCd-MSC-encapsulating macroporous CPC construct is promising for bone regeneration in a wide range of orthopedic and maxillofacial applications. PMID:22633970

Tang, Minghui; Chen, Wenchuan; Weir, Michael D.; Thein-Han, Wahwah; Xu, Hockin H. K.



Processing highly porous calcium phosphate ceramics for use in bioreactor cores for culturing human liver cells in-vitro  

NASA Astrophysics Data System (ADS)

Chronic liver disease is the 11th highest cause of death in the United States claiming over 30,000 lives in 2009. The current treatment for chronic liver failure is liver transplantation but the availability of tissue is far less than the number of patients in need. To develop human liver tissue in the lab a 3D culturing environment must be created to support the growth of a complex tissue. Hydroxyapatite (HAp) has been chosen as a scaffold material because of its biocompatibility in the body and the ability to create a bioresorbable scaffold. By using a ceramic material, it is possible to create a three dimensional, protective environment in which tissue can grow. The first part of this study is to examine the behavior of adult human liver cells grown on composites of HAp and different biocompatible hydrogels. Porous HAp has been created using an emulsion foaming technique and cells are injected into the structure after being suspended in a hydrogel and are kept in culture for up to 28 days. Functional assays, gene expression and fluorescent microscopy will be used to examine these cultures. The second part of this study will be to develop a processing technique to create a resorbable scaffold that incorporates a vascular system template. Previous experiments have shown the high temperature decomposition of HAp into resorbable calcium phosphates will be used to create a multiphase material. By controlling the amount of transformation product formed, it is proposed that the resorption of the scaffold can be tailored. To introduce a pore network to guide the growth of a vascular system, a positive-negative casting technique has also been developed. A positive polymer copy can be made of a natural vascular system and ceramic is foamed around the copy. During sintering, the polymer is pyrolyzed leaving a multiscale pore network in the ceramic. By combining these techniques, it is proposed that a calcium phosphate bioreactor core can be processed that is suitable for the culturing of human liver tissue.

Finoli, Anthony


Determination of molecular weight of a purified fraction of colloidal calcium phosphate derived from the casein micelles of bovine milk.  


Colloidal calcium phosphate (CCP) plays a key role in the formation and integrity of casein (CN) micelles. However, limited information is available on the molecular weight (M(w)) of CCP. Recently, we theoretically derived the M(w) of CCP and the objectives of this study were to experimentally determine the M(w) of CCP. We used 2 methods to prepare CCP fractions: skim milk was enzymatically digested with either trypsin or a combination of papain and proteinase enzymes to remove most CN. The CN phosphopeptides are resistant to trypsin hydrolysis. Digestion was carried out in a membrane tube that was dialyzed against the same bulk milk used in sample preparation to remove small peptides and to minimize perturbation of CCP. After digestion, the protein contents of the enzyme-treated milks were 0.92 and 0.36% for the trypsin and papain-proteinase treatments, respectively. Size-exclusion chromatography, coupled with multi-angle laser light scattering, was used to separate the CCP-phosphopeptide fraction from the digested mixture. Simulated milk ultrafiltrate was used as a mobile phase during size-exclusion chromatography separation to try to preserve the integrity of CCP. Size-exclusion chromatography peaks, which had higher Ca and P contents than the baseline, were identified as the likely fractions containing the phosphopeptide-stabilized CCP; this peak eluted with retention times of 100 to approximately 110 min for trypsinated samples. The papain-proteinase treatment caused excessive loss of CN that were needed to stabilize CCP, which resulted in no obvious peak that had elevated Ca and P contents. Debye plots at these retention times indicated that the weight-average M(w) for the fraction prepared by trypsin was 17,450 g/mol. Attempts to estimate the M(w) of the phosphopeptides associated with CCP using sodium dodecyl sulfate-PAGE were not successful, as we did not observe any peptide bands in these gels, presumably because of their low concentration in the isolated, unconcentrated fraction. Assuming that 4 CN phosphopeptides stabilized each CCP and if the M(w) of each of these phosphopeptides was about 2,500 g/mol, then the M(w) of CCP would be around 7,450 g/mol. This experimental value was close to the theoretically-derived M(w) of 4,897 and 9,757 g/mol for tetrahedron and bi-pyramid shaped objects, respectively, when using the brushite form of calcium phosphate. PMID:21700009

Choi, J; Horne, D S; Lucey, J A



Using calcium silicate to regulate the physicochemical and biological properties when using ?-tricalcium phosphate as bone cement.  


?-Tricalcium phosphate (?-TCP) is an osteoconductive material. For this research we have combined it with a low degradation calcium silicate (CS) to enhance its bioactive and osteostimulative properties. To check its effectiveness, a series of ?-TCP/CS composites with different ratios were prepared to make new bioactive and biodegradable biocomposites for bone repair. Regarding the formation of bone-like apatite, the diametral tensile strength as well as the ion release and weight loss of composites were compared both before and after immersions in simulated body fluid (SBF). In addition, we also examined the behavior of human dental pulp cells (hDPCs) cultured on ?-TCP/CS composites. The results show that the apatite deposition ability of the ?-TCP/CS composites improves as the CS content is increased. For composites with more than a 60% CS content, the samples become completely covered by a dense bone-like apatite layer. At the end of the immersion period, weight losses of 24%, 32%, 34%, 38%, 41%, and 45% were observed for the composites containing 0%, 20%, 40%, 80%, 80% and 100% ?-TCP cements, respectively. In addition, the antibacterial activity of CS/?-TCP composite improves as the CS-content is increased. In vitro cell experiments show that the CS-rich composites promote human dental pulp cell (hDPC) proliferation and differentiation. However, when the CS quantity in the composite is less than 60%, the quantity of cells and osteogenesis protein of hDPCs is stimulated by Si released from the ?-TCP/CS composites. The degradation of ?-TCP and the osteogenesis of CS give strong reason to believe that these calcium-based composite cements will prove to be effective bone repair materials. PMID:25175197

Kao, Chia-Tze; Huang, Tsui-Hsien; Chen, Yi-Jyun; Hung, Chi-Jr; Lin, Chi-Chang; Shie, Ming-You



Dietary calcium phosphate promotes Listeria monocytogenes colonization and translocation in rats fed diets containing corn oil but not milk fat.  


Most Gram-positive bacteria are susceptible to the bactericidal action of fatty acids and bile acids. Because dietary calcium phosphate (CaP(i)) lowers the intestinal concentration of these antimicrobial agents, high CaP(i) intake may enhance intestinal colonization of Gram-positive pathogens and the subsequent pathogenesis. In this study, we tested this hypothesis in a rat model using Listeria monocytogenes. Rats were fed diets containing low (20 micromol/g diet) or high (160 micromol/g diet) amounts of CaP(i). Dietary fat was provided as corn oil or milk fat. Rats were orally inoculated with L. monocytogenes. When rats consumed diets containing corn oil, high CaP(i) intake indeed stimulated colonization of L. monocytogenes and increased L. monocytogenes translocation and diarrhea. In addition, supplemental CaP(i) enhanced ex vivo growth of L. monocytogenes in fecal extracts of rats fed corn oil diets, suggesting that high CaP(i) intake decreased a luminal inhibitory factor. The concentrations of bile salts and fatty acids, which were highly listericidal in vitro, were indeed considerably decreased in fecal water of rats in the high calcium corn oil group. Surprisingly, dietary CaP(i) did not affect colonization and translocation of L. monocytogenes in rats fed the milk fat diet, nor did CaP(i) enhance ex vivo growth in fecal extracts. This absence of Listeria stimulation was associated with a lack of effect of dietary CaP(i) on fecal soluble fatty acids. In addition, residual soluble bile salts were higher in rats fed the high CaP(i) milk fat diet compared with the high CaP(i) corn oil diet. These results suggest that the stimulating effect of CaP(i) on L. monocytogenes infection depends on the type of dietary fat consumed. PMID:12042445

Sprong, R Corinne; Hulstein, Marco F E; Van der Meer, Roelof



Salivary flow rate, pH, and concentrations of calcium, phosphate, and sIgA in Brazilian pregnant and non-pregnant women  

Microsoft Academic Search

BACKGROUND: Studies on salivary variables and pregnancy in Latin America are scarce. This study aimed to compare salivary flow rate, pH, and concentrations of calcium, phosphate, and sIgA of unstimulated whole saliva in pregnant and non-pregnant Brazilians. METHODS: Cross-sectional study. Sample was composed by 22 pregnant and 22 non-pregnant women attending the Obstetrics and Gynecology Clinics, São Lucas Hospital, in

Maria I Rockenbach; Sandra A Marinho; Elaine B Veeck; Laura Lindemann; Rosemary S Shinkai



Indirect rapid prototyping of biphasic calcium phosphate scaffolds as bone substitutes: influence of phase composition, macroporosity and pore geometry on mechanical properties  

Microsoft Academic Search

While various materials have been developed for bone substitute and bone tissue engineering applications over the last decades,\\u000a processing techniques meeting the high demands of scaffold shaping are still under development. Individually adapted and mechanically\\u000a optimised scaffolds can be derived from calcium phosphate (CaP-) ceramics via rapid prototyping (RP). In this study, porous\\u000a ceramic scaffolds with a periodic pattern of

M. Schumacher; U. Deisinger; R. Detsch; G. Ziegler



Complementary Information on In Vitro Conversion of Amorphous (Precursor) Calcium Phosphate to Hydroxyapatite from Raman Microspectroscopy and Wide-Angle X-Ray Scattering  

Microsoft Academic Search

In addition to mechanical functions, bones have an essential role in metabolic activity as mineral reservoirs that are able\\u000a to absorb and release ions. Bioapatite, considered the major component in the mineralized part of mammalian bones, is a calcium\\u000a 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

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



Controlled release of rhBMP-2 loaded poly( dl-lactic- co-glycolic acid)\\/calcium phosphate cement composites in vivo  

Microsoft Academic Search

The release kinetics of recombinant human bone morphogenetic protein-2 (rhBMP-2) loaded poly(dl-lactic-co-glycolic acid)\\/calcium phosphate cement (PLGA\\/Ca–P cement) composites were studied in vivo. RhBMP-2 was radiolabeled with 131I and entrapped within PLGA microparticles or adsorbed onto the microparticle surface. PLGA microparticles were prepared of high molecular weight (HMW) PLGA (weight average molecular weight [Mw] 49,100±1700) or low molecular weight (LMW) PLGA

P. Q. Ruhé; O. C. Boerman; F. G. M. Russel; P. H. M. Spauwen; A. G. Mikos; J. A. Jansen



Nucleation and growth of calcium phosphates in the presence of fibrinogen on titanium implants with four potentially bioactive surface preparations. An in vitro study  

Microsoft Academic Search

The aim of this study was to compare the nucleating and crystal growth behaviour of calcium phosphates on four types of potentially\\u000a bioactive surfaces, using the simulated body fluid (SBF) model with added fibrinogen. Blasted titanium discs were modified\\u000a by alkali and heat treatment, anodic oxidation, fluoride treatment, or hydroxyapatite coating. The discs were immersed in\\u000a SBF with fibrinogen for

Anna Arvidsson; Fredrik Currie; Per Kjellin; Young-Taeg Sul; Victoria Stenport



Acid Resistance of Enamel Subsurface Lesions Remineralized by a Sugar-Free Chewing Gum Containing Casein Phosphopeptide-Amorphous Calcium Phosphate  

Microsoft Academic Search

The aim of this clinical study was to investigate the acid resistance of enamel lesions remineralized in situ by a sugar-free chewing gum containing casein phosphopeptide-amorphous calcium phosphate nanocomplexes (CPP-ACP: Recaldent™). The study utilized a double-blind, randomized, crossover design with two treatments: (i) sugar-free gum containing 18.8 mg of CPP-ACP, and (ii) sugar-free gum not containing CPP-ACP as control. Subjects

Y. Iijima; F. Cai; P. Shen; G. Walker; C. Reynolds; E. C. Reynolds



Effects of Calcium Phosphate Nanoparticles on Ca-PO4 Composite  

PubMed Central

Nano-particles of dicalcium phosphate anhydrous (DCPA) were synthesized for the first time. The objectives of this study were to incorporate DCPA nano-particles into resin for Ca-PO4 release to combat dental caries, and to investigate the filler level effects. Nano-DCPA and nano-silica-fused silicon nitride whiskers at a 1:1 ratio were used at filler mass fractions of 0–75%. The flexural strengths in MPa (mean ± SD; n = 6) of DCPA-whisker composites ranged from (106 ± 39) at 0% fillers to (114 ± 23) at 75% fillers, similar to (112 ± 22) of a non-releasing composite (TPH) (p > 0.1). The composite with 75% fillers in a NaCl solution (133 mmol/L, pH = 7.4, 37°C) yielded a Ca concentration of (0.65 ± 0.02) mmol/L and PO4 of (2.29 ± 0.07) mmol/L. Relationships were established between ion-release and DCPA volume fraction VDCPA: Ca = 4.46 VDCPA1.6, and PO4 = 66.9 VDCPA2.6. Nano-DCPA-whisker composites had high strength and released high levels of Ca-PO4 requisite for remineralization. These new nano-composites could provide the needed combination of stress-bearing and caries-inhibiting capabilities. PMID:17384036

Xu, H.H.K.; Weir, M.D.; Sun, L.; Takagi, S.; Chow, L.C.



Vertebroplasty using bisphosphonate-loaded calcium phosphate cement in a standardized vertebral body bone defect in an osteoporotic sheep model.  


In the context of bone regeneration in an osteoporotic environment, the present study describes the development of an approach based on the use of calcium phosphate (CaP) bone substitutes that can promote new bone formation and locally deliver in situ bisphosphonate (BP) directly at the implantation site. The formulation of a CaP material has been optimized by designing an injectable apatitic cement that (i) hardens in situ despite the presence of BP and (ii) provides immediate mechanical properties adapted to clinical applications in an osteoporotic environment. We developed a large animal model for simulating lumbar vertebroplasty through a two-level lateral corpectomy on L3 and L4 vertebrae presenting a standardized osteopenic bone defect that was filled with cements. Both 2-D and 3-D analysis of microarchitectural parameters demonstrated that implantation of BP-loaded cement in such vertebral defects positively influenced the microarchitecture of the adjacent trabecular bone. This biological effect was dependent on the distance from the implant, emphasizing the in situ effect of the BP and its release from the cement. As a drug device combination, this BP-containing apatitic cement shows good promise as a local approach for the prevention of osteoporotic vertebral fractures through percutaneous vertebroplasty procedures. PMID:25050773

Verron, Elise; Pissonnier, Marie-Line; Lesoeur, Julie; Schnitzler, Verena; Fellah, Borhane Hakim; Pascal-Moussellard, Hugues; Pilet, Paul; Gauthier, Olivier; Bouler, Jean-Michel



Poly(ethylene oxide)-b-poly(3-sulfopropyl methacrylate) Block Copolymers for Calcium Phosphate Mineralization and Biofilm Inhibition.  


Poly(ethylene oxide) (PEO) has long been used as an additive in toothpaste, partly because it reduces biofilm formation on teeth. It does not, however, reduce the formation of dental calculus or support the remineralization of dental enamel or dentine. The present article describes the synthesis of new block copolymers on the basis of PEO and poly(3-sulfopropyl methacrylate) blocks using atom transfer radical polymerization. The polymers have very large molecular weights (over 10(6) g/mol) and are highly water-soluble. They delay the precipitation of calcium phosphate from aqueous solution but, upon precipitation, lead to relatively monodisperse hydroxyapatite (HAP) spheres. Moreover, the polymers inhibit the bacterial colonization of human enamel by Streptococcus gordonii, a pioneer bacterium in oral biofilm formation, in vitro. The formation of well-defined HAP spheres suggests that a polymer-induced liquid precursor phase could be involved in the precipitation process. Moreover, the inhibition of bacterial adhesion suggests that the polymers could be utilized in caries prevention. PMID:25230392

Mai, Tobias; Rakhmatullina, Ekaterina; Bleek, Katrin; Boye, Susanne; Yuan, Jiayin; Völkel, Antje; Gräwert, Marlies; Cheaib, Zeinab; Eick, Sigrun; Günter, Christina; Lederer, Albena; Lussi, Adrian; Taubert, Andreas



Nanocomposites of high-density polyethylene with amorphous calcium phosphate: in vitro biomineralization and cytocompatibility of human mesenchymal stem cells.  


Polyethylene is widely used as a component of implants in medicine. Composites made of high-density polyethylene (HDPE) containing different amounts of amorphous calcium phosphate nanoparticles were investigated concerning their in vitro biomedical performance. The nanoparticles were produced by flame spray synthesis and extruded with HDPE, the latter complying with Food and Drug Administration regulations. Mechanical properties such as Young's modulus and contact angle as well as in vitro biomineralization of the nanocomposites hot-pressed into thin films were evaluated. The deposition of a hydroxyapatite layer occurred upon immersion in simulated body fluid. Additionally, a cell culture study with human mesenchymal stem cells for six weeks allowed a primary assessment of the cytocompatibility. Viability assays (alamarBlue and lactate dehydrogenase detection) proved the absence of cytotoxic effects of the scaffolds. Microscopic images after hematoxylin and eosin staining confirmed typical growth and morphology. A preliminary experiment analyzed the alkaline phosphatase activity after two weeks. These findings motivate further investigations on bioactive HDPE in bone tissue engineering. PMID:22972023

Hild, Nora; Fuhrer, Roland; Mohn, Dirk; Bubenhofer, Stephanie B; Grass, Robert N; Luechinger, Norman A; Feldman, Kirill; Dora, Claudio; Stark, Wendelin J



The influence of cellular source on periodontal regeneration using calcium phosphate coated polycaprolactone scaffold supported cell sheets.  


Cell-based therapy is considered a promising approach to achieving predictable periodontal regeneration. In this study, the regenerative potential of cell sheets derived from different parts of the periodontium (gingival connective tissue, alveolar bone and periodontal ligament) were investigated in an athymic rat periodontal defect model. Periodontal ligament (PDLC), alveolar bone (ABC) and gingival margin-derived cells (GMC) were obtained from human donors. The osteogenic potential of the primary cultures was demonstrated in vitro. Cell sheets supported by a calcium phosphate coated melt electrospun polycaprolactone (CaP-PCL) scaffold were transplanted to denuded root surfaces in surgically created periodontal defects, and allowed to heal for 1 and 4 weeks. The CaP-PCL scaffold alone was able to promote alveolar bone formation within the defect after 4 weeks. The addition of ABC and PDLC sheets resulted in significant periodontal attachment formation. The GMC sheets did not promote periodontal regeneration on the root surface and inhibited bone formation within the CaP-PCL scaffold. In conclusion, the combination of either PDLC or ABC sheets with a CaP-PCL scaffold could promote periodontal regeneration, but ABC sheets were not as effective as PDLC sheets in promoting new attachment formation. PMID:24120045

Dan, Hongxia; Vaquette, Cédryck; Fisher, Anthony G; Hamlet, Stephen M; Xiao, Yin; Hutmacher, Dietmar W; Ivanovski, Saso



Ibuprofen-loaded calcium phosphate granules: combination of innovative characterization methods to relate mechanical strength to drug location.  


This paper studies the impact of the location of a drug substance on the physicochemical and mechanical properties of two types of calcium phosphate granules loaded with seven different contents of ibuprofen, ranging from 1.75% to 46%. These implantable agglomerates were produced by either low or high shear granulation. Unloaded Mi-Pro pellets presented higher sphericity and mechanical properties, but were slightly less porous than Kenwood granules (57.7% vs 61.2%). Nevertheless, the whole expected quantity of ibuprofen could be integrated into both types of granules. A combination of surface analysis, using near-infrared (NIR) spectroscopy coupling chemical imaging, and pellet porosity, by mercury intrusion measurements, allowed ibuprofen to be located. It was shown that, from 0% to 22% drug content, ibuprofen deposited simultaneously on the granule surface, as evidenced by the increase in surface NIR signal, and inside the pores, as highlighted by the decrease in pore volume. From 22%, porosity was almost filled, and additional drug substance coated the granule surfaces, leading to a large increase in the surface NIR signal. This coating was more regular for Mi-Pro pellets owing to their higher sphericity and greater surface deposition of drug substance. Unit crush tests using a microindenter revealed that ibuprofen loading enhanced the mechanical strength of granules, especially above 22% drug content, which was favorable to further application of the granules as a bone defect filler. PMID:19654055

Chevalier, E; Viana, M; Cazalbou, S; Makein, L; Dubois, J; Chulia, D



Stretch of contracting cardiac muscle abruptly decreases the rate of phosphate release at high and low calcium.  


The contractile performance of the heart is linked to the energy that is available to it. Yet, the heart needs to respond quickly to changing demands. During diastole, the heart fills with blood and the heart chambers expand. Upon activation, contraction of cardiac muscle expels blood into the circulation. Early in systole, parts of the left ventricle are being stretched by incoming blood, before contraction causes shrinking of the ventricle. We explore here the effect of stretch of contracting permeabilized cardiac trabeculae of the rat on the rate of inorganic phosphate (P(i)) release resulting from ATP hydrolysis, using a fluorescent sensor for P(i) with millisecond time resolution. Stretch immediately reduces the rate of P(i) release, an effect observed both at full calcium activation (32 ?mol/liter of Ca(2+)), and at a physiological activation level of 1 ?mol/liter of Ca(2+). The results suggest that stretch redistributes the actomyosin cross-bridges toward their P(i)-containing state. The redistribution means that a greater fraction of cross-bridges will be poised to rapidly produce a force-generating transition and movement, compared with cross-bridges that have not been subjected to stretch. At the same time stretch modifies the P(i) balance in the cytoplasm, which may act as a cytoplasmic signal for energy turnover. PMID:22692210

Mansfield, Catherine; West, Tim G; Curtin, Nancy A; Ferenczi, Michael A



Contact nanofatigue shows crack growth in amorphous calcium phosphate on Ti, Co-Cr and Stainless steel.  


Fatigue testing of load-bearing coated implants is usually very time-consuming and so a new contact nanofatigue test using a nanoindenter has been evaluated. A cube corner indenter provided the fastest indication of failure, through crack formation, compared to a spherical indenter. Contact nanofatigue was performed on a sintered hydroxyapatite and then on amorphous calcium phosphate splats produced on titanium, stainless steel and Co-Cr surfaces, made either at room temperature or on 250°C preheated surfaces. Sintered hydroxyapatite showed continual plastic deformation, but this is not that apparent for splats on metal surfaces. Substrate preheating was found to induce cracking in splats, explained by greater thermal residual stresses. Endurance during contact nanofatigue, measured as time to crack formation, was the lowest for splats on titanium followed by Co-Cr and stainless steel. The splat on titanium showed both cracking and plastic deformation during testing. Good agreement has been reached with previous studies with cracking directed to the substrate without splat delamination. Contact nanofatigue with the nanoindenter easily and quickly identifies cracking events that previously required detection with acoustic emission, and shows good feasibility for mechanical testing of discs and splats produced by thermal spraying, spray forming, laser-ablation, aerosol jet and ink jet printing. PMID:23164945

Saber-Samandari, Saeed; Gross, Karlis A



In vitro and in vivo evaluation of a biphasic calcium phosphate scaffold coated with a native allogeneic extracellular matrix.  


This study evaluated the osteogenic properties of biphasic calcium phosphate (BCP) scaffolds coated with extracellular matrix (ECM) derived in vitro from allogeneic mesenchymal stem cells (MSCs). BCP/ECM and plain BCP scaffolds were seeded with MSCs from F344 rats and cultured in osteoinductive medium. At 1, 7, 14 and 21 days post-seeding, assessments were made of cellularity, alkaline phosphatase (ALP) activity and RNA expression of osteocalcin, bone sialoprotein and osteopontin. MSCs seeded on BCP/ECM scaffolds exhibited significantly higher cellularity, ALP activity and transcript levels for the three genes examined. For the in vivo study, BCP/ECM and BCP scaffolds with and without MSCs were implanted subcutaneously into F344 rats. After four weeks of implantation, the extent of new bone formation and tissue response were examined by histology and histomorphometry; histological evidence showed that the seeded cell scaffolds induced new bone formation at the ectopic site and a higher average ratio of bone in the cell-seeded BCP/ECM scaffold group. Results suggest that modification of the BCP scaffold with an in vitro generated allogeneic ECM can effectively enhance osteogenic properties in vitro and in vivo. PMID:22730247

Zhou, Shifeng; Zhao, Wei; Liu, Xiaoqi; Liu, Guodan; Xi, Chunyang; Wang, Xintao; Yan, Jinglong



Enhanced healing of rabbit segmental radius defects with surface-coated calcium phosphate cement/bone morphogenetic protein-2 scaffolds.  


Large osseous defects remain a difficult clinical problem in orthopedic surgery owing to the limited effective therapeutic options, and bone morphogenetic protein-2 (BMP-2) is useful for its potent osteoinductive properties in bone regeneration. Here we build a strategy to achieve prolonged duration time and help inducting new bone formation by using water-soluble polymers as a protective film. In this study, calcium phosphate cement (CPC) scaffolds were prepared as the matrix and combined with sodium carboxymethyl cellulose (CMC-Na), hydroxypropylmethyl cellulose (HPMC), and polyvinyl alcohol (PVA) respectively to protect from the digestion of rhBMP-2. After being implanted in the mouse thigh muscles, the surface-modified composite scaffolds evidently induced ectopic bone formation. In addition, we further evaluated the in vivo effects of surface-modified scaffolds in a rabbit radius critical defect by radiography, three dimensional micro-computed tomographic (?CT) imaging, synchrotron radiation-based micro-computed tomographic (SR?CT) imaging, histological analysis, and biomechanical measurement. The HPMC-modified CPC scaffold was regarded as the best combination for segmental bone regeneration in rabbit radius. PMID:25280712

Wu, Yi; Hou, Juan; Yin, ManLi; Wang, Jing; Liu, ChangSheng



Protein coated microcrystals formulated with model antigens and modified with calcium phosphate exhibit enhanced phagocytosis and immunogenicity?  

PubMed Central

Protein-coated microcrystals (PCMCs) were investigated as potential vaccine formulations for a range of model antigens. Presentation of antigens as PCMCs increased the antigen-specific IgG responses for all antigens tested, compared to soluble antigens. When compared to conventional aluminium-adjuvanted formulations, PCMCs modified with calcium phosphate (CaP) showed enhanced antigen-specific IgG responses and a decreased antigen-specific IgG1:IgG2a ratio, indicating the induction of a more balanced Th1/Th2 response. The rate of antigen release from CaP PCMCs, in vitro, decreased strongly with increasing CaP loading but their immunogenicity in vivo was not significantly different, suggesting the adjuvanticity was not due to a depot effect. Notably, it was found that CaP modification enhanced the phagocytosis of fluorescent antigen-PCMC particles by J774.2 murine monocyte/macrophage cells compared to soluble antigen or soluble PCMCs. Thus, CaP PCMCs may provide an alternative to conventional aluminium-based acellular vaccines to provide a more balanced Th1/Th2 immune response. PMID:24120484

Jones, Sarah; Asokanathan, Catpagavalli; Kmiec, Dorota; Irvine, June; Fleck, Roland; Xing, Dorothy; Moore, Barry; Parton, Roger; Coote, John



Direct and interactive influence of explanatory variables on properties of a calcium phosphate cement for vertebral body augmentation.  


We used the response surface methodology to investigate the direct and interactive effects of three explanatory variables on three properties of a calcium phosphate cement (CPC) for use in vertebroplasty (VP) and balloon kyphoplasty (BKP). The variables were poly(ethylene glycol) content of the cement liquid (PEG), powder-to-liquid ratio (PLR), and the amount of Na2HPO4 added to an aqueous solution of 4 wt/wt% poly(acrylic acid) (as the cement liquid) (SPC). The properties were injectability (I), final setting time (F), and 5-day compressive strength (UCS). We found that (1) there was an interactive effect between the variables on I and F but not on UCS; (2) the maximum I (98%) was obtained with PEG = 20 wt/wt% and PLR = 2 g mL(-1); (3) F = 15 min (the proposed optimum value for a CPC for use in VP and BKP) was obtained with PEG = 4 wt/wt% and PLR = 2.9 g mL(-1); and (4) the maximum UCS (39 MPa) was obtained with SPC = 0 and PLR = 3.5 g mL(-1). PMID:24046084

Werdofa, Daniel M; Lewis, Gladius



Bone healing response to a synthetic calcium sulfate/?-tricalcium phosphate graft material in a sheep vertebral body defect model  

PubMed Central

Abstract The introduction of a material able to promote osteogenesis and remodelling activity in a clinically relevant time frame in vertebroplasty and kyphoplasty procedures may have patient benefit. We report the in-vivo performance of a biphasic synthetic bone graft material (Genex Paste, Biocomposites, UK) [test material], composed of calcium sulfate and ?-tricalcium phosphate, implanted into a sheep vertebral defect model. Cavities drilled into 4 adjacent vertebrae (L2 to L5) of 24 skeletally mature sheep were; (1) filled with the test material; (2) filled with commercially available polymethylmethacrylate [PMMA] cement; (3) remained empty [sham]. Analysis was performed immediately after implantation and at 8, 16, and 36 weeks post implantation. Sites were evaluated for bone growth with microCT analysis, histological examination, and mechanical testing under compression. The test material exhibited an improved tissue response over the PMMA, indicating a superior biological tolerance. MicroCT and histology indicated marked osteoregenerative capacity of the test material when compared with sham and the PMMA. The percentage of new bone formation was higher for the test material than sham at 16 and 36 weeks post implantation, with bone regeneration almost complete at 36 weeks in this group. Resorption of test material and the integration into new bone tissue were demonstrated. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012. PMID:22847979

Yang, H L; Zhu, X S; Chen, L; Chen, C M; Mangham, D C; Coulton, L A; Aiken, S S



Poly(trimethylene carbonate) and biphasic calcium phosphate composites for orbital floor reconstruction: a feasibility study in sheep.  


In the treatment of orbital floor fractures, bone is ideally regenerated. The materials currently used for orbital floor reconstruction do not lead to the regeneration of bone. Our objective was to render polymeric materials based on poly(trimethylene carbonate) (PTMC) osteoinductive, and to evaluate their suitability for use in orbital floor reconstruction. For this purpose, osteoinductive biphasic calcium phosphate (BCP) particles were introduced into a polymeric PTMC matrix. Composite sheets containing 50 wt% BCP particles were prepared. Also laminates with poly(D,L-lactide) (PDLLA) were prepared by compression moulding PDLLA films onto the composite sheets. After sterilisation by gamma irradiation, the sheets were used to reconstruct surgically-created orbital floor defects in sheep. The bone inducing potential of the different implants was assessed upon intramuscular implantation. The performance of the implants in orbital floor reconstruction was assessed by cone beam computed tomography (CBCT). Histological evaluation revealed that in the orbital and intramuscular implantations of BCP containing specimens, bone formation could be seen after 3 and 9 months. Analysis of the CBCT scans showed that the composite PTMC sheets and the laminated composite sheets performed well in orbital floor reconstruction. It is concluded that PTMC/BCP composites and PTMC/BCP composites laminated with PDLLA have osteoinductive properties and seem suitable for use in orbital floor reconstruction. PMID:24488822

van Leeuwen, A C; Yuan, H; Passanisi, G; van der Meer, J W; de Bruijn, J D; van Kooten, T G; Grijpma, D W; Bos, R R M



A novel injectable, cohesive and toughened Si-HPMC (silanized-hydroxypropyl methylcellulose) composite calcium phosphate cement for bone substitution.  


This study reports on the incorporation of the self-setting polysaccharide derivative hydrogel (silanized-hydroxypropyl methylcellulose, Si-HPMC) into the formulation of calcium phosphate cements (CPCs) to develop a novel injectable material for bone substitution. The effects of Si-HPMC on the handling properties (injectability, cohesion and setting time) and mechanical properties (Young's modulus, fracture toughness, flexural and compressive strength) of CPCs were systematically studied. It was found that Si-HPMC could endow composite CPC pastes with an appealing rheological behavior at the early stage of setting, promoting its application in open bone cavities. Moreover, Si-HPMC gave the composite CPC good injectability and cohesion, and reduced the setting time. Si-HPMC increased the porosity of CPCs after hardening, especially the macroporosity as a result of entrapped air bubbles; however, it improved, rather than compromised, the mechanical properties of composite CPCs, which demonstrates a strong toughening and strengthening effect. In view of the above, the Si-HPMC composite CPC may be particularly promising as bone substitute material for clinic application. PMID:24657196

Liu, Weizhen; Zhang, Jingtao; Rethore, Gildas; Khairoun, Khalid; Pilet, Paul; Tancret, Franck; Bouler, Jean-Michel; Weiss, Pierre



Biomedical nanocomposites of poly(lactic acid) and calcium phosphate hybridized with modified carbon nanotubes for hard tissue implants.  


Degradable polymer-based materials are attractive in orthopedics and dentistry as an alternative to metallic implants for use as bone fixatives. Herein, a degradable polymer poly(lactic acid) (PLA) was combined with novel hybrid nanopowder of carbon nanotubes (CNTs)-calcium phosphate (CP) for this application. In particular, CNTs-CP hybrid nanopowders (0.1 and 0.25% CNTs) were prepared from the solution of ionically modified CNTs (mCNTs), which was specifically synthesized to be well-dispersed and thus to effectively adsorb onto the CP nanoparticles. The mCNTs-CP hybrid nanopowders were then mixed with PLA (up to 50%) to produce mCNTs-CP-PLA nanocomposites. The mechanical tensile strength of the nanocomposites was significantly improved by the addition of mCNTs-CP hybrid nanopowders. Moreover, nanocomposites containing low concentration of mCNTs (0.1%) showed significantly stimulated biological responses including cell proliferation and osteoblastic differentiation in terms of gene and protein expressions. Based on this study, the addition of novel mCNT-CP hybrid nanopowders to PLA biopolymer may be considered a new material choice for developing hard tissue implants. PMID:21591250

Lee, Hae-Hyoung; Sang Shin, Ueon; Lee, Jae-Ho; Kim, Hae-Won



Formulation of Newcastle disease virus coupled calcium phosphate nanoparticles: an effective strategy for oculonasal delivery to chicken.  


In this report, calcium phosphate (CaP) nanoparticles were synthesized by continuous flow method using ?-cyclodextrin (?-CD) as a medium and functionalized with amino propyl triethoxy silane (APTES). The blood biocompatibility of the nanoparticles was assessed using the whole blood haemolysis, erythrocytes haemolysis and erythrocyte aggregation tests. Based on the results, we found that the synthesized ?-CD-CaP nanoparticles did not cause any remarkable toxic effect. The 5-dimethylthiazol-2-yl-2, 5-diphenyltetrazolium bromide (MTT) assay of chicken peripheral blood mononucleated cells (PBMCs) incubated with these nanoparticles indicated that these particles did not exert any significant cytotoxicity. The aminosilane functional group modified ?-CD-CaP was used as tool for coupling of Newcastle disease virus (NDV). The NDV conjugated nanoparticles were confirmed by using Fourier transformed infrared spectroscopy, X-ray diffraction patterns, Raman spectroscopy differential scanning calorimetry and energy-dispersive X-ray spectroscopy. Immunogenicity trials in chickens proved that ?-CD-CaP-NDV used as a vaccine was better than the commercial vaccine when given oculonasally during the first 2 weeks post vaccination. The birds vaccinated with the above nano-NDV vaccine were completely protected against virulent NDV challenge. This study confirms that the oculonasal ?-CD-CaP-NDV delivery of vaccines is a potential method for enhancing the immune responses of existing commercial vaccines. PMID:24441177

Viswanathan, Kaliyaperumal; Gopinath, Vadivel Ponnuswamy; Raj, Gopal Dhinakar