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1

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

1998-01-01

2

Calcium Phosphate Nanoparticle Adjuvant  

Microsoft Academic Search

Vaccination to protect against human infectious diseases may be enhanced by using adjuvants that can selec- tively stimulate immunoregulatory responses. In a murine model, a novel nanoparticulate adjuvant composed of calcium phosphate (CAP) was compared with the commonly used aluminum (alum) adjuvants for its ability to induce immunity to herpes simplex virus type 2 (HSV-2) and Epstein-Barr virus (EBV) infections.

QING HE; ALAINA R. MITCHELL; STACY L. JOHNSON; CLAUS WAGNER-BARTAK; TULIN MORCOL; STEVE J. D. BELL

2000-01-01

3

Calcium Phosphates and Human Beings  

NASA Astrophysics Data System (ADS)

This article describes the general importance of calcium phosphates for human beings. The basic information on the structure and chemical properties of the biologically relevant calcium phosphates is summarized. Basic facts on the natural occurrence and the industrial use of natural calcium phosphates are discussed. Fundamental details on the presence of calcium phosphates in major calcified tissues (bones and teeth) of humans and mammals, as well as on biomaterials made of calcium phosphates are discussed. The article will be of value for chemistry teachers for expansion of their general background and point the students' attention to the rapidly growing topic of bone-substituting biomaterials.

Dorozhkin, Sergey V.

2006-05-01

4

Reaction between Monocalcium Phosphate and Calcium Carbonate  

Microsoft Academic Search

WHEN an acid phosphate is applied to a soil containing calcium carbonate or mixed with liming material a reaction will occur leading to the formation of more basic phosphates such as dicalcium phosphate, octocalcium phosphate and hydroxyapatite.

S. Larsen; D. J. Parton; Inga-Lisa Svensson

1963-01-01

5

Doped nanocrystalline calcium carbonate phosphates  

Microsoft Academic Search

The formation of nanocrystalline calcium carbonate phosphates doped with Fe2+, Mg2, Zn2+, K+, Si4+, and Mn2+ has been studied by X-ray diffraction, IR spectroscopy, differential thermal analysis, and energy dispersive X-ray fluorescence\\u000a analysis. The results indicate that the synthesis involves the formation of hydroxy carbonate complexes from the three calcium\\u000a carbonate polymorphs (calcite, vaterite, and aragonite) in a solution of

L. F. Koroleva

2010-01-01

6

21 CFR 182.8217 - Calcium phosphate.  

Code of Federal Regulations, 2012 CFR

...CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2012-04-01

7

21 CFR 182.8217 - Calcium phosphate.  

Code of Federal Regulations, 2010 CFR

...CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2010-04-01

8

21 CFR 182.8217 - Calcium phosphate.  

Code of Federal Regulations, 2011 CFR

...CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2011-04-01

9

21 CFR 182.8217 - Calcium phosphate.  

Code of Federal Regulations, 2014 CFR

...CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2014-04-01

10

21 CFR 582.5217 - Calcium phosphate.  

Code of Federal Regulations, 2013 CFR

...RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2013-04-01

11

21 CFR 582.5217 - Calcium phosphate.  

Code of Federal Regulations, 2010 CFR

...RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2010-04-01

12

21 CFR 182.1217 - Calcium phosphate.  

Code of Federal Regulations, 2013 CFR

...GENERALLY RECOGNIZED AS SAFE Multiple Purpose GRAS Food Substances § 182.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2013-04-01

13

21 CFR 182.1217 - Calcium phosphate.  

Code of Federal Regulations, 2012 CFR

...GENERALLY RECOGNIZED AS SAFE Multiple Purpose GRAS Food Substances § 182.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2012-04-01

14

21 CFR 582.5217 - Calcium phosphate.  

Code of Federal Regulations, 2014 CFR

...RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2014-04-01

15

21 CFR 582.1217 - Calcium phosphate.  

Code of Federal Regulations, 2014 CFR

...GENERALLY RECOGNIZED AS SAFE General Purpose Food Additives § 582.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2014-04-01

16

21 CFR 182.1217 - Calcium phosphate.  

Code of Federal Regulations, 2014 CFR

...GENERALLY RECOGNIZED AS SAFE Multiple Purpose GRAS Food Substances § 182.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2014-04-01

17

21 CFR 582.5217 - Calcium phosphate.  

Code of Federal Regulations, 2011 CFR

...RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2011-04-01

18

21 CFR 582.1217 - Calcium phosphate.  

Code of Federal Regulations, 2013 CFR

...GENERALLY RECOGNIZED AS SAFE General Purpose Food Additives § 582.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2013-04-01

19

21 CFR 582.1217 - Calcium phosphate.  

Code of Federal Regulations, 2012 CFR

...GENERALLY RECOGNIZED AS SAFE General Purpose Food Additives § 582.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2012-04-01

20

21 CFR 582.1217 - Calcium phosphate.  

Code of Federal Regulations, 2011 CFR

...GENERALLY RECOGNIZED AS SAFE General Purpose Food Additives § 582.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2011-04-01

21

21 CFR 182.1217 - Calcium phosphate.  

Code of Federal Regulations, 2010 CFR

...GENERALLY RECOGNIZED AS SAFE Multiple Purpose GRAS Food Substances § 182.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2010-04-01

22

21 CFR 582.5217 - Calcium phosphate.  

Code of Federal Regulations, 2012 CFR

...RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2012-04-01

23

21 CFR 582.1217 - Calcium phosphate.  

Code of Federal Regulations, 2010 CFR

...GENERALLY RECOGNIZED AS SAFE General Purpose Food Additives § 582.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2010-04-01

24

21 CFR 182.8217 - Calcium phosphate.  

Code of Federal Regulations, 2013 CFR

...CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2013-04-01

25

21 CFR 182.1217 - Calcium phosphate.  

Code of Federal Regulations, 2011 CFR

...GENERALLY RECOGNIZED AS SAFE Multiple Purpose GRAS Food Substances § 182.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b) Conditions of use. This substance is generally recognized as...

2011-04-01

26

Injectability of calcium phosphate pastes.  

PubMed

A theoretical model was developed to assess ways to improve the injectability of calcium phosphate pastes. The theoretical results were then compared to experimental data obtained on calcium phosphate slips. The theoretical approach predicted that the injectability of a cement paste could be improved by an increase of the liquid-to-powder ratio, and a decrease of the particle size and the plastic limit (PL) of the powder. The theoretical results were confirmed by experimental data. Interestingly, an increase of the viscosity of the mixing liquid with small additions of xanthan had a positive effect on the paste injectability. This effect could be due to a change of the PL of the powder or to the lubricating effect of the polymer. PMID:15522757

Bohner, Marc; Baroud, Gamal

2005-05-01

27

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

1970-01-01

28

Development of Calcium Phosphate-gelatin Composites  

NSDL National Science Digital Library

This study was performed to investigate and develop a biomaterial of calcium phosphate/gelatin to be used as an injectable bone substitute. Gelatin is an ideal medium to transfer calcium phosphate because it is biocompatible, biodegradable, cheap, and can be injected without open surgery. The interaction of calcium and phosphate with gelatin will be studied; these include solubility, titration and precipitation. The calcium phosphate/gelatin composites will be characterized by chemical analysis, x-ray powder diffraction, and infrared spectroscopy. The mechanical strength, such as DTS, will also be investigated.

Hwang, Jesse

2005-01-01

29

Application of Calcium Phosphate Materials in Dentistry  

PubMed Central

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

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

2013-01-01

30

Application of calcium phosphate materials in dentistry.  

PubMed

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

Al-Sanabani, Jabr S; Madfa, Ahmed A; Al-Sanabani, Fadhel A

2013-01-01

31

21 CFR 182.6215 - Monobasic calcium phosphate.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Monobasic calcium phosphate. 182.6215 Section 182...Sequestrants 1 § 182.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2014-04-01

32

21 CFR 582.6215 - Monobasic calcium phosphate.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Monobasic calcium phosphate. 582.6215 Section 582...Sequestrants 2 § 582.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2014-04-01

33

21 CFR 182.6215 - Monobasic calcium phosphate.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Monobasic calcium phosphate. 182.6215 Section 182...Sequestrants 1 § 182.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2013-04-01

34

21 CFR 182.6215 - Monobasic calcium phosphate.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Monobasic calcium phosphate. 182.6215 Section 182...Sequestrants 1 § 182.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2012-04-01

35

21 CFR 582.6215 - Monobasic calcium phosphate.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Monobasic calcium phosphate. 582.6215 Section 582...Sequestrants 2 § 582.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2013-04-01

36

21 CFR 182.6215 - Monobasic calcium phosphate.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Monobasic calcium phosphate. 182.6215 Section 182...Sequestrants 1 § 182.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2011-04-01

37

21 CFR 582.6215 - Monobasic calcium phosphate.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Monobasic calcium phosphate. 582.6215 Section 582...Sequestrants 2 § 582.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2011-04-01

38

21 CFR 582.6215 - Monobasic calcium phosphate.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Monobasic calcium phosphate. 582.6215 Section 582...Sequestrants 2 § 582.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2012-04-01

39

21 CFR 582.6215 - Monobasic calcium phosphate.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Monobasic calcium phosphate. 582.6215 Section 582...Sequestrants 2 § 582.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of...

2010-04-01

40

21 CFR 182.6215 - Monobasic calcium phosphate.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 true Monobasic calcium phosphate. 182.6215 Section 182.6215 Food...Sequestrants 1 § 182.6215 Monobasic calcium phosphate. (a) Product. Monobasic calcium phosphate. (b) Conditions of use. This...

2010-04-01

41

Effects of Nickel on Calcium Phosphate Formation  

NASA Astrophysics Data System (ADS)

We have investigated the effect of nickel on calcium phosphate formation from aqueous solutions. The calcium phosphates prepared under different reaction conditions (pH, temperature, and nickel concentration) were characterized by X-ray diffraction, FTIR spectroscopy, and chemical analysis. The apatite compounds were also studied thermogravimetrically. From the combined results of the techniques employed we have determined that nickel favors the formation of brushite and amorphous calcium phosphate. We have found, as well, that the presence of nickel in the solution inhibits calcium hydroxyapatite (CaHAP) and octacalcium phosphate formation. However in the synthesis performed at basic pH and 95°C the apatitic phase (HAP) could be obtained. The present results suggest that the presence of nickel may modify the precipitation of oral calcium phosphate.

Guerra-López, J.; González, R.; Gómez, A.; Pomés, R.; Punte, G.; Della Védova, C. O.

2000-05-01

42

Calcium metal to synthesize amorphous or cryptocrystalline calcium phosphates A. Cuneyt Tas  

E-print Network

Calcium metal to synthesize amorphous or cryptocrystalline calcium phosphates A. Cuneyt Tas Accepted 30 January 2012 Available online 10 February 2012 Keywords: Amorphous Cryptocrystalline Calcium Metal Phosphate Synthesis Metallic calcium was never used before as the calcium source in synthesizing

Tas, A. Cuneyt

43

Calcium and Phosphate Control by Dialysis Treatments  

Microsoft Academic Search

Calcium and phosphate changes, besides their involvement in bone disease, have been claimed to also be involved in the increased vascular morbidity and mortality of dialysis patients. Even after the recent advances of therapeutic options, their control still remains a challenging problem. Dialysis treatment is a basic approach to the control of these two electrolytes. Calcium control by dialysis is

Piergiorgio Messa; Roberta Cerutti; Brigida Brezzi; Carlo Alfieri; Mario Cozzolino

2009-01-01

44

Evaluation of calcium phosphates and experimental calcium phosphate bone cements using osteogenic cultures.  

PubMed

In this study, rat bone marrow cells (RBM) were used to evaluate two biodegradable calcium phosphate bone cements and bioactive calcium phosphate ceramics. The substances investigated were: two novel calcium phosphate cements, Biocement F and Biocement H, tricalcium phosphate (TCP), surface-modified alpha-tricalcium phosphate [TCP (s)] and a rapid resorbable calcium phosphate ceramic consisting of CaKPO(4) (sample code R5). RBM cells were cultured on disc-shaped test substrates for 14 days. The culture medium was changed daily and also examined for calcium, phosphate, and potassium concentrations. Specimens were evaluated using light microscopy, and morphometry of the cell-covered substrate surface, scanning electron microscopy, and energy dispersive X-ray analysis and morphometry of the cell-covered substrate surface. Areas of mineralization were identified by tetracyline labeling. Except for R 5, rat bone-marrow cells attached and grew on all substrate surfaces. Of the different calcium phosphate materials tested, TCP and TCP (s) facilitated osteoblast growth and extracellular matrix elaboration to the highest degree, followed by Biocements H and F. The inhibition of cell growth encountered with R 5 seems to be related to its high phosphate and potassium ion release. PMID:11007618

Knabe, C; Driessens, F C; Planell, J A; Gildenhaar, R; Berger, G; Reif, D; Fitzner, R; Radlanski, R J; Gross, U

2000-12-01

45

Physiology of Calcium and Phosphate Metabolism: 1980 Refresher Course, Syllabus.  

ERIC Educational Resources Information Center

This syllabus reviews information concerning calcium and phosphate regulation. Topics of interest include the following: calcium metabolism, phosphorus metabolism, bone, parathyroid hormone, calcitonin, and vitamin D. (CS)

Knox, Franklyn G., Ed.

1980-01-01

46

Calcium phosphate scaffolds for bone repair  

NASA Astrophysics Data System (ADS)

Calcium phosphates, with their chemical similarity to bone mineral, show biocompatibility with hard and soft tissues and offer massive potential for bone repair, both as scaffolds to be implanted directly into the defect and as structures for cell transplantation or to guide new bone growth in tissue engineering. This paper reviews the requirements and motivation for synthetic bone graft alternatives and the production routes for, particularly, hydroxyapatite porous scaffolds. It also considers the important role of substitution of ions such as silicate into calcium phosphates so as to more closely mirror the chemistry of bone mineral and to elicit specific biological responses.

Shepherd, J. H.; Best, S. M.

2011-04-01

47

The stability mechanisms of an injectable calcium phosphate ceramic suspension  

Microsoft Academic Search

Calcium phosphate ceramics are widely used as bone substitutes in dentistry and orthopedic applications. For minimally invasive\\u000a surgery an injectable calcium phosphate ceramic suspension (ICPCS) was developed. It consists in a biopolymer (hydroxypropylmethylcellulose:\\u000a HPMC) as matrix and bioactive calcium phosphate ceramics (biphasic calcium phosphate: BCP) as fillers. The stability of the\\u000a suspension is essential to this generation of “ready to

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

2010-01-01

48

Preparation of porous apatite granules from calcium phosphate cement  

E-print Network

Preparation of porous apatite granules from calcium phosphate cement A. C. Tas Received: 30 March­10 and macro: 150­ 550 lm pores), carbonated apatitic calcium phosphate (Ap-CaP) granules (2­4 mm in size the first spherical and porous CaP granules ever produced from a self-setting calcium phosphate cement

Tas, A. Cuneyt

49

Calcium orthophosphates in medicine: from ceramics to calcium phosphate cements  

Microsoft Academic Search

Calcium phosphate (CaP) compounds are becoming of increasingly great importance in the fiel of biomaterials and, in particular, as bone substitutes. Recent discoveries have accelerated this process, but have simultaneously rendered the field more complicated for the everyday user. Subtle differences in composition and structure of CaP compounds may have a profound effect on their in vivo behaviour. Therefore, the

M. Bohner

2000-01-01

50

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

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

51

Fabrications of zinc-releasing biocement combining zinc calcium phosphate to calcium phosphate cement.  

PubMed

Recently, zinc-releasing bioceramics have been the focus of much attention owing to their bone-forming ability. Thus, some types of zinc-containing calcium phosphate (e.g., zinc-doped tricalcium phosphate and zinc-substituted hydroxyapatite) are examined and their osteoblastic cell responses determined. In this investigation, we studied the effects of zinc calcium phosphate (ZCP) derived from zinc phosphate incorporated into calcium phosphate cement (CPC) in terms of its setting reaction and MC3T3-E1 osteoblast-like cell responses. Compositional analysis by powder X-ray diffraction analysis revealed that HAP crystals were precipitated in the CPC containing 10 or 30wt% ZCP after successfully hardening. However, the crystal growth observed by scanning electron microscopy was delayed in the presence of additional ZCP. These findings indicate that the additional zinc inhibits crystal growth and the conversion of CPC to the HAP crystals. The proliferation of the cells and alkaline phosphatase (ALP) activity were enhanced when 10wt% ZCP was added to CPC. Taken together, ZCP added CPC at an appropriate fraction has a potent promotional effect on bone substitute biomaterials. PMID:24090874

Horiuchi, Shinya; Hiasa, Masahiro; Yasue, Akihiro; Sekine, Kazumitsu; Hamada, Kenichi; Asaoka, Kenzo; Tanaka, Eiji

2014-01-01

52

Tissue responses of calcium phosphate cement: a study in dogs  

Microsoft Academic Search

The in vivo properties of a new kind of calcium phosphate cement were investigated in this study. Calcium phosphate cement was implanted as paste into femoral bone and dorsal muscle of dogs for 3 and 6 months, and as prehardened form into thigh muscles of dogs for 1, 2 and 6 months. Histology was performed on thin un-decalcified sections. No

Huipin Yuan; Yubao Li; JD de Bruijn; K de Groot; Xingdong Zhang

2000-01-01

53

Setting Reaction and Hardening of an Apatitic Calcium Phosphate Cement  

Microsoft Academic Search

The combination of self-setting and biocompatibility makes calcium phosphate cements potentially useful materials for a variety of dental applications. The objective of this study was to investigate the setting and hardening mechanisms of a cement-type reaction leading to the formation of calcium-deficient hydroxyapatite at low temperature. Reactants used were a-tricalcium phosphate containing 17 wt% ?-tricalcium phosphate, and 2 wt% of

M. P. Ginebra; E. Fernández; E. A. P. De Maeyer; R. M. H. Verbeeck; M. G. Boltong; J. Ginebra; F. C. M. Driessens; J. A. Planell

1997-01-01

54

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

2003-01-01

55

Influence of phosphate on cadmium sorption by calcium carbonate  

Microsoft Academic Search

Laboratory investigation was conducted to investigate the mechanism of cadmium sorption by pure calcium carbonate and to examine whether, reaction products of phosphate with calcium carbonate serve as a sink for sorption of toxic heavy metal cations like cadmium. The phosphatization of calcium carbonate (G.R) was carried out by treating it with orthophosphoric acid in Ca:P ratio of 5:3, 3:2,

S. K. Thakur; N. K. Tomar; S. B. Pandeya

2006-01-01

56

Phase transformation of calcium phenyl phosphate in calcium hydroxyapatite  

SciTech Connect

Calcium phenyl phosphate (CaPP) was synthesized from a mixture of Ca(OH){sub 2} and phenyl phosphate (C{sub 6}H{sub 5}PO{sub 4}H{sub 2}) in an aqueous media. XRD pattern of CaPP exhibited five diffraction peaks at 2{theta} = 6.6, 13.3, 20.0, 26.8 and 33.7{sup o}. The d-spacing ratio of these peaks was ca. 1:1/2:1/3:1/4:1/5. The molar ratios of Ca/P and phenyl/P of CaPP were 1.0 and 0.92, respectively, and the chemical formula of the material was expressed as (C{sub 6}H{sub 5}PO{sub 4}){sub 0.92}(HPO{sub 4}){sub 0.08}Ca.1.3H{sub 2}O, similar to that of dicalcium phosphate dihydrate (CaHPO{sub 4}.2H{sub 2}O: DCPD). These results allowed us to infer that CaPP is composed of a multilayer alternating bilayer of phenyl groups of the phosphates and DCPD-like phase. The structure of the material was essentially not altered after aging at pH 9.0-11.0 and 85 deg. C in an aqueous media. While, after aging at pH {<=}8.0, the diffraction peaks of CaPP were suddenly weakened and disappeared at pH 7.0. Besides, new peaks due to calcium hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}: Hap) appeared and their intensity was strengthened with decreasing the solution pH. TEM observation revealed that the Hap particles formed at pH 6.0 are fibrous with ca. 1.5 {mu}m in length and ca. 0.2 {mu}m in width. From these results, it is presumed that the layered CaPP was dissolved, hydrolyzed and reprecipitated to fibrous Hap particles at pH {<=}8.0 and 85 deg. C in aqueous media. This phase transformation of CaPP in Hap resembled to the formation mechanism of Hap in animal organism.

Tanaka, Hidekazu [Department of Material Science, Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504 (Japan)]. E-mail: hidekazu@riko.shimane-u.ac.jp; Ibaraki, Koshiro [Department of Material Science, Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504 (Japan); Uemura, Masao [Department of Material Science, Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504 (Japan); Hino, Ryozi [Department of Material Science, Faculty of Science and Engineering, Shimane University, 1060 Nishikawatsu, Matsue, Shimane 690-8504 (Japan); Kandori, Kazuhiko [School of Chemistry, Osaka University of Education, 4-698-1 Asahigaoka, Kashiwara, Osaka 582-8582 (Japan); Ishikawa, Tatsuo [School of Chemistry, Osaka University of Education, 4-698-1 Asahigaoka, Kashiwara, Osaka 582-8582 (Japan)

2007-07-03

57

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)

2009-12-01

58

Physical properties and self-setting mechanism of calcium phosphate cements from calcium bis-dihydrogenophosphate monohydrate and calcium oxide  

Microsoft Academic Search

An apatitic calcium phosphate cement was developed from calcium bis-dihydro-genophosphate monohydrate (or monocalcium phosphate monohydrate, MCPM) and calcium oxide (CaO). The powder had a Ca\\/P molar ratio of 1.67, and the liquid was either pure water or 0.25 M–1 M sodium phosphate buffer, pH 7.4. The influence of the powder-to-liquid (P\\/L) ratio on the setting time and the mechanical strength

P. BOUDEVILLE; S. SERRAJ; J.-M. LELOUP; J. MARGERIT; B. PAUVERT; A. TEROL

1999-01-01

59

Calcium phosphate scaffold from biogenic calcium carbonate by fast ambient condition reactions  

NASA Astrophysics Data System (ADS)

Calcium phosphate biogenic materials are biocompatible and promote bioactivity and osteoconductivity, which implies their natural affinity and tendency to bond directly to bones subsequently replacing the host bone after implantation owing to its biodegradability. Calcium hydrogen phosphate dihydrate, CaHPO 4·2H 2O, is known to be a nucleation precursor, in aqueous solutions, for apatitic calcium phosphates and, hence, a potential starting material for bone substitutes. Numerous approaches, via hydrothermal and ambient synthetic routes, have been used to produce calcium phosphate from biogenic calcium carbonate, taking advantage of the peculiar architecture and composition of the latter. In this article, the lamellar region of the cuttlefish bone ( Sepia officinalis) was used as a framework for the organized deposition of calcium phosphate crystals, at ambient conditions via a fast procedure involving an amorphous calcium carbonate intermediate, and ending with a conversion to calcium phosphate and a fixation procedure, thereby resulting in direct conversion of biogenic calcium carbonate into calcium phosphates at ambient conditions from the scale of months to hours.

Dutta, Abhishek; Fermani, Simona; Arjun Tekalur, Srinivasan; Vanderberg, Abigail; Falini, Giuseppe

2011-12-01

60

Effect of calcium carbonate on the compliance of an apatitic calcium phosphate bone cement  

Microsoft Academic Search

Clinical requirements for calcium phosphate bone cements were formulated in terms of the initial setting time, the final setting time, the cohesion time and the ultimate compressive strength. Three cement formulations were tested. The previously developed Biocement H was made of a powder containing ?-tertiary calcium phosphate and precipitated hydroxyapatite. Biocement B2 powder was made by adding some CaCO3 to

I. Khairoun; M. G. Boltong; F. C. M. Driessens; J. A. Planell

1997-01-01

61

Mapping calcium phosphate activated gene networks as a strategy for targeted osteoinduction of human progenitors  

E-print Network

Mapping calcium phosphate activated gene networks as a strategy for targeted osteoinduction: Received 8 January 2013 Accepted 5 March 2013 Available online 26 March 2013 Keywords: Calcium phosphate phosphate-containing biomaterials are promising scaffolds for bone regenerative strategies

Chen, Christopher S.

62

Porous calcium phosphate ceramics modified with PLGA–bioactive glass  

Microsoft Academic Search

Porous calcium phosphate ceramics (mainly hydroxyapatite) with interconnected macropores (?1 mm) and micropores (?5 ?m) as well as high porosities (?80%) were prepared by firing polyurethane foams that were coated with calcium phosphate cement at 1200 °C. In order to improve the mechanical properties such as compressive strength and compressive modulus and maintain the desirable bioactivity (i.e. the ability of apatite layer formation),

X. Miao; L.-P. Tan; L.-S. Tan; X. Huang

2007-01-01

63

Calcium phosphate-based ceramic and composite materials for medicine  

NASA Astrophysics Data System (ADS)

The topical problems in chemistry and technology of materials based on calcium phosphates aimed at both the replacement of damaged bone tissue and its regeneration are discussed. Specific features of the synthesis of nanocrystalline powders and the fabrication of ceramic implants are described. Advances in the development of porous scaffolds from resorbable and osteoconductive calcium phosphates and of hybrid composites that form the basis of bone tissue engineering are considered.

Barinov, Sergei M.

2010-01-01

64

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.

2003-02-01

65

Transient amorphous calcium phosphate in forming enamel.  

PubMed

Enamel, the hardest tissue in the body, begins as a three-dimensional network of nanometer size mineral particles, suspended in a protein gel. This mineral network serves as a template for mature enamel formation. To further understand the mechanisms of enamel formation we characterized the forming enamel mineral at an early secretory stage using X-ray absorption near-edge structure (XANES) spectromicroscopy, transmission electron microscopy (TEM), FTIR microspectroscopy and polarized light microscopy. We show that the newly formed enamel mineral is amorphous calcium phosphate (ACP), which eventually transforms into apatitic crystals. Interestingly, the size, shape and spatial organization of these amorphous mineral particles and older crystals are essentially the same, indicating that the mineral morphology and organization in enamel is determined prior to its crystallization. Mineralization via transient amorphous phases has been previously reported in chiton teeth, mollusk shells, echinoderm spicules and spines, and recent reports strongly suggest the presence of transient amorphous mineral in forming vertebrate bones. The present finding of transient ACP in murine tooth enamel suggests that this strategy might be universal. PMID:19217943

Beniash, Elia; Metzler, Rebecca A; Lam, Raymond S K; Gilbert, P U P A

2009-05-01

66

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.

2009-01-01

67

Ranitidine reduces phosphate binding in dialysis patients receiving calcium carbonate  

Microsoft Academic Search

Background. In a previous controlled study we showed that ranitidine significantly reduced the phosphate binding of aluminium hydroxide in patients with renal failure, probably by increasing intragastric pH. Methods. In this study we have investigated the effect of ranitidine on the phosphate binding of calcium carbonate in fifteen dialysis patients. Ranitidine 300 mg or a placebo tablet was taken before

C. C. Tan; P. N. Harden; R. S. C. Rodger; P. A. Rowe; R. J. Spooner; B. J. R. Junor; J. D. Briggs

68

Calcium phosphate and fluorinated calcium phosphate coatings on titanium deposited by Nd:YAG laser at a high fluence  

Microsoft Academic Search

Calcium phosphate coatings are known to enhance long-term fixation, reliability and promote osteointegration of cementless titanium-based implant devices. This study was aimed at the pulsed laser deposition of calcium phosphate coatings onto titanium using hydroxyapatite and hydroxyapatite–fluorapatite targets. The deposition was carried out at the high laser beam fluence conditions, about 12J\\/cm2. The coatings were characterized with respect to their

Daniela Ferro; Sergey M. Barinov; Jiulietta V. Rau; Roberto Teghil; Alessandro Latini

2005-01-01

69

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

PubMed

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

2014-06-01

70

[Crystallization of calcium phosphate in the presence of magnesium].  

PubMed

Formation and evolution of calcium phosphates are investigated, at 37 degrees C, in urine and aqueous solutions whose concentrations in calcium and magnesium are close to those of urine. Although the solutions are supersaturated with respect to all calcium phosphates, only an amorphous phase (ACP) and brushite (B) precipitate at time zero. Later on, ACP transforms either into whitlockite (W) or into apatite (HAP) depending on the solution composition. Phase transformations are discussed in terms of supersaturation, parameter which includes concentrations and pH. It is also shown that magnesium is a powerful inhibitor of the evolution towards HAP. PMID:8145884

Boistelle, R; Lopez-Valero, I; Abbona, F

1993-01-01

71

Calcium carbonate suppresses haem toxicity markers without calcium phosphate side effects on colon carcinogenesis  

PubMed Central

Red meat intake is associated with increased risk of colorectal cancer. We have previously shown that haemin, haemoglobin and red meat promote carcinogen-induced preneoplastic lesions, aberrant crypt foci, in the colon of rats. We have also shown that dietary calcium phosphate inhibits haemin-induced promotion, and normalizes faecal lipoperoxides and cytotoxicity. Unexpectedly, high-calcium phosphate control diet-fed rats had more preneoplastic lesions in the colon than low-calcium control diet-fed rats. The present study was designed to find a calcium supplementation with no adverse effect, by testing several doses and types of calcium salts. One in vitro study and two short-term studies in rats identified calcium carbonate as the most effective calcium salt to bind haem in vitro and to decrease faecal biomarkers previously associated with increased carcinogenesis: faecal water cytotoxicity, thiobarbituric acid reactive substances. A long term carcinogenesis study in dimethylhydrazine-injected rats demonstrated that a diet containing 100 ?mol/g calcium carbonate did not promote aberrant crypt foci, in contrast with previously tested calcium phosphate diet. The results suggest that calcium carbonate, and not calcium phosphate, should be used to reduce haem-associated colorectal cancer risk in meat-eaters. They support the concept that the nature of the associated anion to a protective metal ion is important for chemoprevention. PMID:21134327

Allam, Ossama; Bahuaud, Diane; Taché, Sylviane; Naud, Nathalie; Corpet, Denis E; Pierre, Fabrice H F

2011-01-01

72

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-of-flight cluster static secondary ion mass spectra (ToF-SSIMS) were obtained for various standard calcium phosphate(PO4)2], -tricalcium phosphate [ -Ca3- (PO4)2], amorphous calcium phosphate [Ca3(PO4)2, xH2O

Goodman, Wayne

73

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

PubMed

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

2014-01-01

74

A Review Paper on Biomimetic Calcium Phosphate Coatings  

PubMed Central

Biomimetic calcium phosphate coatings have been developed for bone regeneration and repair because of their biocompatibility, osteoconductivity, and easy preparation. They can be rendered osteoinductive by incorporating an osteogenic agent, such as bone morphogenetic protein 2 (BMP-2), into the crystalline lattice work in physiological situations. The biomimetic calcium phosphate coating enables a controlled, slow and local release of BMP-2 when it undergoes cell mediated coating degradation induced by multinuclear cells, such as osteoclasts and foreign body giant cells, which mimics a physiologically similar release mode, to achieve sustained ectopic or orthotopic bone formation. Therefore, biomimetic calcium phosphate coatings are considered to be a promising delivery vehicle for osteogenic agents. In this review, we present an overview of biomimetic calcium phosphate coatings including their preparation techniques, physico-chemical properties, potential as drug carrier, and their pre-clinical application both in ectopic and orthotopic animal models. We briefly review some features of hydroxyapatite coatings and their clinical applications to gain insight into the clinical applications of biomimetic calcium phosphate coatings in the near future.

Lin, X.; de Groot, K.; Wang, D.; Hu, Q.; Wismeijer, D.; Liu, Y.

2015-01-01

75

Alternative technique for calcium phosphate coating on titanium alloy implants.  

PubMed

As an alternative technique for calcium phosphate coating on titanium alloys, we propose to functionalize the metal surface with anionic bath containing chlorides of palladium or silver as activators. This new deposition route has several advantages such as controlled conditions, applicability to complex shapes, no adverse effect of heating, and cost effectiveness. A mixture of hydroxyapatite and calcium phosphate hydrate is deposited on the surface of Ti-6Al-4V. Calcium phosphate coating is built faster compared with the one by Simulated Body Fluid. Cell morphology and density are comparable to the control one; and the results prove no toxic compound is released into the medium during the previous seven days of immersion. Moreover, the cell viability is comparable with cells cultivated with the virgin medium. These experimental treatments allowed producing cytocompatible materials potentially applicable to manufacture implantable devices for orthopedic and oral surgeries. PMID:24646569

Le, Van Quang; Pourroy, Geneviève; Cochis, Andrea; Rimondini, Lia; Abdel-Fattah, Wafa I; Mohammed, Hadeer I; Carradò, Adele

2014-01-01

76

Alternative technique for calcium phosphate coating on titanium alloy implants  

PubMed Central

As an alternative technique for calcium phosphate coating on titanium alloys, we propose to functionalize the metal surface with anionic bath containing chlorides of palladium or silver as activators. This new deposition route has several advantages such as controlled conditions, applicability to complex shapes, no adverse effect of heating, and cost effectiveness. A mixture of hydroxyapatite and calcium phosphate hydrate is deposited on the surface of Ti–6Al–4V. Calcium phosphate coating is built faster compared with the one by Simulated Body Fluid. Cell morphology and density are comparable to the control one; and the results prove no toxic compound is released into the medium during the previous seven days of immersion. Moreover, the cell viability is comparable with cells cultivated with the virgin medium. These experimental treatments allowed producing cytocompatible materials potentially applicable to manufacture implantable devices for orthopedic and oral surgeries. PMID:24646569

Le, Van Quang; Pourroy, Geneviève; Cochis, Andrea; Rimondini, Lia; Abdel-Fattah, Wafa I; Mohammed, Hadeer I; Carradò, Adele

2014-01-01

77

Synthesis and property of a novel calcium phosphate cement.  

PubMed

The beta-cyclodextrins (beta-CDs) and amorphous calcium phosphate were used to prepare a novel calcium phosphate cement (CPC) after mechanochemical activation. Under the mechanochemical treatment, hydrogen bonding formed between beta-CD molecules, which induced strong interaction among beta-CD molecules in aqueous solution, thus conferring good antiwashout property for CPC. After mechanochemical treatment, the solubility of beta-CD was increased and so beta-CD showed different behaviors within and on the outer surface of CPC. During the setting process, when beta-CD was injected it flowed to the surface of CPC, forming a beta-CD film on the surface of CPC; inside the cement, the hydration reaction of calcium phosphates was not affected. Moreover, the antiwashout CPC with beta-CD also showed good mechanical setting, rheological properties, and injectability. The novel CPC was supposed to be developed as a good injectable bone substitute material in the clinical application. PMID:19301287

Yu, Tao; Ye, Jiandong; Wang, Yingjun

2009-08-01

78

Dual-Setting Calcium Phosphate Cement Modified with Ammonium Polyacrylate  

Microsoft Academic Search

a-Tricalcium phosphate bone cement, as for- merly designed and developed by Driessens et al., consists of a powder composed by a-tricalcium phosphate (a-TCP) and hydroxyapatite (HA) seeds, and an aqueous solution of Na2HPO4 as mixing liquid. After mixing powder and liquid, a-TCP dissolves into the liquid and calcium defi- cient hydroxyapatite (CDHA), more insoluble than the former, precipitates as an

Raúl García Carrodeguas; Anselmo Ortega Boschi; Antônio Celso; Fonseca de Arruda

79

Phosphate-bonded calcium aluminate cements  

DOEpatents

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.

1993-09-21

80

Phosphate-bonded calcium aluminate cements  

DOEpatents

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.degree. C. to about 300.degree. 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.

Sugama, Toshifumi (Mastic Beach, NY)

1993-01-01

81

Optimization of calcium phosphate fine ceramic powders preparation  

NASA Astrophysics Data System (ADS)

The effect of biomimetic synthesis method, reaction medium and further precursor treatments on the chemical and phase composition, crystal size and morphology of calcium phosphates was examined. Nanosized calcium phosphate precursors were biomimetically precipitated by the method of continuous precipitation in three types of reaction media at pH 8: (i) SBF as an inorganic electrolyte system; (ii) organic (glycerine) modified SBF (volume ratio of 1:1); (iii) polymer (10 g/l xanthan gum or 10 g/l guar gum) modified SBF (volume ratio of 1:1). After maturation (24 h) the samples were lyophilized, calcinated at 300°C for 3 hours, and washed with water, followed by new gelation, lyophilization and step-wise (200, 400, 600, 800, and 1000°C, each for 3 hours) sintering. The reaction medium influenced the chemical composition and particle size but not the morphology of the calcium phosphate powders. In all studied cases bi-phase calcium phosphate fine powders with well-shaped spherical grains, consisting of ?-tricalcium phosphate (?-TCP) and hydroxyapatite (HA) with a Ca/P ratio of 1.3 - 1.6 were obtained. The SBF modifiers decreased the particle size of the product in the sequence guar gum ˜ xanthan gum < glycerin < SBF medium.

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

2013-12-01

82

Molecular mechanisms of crystallization impacting calcium phosphate cements  

PubMed Central

The biomineral calcium hydrogen phosphate dihydrate (CaHPO4·2H2O), known as brushite, is a malleable material that both grows and dissolves faster than most other calcium minerals, including other calcium phosphate phases, calcium carbonates and calcium oxalates. Within the body, this ready formation and dissolution can play a role in certain diseases, such as kidney stone and plaque formation. However, these same properties, along with brushite’s excellent biocompatibility, can be used to great benefit in making resorbable biomedical cements. To optimize cements, additives are commonly used to control crystallization kinetics and phase transformation. This paper describes the use of in situ scanning probe microscopy to investigate the role of several solution parameters and additives in brushite atomic step motion. Surprisingly, this work demonstrates that the activation barrier for phosphate (rather than calcium) incorporation limits growth kinetics and that additives such as magnesium, citrate and bisphosphonates each influence step motion in distinctly different ways. Our findings provide details of how, and where, molecules inhibit or accelerate kinetics. These insights have the potential to aid in designing molecules to target specific steps and to guide synergistic combinations of additives. PMID:20308110

Giocondi, Jennifer L.; El-Dasher, Bassem S.; Nancollas, George H.; Orme, Christine A.

2010-01-01

83

J Mater Sci Mater Med . Author manuscript The stability mechanisms of an injectable calcium phosphate ceramic  

E-print Network

Keywords Biocompatible Materials ; pharmacology ; Bone Substitutes ; pharmacology ; Calcium Phosphates ; pharmacology ; Ceramics ; pharmacology ; Injections ; Methylcellulose ; analogs & derivatives ; Particle Size ; Polymers ; pharmacology ; Rheology ; Viscosity Introduction Calcium phosphate (CaP) ceramics are the main

Paris-Sud XI, Université de

84

In vitro testing of calcium phosphate (HA, TCP, and biphasic HA-TCP) whiskers  

E-print Network

In vitro testing of calcium phosphate (HA, TCP, and biphasic HA-TCP) whiskers Sahil Jalota, Sarit B: Calcium phosphate [single-phase hydroxyapa- tite (HA, Ca10(PO4)6(OH)2), single-phase tricalcium phos for 1 h to obtain the whiskers of the desired calcium phosphate (CaP) bioceramics. These whis- kers were

Tas, A. Cuneyt

85

Calcium phosphate cement augmentation of cancellous bone screws can compensate for the absence of cortical fixation  

E-print Network

Calcium phosphate cement augmentation of cancellous bone screws can compensate for the absence Keywords: Screw fixation Pullout force Calcium phosphate cement Osteoporotic bone a b s t r a c with cement. Previous studies have shown that bone augmentation with Calcium Phosphate (CaP) cement

Guerraoui, Rachid

86

Parameters influencing calcium phosphate precipitation in granular sludge sequencing batch reactor  

E-print Network

Parameters influencing calcium phosphate precipitation in granular sludge sequencing batch reactor BP 84234, F-31432 Toulouse Cedex 4, France a b s t r a c t Calcium phosphate precipitation inside to accumulate in the granule, the main calcium phosphate precursors that form prior to HAP are here investigated

Mailhes, Corinne

87

CRYSTALLIZATION OF CALCIUM PHOSPHATE ORIENTED BY SELF-ASSEMBLING DIBLOCK COPOLYMERS,  

E-print Network

CRYSTALLIZATION OF CALCIUM PHOSPHATE ORIENTED BY SELF-ASSEMBLING DIBLOCK COPOLYMERS, IN SOLUTION. MINERALIZATION OF CALCIUM PHOSPHATE IN PRESENCE OF DHBC 28 B. AMPHIPHILIC POLY(ETHYLENE OXIDE)-BLOCK-POLY(VALEROLACTONE) DIBLOCK COPOLYMERS AS TEMPLATE FOR CALCIUM PHOSPHATE MINERALIZATION 30 1. SELF-ASSEMBLY IN AQUEOUS

Amrhein, Valentin

88

Calcium Gluconate in Phosphate Buffered Saline Increases Gene Delivery with Adenovirus Type 5  

E-print Network

Calcium Gluconate in Phosphate Buffered Saline Increases Gene Delivery with Adenovirus Type 5 Marko the calcium and phosphate present in the serum mix to precipitate, and this was responsible for enhanced gene calcium and phosphate are present in many solutions. To translate this into an approach potentially

Hemminki, Akseli

89

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

1975-01-01

90

Agronomic effectiveness of calcium phosphate recovered from liquid swine manure  

Technology Transfer Automated Retrieval System (TEKTRAN)

A new manure treatment technology developed as an alternative to anaerobic lagoons on swine (Sus scrofa domesticus) farms includes solid-liquid separation and subsequent recovery of soluble phosphorus (P) as calcium phosphate from the wastewater. The objective was to determine the agronomic effectiv...

91

A new method to produce macropores in calcium phosphate cements  

Microsoft Academic Search

A new way to create macropores in calcium phosphate cements has been developed. The method consists in adding NaHCO3 to the starting cement powder (Biocement D) and using two different liquids: first a basic liquid to form the paste and later an acid liquid to obtain CO2 bubbles. Mercury intrusion measurements showed a dramatic increase both in macropores with an

R. P del Real; J. G. C Wolke; M Vallet-Reg??; J. A Jansen

2002-01-01

92

Atomic structure of intracellular amorphous calcium phosphate deposits.  

PubMed Central

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 A in longest dimension, whose probable composition is expressed by the formula Ca9(PO4)6. The minor differences observed are attributed to the presence in the biological mineral of significant amounts of Mg-2+ and ATP. Synthetic amorphous calcium phosphate in contact with a solution containing an amount of ATP equivalent to that of the biological mineral failed to undergo conversion to the thermodynamically more stable hydroxyapatite. The amorphous calcium phosphate of the cytoplasmic mineral granules is similarly stable, and does not undergo conversion to hydroxyapatite, presumably owing to the presence of ATP and Mg-2+, known in inhibitors of the conversion process. The physiological implications of mineral deposits consisting of stabilized calcium phosphate ion clusters are discussed. PMID:1056015

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

1975-01-01

93

Amorphous calcium phosphate and its application in dentistry  

PubMed Central

Amorphous Calcium Phosphate (ACP) is an essential mineral phase formed in mineralized tissues and the first commercial product as artificial hydroxyapatite. ACP is unique among all forms of calcium phosphates in that it lacks long-range, periodic atomic scale order of crystalline calcium phosphates. The X-ray diffraction pattern is broad and diffuse with a maximum at 25 degree 2 theta, and no other different features compared with well-crystallized hydroxyapatite. Under electron microscopy, its morphological form is shown as small spheroidal particles in the scale of tenths nanometer. In aqueous media, ACP is easily transformed into crystalline phases such as octacalcium phosphate and apatite due to the growing of microcrystalline. It has been demonstrated that ACP has better osteoconductivity and biodegradability than tricalcium phosphate and hydroxyapatite in vivo. Moreover, it can increase alkaline phosphatase activities of mesoblasts, enhance cell proliferation and promote cell adhesion. The unique role of ACP during the formation of mineralized tissues makes it a promising candidate material for tissue repair and regeneration. ACP may also be a potential remineralizing agent in dental applications. Recently developed ACP-filled bioactive composites are believed to be effective anti-demineralizing/remineralizing agents for the preservation and repair of tooth structures. This review provides an overview of the development, structure, chemical composition, morphological characterization, phase transformation and biomedical application of ACP in dentistry. PMID:21740535

2011-01-01

94

Interaction between hydroxypropyl methylcellulose and biphasic calcium phosphate after steam sterilisation  

E-print Network

, and a dialytic method was then use to extract calcium phosphate salts from HPMC. The percentage of HPMC extracted molecules and transforms mineral phosphate into organic phosphate detectable by flame ionisation

Boyer, Edmond

95

Self-Assembly of Filamentous Amelogenin Requires Calcium and Phosphate: From Dimers via Nanoribbons to Fibrils  

E-print Network

calcium, phosphate, and pH 4.0-6.0. The pH range suggests that the formation of ion bridges throughSelf-Assembly of Filamentous Amelogenin Requires Calcium and Phosphate: From Dimers via Nanoribbons phosphate- binding proteins predicting 12 phosphate-binding histidines. Thermophoretic analysis verified

Sali, Andrej

96

Diagnosis and clinical manifestations of calcium pyrophosphate and basic calcium phosphate crystal deposition diseases.  

PubMed

Basic calcium phosphate and pyrophosphate calcium crystals are the 2 main calcium-containing crystals that can deposit in all skeletal tissues. These calcium crystals give rise to numerous manifestations, including acute inflammatory attacks that can mimic alarming and threatening differential diagnoses, osteoarthritis-like lesions, destructive arthropathies, and calcific tendinitis. Awareness of uncommon localizations and manifestations such as intraspinal deposition (eg, crowned dens syndrome, tendinitis of longus colli muscle, massive cervical myelopathy compression) prevents inappropriate procedures and cares. Coupling plain radiography, ultrasonography, computed tomography, and synovial fluid analysis allow accurate diagnosis by directly or indirectly identifying the GRAAL of microcrystal-related symptoms. PMID:24703344

Ea, Hang-Korng; Lioté, Frédéric

2014-05-01

97

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

2012-01-01

98

Chromatography of Venezuelan Equine Encephalomyelitis Virus Strains on Calcium Phosphate  

PubMed Central

Column chromatography of selected Venezuelan equine encephalomyelitis (VEE) viruses on calcium phosphate gel offered a simple and reproducible method for examination of biochemical characteristics and relatedness of strains within the VEE complex. Members of antigenic subgroup I demonstrated a series of elution profiles within a narrow range of 0.22 to 0.25 M phosphate buffer. Members of antigenic subgroups II, III, and IV differed substantially among themselves and viruses of antigenic subgroup I. These differences in elution behavior may contribute to understanding of observed differences in biological behavior and antigenic variation among VEE viruses. PMID:5057376

Pedersen, Carl E.; Slocum, Donald R.; Levitt, Neil H.

1972-01-01

99

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

1994-01-01

100

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

Microsoft Academic Search

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

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

2004-01-01

101

Calcium phosphate cements prepared by acid-base reaction  

Microsoft Academic Search

In this paper, the authors investigate the characteristics of calcium phosphate cements (CPC) prepared by an exothermic acid-base reaction between NH[sub 4]H[sub 2]PO[sub 4]-based fertilizer (Poly-N) and calcium aluminate compounds (CAC), such as 3CaO[center dot]Al[sub 2]O[sub 3] (C[sub 3]A), CaO[center dot] Al[sub 2]O[sub 3] (CA), and CaO[center dot] 2Al[sub 2]O[sub 3] (CA[sub 2]), in a series of integrated studies of

Toshifumi Sugama; Marita Allan; Janet M. Hill

1992-01-01

102

Bone regeneration: molecular and cellular interactions with calcium phosphate ceramics  

PubMed Central

Calcium phosphate bioceramics are widely used in orthopedic and dental applications and porous scaffolds made of them are serious candidates in the field of bone tissue engineering. They have superior properties for the stimulation of bone formation and bone bonding, both related to the specific interactions of their surface with the extracellular fluids and cells, ie, ionic exchanges, superficial molecular rearrangement and cellular activity. PMID:17717972

Barrère, Florence; van Blitterswijk, Clemens A; de Groot, Klaas

2006-01-01

103

Soft-tissue response to injectable calcium phosphate cements  

Microsoft Academic Search

In this study, the soft tissue reaction to two newly developed injectable calcium phosphate bone cements (cement D and W) was evaluated after implantation in the back of goats. For one of the cements (cement D) the tissue reaction was also investigated after varying the concentration of accelerator Na2HPO4 in the cement liquid (resulting in cement D1 and D2). Eight

E. M. Ooms; E. A. Egglezos; J. G. C. Wolke; J. A. Jansen

2003-01-01

104

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

PubMed

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

2014-05-01

105

Single Step Sintered Calcium Phosphate Fibers from Avian EGG Shell  

NASA Astrophysics Data System (ADS)

Different forms of calcium-phosphate (Hydoxyapatite, ?-TCP, ?-TCP, CDHA) minerals are found to be major component of bone tissue. Development of calcium-phosphate (CaP) based fibrous microstructures is of significant research interest worldwide owing to its improved mechanical properties and higher interconnectivity. Here we represent a method for single step sintered wet-spun Fibers of calcium phosphate from avian egg shells for biomedical applications. Raw egg shell powder was mixed with chitosan solution and Phosphoric acid. The mixture is milled in a ball mill overnight and then filtered. The slurry was de-aired using 100 microliter 1-octanol per 100 ml of slurry as antifoaming and wet spun in coagulation bath. Fiber was dried overnight and sintered at different temperatures for microstructure and phase analysis. Both green and sintered Fibers were physico-chemical characterized by SEM, EDX, XRD, TGA, DSC, FTIR, and stereo-zoom microscopy. The fibers obtained in this procedure are found to have highly porous interconnected structures which can provide good cell adhesion and therefore can be used for bioactive scaffold making.

Dadhich, Prabhash; Das, Bodhisatwa; Dhara, Santanu

2013-11-01

106

Gene delivery with bisphosphonate-stabilized calcium phosphate nanoparticles.  

PubMed

Nucleic acid drugs are promising new therapeutics, due to their possible applications in a wide variety of diseases and their strong targeting potential and associated lower off-target effects compared to conventional pharmaceuticals. However, their poor intracellular bioavailability and rapid degradation hinder their development as drugs. Therefore, efficient delivery is a major challenge. Various systems have been developed to overcome this problem. The entrapment of genetic material into nanoparticles constitutes a promising approach to increase the in vitro and in vivo transfection activity. Calcium phosphate-DNA co-precipitates have been used for gene delivery for more than 35 years and have the advantage of being nontoxic, easy to produce, and having the ability to complex nucleic acids leading to efficient transfection. Conventional synthetic methods yield particles that are only stable for a short period of time. Herein is proposed a versatile, surfactant-free method to stabilize calcium phosphate-DNA nanoparticles based on the use of poly(ethylene glycol)-functionalized bisphosphonate. The strength of the interaction between the bisphosphonate and the calcium phosphate enabled the formation of stable, but bioresorbable particles of around 200 nm, which exhibited physical stability over several days. Additionally, the nanoparticles revealed good and sustained ability to transfect cells while displaying low toxicity. PMID:21111013

Giger, Elisabeth V; Puigmartí-Luis, Josep; Schlatter, Rahel; Castagner, Bastien; Dittrich, Petra S; Leroux, Jean-Christophe

2011-02-28

107

Injectable biphasic calcium phosphate cements as a potential bone substitute.  

PubMed

Apatitic calcium phosphate cements (CPCs) have been widely used as bone grafts due to their excellent osteoconductive properties, but the degradation properties are insufficient to stimulate bone healing in large bone defects. A novel approach to overcome the lack of degradability of apatitic CPC involves the development of biphasic CPCs (BCPC) based on tricalcium phosphate (TCP) in both ?- and ?-polymorphs. The aim of the current study was to prepare and analyze the physicochemical properties of BCPCs based on dual phase ?/?-TCP as obtained by heat treatment of pure ?-TCP. The handling and mechanical characteristics of the samples as well as the degradation behavior under in vitro condition were investigated and compared with a standard monophasic ?-TCP-based CPC. The results showed that different heat treatments of commercially available ?-TCP allowed the formation of biphasic calcium phosphate powder with a variety of ?/?-TCP ratios. The use of biphasic powder particles as a reactant for CPCs resulted into increased setting and injectability times of the final BCPCs. During hardening of the cements, the amount of apatite formation decreased with increasing ?-TCP content in the biphasic precursor powders. The morphology of the monophasic CPC consisted of plate-like crystals, whereas needle-like crystals were observed for BCPCs. In vitro degradation tests demonstrated that dissolution rate and corresponding calcium release from the set cements increased considerably with increasing ?-TCP content, suggesting that apatitic CPCs can be rendered degradable by using biphasic ?/?-TCP as powder precursor phase. PMID:24106108

Sariibrahimoglu, Kemal; Wolke, Joop G C; Leeuwenburgh, Sander C G; Yubao, Li; Jansen, John A

2014-04-01

108

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

2010-01-01

109

Development of magnesium calcium phosphate biocement for bone regeneration.  

PubMed

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(H(2)PO(4))(2).H(2)O). 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(H(2)PO(4))(2).H(2)O in a molar ratio of 2 : 1, the final hydrated products were Mg(3)(PO(4))(2) and Ca(3)(PO(4))(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 MG(63) cells on the MCPB were significantly enhanced in comparison with CPB, and the alkaline phosphatase activity of MG(63) cells on the MCPB was significantly higher than on the CPB at 7 and 14 days. The MG(63) 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

2010-08-01

110

In vitro studies of calcium phosphate silicate bone cements.  

PubMed

A novel calcium phosphate silicate bone cement (CPSC) was synthesized in a process, in which nanocomposite forms in situ between calcium silicate hydrate (C-S-H) gel and hydroxyapatite (HAP). The cement powder consists of tricalcium silicate (C(3)S) and calcium phosphate monobasic (CPM). During cement setting, C(3)S hydrates to produce C-S-H and calcium hydroxide (CH); CPM reacts with the CH to precipitate HAP in situ within C-S-H. This process, largely removing CH from the set cement, enhances its biocompatibility and bioactivity. The testing results of cell culture confirmed that the biocompatibility of CPSC was improved as compared to pure C(3)S. The results of XRD and SEM characterizations showed that CPSC paste induced formation of HAP layer after immersion in simulated body fluid for 7 days, suggesting that CPSC was bioactive in vitro. CPSC cement, which has good biocompatibility and low/no cytotoxicity, could be a promising candidate as biomedical cement. PMID:23114635

Zhou, Shuxin; Ma, Jingzhi; Shen, Ya; Haapasalo, Markus; Ruse, N Dorin; Yang, Quanzu; Troczynski, Tom

2013-02-01

111

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

2001-01-01

112

Synthesis of Calcium HydroxyapatiteTricalcium Phosphate (HATCP) Composite Bioceramic Powders and Their Sintering Behavior  

E-print Network

Synthesis of Calcium Hydroxyapatite­Tricalcium Phosphate (HA­TCP) Composite Bioceramic Powders important inorganic phases of synthetic bone applications--namely, calcium hydroxyapatite (Ca10(PO4)6(OH)2 (HA)) and tri- calcium phosphate (Ca3(PO4)2 (TCP))--were prepared as submicrometer-sized, chemically

Tas, A. Cuneyt

113

Response to "Chemistry misconceptions associated with understanding calcium and phosphate homeostasis"  

NSDL National Science Digital Library

I enjoyed Dr. Cliff's "conceptual diagnostic test" regarding calcium phosphate equilibrium and was relieved that I chose the correct answers (1). Question 2 was the more difficult one, and I hesitated before almost answering it incorrectly. Dr. Cliff asks what would happen if more calcium phosphate is added to a beaker containing calcium, phosphate, and calcium phosphate "at equilibrium." His answer states the question differently: "Only 11% of the students correctly answered the conceptual diagnostic question about the addition of solid calcium phosphate to a saturated [emphasis added] solution of calcium phosphate." The question did not specify that the solution was saturated but that it was "at equilibrium." It is not simply a question about understanding "mass action." One also needs to realize that the solvent is saturated if a solid in the solvent is at equilibrium. That is an additional concept itself and, when not made explicit, might explain why only 11% of the students answered it correctly.

David S. Goldfarb (St. Vincent's Hospital, and New York University School of Medicine)

2010-03-01

114

Calcium phosphate bone cements for local vancomycin delivery.  

PubMed

Among calcium phosphate biomaterials, calcium phosphate bone cements (CPCs) have attracted increased attention because of their ability of self-setting in vivo and injectability, opening the new opportunities for minimally invasive surgical procedures. However, any surgical procedure carries potential inflammation and bone infection risks, which could be prevented combining CPC with anti-inflammatory drugs, thus overcoming the disadvantages of systemic antibiotic therapy and controlling the initial burst and total release of active ingredient. Within the current study ?-tricalcium phosphate based CPCs were prepared and it was found that decreasing the solid to liquid phase ratio from 1.89g/ml to 1.23g/ml, initial burst release of vancomycin within the first 24h increased from 40.0±2.1% up to 57.8±1.2% and intrinsic properties of CPC were changed. CPC modification with vancomycin loaded poly(lactic acid) (PLA) microcapsules decreased the initial burst release of drug down to 7.7±0.6%, while only 30.4±1.3% of drug was transferred into the dissolution medium within 43days, compared to pure vancomycin loaded CPC, where 100% drug release was observed already after 12days. During the current research a new approach was found in order to increase the drug bioavailability. Modification of CPC with novel PLA/vancomycin microcapsules loaded and coated with nanosized hydroxyapatite resulted in 85.3±3.1% of vancomycin release within 43days. PMID:25686933

Loca, Dagnija; Sokolova, Marina; Locs, Janis; Smirnova, Anastasija; Irbe, Zilgma

2015-04-01

115

Method of coating a substrate with a calcium phosphate compound  

DOEpatents

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)

2000-01-01

116

Enamel Subsurface Lesion Remineralisation with Casein Phosphopeptide Stabilised Solutions of Calcium, Phosphate and Fluoride  

Microsoft Academic Search

Casein phosphopeptide stabilised amorphous calcium phosphate (CPP-ACP) and amorphous calcium fluoride phosphate (CPP-ACFP) solutions have been shown to remineralise enamel subsurface lesions. The aim of this study was to determine the effect of ion composition of CPP-ACP and CPP-ACFP solutions on enamel subsurface lesion remineralisation in vitro. CPP-bound and free calcium, phosphate and fluoride ion concentrations in the solutions were

N. J. Cochrane; S. Saranathan; F. Cai; K. J. Cross; E. C. Reynolds

2008-01-01

117

Calcium phosphate stabilization of fly ash with chloride extraction.  

PubMed

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

2002-01-01

118

Calcium phosphate microcrystal deposition in the human intervertebral disc  

PubMed Central

A variety of crystals have been identified in both normal and pathological connective tissues. Calcium phosphate ‘cuboidal’ microcrystal deposition has been found, using transmission electron microscopy (TEM), in femoral articular cartilage, where they are distributed as a band 5–50 µm beneath the articular surface. These cuboid microcrystals have been identified as magnesium whitlockite. Our objective was to investigate their presence in the human intervertebral disc. In this study, two degenerate and 15 scoliotic discs were examined using light microscopy and TEM techniques to determine the presence of calcium phosphate crystals. Calcium pyrophosphate dihydrate (CPPD) deposition was identified in one degenerate disc specimen. Using TEM and electron probe analysis, cuboid microcrystals were identified in the annulus fibrosus and nucleus pulposus of both degenerate specimens, but not in the discs from young scoliotic patients. Cuboid microcrystal deposition was found predominantly around cells, which were mainly necrotic, with some association with extracellular lipidic/membranous debris. This is the first TEM report of whitlockite in the intervertebral disc. In one specimen coexistence of cuboid and CPPD crystal deposition was found. PMID:16420375

Lee, Robert S; Kayser, Mike V; Yousuf Ali, S

2006-01-01

119

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

2012-01-01

120

Preparation and mechanical properties of calcium phosphate\\/copoly-L-lactide composites  

Microsoft Academic Search

New artificial bone materials were prepared using calcium phosphates, hydroxyapatite and ß-tricalicum phosphate, and copoly-L-lactide, CPLA. Calcium phosphate powder and CPLA were mixed at 453 K for 10 min with various mixing ratios. Scanning electron microscope observations indicated that the composites of ß-tricalicum phosphate and CPLA were homogeneously dispersed and highly adhesive. Young’s modulus of the composites was the same

M KIKUCHI; Y SUETSUGU; J TANAKA; M AKAO

1997-01-01

121

Selective laser sintering of calcium phosphate materials for orthopedic implants  

NASA Astrophysics Data System (ADS)

Two technologies, Solid Freeform Fabrication (SFF) and bioceramics are combined in this work to prepare bone replacement implants with complex geometry. SFF has emerged as a crucial technique for rapid prototyping in the last decade. Selective Laser Sintering (SLS) is one of the established SFF manufacturing processes that can build three-dimensional objects directly from computer models without part-specific tooling or human intervention. Meanwhile, there have been great efforts to develop implantable materials that can assist in regeneration of bone defects and injuries. However, little attention has been focused in shaping bones from these materials. The main thrust of this research was to develop a process that can combine those two separate efforts. The specific objective of this research is to develop a process that can construct bone replacement material of complex geometry from synthetic calcium phosphate materials by using the SLS process. The achievement of this goal can have a significant impact on the quality of health care in the sense that complete custom-fit bone and tooth structures suitable for implantation can be prepared within 24--48 hours of receipt of geometric information obtained either from patient Computed Tomographic (CT) data, from Computer Aided Design (CAD) software or from other imaging systems such as Magnetic Resonance Imaging (MRI) and Holographic Laser Range Imaging (HLRI). In this research, two different processes have been developed. First is the SLS fabrication of porous bone implants. In this effort, systematic procedures have been established and calcium phosphate implants were successfully fabricated from various sources of geometric information. These efforts include material selection and preparation, SLS process parameter optimization, and development of post-processing techniques within the 48-hour time frame. Post-processing allows accurate control of geometry and of the chemistry of calcium phosphate, as well as control of micro and macro pore structure, to maximize bone healing and provide sufficient mechanical strength. It also permits the complete removal of the polymeric binders that are resided in the SLS process. In collaboration with the University of Texas Health Science Center at San Antonio and BioMedical Enterprises, Inc., porous implants based on anatomical geometry have been successfully implanted in rabbits and dogs. These histologic animal studies reveal excellent biocompatibility and show its great potential for commercial custom-fit implant manufacture. The second research effort involves fabrication of fully dense bone for application in dental restoration and load-bearing orthopedic functions. Calcium phosphate glass melts, proven to be biocompatible in the first effort, were cast into carbon molds. Processes were developed for preparing the molds. These carbon molds of anatomic shape can be prepared from either Computer Numerical Control (CNC) milling of slab stock or SLS processing of thermoset-coated graphite powder. The CNC milling method provides accurate dimension of the molds in a short period of time, however, the capable geometries are limited; generally two pieces of molds are required for complex shapes. The SLS method provides very complex shape green molds. However, they need to go through pyrolysis of thermoset binder to provide the high temperature capability reached at calcium phosphate melt temperatures (1100°C) and noticeable shrinkage was observed during pyrolysis. The cast glass was annealed to develop polycrystalline calcium phosphate. This process also exhibits great potential.

Lee, Goonhee

122

Bone repair in radii and tibias of rabbits with phosphorylated chitosan reinforced calcium phosphate cements  

Microsoft Academic Search

Biocompatibility of two calcium phosphate cements (CPCs), reinforced with phosphorylated chitosan (P-chitosan), was investigated in rabbits in present study. The two CPCs are monocalcium phosphate monohydrate (MPCM) with calcium oxide (CaO) in 1m phosphate buffer (i.e. MCPM\\/CaO\\/1m phosphate buffer cement, CPC-I) and dicalcium phosphate dihydrate (DCPD) with calcium hydroxide [Ca(OH)2] in 1m Na2HPO4 solution (i.e. DCPD\\/Ca(OH)2\\/1m Na2HPO4 cement, CPC-II). Different

Xiaohong Wang; Jianbiao Ma; Yinong Wang; Binglin He

2002-01-01

123

Effect of calcium carbonate on clinical compliance of apatitic calcium phosphate bone cement.  

PubMed

Clinical requirements for calcium phosphate bone cements were formulated in terms of the initial setting time, the final setting time, the cohesion time, and the ultimate compressive strength. Two cement formulations were tested. Biocement F was made of a powder containing alpha-tertiary calcium phosphate, precipitated hydroxyapatite, and monetite. Biocement D powder also contained CaCO3. The liquid/powder (L/P) ratio of the cement paste and the accelerator concentrations (% Na2HPO4) in the cement liquid were varied. For Biocement F there was a small area of combinations of L/P ratio and percent Na2HPO4 for which all clinical requirements were satisfied. This area covered only pastes that could be applied as doughs. However, Biocement D showed a much larger area of full compliance and it covered both doughlike and injectable pastes. PMID:9421757

Khairoun, I; Boltong, M G; Driessens, F C; Planell, J A

1997-01-01

124

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

PubMed

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

2014-12-01

125

Fully injectable calcium phosphate cement--a promise to dentistry.  

PubMed

Calcium phosphate cements (CPC) are self setting and biocompatible bone substitute materials with potential applications in dentistry. However, its clinical use has been challenged by poor rheological properties. A novel formulation of CPC has been developed, which gives a fully injectable and cohesive paste. This work investigates the suitability of the new "fully injectable calcium phosphate cement" (FI-CPC) for dental applications. The cementing properties, material characteristics, and the rheological properties were tested using a battery of material characteristics methods. The biocompatibility was also evaluated as per ISO 7405. The setting time (20 min) and compressive strength (>11 Mpa) of FI-CPC satisfy the clinical requirements. It underwent setting without any exothermic reaction, keeping good dimensional stability. The cement paste could be extruded through a 18-gauge needle, easily and fully. It showed excellent cohesion when immersed in water. FI-CPC was seen to set into a micro-porous mass of hydroxyapatite, the mineral part of human dentin. It showed good attachment to dentin walls, when filled in tooth perforations. FI-CPC was found non-toxic, non-allergic, non-pyrogenic, and soft-tissue compatible. The study shows that FI-CPC provides a self setting bio-compatible paste with excellent rheological properties for surgical applications. The set cement provides good and stable sealing. The osteoconductive property is an added advantage. FI-CPC proves to be an ideal material for endodontic sealing/filling and periodontic repair. PMID:15915629

Komath, Manoj; Varma, H K

2004-01-01

126

Premixed injectable calcium phosphate cement with excellent suspension stability.  

PubMed

Premixed injectable calcium phosphate cement (p-ICPC) pastes have advantages over aqueous injectable calcium phosphate cement (a-ICPC) because p-ICPC remain stable during storage and harden only after placement into the defect. This paper focused on the suspension stability of p-ICPC paste by using fumed silica as a stabilizing agent and propylene glycol (PEG) as a continuous phase. Multiple light scanning techniques were first applied to evaluate the suspension stability. The results indicated that fumed silica effectively enhanced the suspension stability of p-ICPC pastes. The stabilizing effect of fumed silica results from the network structure formed in PEG because of its thixotropy. The p-ICPC could be eventually hydrated to form hydroxyapatite under aqueous circumstances by the unique replacement between water and PEG. p-ICPC (1) not only possesses proper thixotropy and compressive strength but has good injectability as well. p-ICPC (1) was cytocompatible and had no adverse effect on the attachment and proliferation of MG-63 cells in vitro. These observations may have applicability to the development of other nonaqueous injectable biomaterials for non-immediate filling and long-term storage. PMID:23563980

Chen, Fangping; Mao, Yuhao; Liu, Changsheng

2013-07-01

127

Preparation of porous apatite granules from calcium phosphate cement.  

PubMed

A versatile method for preparing spherical, micro- and macroporous (micro: 2-10 and macro: 150-550 microm pores), carbonated apatitic calcium phosphate (Ap-CaP) granules (2-4 mm in size) was developed by using NaCl crystals as the porogen. The entire granule production was performed between 21 and 37 degrees C. A CaP cement powder, comprising alpha-Ca3(PO4)2 (61 wt.%), CaHPO4 (26%), CaCO3 (10%) and precipitated hydroxyapatite, Ca10(PO4)6(OH)2 (3%), was dry mixed with NaCl crystals varying in size from 420 microm to 1 mm. Cement powder (35 wt.%) and NaCl (65 wt.%) mixture was kneaded with an ethanol-Na2HPO4 initiator solution, and the formed dough was immediately agitated on an automatic sieve shaker for a few minutes to produce the spherical granules. Embedded NaCl crystals were then leached out of the granules by soaking them in deionized water. CaP granules were micro- and macroporous with a total porosity of 50% or more. Granules were composed of carbonated, poorly crystallized, apatitic CaP phase. These were the first spherical and porous CaP granules ever produced from a self-setting calcium phosphate cement. The granules reached their final handling strength at the ambient temperature through the cement setting reaction, without having a need for sintering. PMID:18049869

Tas, A C

2008-05-01

128

Microporous calcium phosphate ceramics driving osteogenesis through surface architecture.  

PubMed

The presence of micropores in calcium phosphate (CaP) ceramics has shown its important role in initiating inductive bone formation in ectopic sites. To investigate how microporous CaP ceramics trigger osteoinduction, we optimized two biphasic CaP ceramics (i.e., BCP-R and BCP-S) to have the same chemical composition, equivalent surface area per volume, comparable protein adsorption, similar ion (i.e., calcium and phosphate) exchange and the same surface mineralization potential, but different surface architecture. In particular, BCP-R had a surface roughness (Ra) of 325.4 ± 58.9 nm while for BCP-S it was 231.6 ± 35.7 nm. Ceramic blocks with crossing or noncrossing channels of 250, 500, 1000, and 2000 µm were implanted in paraspinal muscle of dogs for 12 weeks. The percentage of bone volume in the channels was not affected by the type of pores (i.e., crossing vs. closed) or their size, but it was greatly influenced by the ceramic type (i.e., BCP-R vs. BCP-S). Significantly, more bone was formed in the channels of BCP-R than in those of BCP-S. Since the two CaP ceramics differed only in their surface architecture, the results hereby demonstrate that microporous CaP ceramics may induce ectopic osteogenesis through surface architecture. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 1188-1199, 2015. PMID:25044678

Zhang, Jingwei; Barbieri, Davide; Ten Hoopen, Hetty; de Bruijn, Joost D; van Blitterswijk, Clemens A; Yuan, Huipin

2015-03-01

129

Amorphous calcium phosphate composites with improved mechanical properties  

PubMed Central

Hybridized zirconium amorphous calcium phosphate (ACP)-filled methacrylate composites make good calcium and phosphate releasing materials for anti-demineralizing/remineralizing applications with low mechanical demands. The objective of this study was to assess the effect of the particle size of the filler on the mechanical properties of these composites. Photo-curable resins were formulated from ethoxylated bisphenol A dimethacrylate, triethylene glycol dimethacrylate, 2-hydroxyethyl methacrylate and methacryloxyethyl phthalate. Camphorquinone and ethyl-4-N,N-dimethylaminobenzoate were utilized as components of the photoinitiator system. After 2 h of mechanical milling in isopropanol, an approximate 64 % reduction in the median particle diameter was observed [27.48 ?m vs. 9.98 ?m] for unmilled and milled wet ACP, respectively. Dry ACP showed a 43 % reduction in particle size from pre- to post-milling. As well as dry composites, those that had been immersed in aqueous media were evaluated for their Young’s Modulus, water sorption, biaxial tensile, three-point flexural and diametral tensile strength. Mechanically milling the filler increased the volume of fine particles in the composite specimens, resulting in a more homogeneous intra-composite distribution of ACP and a reduction in voids. In turn, less water diffused into the milled composites upon aqueous exposure, and they showed a marked improvement in biaxial flexure strength and a moderate improvement in flexural strength over composites with unmilled ACP. The demonstrated improvement in the mechanical stability of milled Zr-ACP composites may help in extending their dental applicability. PMID:18688290

O’Donnell, J.N.R.; Antonucci, J.M.; Skrtic, D.

2008-01-01

130

Sand consolidation with calcium phosphate-polyelectrolyte composites.  

PubMed

A new method for the consolidation of loose sand formations has been developed. The method involves in situ precipitation of a composite calcium phosphate-polyelectrolyte salt that binds together with loose sand grains, thus resulting to their consolidation. Three different polyelectrolytes (PE) were tested, i.e., polyacrylic acid (PAA), polyallylamine hydrochloride (PAH), and polyethylenimine (PEI). The effect of PE tested on the thermodynamics and the kinetics of precipitation of calcium phosphate salts was investigated. Three types of experiments were done. Investigation of the adsorption of PE on either hydroxyapatite (Ca(5)(PO(4))(3)OH, HAP) crystals or on sand grains. Measurement of the kinetics of heterogeneous nucleation of HAP on the solid substrates and the mechanical properties of the obtained crystals in batch experiments of low and high supersaturation solutions, respectively. Evaluation of the consolidation in sand packs in order to investigate the effectiveness of the method. The crystallization rates, R(p), on HAP crystals in the presence of the PE tested were found in the order R(p)(PAA)>R(p)(PEI)>R(p)(PAH), while nucleation and crystal growth on silicate sand took place only in the absence of adsorbed PE. PAH favored strongly the consolidation process, whereas PEI and PAA resulted in the formation of poorly consolidated grain agglomerates. PMID:21851950

Hafez, Iosif T; Paraskeva, Christakis A; Klepetsanis, Pavlos G; Koutsoukos, Petros G

2011-11-01

131

Formation of apatitic calcium phosphates in a Na-K-phosphate solution of pH 7.4  

Microsoft Academic Search

Poorly crystalline, apatitic calcium phosphate powders have been synthesized by slowly adding a Na- and K-containing reference phosphate solution with a pH value of 7.4 to an aqueous calcium nitrate solution at 37°C. Nano-particulated apatitic powders obtained were shown to contain small amounts of Na and K, which render them more similar in chemical composition to that of the bone

A. C. Tas; F. Aldinger

2005-01-01

132

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

2014-10-01

133

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.

1957-01-01

134

Limited compliance of some apatitic calcium phosphate bone cements with clinical requirements  

Microsoft Academic Search

Clinical requirements for calcium phosphate bone cements were formulated in terms of the initial setting time, the final setting time, the cohesion time and the ultimate compressive strength. Two cements were tested. Biocement H was made of a powder containing a-tertiary calcium phosphate and precipitated hydroxyapatite. Biocement F was made of a powder containing, in addition, some monetite. The liquid\\/powder

I. Khairoun; M. G. Boltong; F. C. M. Driessens; J. A. Planell

1998-01-01

135

Reinforcement of calcium phosphate cement by incorporating with high-strength ?-tricalcium phosphate aggregates.  

PubMed

Calcium phosphate cement (CPC) sets to form hydroxyapatite after implantation and has been used in orthopedic and dental procedures. However, the brittleness and low strength of CPC prohibit its use in many stress-bearing locations, and so the improvement of the compressive strength is one of the focuses of research on CPC. In this study, a novel way was used to improve the mechanical performance of CPC by dispersion of high-strength degradable ?-tricalcium phosphate (?-TCP) granules sized between 200 ?m and 450 ?m in the cement as aggregates. Intimate bonding was formed between the aggregates and CPC matrix after hydration. The results showed that, by addition of 20 wt % the as-prepared ?-TCP aggregates, the compressive strength of the calcium phosphate cement was increased by about 70%, while the paste of the CPC concrete still maintained injectable, and the heat release decreased obviously (about 25%) in the hydration process. The high strength or high rigidity of the ?-TCP aggregates and good interfacial bonding between the aggregates and the CPC matrix seemed to contribute to the significant improvement in the mechanical performance. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 100B: 350-359, 2012. PMID:22113933

Gu, Tao; Shi, Haishan; Ye, Jiandong

2012-02-01

136

Calcium phosphate and fluorinated calcium phosphate coatings on titanium deposited by Nd:YAG laser at a high fluence.  

PubMed

Calcium phosphate coatings are known to enhance long-term fixation, reliability and promote osteointegration of cementless titanium-based implant devices. This study was aimed at the pulsed laser deposition of calcium phosphate coatings onto titanium using hydroxyapatite and hydroxyapatite-fluorapatite targets. The deposition was carried out at the high laser beam fluence conditions, about 12 J/cm(2). The coatings were characterized with respect to their morphology, phase composition and hardness. X-ray energy dispersive analysis revealed the coatings retain their elemental composition, and fluoride content within the film is the same as in the initial target. However, unlike sintered targets, the deposited films contain no apatite-like phases. The hardness of the films, about 18 GPa, is surprisingly high compared to that of hydroxyapatite and hydroxyapatite-fluorapatite ceramic targets. The deposited coatings of 2.7-2.9 microm thickness have uniform and dense microstructure, containing the solidified droplets of the expulsed from the target phase. The uncommon structure and hardness of the films can be attributed to the melting and phase decomposition of the initial material in the laser plasma. PMID:15350786

Ferro, Daniela; Barinov, Sergey M; Rau, Jiulietta V; Teghil, Roberto; Latini, Alessandro

2005-03-01

137

Nanocomposite containing amorphous calcium phosphate nanoparticles for caries inhibition  

PubMed Central

Objectives The main challenges facing composite restorations are secondary caries and bulk fracture. The objectives of this study were to synthesize novel nanoparticles of amorphous calcium phosphate (NACP), develop NACP nanocomposite with calcium (Ca) and phosphate (PO4) ion release to combat caries, and investigate the effects of NACP filler level and glass co-filler reinforcement on composite properties. Methods NACP (diameter = 116 nm) were synthesized via a spray-drying technique for the first time. Since the local plaque pH in the oral cavity can decrease to 5 or 4, photo-activated composites were tested with immersion in solutions of pH 7, 5.5, and 4. Composite mechanical properties as well as Ca and PO4 ion release were measured vs. pH and filler level. Results Increasing the NACP filler level increased the ion release. At 28 d and pH 4, the Ca release was (4.66 ± 0.05) mmol/L at 20% NACP, much higher than (0.33 ± 0.08) at 10% NACP (p < 0.05). Decreasing the pH increased the ion release. At 20% NACP, the PO4 release at 28 d was (1.84 ± 0.12) mmol/L at pH 4, higher than (0.59 ± 0.08) at pH 5.5, and (0.12 ± 0.01) at pH 7 (p < 0.05). However, pH had little effect on composite mechanical properties. Flexural strength at 15% NACP was (96 ± 13) MPa at pH 4, similar to (89 ± 13) MPa at pH 5.5, and (89 ± 19) MPa at pH 7 (p > 0.1). The new NACP nanocomposites had strengths that were 2-fold those of previous calcium phosphate composites and resin-modified glass ionomer control. Significance NACP composites were developed for the first time. Their strengths matched or exceeded a commercial composite with little ion release, and were 2-fold those of previous Ca-PO4 composites. The nanocomposite was “smart” as it greatly increased the ion release at a cariogenic pH 4, when these ions would be most needed to inhibit caries. Hence, the new NACP composite may be promising for stress-bearing and caries-inhibiting restorations. PMID:21514655

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

2011-01-01

138

Calcium phosphate supersaturation regulates stone formation in genetic hypercalciuric stone-forming rats  

Microsoft Academic Search

Calcium phosphate supersaturation regulates stone formation in genetic hypercalciuric stone-forming rats.BackgroundHypercalciuria is the most common metabolic abnormality observed in patients with nephrolithiasis. Hypercalciuria raises urine supersaturation with respect to the solid phases of calcium oxalate and calcium phosphate, leading to an enhanced probability for nucleation and growth of crystals into clinically significant stones. However, there is little direct proof that

David A Bushinsky; Walter R Parker; John R Asplin

2000-01-01

139

The Inhibition of Calcium Phosphate Precipitation by Fetuin Is Accompanied by the Formation of a Fetuin-Mineral Complex*  

E-print Network

of a Fetuin-Mineral Complex* Received for publication, January 22, 2003, and in revised form, April 1, 2003 of the fetuin-mineral complex, a high molecular mass com- plex of calcium phosphate mineral and the proteins fe inhibited the precip- itation of calcium phosphate mineral when the concen- tration of calcium and phosphate

Price, Paul A.

140

Physico-chemical and in vitro biological properties of novel doped amorphous calcium phosphate-based cements.  

E-print Network

1 Physico-chemical and in vitro biological properties of novel doped amorphous calcium phosphate Abstract Calcium phosphate cements (CPC) are successfully used as bone substitutes in dentistry of a settable matrix and biphasic calcium phosphates (BCP) granules. X-ray diffraction data of the cement

Paris-Sud XI, Université de

141

In vivo dentin microhardness beneath a calcium-phosphate cement.  

PubMed

A minimally invasive caries-removal technique preserves potentially repairable, caries-affected dentin. Mineral-releasing cements may promote remineralization of soft residual dentin. This study evaluated the in vivo remineralization capacity of resin-based calcium-phosphate cement (Ca-PO(4)) used for indirect pulp-capping. Permanent carious and sound teeth indicated for extraction were excavated and restored either with or without the Ca-PO(4) base (control), followed by adhesive restoration. Study teeth were extracted after 3 months, followed by sectioning and in vitro microhardness analysis of the cavity floor to 115-microm depth. Caries-affected dentin that received acid conditioning prior to Ca-PO(4) basing showed significantly increased Knoop hardness near the cavity floor. The non-etched group presented results similar to those of the non-treated group. Acid etching prior to cement application increased microhardness of residual dentin near the interface after 3 months in situ. PMID:20511564

Bresciani, E; Wagner, W C; Navarro, M F L; Dickens, S H; Peters, M C

2010-08-01

142

Surface modification of biphasic calcium phosphate bioceramic powders  

NASA Astrophysics Data System (ADS)

Biphasic calcium phosphate (BCP)/poly L-lactide (PLLA) biocomposite is proven to be a promising bone graft material or scaffold for bone tissue engineering. To improve the interfacial compatibility of BCP bioceramic with biopolymer-PLLA, BCP powders were surface-modified in different condition to graft polymer groups onto the surface of the BCP powders. L-lactide and L-lactic acid (LA) oligomer were used to modify the BCP surface with stannous octanoate (Sn(Oct) 2) and stannous chloride (SnCl 2) as catalyst, respectively. Results show that the surface modification effect is obvious and the amount of grafted organic group is above 6.5 wt.%. Sn(Oct) 2 and SnCl 2 are the optimal catalysts for the surface grafting reaction of L-lactide and L-LA oligomer, respectively. The surface grafting slightly increase the particle size of BCP powders and reduce the tendency for their agglomeration.

Yang, W. Z.; Zhou, D. L.; Yin, G. F.; Li, G. D.

2008-11-01

143

A new method to produce macropores in calcium phosphate cements.  

PubMed

A new way to create macropores in calcium phosphate cements has been developed. The method consists in adding NaHCO3 to the starting cement powder (Biocement D) and using two different liquids: first a basic liquid to form the paste and later an acid liquid to obtain CO2 bubbles. Mercury intrusion measurements showed a dramatic increase both in macropores with an average size of 100 m and in the total porosity (even higher than 50% with respect to the Biocement D). This method does not change in any significant way the final reaction products of the starting material after being soaked 3 days in Ringer solution. Only, due to the increase of the porosity. the compressive strength of the porous cement decreases significantly. PMID:12109693

del Real, R P; Wolke, J G C; Vallet-Regí, M; Jansen, J A

2002-09-01

144

Novel dental adhesive containing antibacterial agents and calcium phosphate nanoparticles  

PubMed Central

Secondary caries remains the main reason for dental restoration failure. Replacement of failed restorations accounts for 50-70% of all restorations performed. Antibacterial adhesives could inhibit biofilm acids at tooth-restoration margins, and calcium phosphate (CaP) ions could remineralize tooth lesions. The objectives of this study were to: (1) incorporate nanoparticles of silver (NAg), quaternary ammonium dimethacrylate (QADM), and nanoparticles of amorphous calcium phosphate (NACP) into bonding agent; and (2) investigate their effects on dentin bonding and microcosm biofilms. An experimental primer was made with pyromellitic glycerol dimethacrylate (PMGDM) and 2-hydroxyethyl methacrylate (HEMA). An adhesive was made with bisphenol-A-glycerolate dimethacrylate (BisGMA) and triethylene glycol dimethacrylate (TEGDMA). NAg was incorporated into primer at 0.1wt%. The adhesive contained 0.1% NAg and 10% QADM, and 0-40% NACP. Incorporating NAg into primer and NAg-QADM-NACP into adhesive did not adversely affect dentin bond strength (p>0.1). SEM showed numerous resin tags, and TEM revealed NAg and NACP in dentinal tubules. Viability of human saliva microcosm biofilms on primer/adhesive/composite disks was substantially reduced via NAg and QADM. Metabolic activity, lactic acid, and colony-forming units of biofilms were much lower on the new bonding agents than control (p<0.05). In conclusion, novel dental bonding agents containing NAg, QADM and NACP were developed with the potential to kill residual bacteria in the tooth cavity and inhibit the invading bacteria along tooth-restoration margins, with NACP to remineralize tooth lesions. The novel method of combining antibacterial agents (NAg and QADM) with remineralizing agent (NACP) may have wide applicability to other adhesives for caries inhibition. PMID:23281264

Melo, Mary Anne S.; Cheng, Lei; Weir, Michael D.; Hsia, Ru-ching; Rodrigues, Lidiany K. A.; Xu, Hockin H. K.

2013-01-01

145

Novel dental adhesive containing antibacterial agents and calcium phosphate nanoparticles.  

PubMed

Secondary caries remains the main reason for dental restoration failure. Replacement of failed restorations accounts for 50%-70% of all restorations performed. Antibacterial adhesives could inhibit biofilm acids at tooth-restoration margins, and calcium phosphate (CaP) ions could remineralize tooth lesions. The objectives of this study were to: (1) incorporate nanoparticles of silver (NAg), quaternary ammonium dimethacrylate (QADM), and nanoparticles of amorphous calcium phosphate (NACP) into bonding agent; and (2) investigate their effects on dentin bonding and microcosm biofilms. An experimental primer was made with pyromellitic glycerol dimethacrylate (PMGDM) and 2-hydroxyethyl methacrylate (HEMA). An adhesive was made with bisphenol-A-glycerolate dimethacrylate (BisGMA) and triethylene glycol dimethacrylate (TEGDMA). NAg was incorporated into primer at 0.1 wt %. The adhesive contained 0.1% NAg and 10% QADM, and 0%-40% NACP. Incorporating NAg into primer and NAg-QADM-NACP into adhesive did not adversely affect dentin bond strength (p > 0.1). Scanning electron microscopy showed numerous resin tags, and transmission electron microscopy revealed NAg and NACP in dentinal tubules. Viability of human saliva microcosm biofilms on primer/adhesive/composite disks was substantially reduced via NAg and QADM. Metabolic activity, lactic acid, and colony-forming units of biofilms were much lower on the new bonding agents than control (p < 0.05). In conclusion, novel dental bonding agents containing NAg, QADM, and NACP were developed with the potential to kill residual bacteria in the tooth cavity and inhibit the invading bacteria along tooth-restoration margins, with NACP to remineralize tooth lesions. The novel method of combining antibacterial agents (NAg and QADM) with remineralizing agent (NACP) may have wide applicability to other adhesives for caries inhibition. PMID:23281264

Melo, Mary Anne S; Cheng, Lei; Weir, Michael D; Hsia, Ru-Ching; Rodrigues, Lidiany K A; Xu, Hockin H K

2013-05-01

146

On the effect of the injection of potassium phosphate in vivo inducing the precipitation of serum calcium with inorganic phosphate  

PubMed Central

High concentrations of inorganic phosphate (Pi) resulted from the hydrolysis of ATP is strongly associated to the weakness of the contractile mechanism of muscles due to its attractiveness to calcium. The majority of the experiments to study such effect are conducted in vitro. This work investigates the effects of different concentrations of Pi, induced by the injection of potassium phosphate in live animals, in the precipitation with serum calcium and the generation of calcium phosphate composites. The experiments were also designed to find out the ideal amount of potassium phosphate to induce an effective reaction. Potassium phosphate was injected in Wistar rats, randomly separated and distributed into seven groups. Group I was injected with 0.5 ml of saline solution (control) and groups II through VII were injected with 0.5, 1.5, 2.5, 5.0, 7.5 and 10.0 mg/kg of potassium phosphate, respectively. Blood collected from the inferior vena cava was submitted to biochemical analyses to measure the concentrations of calcium, Pi, urea and creatinine. The results showed that Pi, induced by the injection of potassium phosphate in live animals, causes precipitation with serum calcium, with statistically significant differences between the control and the treatment groups for doses up to 5.0 mg/kg. No statistically significant differences were found between the different doses and the concentration of urea and creatinine in the plasma. We conclude that potassium phosphate can be used to induce serum calcium precipitation in-vivo, with minor effects on other physiological variables, and the ideal dose to do so is 5.0 mg/kg. PMID:24379908

Soares, Alcimar B; Ticianeli, José G; Soares, Letícia B M; Amaro, George

2013-01-01

147

Calcium phosphate nanoparticles functionalized with a dimethacrylate monomer.  

PubMed

The synthesis of calcium phosphate nanoparticles may include modifying agents to tailor particle size, reduce agglomeration and add specific functionalities. This study describes the synthesis of dicalcium phosphate dihydrate (DCPD) nanoparticles functionalized with triethylene glycol dimethacrylate (TEGDMA), added to one of the reacting solutions, with the purpose of reducing agglomeration and improving the compatibility with vinyl-based resin matrices. The nanoparticles were characterized by X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), elemental analysis, thermogravimetric analysis (TGA), transmission electronic microscopy (TEM), dynamic light scattering (DLS), and surface area (BET). As controls, proprietary DCPD nanoparticles and nanoparticles synthesized without the addition of TEGDMA ("bare") were subjected to the same analytical methods. XRD revealed a similar crystalline structure of the synthesized materials in comparison to the proprietary nanoparticles. The presence of a TEGDMA layer was confirmed by elemental analysis and TGA, corresponding to a mass fraction of 8.5%. FTIR analysis of the functionalized nanoparticles revealed the suppression of some absorbance bands found in the neat TEGDMA. A chemisorption mechanism between TEGDMA and the surface of primary particles by ion-dipole interaction involving TEGDMA oxyethylene, and also an interaction mechanism between the particle surface and terminal-CH3 groups are proposed. Functionalized nanoparticles showed 3 to 11 times higher surface area than the controls, in agreement with DLS data, indicating lower agglomeration. PMID:25491810

Rodrigues, Marcela Charantola; Hewer, Thiago Lewis Reis; Brito, Giancarlo Espósito de Souza; Arana-Chavez, Victor Elias; Braga, Roberto Ruggiero

2014-12-01

148

Intergrowth of calcium phosphates: an interfacial energy approach  

NASA Astrophysics Data System (ADS)

A factor which is usually ignored in discussions of the induced crystallization of one phase by the surface of another is the surface free energy of the nucleus/substratum interface. Interfacial energies of hydroxyapatite (HAP), octacalcium phosphate (OCP) and fluorapatite (FAP) microcrystals against aqueous solutions, measured using a thin-layer wicking technique, were 9.0, 4.3 and 18.5 mJ m -2, respectively. The calculated low interfacial energy, 0.93 mJ m -2, between OCP and HAP provides strong support for the suggestion that OCP is the first forming phase that induces HAP crystallization in calcium phosphate precipitation reactions. Using the constant composition kinetics method, the nucleation and growth of OCP on titanium oxide surfaces were investigated. The interfacial energy calculated from the nucleation and growth data compared favorably with that obtained by thin layer wicking. Extending the interfacial energy approach to polymeric substrata such as poly(methyl methacrylate) (PMMA), and the radiofrequency glow discharge treated PMMA demonstrates, in predicting the ability of surfaces to induce mineral nucleation, the importance of the Lewis base parameter.

Liu, Y.; Wu, W.; Sethuraman, G.; Nancollas, G. H.

1997-04-01

149

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.

2013-10-01

150

The initial phases of calcium and magnesium phosphates precipitated from solutions of high to medium concentrations  

NASA Astrophysics Data System (ADS)

The precipitation of calcium and magnesium phosphates is performed at 25°C by mixing solutions of ammonium phosphate and solutions of calcium and magnesium chlorides under the condition [ P] = [ Ca] + [ Mg] in large pH intervals. Before any nucleation the phosphate concentration ranges from 0.50M to 0.01M. The phases first precipitated are CaHPO 4·2H 2O (brushite), CaHPO 4 (monetite), Ca 3(PO 4) 2· xH 2O (amorphous calcium phosphate), MgNH 4PO 4·6H 2O (struvite), and MgHPO 4·3H 2O (newberyite). The precipitation fields of each phase are determined and discussed as a function of pH, composition and supersaturation. The solutions are even supersaturated with respect to several other calcium phosphates but they never occur first even if their supersaturation is the highest.

Abbona, F.; Madsen, H. E. Lundager; Boistelle, R.

1986-04-01

151

Precipitation of calcium carbonate and calcium phosphate under diffusion controlled mixing  

SciTech Connect

Multi-component mineral precipitation in porous, subsurface environments is challenging to simulate or engineer when in situ reactant mixing is controlled by diffusion. In contrast to well-mixed systems, the conditions that favor mineral precipitation in porous media are distributed along chemical gradients, which evolve spatially due to concurrent mineral precipitation and modification of solute transport in the media. The resulting physical and chemical characteristics of a mixing/precipitation zone are a consequence of coupling between transport and chemical processes, and the distinctive properties of individual chemical systems. We examined the spatial distribution of precipitates formed in “double diffusion” columns for two chemical systems, calcium carbonate and calcium phosphate. Polyacrylamide hydrogel was used as a low permeability, high porosity medium to maximize diffusive mixing and minimize pressure- and density-driven flow between reactant solutions. In the calcium phosphate system, multiple, visually dense and narrow bands of precipitates were observed that were reminiscent of previously reported Liesegang patterns. In the calcium carbonate system, wider precipitation zones characterized by more sparse distributions of precipitates and a more open channel structure were observed. In both cases, formation of precipitates inhibited, but did not necessarily eliminate, continued transport and mixing of the reactants. A reactive transport model with fully implicit coupling between diffusion, chemical speciation and precipitation kinetics, but where explicit details of nucleation processes were neglected, was able to qualitatively simulate properties of the precipitation zones. The results help to illustrate how changes in the physical properties of a precipitation zone depend on coupling between diffusion-controlled reactant mixing and chemistry-specific details of precipitation kinetics.

Tsigabu Gebrehiwet; James R. Henriksen; Luanjing Guo; Don T. Fox; Hai Huang; Lee Tu; Yoshiko Fujita; Robert W. Smith; George Redden

2014-07-01

152

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

PubMed

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

2014-01-01

153

Effect of calcium carbonate on the compliance of an apatitic calcium phosphate bone cement.  

PubMed

Clinical requirements for calcium phosphate bone cements were formulated in terms of the initial setting time, the final setting time, the cohesion time and the ultimate compressive strength. Three cement formulations were tested. The previously developed Biocement H was made of a powder containing alpha-tertiary calcium phosphate and precipitated hydroxyapatite. Biocement B2 powder was made by adding some CaCO3 to Biocement H, whereas Biocement B1 was made by adding some CaCO3 but with simultaneous adjustment of the amount of precipitated hydroxyapatite.The liquid/ powder ratio of the cement paste and the accelerator concentrations (percentage Na2HPO4) in cement liquid were varied. For Biocement H there was no combination of L/P ratio and percentage Na2HPO4 for which all clinical requirements were satisfied. However, there was an area of full compliance for Biocements B1 and B2, of which that for B1 was the largest. Therefore, Biocement B1 may be applied in clinical situations as those in orthopaedics, plastic and reconstructive surgery and oral and maxillofacial surgery, even when early contact with blood is inevitable. PMID:9430336

Khairoun, I; Boltong, M G; Driessens, F C; Planell, J A

1997-12-01

154

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

PubMed Central

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

2014-01-01

155

Synthesis of spherical calcium phosphate particles for dental and orthopedic applications  

PubMed Central

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

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

2013-01-01

156

Synthesis of spherical calcium phosphate particles for dental and orthopedic applications.  

PubMed

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

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

2013-01-01

157

Randomized crossover study comparing the phosphate-binding efficacy of calcium ketoglutarate versus calcium carbonate in patients on chronic hemodialysis.  

PubMed

The objective of the study was to evaluate the phosphate-binding efficacy, side effects, and cost of therapy of calcium ketoglutarate granulate as compared with calcium carbonate tablets in patients on chronic hemodialysis. The study design used was a randomized, crossover open trial, and the main outcome measurements were plasma ionized calcium levels, plasma phosphate levels, plasma intact parathyroid hormone (PTH) levels, requirements for supplemental aluminum-aminoacetate therapy, patient tolerance, and cost of therapy. Nineteen patients on chronic hemodialysis were treated with a dialysate calcium concentration of 1.25 mmol/L and a fixed alfacalcidol dose for at least 2 months. All had previously tolerated therapy with calcium carbonate. Of the 19 patients included, 10 completed both treatment arms. After 12 weeks of therapy, the mean (+/-SEM) plasma ionized calcium level was significantly lower in the ketoglutarate arm compared with the calcium carbonate arm (4.8+/-0.1 mg/dL v 5.2+/-0.1 mg/dL; P = 0.004), whereas the mean plasma phosphate (4.5+/-0.3 mg/dL v 5.1+/-0.1 mg/dL) and PTH levels (266+/-125 pg/mL v 301+/-148 pg/mL) did not differ significantly between the two treatment arms. Supplemental aluminum-aminoacetate was not required during calcium ketoglutarate treatment, while two patients needed this supplement when treated with calcium carbonate. Five of 17 (29%) patients were withdrawn from calcium ketoglutarate therapy within 1 to 2 weeks due to intolerance (anorexia, vomiting, diarrhea, general uneasiness), whereas the remaining 12 patients did not experience any side effects at all. The five patients with calcium ketoglutarate intolerance all had pre-existing gastrointestinal symptoms; four of them had received treatment with cimetidine or omeprazol before inclusion into the study. Calculations based on median doses after 12 weeks showed that the cost of the therapy in Denmark was 10 times higher for calcium ketoglutarate compared with calcium carbonate (US$6.00/d v US$0.65/d). Calcium ketoglutarate may be an effective and safe alternative to treatment with aluminum-containing phosphate binders in patients on hemodialysis who are intolerant of calcium carbonate or acetate because of hypercalcemia. However, care must be exercised when dealing with patients with pre-existing gastrointestinal discomfort. Due to the high cost of the therapy, calcium ketoglutarate should be used only for selected patients. PMID:9469496

Bro, S; Rasmussen, R A; Handberg, J; Olgaard, K; Feldt-Rasmussen, B

1998-02-01

158

Premixed rapid-setting calcium phosphate composites for bone repair?  

PubMed Central

Although calcium phosphate cement (CPC) is promising for bone repair, its clinical use requires on site powder–liquid mixing. To shorten surgical time and improve graft properties, it is desirable to develop premixed CPC in which the paste remains stable during storage and hardens only after placement into the defect. The objective of this study was to develop premixed CPC with rapid setting when immersed in a physiological solution. Premixed CPCs were formulated using the following approach: Premixed CPC = CPC powder+nonaqueous liquid+gelling agent+hardening accelerator. Three premixed CPCs were developed: CPC–monocalcium phosphate monohydrate (MCPM), CPC–chitosan, and CPC–tartaric. Setting time for these new premixed CPCs ranged from 5.3 to 7.9 min, significantly faster than 61.7 min for a premixed control CPC reported previously (p<05). SEM revealed the formation of nano-sized needle-like hydroxyapatite crystals after 1 d immersion and crystal growth after 7 d. Diametral tensile strength for premixed CPCs at 7 d ranged from 2.8 to 6.4 MPa, comparable to reported strengths for cancellous bone and sintered porous hydroxyapatite implants. Osteoblast cells attained a normal polygonal morphology on CPC–MCPM and CPC–chitosan with cytoplasmic extensions adhering to the nano-hydroxyapatite crystals. In summary, fast-setting premixed CPCs were developed to avoid the powder–liquid mixing in surgery. The pastes hardened rapidly once immersed in physiological solution and formed hydroxyapatite. The cements had strengths matching those of cancellous bone and sintered porous hydroxyapatite and non-cytotoxicity similar to conventional non-premixed CPC. PMID:15769536

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

2009-01-01

159

In vivo bone response to porous calcium phosphate cement.  

PubMed

We conducted an in vivo experiment to evaluate the resorption rate of a calcium phosphate cement (CPC) with macropores larger than 100 microm, using the CPC called Biocement D (Merck Biomaterial, Darmstadt, Germany), which after setting only shows pores smaller than 1 microm. The gas bubble method used during the setting process created macroporosity. Preset nonporous and porous cement implants were inserted into the trabecular bone of the tibial metaphysis of goats. The size of the preset implants was 6 mm and the diameter of the drill hole was 6.3 mm, leaving a gap of 0.3 mm between implant surface and drill wall. After 2 and 10 weeks, the animals were euthanized and cement implants with surrounding bone were retrieved for histologic evaluation. Light microscopy at 2 weeks revealed that the nonporous implants were surrounded by connective tissue. On the cement surface, we observed a monolayer of multinucleated cells. Ten weeks after implantation, the nonporous implants were still surrounded by connective tissue. However, a thin layer of bone now covered the implant surface. No sign of cement resorption was observed. In contrast, the porous cement evoked a completely different bone response. At 2 weeks, bone formation had already occurred inside the implant porosity. Bone formation even appeared to occur as a result of osteoinduction. Also, at their outer surface, the porous implants were completely surrounded by bone. At 2 weeks, about 31% of the initial cement was resorbed. After 10 weeks, 81% of the initial phosphate cement was resorbed and new bone was deposited. On the basis of these observations, we conclude that the creation of macropores can significantly improve the resorption rate of CPC. This increased degradation is associated with almost complete bone replacement. PMID:12635151

del Real, R P; Ooms, E; Wolke, J G C; Vallet-Regí, M; Jansen, J A

2003-04-01

160

The periapical tissue reactions to a calcium phosphate cement in the teeth of monkeys.  

PubMed

A calcium phosphate cement, Grossman sealer, and Sargenti N2 were compared under conditions where root canals of monkey incisors were deliberately overfilled and the apical tissue responses were evaluated histologically. The periapical tissues exposed to Sargenti N2 revealed severe irritation at all times through the 6-month experimental period. The reactions to Grossman sealer were milder but persisted throughout the observation period. The calcium-phosphate-cement treated animals showed mild tissue irritation after 1 month, but thereafter the adverse tissue reactions were minimal. New bone formation adjacent to the cement was also observed. These results point to the possibility that calcium phosphate cement might be used in simplified endodontic procedures. The compatibility of calcium phosphate cement with the periapical tissue suggests that the cement may have other applications in dentistry and medicine. PMID:2050712

Hong, Y C; Wang, J T; Hong, C Y; Brown, W E; Chow, L C

1991-04-01

161

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

NASA Astrophysics Data System (ADS)

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

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

2007-09-01

162

Effect of phosphate, calcium, and pH on the dissolution of a phosphate rock in soil  

Microsoft Academic Search

The effect of phosphate (P), calcium (Ca), and pH on the dissolution of Sechura phosphate rock (SPR) in a Typic Dystrochrept was investigated in an incubation study over 90 days. Increasing the P status of the soil had little effect on either the rate or extent of dissolution of SPR, as measured by a single extraction with 0.5M NaOH, or

AD Mackay; JK Syers

1986-01-01

163

Carbonated calcium phosphates are suitable pH-stabilising fillers for biodegradable polyesters  

Microsoft Academic Search

Carbonated amorphous calcium phosphates were prepared with different carbonate content. Their ability to neutralise acidity was probed by time-resolved titration experiments with lactic acid, the monomer that results from degradation of polylactide. The results show that although calcium phosphate as such can reduce acidity, their buffering range lies at a pH of about 4, i.e. outside the physiological range. This

Carsten Schiller; Matthias Epple

2003-01-01

164

Preparation and mechanism of calcium phosphate coatings on chemical modified carbon fibers by biomineralization  

Microsoft Academic Search

In order to prepare HA coatings on the carbon fibers, chemical modification and biomineralization processes were applied. The phase components, morphologies, and possible growth mechanism of calcium phosphate were studied by infrared spectroscopy(IR), X-ray diffractometry(XRD) and scanning electron microscopy(SEM). The results show that calcium phosphate coating on carbon fibers can be obtained by biomineralization. But the phase components and morphologies

Su-ping HUANG; Ke-chao ZHOU; Zhi-you LI

2008-01-01

165

Formation of Phosphate-Containing Calcium Fluoride at the Expense of Enamel, Hydroxyapatite and Fluorapatite  

Microsoft Academic Search

During the caries process complex reactions involving calcium, phosphate, hydrogen and fluoride ions as main species take place. In this study the precipitation and dissolution reactions occurring in suspensions of enamel, hydroxyapatite (HAP) and fluorapatite (FAP) on addition of fluoride were investigated under well-defined conditions. pH and pF were monitored; calcium and phosphate concentrations were measured at selected times; the

J. Christoffersen; M. R. Christoffersen; J. Arends; E. S. Leonardsen

1995-01-01

166

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

1996-01-01

167

Ethoxylated Bisphenol Dimethacrylate-based Amorphous Calcium Phosphate Composites  

PubMed Central

Improving the anti-demineralizing/remineralizing and mechanical properties of amorphous calcium phosphate (ACP) composites has been the focus of our recent research. In this study, an ethoxylated bisphenol A dimethacrylate (EBPADMA) was blended with triethylene glycol dimethacrylate (TEGDMA), 2-hydroxyethyl methacrylate (HEMA) and methacryloxyethyl phthalate (MEP) to form three experimental resins. The resins were formulated to have 3 different EBPADMA/TEGDMA molar ratios (0.50, 0.85 and 1.35) and a constant HEMA/MEP molar ratio (8.26 ± 0.33). The resins were photo-activated for visible light polymerization and composites were prepared by admixture of either unmilled or milled zirconia-ACP filler (40 % by mass). One aim of the study was to test if improved ion release can be achieved by elevating the EBPADMA/TEGDMA ratio while lowering the level of surface active methacryloxyethyl phthalate in the resin without adversely affecting the strength, degree of vinyl conversion and water sorption of composites. A second aim was to assess the effect of using milled vs. unmilled ACP on these properties of the various composites. Both copolymers blends and composites were assessed for the biaxial flexure strength, degree of vinyl conversion and water sorption, and the composites were evaluated for the mineral ion release as well. Overall ion release of all composites was significantly above the theoretical minimum necessary for remineralization and calcium ion release was not impeded by calcium binding with the carboxylic acid groups of methacryloxyethyl phthalate. Increased supersaturation was attained with increasing EBPADMA/TEGDMA ratio in the resin. Variations in resin composition had no effect on the biaxial flexure strength or degree of vinyl conversion of composites. The biaxial flexure strength values of the milled ACP composites were higher than the biaxial flexure strength values of unmilled ACP composites (56 % and 79 %, respectively for dry and wet specimens). Degree of vinyl conversion of composites was only moderately reduced (13.6 % and 7.3 %, for unmilled and milled ACP, respectively) compared to unfilled resins [(80.2 ± 3.1) %]. Water sorption decreased in the following order: unmilled ACP composites > milled ACP composites ? copolymer blends. Fine-tuning of the resin and utilizing milled ACP filler improved the remineralizing potential of ACP composites without impeding their vinyl conversion, mechanical strength or water sorption. PMID:16701862

Skrtic, D.; Antonucci, J.M.; Liu, D.W.

2006-01-01

168

Fade and quench-resistant emission in calcium phosphate nanoreactors  

NASA Astrophysics Data System (ADS)

The fluorescence emission and photodegradation properties of fluorescein dye inside fluid-filled spherical nanoreactors ~ 150 nm in diameter and surrounded by a few nanometres thick layer of calcium phosphate are considered in detail. Steady state, stopped flow, and laser pulsed fluorescence spectroscopies, absorption spectroscopy, dynamic light scattering and electron microscopy were used to characterize the materials as a function of encapsulated dye concentration, particle concentration, illumination time, and pH. Fluorescein tends to form stable J-aggregates inside the nanoreactors. The molecular collision rate constants between the dye aggregates and between the dyes and soluble quenchers are greatly reduced inside the nanoreactors and are responsible for the observed resistance to photodegradation and reduced emission quenching. A model for dye behaviour in nanoreactors is suggested. Nanoreactors can be concentrated to a high suspension concentration, yielding exceptionally strong luminescence affected only by inner filter effects absent particle-particle crosstalk. These and similar nanoreactors can be utilized as building blocks for three-dimensional photo-optical devices, and as versatile and resilient supramolecular chromophores or tracers in complex fluids, cells and microfluidic systems where high resolution visualization is needed.

Chen, Yen-Chi; Han, Kyu-Bum; Mizukami, Hiroshi; Wojcik, Aleksandra; Ostafin, Agnes

2010-11-01

169

Stem Cell-Calcium Phosphate Constructs for Bone Engineering  

PubMed Central

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 CPC construct with chitosan and fiber reinforcement reached the strength of cancellous bone, which was much stronger than previous injectable carriers for cell delivery. hUCMSCs and hBMSCs inside the constructs showed excellent viability and osteo-differentiation. The encapsulated hUCMSCs synthesized nearly three-fold more bone minerals than the hBMSCs in vitro. Hence, stem-cell-encapsulating CPC-chitosan-fiber construct may be promising for dental and orthopedic applications. This study indicated that the hUCMSCs were a potent alternative to the gold-standard hBMSCs, which may have a broad impact on regenerative medicine and dental tissue engineering. PMID:20929721

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

2010-01-01

170

Dibasic calcium phosphate dihydrate, USP material compatibility with gamma radiation  

NASA Astrophysics Data System (ADS)

Gamma radiation is a commonly used method to reduce the microbial bioburden in compatible materials when it is applied at appropriate dose levels. Gamma irradiation kills bacteria and mold by breaking down the organism’s DNA and inhibiting cell division. The purpose of this study is to determine the radiation dosage to be used to treat Dibasic Calcium Phosphate Dihydrate, USP (DCPD) and to evaluate its physicochemical effects if any, on this material. This material will be submitted to various doses of gamma radiation that were selected based on literature review and existing regulations that demonstrate that this method is effective to reduce or eliminate microbial bioburden in natural source and synthetic materials. Analytical testing was conducted to the DCPD exposed material in order to demonstrate that gamma radiation does not alter the physicochemical properties and material still acceptable for use in the manufacture of pharmaceutical products. The results obtained through this study were satisfactory and demonstrated that the gamma irradiation dosages from 5 to 30 kGy can be applied to DCPD without altering its physicochemical properties. These are supported by the Assay test data evaluation of lots tested before and after gamma irradiation implementation that show no significant statistical difference between irradiated and non irradiated assay results. The results of this study represent an achievement for the industry since they provide as an alternative the use of Gamma irradiation technology to control the microbial growth in DCPD.

Betancourt Quiles, Maritza

171

Current perspectives: calcium phosphate nanocoatings and nanocomposite coatings in dentistry.  

PubMed

The purpose of coatings on implants is to achieve some or all of the improvements in biocompatibility, bioactivity, and increased protection from the release of harmful or unnecessary metal ions. During the last decade, there has been substantially increased interest in nanomaterials in biomedical science and dentistry. Nanocomposites can be described as a combination of two or more nanomaterials. By this approach, it is possible to manipulate mechanical properties, such as strength and modulus of the composites, to become closer to those of natural bone. This is feasible with the help of secondary substitution phases. Currently, the most common composite materials used for clinical applications are those selected from a handful of available and well-characterized biocompatible ceramics and natural and synthetic polymers. This approach is currently being explored in the development of a new generation of nanocomposite coatings with a wider range of oral and dental applications to promote osseointegration. The aim of this review is to give a brief introduction into the new advances in calcium phosphate nanocoatings and their composites, with a range of materials such as bioglass, carbon nanotubes, silica, ceramic oxide, and other nanoparticles being investigated or used in dentistry. PMID:23857642

Choi, A H; Ben-Nissan, B; Matinlinna, J P; Conway, R C

2013-10-01

172

Genetic Responses to Nanostructured Calcium-phosphate-coated Implants  

PubMed Central

Nanostructured calcium phosphate (CaP) has been histologically and biomechanically proven to enhance osseointegration of implants; however, conventional techniques were not sufficiently sensitive to capture its biological effects fully. Here, we compared the conventional removal torque (RTQ) evaluation and gene expression in tissues around nanostructured CaP-coated implants, using real-time RT-PCR, with those of uncoated implants, in a rabbit model. At 2 wks, RTQ values were significantly higher, alkaline phosphatase (ALP) expression was significantly higher, and runt-related transcription factor 2 and tumor necrosis factor-? expressions were significantly lower in the coated than in the uncoated implants. This indicates that inflammatory responses were suppressed and osteoprogenitor activity increased around the CaP-coated surface. At 4 wks, although RTQ values did not significantly differ between the 2 groups, ALP and osteocalcin (OCN) were significantly up-regulated in the coated group, indicating progressive mineralization of the bone around the implant. Moreover, an osteoclast marker, adenosine triphosphatase, which indicates acidification of the resorption lacunae, was significantly higher for the coated implants, suggesting gradual resorption of the CaP coating. This study reveals detailed genetic responses to nanostructured CaP-coated implants and provides evidence that the effect of nanotopography is significant during the osseointegration cascade. PMID:21933935

Jimbo, R.; Xue, Y.; Hayashi, M.; Schwartz-Filho, H.O.; Andersson, M.; Mustafa, K.; Wennerberg, A.

2011-01-01

173

Porous calcium phosphate cement for alveolar bone regeneration.  

PubMed

The present study aimed to provide information on material degradation and subsequent alveolar bone formation, using composites consisting of calcium phosphate cement (CPC) and poly(lactic-co-glycolic) acid (PLGA) with different microsphere morphology (hollow vs dense). In addition to the plain CPC-PLGA composites, loading the microspheres with the growth factors platelet-derived growth factor (PDGF) and insulin-like growth factor (IGF) was investigated. A total of four different CPC composites were applied into one-wall mandible bone defects in beagle dogs in order to evaluate them as candidates for alveolar bone regeneration. These composites consisted of CPC and hollow or dense PLGA microspheres, with or without the addition of PDGF-IGF growth factor combination (CPC-hPLGA, CPC-dPLGA, CPC-hPLGAGF , CPC-dPLGAGF ). Histological evaluation revealed significantly more bone formation in CPC-dPLGA than in CPC-hPLGA composites. The combination PDGF-IGF enhanced bone formation in CPC-hPLGA materials, but significantly more bone formation occurred when CPC-dPLGA was used, with or without the addition of growth factors. The findings demonstrated that CPC-dPLGA composite was the biologically superior material for use as an off-the-shelf material, due to its good biocompatibility, enhanced degradability and superior bone formation. PMID:22777771

Félix Lanao, R P; Hoekstra, J W M; Wolke, J G C; Leeuwenburgh, S C G; Plachokova, A S; Boerman, O C; van den Beucken, J J J P; Jansen, J A

2014-06-01

174

Calcium-phosphate-coated oral implants promote osseointegration in osteoporosis.  

PubMed

Osteoporotic conditions are anticipated to affect the osseointegration of dental implants. This study aimed to evaluate the effect of a radiofrequent magnetron-sputtered calcium phosphate (CaP) coating on dental implant integration upon installment in the femoral condyles of both healthy and osteoporotic rats. At 8 weeks post-implantation, bone volume and histomorphometric bone area were lower around non-coated implants in osteoporotic rats compared with healthy rats. Interestingly, push-out tests revealed significantly enhanced implant fixation for CaP-coated compared with non-coated implants in both osteoporotic (i.e., 2.9-fold) and healthy rats (i.e., 1.5-fold), with similar implant fixation for CaP-coated implants in osteoporotic conditions compared with that of non-coated implants in healthy conditions. Further, the presence of a CaP coating significantly increased bone-to-implant contact compared with that in non-coated implants in both osteoporotic (i.e., 1.3-fold) and healthy rats (i.e., 1.4-fold). Sequential administration of fluorochrome labels showed significantly increased bone dynamics close to CaP-coated implants at 3 weeks of implantation in osteoporotic conditions and significantly decreased bone dynamics in osteoporotic compared with healthy conditions. In conclusion, analysis of the data obtained demonstrated that dental implant modification with a thin CaP coating effectively improves osseointegration in both healthy and osteoporotic conditions. PMID:24056224

Alghamdi, H S; Cuijpers, V M J I; Wolke, J G C; van den Beucken, J J J P; Jansen, J A

2013-11-01

175

Antibacterial Property Expressed by a Novel Calcium Phosphate Glass  

PubMed Central

We have developed a calcium phosphate glass (CPG) doped with Zn2+ or F? or combined Zn2+ 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 Zn2+ 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. 0.01g and 0.05g of CPGs were incubated with Streptococcus 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 Zn2+ 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

2014-01-01

176

Heparin modification of calcium phosphate bone cements for VEGF functionalization.  

PubMed

A promising strategy to promote angiogenesis within an engineered tissue is the local and sustained delivery of an angiogenic factor by the substitute itself. Recently, we reported on functionalization of Biocement D (BioD) and several modifications of this calcium phosphate bone cement with vascular endothelial growth factor (VEGF). Maintenance of biological activity of VEGF after release from the cement was improved by modification of BioD with mineralized collagen type I (BioD/coll). However, BioD/coll composites showed a higher initial burst of VEGF release than do the unmodified BioD. In the present study, VEGF release from BioD/coll composites modified with different amounts of heparin was investigated. We found a distinct reduction of the initial burst of release by adding heparin in a concentration-dependent manner. Moreover, the heparin modification had a positive impact on the biological activity of released VEGF. An advancement of biological properties of BioD/coll by addition of heparin was further shown by improved adhesion of endothelial cells on the cement surface. Characterization of material properties of the heparin-modified BioD/coll composites revealed a finer microstructure with smaller HA-particles and a higher specific surface area than heparin-free BioD/coll. However, higher amounts of heparin resulted in a reduced compressive strength. The rheological properties of these cement pastes have been found to be favorable for good handling particularly with regard to their clinical application. PMID:18041720

Lode, A; Reinstorf, A; Bernhardt, A; Wolf-Brandstetter, C; König, U; Gelinsky, M

2008-09-01

177

Remineralization of Demineralized Enamel via Calcium Phosphate Nanocomposite  

PubMed Central

Secondary caries remains the main problem limiting the longevity of composite restorations. The objective of this study was to investigate the remineralization of demineralized human enamel in vitro via a nanocomposite containing nanoparticles of amorphous calcium phosphate (NACP). NACP were synthesized by a spray-drying technique and incorporated into a dental resin. First, caries-like subsurface enamel lesions were created via an acidic solution. Then, NACP nanocomposite or a commercial fluoride-releasing control composite was placed on the demineralized enamel, along with control enamel without a composite. These specimens were then treated with a cyclic demineralization/remineralization regimen for 30 days. Quantitative microradiography showed typical enamel subsurface demineralization before cyclic demineralization/remineralization treatment, and significant remineralization in enamel under the NACP nanocomposite after the demineralization/remineralization treatment. The NACP nanocomposite had the highest enamel remineralization (mean ± SD; n = 6) of 21.8 ± 3.7%, significantly higher than the 5.7 ± 6.9% for fluoride-releasing composite (p < 0.05). The enamel group without composite had further demineralization of ?26.1 ± 16.2%. In conclusion, a novel NACP nanocomposite was effective in remineralizing enamel lesions in vitro. Its enamel remineralization was 4-fold that of a fluoride-releasing composite control. Combined with the good mechanical and acid-neutralization properties reported earlier, the new NACP nanocomposite is promising for remineralization of demineralized tooth structures. PMID:22933607

Weir, M.D.; Chow, L.C.; Xu, H.H.K.

2012-01-01

178

Relationship between Salivary Alkaline Phosphatase Enzyme Activity and The Concentrations of Salivary Calcium and Phosphate Ions.  

PubMed

Although salivary alkaline phosphatase (ALP) can balance deand remineralization processes of enamel, there is no evidence regarding its effects on the concentrations of calcium and phosphate in saliva. The present study aims to determine the relationship between salivary ALP activity and the concentrations of calcium and phosphate in saliva. In this cross-sectional study, we evaluated salivary markers in 120 males, ages 19 to 44 years. All participants provided 5 mL of unstimulated whole saliva and the level of enzyme activity as well as calcium and phosphate concentrations were measured using a colorimetric method. Data were gathered and analyzed by statistical package for social sciences (SPSS) 13.00 using Pearson correlation test. A p value of <0.05 was considered statistically significant. The mean age of participants in the present study was 32.95 ± 8.09 years. The mean pH of saliva was 6.65 ± 0.62. Salivary parameters included average ALP activity (5.04 ± 1.866 U/dL), calcium (4.77 ± 0.877 mg/dL) and phosphate (10.38 ± 2.301 mg/dL). Pearson correlation test showed no significant relationship between ALP activity and calcium and phosphate concentrations in saliva (p>0.05). According to the results of the present study, there was no significant relation between salivary ALP activity and calcium and phosphate concentrations in saliva. However, further research is highly recommended. PMID:25870846

Jazaeri, Mina; Malekzadeh, Hosein; Abdolsamadi, Hamidreza; Rezaei-Soufi, Loghman; Samami, Mohammad

2015-01-01

179

Relationship between Salivary Alkaline Phosphatase Enzyme Activity and The Concentrations of Salivary Calcium and Phosphate Ions  

PubMed Central

Although salivary alkaline phosphatase (ALP) can balance deand remineralization processes of enamel, there is no evidence regarding its effects on the concentrations of calcium and phosphate in saliva. The present study aims to determine the relationship between salivary ALP activity and the concentrations of calcium and phosphate in saliva. In this cross-sectional study, we evaluated salivary markers in 120 males, ages 19 to 44 years. All participants provided 5 mL of unstimulated whole saliva and the level of enzyme activity as well as calcium and phosphate concentrations were measured using a colorimetric method. Data were gathered and analyzed by statistical package for social sciences (SPSS) 13.00 using Pearson correlation test. A p value of <0.05 was considered statistically significant. The mean age of participants in the present study was 32.95 ± 8.09 years. The mean pH of saliva was 6.65 ± 0.62. Salivary parameters included average ALP activity (5.04 ± 1.866 U/dL), calcium (4.77 ± 0.877 mg/dL) and phosphate (10.38 ± 2.301 mg/dL). Pearson correlation test showed no significant relationship between ALP activity and calcium and phosphate concentrations in saliva (p>0.05). According to the results of the present study, there was no significant relation between salivary ALP activity and calcium and phosphate concentrations in saliva. However, further research is highly recommended.

Jazaeri, Mina; Malekzadeh, Hosein; Abdolsamadi, Hamidreza; Rezaei-Soufi, Loghman; Samami, Mohammad

2015-01-01

180

382 Mlle J. BRIGANDO ET MM. CHAMP ET CLOSSON. -LES PHOSPHATES LES PHOSPHATES DE CALCIUM DU LAIT  

E-print Network

rapport -- est égal à 0,58. CaO Le lait titre 22° D. et son pH est ramené à 6,67. p205 Dans le phosphate publié à la Société de Chimie Industrielle, et ci-dessus mentionné. A un lait titrant 28° Dornic.etde pH382 Mlle J. BRIGANDO ET MM. CHAMP ET CLOSSON. -LES PHOSPHATES LES PHOSPHATES DE CALCIUM DU LAIT

Paris-Sud XI, Université de

181

Casein precipitation equilibria in the presence of calcium ions and phosphates  

E-print Network

and steeper slope at the lower pH. The addition of phosphates leads to better precipitation of the protein of mono- and polyphosphates at pH 5.5 and 7.5. We analyze the data by assuming ion binding at a wellCasein precipitation equilibria in the presence of calcium ions and phosphates C. Guo a , B

Velev, Orlin D.

182

Solubilization of calcium phosphate as a consequence of carbon translocation by Rhizoctonia solani  

Microsoft Academic Search

A model system based on arrays of three concentric rings of discrete agar droplets is described which allowed study of fungal growth in vitro in nutritionally-heterogeneous conditions. Droplets containing different combinations of glucose and calcium phosphate were used to study the consequences of spatially separating these components in relation to metal phosphate solubilization by Rhizoctonia solani. A pH indicator, bromocresol

Helen Jacobs; Graeme P Boswell; Karl Ritz; Fordyce A Davidson; Geoffrey M Gadd

2002-01-01

183

Formation of Biomimetic Porous Calcium Phosphate Coatings on Surfaces of Polyethylene/Zinc Stearate Blends  

E-print Network

Formation of Biomimetic Porous Calcium Phosphate Coatings on Surfaces of Polyethylene/Zinc Stearate- phosphate solutions elicits growth of porous CaP coatings, although at a very slow rate, ~0.1 m/day. Introduction Polyethylene is a commonly used material for bearing surfaces in total shoulder, knee and hip

Drelich, Jaroslaw W.

184

Calcium Phosphate Nanoparticles Synthesis Make sure the hood is clean and free of all chemicals other than the ones required.  

E-print Network

Calcium Phosphate Nanoparticles Synthesis Procedure: · Make sure the hood is clean and free of all 10-2 M calcium chloride solution in the above degassed water (make sure to sonicate for 10 min to dissolve calcium chloride completely). · Likewise prepare 6 x 10-3 M disodium phosphate solution from

Burgess, Kevin

185

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.

186

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

2010-01-01

187

A 31P and 1H MAS NMR study of phosphate sorption onto calcium carbonate  

Microsoft Academic Search

The sorption of inorganic phosphate by two calcium carbonates, characterized by specific surface areas equivalent to 0.37 and 22 m 2 g-~, is studied using ~H and 3~p MAS NMR spectroscopy. The 3~p MAS and CP-MAS NMR spectra of the low-phosphate-concentration (0.79 ~mol P sorbed g-1 CaCO3) sample show that the sorbed phosphate is most likely unprotonated, but the 3~p

Z. R. HINEDI; S. GOLDBERG; A. C. CHANG

1992-01-01

188

Prevalence and possible pathological significance of calcium phosphate salt accumulation in tendon matrix degeneration  

Microsoft Academic Search

OBJECTIVES: To investigate the prevalence of calcium phosphate mineral salt accumulation in degenerative supraspinatus 'tendinitis' compared with a normal sample of human tendons, and to determine whether there is an association of calcium salt deposition with pathological changes in the tendon extracellular matrix. METHODS: Cadaver tendons (supraspinatus and common biceps tendons, n = 96) and fragments of supraspinatus tendons obtained

G P Riley; R L Harrall; C R Constant; T E Cawston; B L Hazleman

1996-01-01

189

Technology for recovery of phosphorus from animal wastewater through calcium phosphate precipitation  

Technology Transfer Automated Retrieval System (TEKTRAN)

A wastewater treatment process was developed for removal of phosphorus from livestock wastewater. The phosphorus is recovered as calcium phosphate with addition of only small quantities of liquid lime. The process is based on the distinct chemical equilibrium between phosphorus and calcium ions when...

190

Combustion synthesis of calcium phosphate bioceramic powders A. Cu neyt Tas *,1  

E-print Network

Combustion synthesis of calcium phosphate bioceramic powders A. CuÃ? neyt Tas *,1 Department)2; Combustion synthesis; Hydroxyapatite 1. Introduction Calcium hydroxyapatite (HA: Ca10(PO4)6(OH)2), the major), instead of water, as the precipitation medium. Self-propagating combustion synthesis (SPCS

Tas, A. Cuneyt

191

In vivo behavior of a novel injectable calcium phosphate cement compared with two other commercially available calcium phosphate cements.  

PubMed

The aim of this study was to investigate the physicochemical and biological properties of a newly developed calcium phosphate cement (CPC). The novel cement was compared with two other commercially available CPCs. After mixing the powder and liquid phase, the CPCs were injected as a paste into a rabbit distal femoral defect model. The CPCs were evaluated after 24 h, 6 weeks, 26 weeks, and 52 weeks. The novel CPC was easy to handle and was fast setting. X-ray diffraction (XRD) and Fourier Transform Infrared Spectrometry (FTIR) at the different implantation periods showed that the cement had converted to carbonated hydroxyapatite and remained stable over time. Histological evaluation showed bone apposition on the cement surface without any inflammatory response or fibrous encapsulation. At later time points, all CPCs were completely covered by a thin layer of bone. Osteoclast-like cells present at the interface resorbed parts of the cement mass. Histological and histomorphometrical analyses did not show any significant differences between the three implanted CPCs. The results indicate that the investigated CPC is biocompatible, osteoconductive, as well as osteotransductive and seems to be both biologically safe and effective as a bone void filler. PMID:18098203

Hannink, Gerjon; Wolke, Joop G C; Schreurs, B Willem; Buma, Pieter

2008-05-01

192

Calcium phosphate coating on titanium using laser and plasma spray  

NASA Astrophysics Data System (ADS)

Though calcium phosphate (CaP) coated implants are commercially available, its acceptance is still not wide spread due to challenges related to weaker interfacial bonding between metal and ceramic, and low crystallinity of hydroxyapatite (HA). The objectives of this research are to improve interfacial strength, crystallinity, phase purity and bioactivity of CaP coated metallic implants for orthopaedic applications. The rationale is that forming a diffuse and gradient metal-ceramic interface will improve the interfacial strength. Moreover, reducing CaP particles exposure to high temperature during coating preparation, can lead to improvement in both crystallinity and phase purity of CaP. In this study, laser engineered net shaping (LENS(TM)) was used to coat Ti metal with CaP. LENS(TM) processing enabled generation of Ti+TCP (tricalcium phosphate) composite coating with diffused interface, that also increased the coating hardness to 1049+/-112 Hv compared to a substrate hardness of 200+/-15 Hv. In vitro bone cell-material interaction studies confirmed the bioactivity of TCP coatings. Antimicrobial properties of the TCP coatings were improved by silver (Ag) electrodeposition. Along with LENS(TM), radio frequency induction plasma spray, equipped with supersonic plasma nozzle, was used to prepare HA coatings on Ti with improved crystallinity and phase purity. The coating was made of multigrain HA particles of ˜200 nm in size, which consisted of 15--20 nm HA grains. In vitro bone cell-material interaction and in vivo rat model studies confirmed the HA coatings to be bioactive. Furthermore, incorporation of Sr2+ improved bone cell of HA coatings interaction. A combination of LENS(TM) and plasma spray was used to fabricate a compositionally graded HA coatings on Ti where the microstructure varied from pure HA at the surface to pure Ti substrate with a diffused Ti+TCP composite region in between. The plasma spray system was used to synthesize spherical HA nano powder from HA sol, where the production rate was 20 g/h, which is only 16% of the total powder produced. The effects of Sr2+ and Mg2+ doping on bone cell-CaP interaction was further studied with osteoclast cells. Mg2+ doing was found to be an effective way of controlling osteoclast differentiation.

Roy, Mangal

193

Calcium carbonate-calcium phosphate mixed cement compositions for bone reconstruction.  

PubMed

The feasibility of making calcium carbonate-calcium phosphate (CaCO(3)-CaP) mixed cements, comprising at least 40% (w/w) CaCO(3) in the dry powder ingredients, has been demonstrated. Several original cement compositions were obtained by mixing metastable crystalline CaCO(3) phases with metastable amorphous or crystalline CaP powders in aqueous medium. The cements set within at most 1 h at 37 degrees C in atmosphere saturated with water. The hardened cement is microporous and exhibits weak compressive strength. The setting reaction appeared to be essentially related to the formation of a highly carbonated nanocrystalline apatite phase by reaction of the metastable CaP phase with part or almost all of the metastable CaCO(3) phase. The recrystallization of metastable CaP varieties led to a final cement consisting of a highly carbonated poorly crystalline apatite analogous to bone mineral associated with various amounts of vaterite and/or aragonite. The presence of controlled amounts of CaCO(3) with a higher solubility than that of the apatite formed in the well-developed CaP cements might be of interest to increase resorption rates in biomedical cement and favors its replacement by bone tissue. Cytotoxicity testing revealed excellent cytocompatibility of CaCO(3)-CaP mixed cement compositions. PMID:16817210

Combes, C; Bareille, R; Rey, C

2006-11-01

194

Formation of phosphate-containing calcium fluoride at the expense of enamel, hydroxyapatite and fluorapatite.  

PubMed

During the caries process complex reactions involving calcium, phosphate, hydrogen and fluoride ions as main species take place. In this study the precipitation and dissolution reactions occurring in suspensions of enamel, hydroxyapatite (HAP) and fluorapatite (FAP) on addition of fluoride were investigated under well-defined conditions. pH and pF were monitored; calcium and phosphate concentrations were measured at selected times; the solid phases were examined by infra-red, X-ray diffraction and transmission electron microscopy. Precipitation of phosphate-containing calcium fluoride crystals, CaF2(P), can cause severe reduction in the calcium ion concentration and release of hydrogen ions from the precipitated phosphate. These reactions result in considerable dissolution of enamel, HAP and even of FAP. More of the added mineral dissolves with 50 mmol/l fluoride than with 10 mmol/l fluoride, mainly due to the greater reduction in calcium ion concentration. This work shows that phosphate-containing calcium fluoride is most likely an important compound to be considered in the caries process. PMID:7621499

Christoffersen, J; Christoffersen, M R; Arends, J; Leonardsen, E S

1995-01-01

195

Low temperature method for the production of calcium phosphate fillers  

PubMed Central

Background Calcium phosphate manufactured samples, prepared with hydroxyapatite, are used as either spacers or fillers in orthopedic surgery, but these implants have never been used under conditions of mechanical stress. Similar conditions also apply with cements. Many authors have postulated that cements are a useful substitute material when implanted in vivo. The aim of this research is to develop a low cristalline material similar to bone in porosity and cristallinity. Methods Commercial hydroxyapatite (HAp) and monetite (M) powders are mixed with water and compacted to produce cylindrical samples. The material is processed at a temperature of 37–120 degrees C in saturated steam to obtain samples that are osteoconductive. The samples are studied by X-ray powder diffraction (XRD), Vickers hardness test (HV), scanning electron microscopy (SEM), and porosity evaluation. Results The X-ray diffractions of powders from the samples show patterns typical of HAp and M powders. After thermal treatment, no new crystal phase is formed and no increase of the relative intensity of the peaks is obtained. Vicker hardness data do not show any relationship with treatment temperature. The total porosity decreases by 50–60% according to the specific thermal treatment. Scanning electron microscopy of the surfaces of the samples with either HAp 80%-M 20% (c) or Hap 50%-M 50% (f), show cohesion of the powder grains. Conclusions The dissolution-reprecipitation process is more intesive in manufactured samples (c) and (f), according to Vickers hardness data. The process occurs in a steam saturated environment between 37 degrees and 120 degrees C. (c) (f) manufactured samples show pore dimension distributions useful to cellular repopulation in living tissues. PMID:15035671

Calafiori, Anna Rita; Marotta, Marcello; Nastro, Alfonso; Martino, Guglielmo

2004-01-01

196

Soft-tissue response to injectable calcium phosphate cements.  

PubMed

In this study, the soft tissue reaction to two newly developed injectable calcium phosphate bone cements (cement D and W) was evaluated after implantation in the back of goats. For one of the cements (cement D) the tissue reaction was also investigated after varying the concentration of accelerator Na(2)HPO(4) in the cement liquid (resulting in cement D1 and D2). Eight healthy mature female Saanen goats were used. The cement was applied 10min after mixing while it was still moldable and plastic. The material was given a standardized cylindrical shape. Thirty-two implants of each cement formulation were inserted and left in place for 1, 2, 4, and 8weeks. At the end of the study, eight specimens of each material and healing period were available for further analysis. Two specimens were used for X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) and six specimens were used for light microscopical evaluation. XRD and FTIR showed that the cements did set as microcrystalline carbonate apatite with the disappearance of monetite from the cements during implantation. Histological analysis showed that after 8weeks of implantation around all materials a thin soft-tissue capsule was formed (thickness ranging from 5 to 15 cell layers) with almost complete absence of inflammatory cells. Only in some specimens a slightly higher inflammatory reaction was observed. This was due to cement surface defects and a zone of dispersed particles near the cement-soft tissue interface. There was almost no resorption of the material after 8 weeks of implantation. In a few 4 and 8weeks samples, small areas of calcification were found in the fibrous capsule surrounding the implants. On the basis of our observations, we conclude that the tested cements were biocompatible and can be used next to soft tissue. PMID:12485793

Ooms, E M; Egglezos, E A; Wolke, J G C; Jansen, J A

2003-02-01

197

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

2014-08-01

198

Characterization of titanium surfaces with calcium and phosphate and osteoblast adhesion.  

PubMed

The titanium surfaces containing calcium, phosphate ions and the carbonate apatite were characterized. The effect of surface chemistry on the initial rabbit osteoblast response on these surfaces was investigated. The cell count and alkaline phosphatase (ALP) specific activity assay were used for biochemical analyses. Scanning electron microscopy was used for morphology observation and in particular X-ray photoelectron spectroscopy (XPS) for surface chemistry characterization. The number of cells adhering to the apatite coating surface was the maximum, the number of cells on the surface containing calcium without phosphate ions was higher than that containing phosphate without calcium, and the number on the unmodified titanium surface was the least. The osteoblasts cultured on the apatite surface exhibited the highest ALP specific activity, next were the ones on the surface containing solely calcium, the lowest were on the unmodified titanium surface. On the substrate surfaces removed of adhered cells, the order of nitrogen amounts detected by XPS was consistent with ones of ALP specific activity and cell number, except for the unmodified titanium surface. For the substrate surfaces removed of adhered osteoblasts, XPS analysis showed that calcium and phosphorous amounts decreased during cell adhesion. After cell culture the Ca2p binding energy (BE) values for apatite coating and the surface containing solely calcium were similar to those of the two surfaces adsorbed bovine serum albumin (BSA). The P2p BE values for the surfaces containing phosphate ions, including the apatite coating and the surface containing solely phosphate ions, showed the same change. But after cell culture the decrease of the P2p BE value for the coating surface was larger than the one for the surface containing solely phosphate ions. Considering the bovine serum albumin adsorption on the same samples, these results indicated that calcium ions on titanium surfaces play a more important role than phosphate ions in initial interactions among culture medium, osteoblasts and titanium surfaces. On the apatite coating surface, calcium ions are active sites for osteoblast adhesion, while calcium and phosphate ions co-exist on titanium surfaces, the former promotes the osteoblast adhesion onto the phosphate sites on titanium surfaces. The cell adhesion was a complicated biological and chemical process relating to surface several elements similar to protein adsorption. PMID:15020115

Feng, B; Weng, J; Yang, B C; Qu, S X; Zhang, X D

2004-08-01

199

Four calcium phosphate ceramics as bone substitutes for non-weight-bearing.  

PubMed

Calcium phosphate ceramics, beta-calcium pyrophosphate (Ca2P2O7), beta-tricalcium phosphate (Ca3(PO4)2), hydroxyapatite (Ca10(PO4)6(OH)2) and tetracalcium phosphate (Ca4(PO4)2O), were prepared. The calcium:phosphorus ratios and microporosities were 1 (31.6%), 1.5 (1.6%), 1.66 (1%) and 2 (34.6%) respectively. Samples (15 mm x 10 mm x 2 mm), abraded with No. 2000 alumina powder, were implanted into the tibial metaphysis of mature male rabbits. Failure load, when an implant detached from the bone or the bone itself broke, was measured. At 10 wk after implantation, the failure loads in beta-calcium pyrophosphate, beta-tricalcium phosphate, hydroxyapatite and tetracalcium phosphate were 31.65 +/- 9.90 N, 72.81 +/- 19.01 N, 49.49 +/- 17.25 N and 43.22 +/- 14.99 N respectively. At 25 wk after implantation, the values were 47.04 +/- 14.90 N, 71.34 +/- 19.50 N, 69.09 +/- 16.17 N and 62.03 +/- 18.62 N respectively. Histologically, bone bonding behaviour of calcium phosphate ceramics did not vary with the calcium:phosphorus ratio, as observed by contact microradiogram, Giemsa surface staining and scanning electron micrograph-electron probe micro analysis. There was no intervening soft tissue at the interface of bone and ceramics. Hydroxyapatite or tricalcium phosphate are used as bone substitutes. However, their mechanical strength is insufficient for weight-bearing and they are used as bone filler. This study showed that the apparent insignificance of strict calcium:phosphorus ratio with respect to the biological results greatly simplifies processing of calcium phosphate ceramics for clinical application. In clinical application, calcium phosphate ceramics with different Ca:P can be used as bone fillers for bone defects or bone cavities under non-weight-bearing conditions. PMID:8386554

Kitsugi, T; Yamamuro, T; Nakamura, T; Kotani, S; Kokubo, T; Takeuchi, H

1993-02-01

200

Formation of apatitic calcium phosphates in a Na-K-phosphate solution of pH 7.4.  

PubMed

Poorly crystalline, apatitic calcium phosphate powders have been synthesized by slowly adding a Na- and K-containing reference phosphate solution with a pH value of 7.4 to an aqueous calcium nitrate solution at 37 degrees C. Nano-particulated apatitic powders obtained were shown to contain small amounts of Na and K, which render them more similar in chemical composition to that of the bone mineral. Precipitated and dried powders were found to exhibit self-hardening cement properties when kneaded in a mortar with a sodium citrate- and sodium phosphate-containing starter solution. The same phosphate solution used in powder synthesis was found to be able to partially convert natural, white and translucent marble pieces of calcite (CaCO3) into calcium-deficient hydroxyapatite upon aging the samples in that solution for 3 days at 60 degrees C. Sample characterization was performed by using scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, inductively-coupled plasma atomic emission spectroscopy, and simultaneous thermogravimetry and differential thermal analysis. PMID:15744606

Tas, A C; Aldinger, F

2005-02-01

201

Efficacy of coral-hydroxyapatite and biphasic calcium phosphate for early bacterial detection.  

PubMed

Nano- or microhydroxyapatites with microbiological properties are being used to detect pathogens in clinical samples and industrial environments. In this study, the calcium phosphates coral-hydroxyapatite and biphasic calcium phosphate were characterized physicochemically using x-ray diffraction, thermogravimetric, and differential thermal analysis. The morphology, texture, and chemical composition of the ceramics were also investigated using scanning electron microscopy with energy dispersive spectroscopy. The biocompatibility of the ceramics was evaluated using Escherichia coli and Enterococcus faecalis. Microorganisms were detected by incorporating the enzyme markers 4-metilumbelliferil-?-d-glucoside and 4-metilumbelliferil-?-d-glucuronide in the ceramic powders and evaluating fluorescence. The characterization of the ceramics revealed typical characteristics, such as crystallinity, thermal stability, and chemical composition, consistent with other calcium phosphates. The calcium phosphates coral-hydroxyapatite and biphasic calcium phosphate ceramics differed from one another in morphology, structural topography, particle size distribution, and the capacity to absorb water. These properties can influence the rates of microbiological responses and bacterial detection. Although both materials are suitable for use as structural supports in microbial diagnostic systems, BCP was more efficient and detected E. coli and E. faecalis more rapidly than CHA. PMID:24985222

Lobaina, Tamara; Zhurbenko, Raisa; Alfonso, Ivonne; Rodríguez, Claudio; Gala-García, Alfonso; Gontijo, Sávio Lacerda; Cortés, Maria E; Gomes, Alinne; Sinisterra, Ruben Dario

2014-06-01

202

Direct transformation from amorphous to crystalline calcium phosphate facilitated by motif-programmed artificial proteins.  

PubMed

An animal's hard tissue is mainly composed of crystalline calcium phosphate. In vitro, small changes in the reaction conditions affect the species of calcium phosphate formed, whereas, in vivo, distinct types of crystalline calcium phosphate are formed in a well-controlled spatiotemporal-dependent manner. A variety of proteins are involved in hard-tissue formation; however, the mechanisms by which they regulate crystal growth are not yet fully understood. Clarification of these mechanisms will not only lead to the development of new therapeutic regimens but will also provide guidance for the application of biomineralization in bionanotechnology. Here, we focused on the peptide motifs present in dentin matrix protein 1 (DMP1), which was previously shown to enhance hydroxylapatite (HAP) formation when immobilized on a glass substrate. We synthesized a set of artificial proteins composed of combinatorial arrangements of these motifs and successfully obtained clones that accelerated formation of HAP without immobilization. Time-resolved static light-scattering analyses revealed that, in the presence of the protein, amorphous calcium phosphate (ACP) particles increased their fractal dimension and molecular mass without increasing their gyration radii during a short period before precipitation. The protein thus facilitated reorganization of the internal structure of amorphous particles into ordered crystalline states, i.e., the direct transformation of ACP to HAP, thereby acting as a nucleus for precipitation of crystalline calcium phosphate. Without the protein, the fractal dimension, molecular mass, and gyration radii of ACP particles increased concurrently, indicating heterogeneous growth transformation. PMID:18957547

Tsuji, Toru; Onuma, Kazuo; Yamamoto, Akira; Iijima, Mayumi; Shiba, Kiyotaka

2008-11-01

203

Encapsulation of plasmid DNA in calcium phosphate nanoparticles: stem cell uptake and gene transfer efficiency  

PubMed Central

Background The purpose of this study was to develop calcium phosphate nanocomposite particles encapsulating plasmid DNA (CP-pDNA) nanoparticles as a nonviral vector for gene delivery. Methods CP-pDNA nanoparticles employing plasmid transforming growth factor beta 1 (TGF-?1) were prepared and characterized. The transfection efficiency and cell viability of the CP-pDNA nanoparticles were evaluated in mesenchymal stem cells, which were identified by immunofluorescence staining. Cytotoxicity of plasmid TGF-?1 and calcium phosphate to mesenchymal stem cells were evaluated by MTT assay. Results The integrity of TGF-?1 encapsulated in the CP-pDNA nanoparticles was maintained. The well dispersed CP-pDNA nanoparticles exhibited an ultralow particle size (20–50 nm) and significantly lower cytotoxicity than Lipofectamine™ 2000. Immunofluorescence staining revealed that the cultured cells in this study were probably mesenchymal stem cells. The cellular uptake and transfection efficiency of the CP-pDNA nanoparticles into the mesenchymal stem cells were higher than that of needle-like calcium phosphate nanoparticles and a standard calcium phosphate transfection kit. Furthermore, live cell imaging and confocal laser microscopy vividly showed the transportation process of the CP-pDNA nanoparticles in mesenchymal stem cells. The results of a cytotoxicity assay found that both plasmid TGF-?1 and calcium phosphate were not toxic to mesenchymal stem cells. Conclusion CP-pDNA nanoparticles can be developed into an effective alternative as a nonviral gene delivery system that is highly efficient and has low cytotoxicity. PMID:22229000

Cao, Xia; Deng, Wenwen; Wei, Yuan; Su, Weiyan; Yang, Yan; Wei, Yawei; Yu, Jiangnan; Xu, Ximing

2011-01-01

204

Comparative reduction of enamel demineralization by calcium and phosphate in vitro.  

PubMed

In theory, calcium and phosphate in the plaque fluid exert a large influence on the demineralization of enamel surface. In order to know the effect of increasing the concentration of either of these factors, the following in vitro experiment was conducted. Three thin sections, about 150 Im thick, were cut out from each of 13 human premolars. All surfaces of the sections, except for the original enamel surface, were coated with nail varnish. These sections were immersed into one of two sets of demineralizing solutions for 1 week at 25 degrees C. Each set, the 'calcium set' and the 'phosphate set', contained three solutions. The composition of these solutions differed mainly in calcium or phosphate concentrations. After 1 week, the degree of demineralization was determined by image analysis of contact microradiograms from each section. The subsurface demineralization in enamel was reduced by 95% by increasing the calcium concentration of the demineralizing solution from 7 to 21 mmol/l. A similar reduction (87%) was observed by increasing the phosphate concentration. However, the amount of phosphate needed was approximately 20 times more than that of calcium. The larger inhibitory effect that calcium has on enamel demineralization was related to the larger effect it has on the degree of saturation of the solution. Even though no statistically significant difference was found between the effect of calcium and phosphate on the demineralization of enamel (when the solutions had the same degree of saturation), the difference in the standard deviation of demineralization suggests the existence of some other factors which have an influence on the demineralization reaction. PMID:10867423

Tanaka, M; Kadoma, Y

2000-01-01

205

Non-calcium-containing phosphate binders: comparing efficacy, safety, and other clinical effects.  

PubMed

Phosphate-binder therapy for hyperphosphataemia is key to the treatment of patients with chronic kidney disease (CKD)-mineral and bone disorder (MBD). Calcium-free phosphate binders are increasingly favoured since calcium-based agents potentially cause harmful calcium overload and vascular calcification that confound the benefits of reducing serum phosphorus. Several calcium-free phosphate binders are available, including the non-absorbed agent sevelamer and the absorbed agents, e.g. lanthanum and magnesium salts. Randomised controlled studies consistently show that sevelamer and lanthanum carbonate offer equivalent lowering of serum phosphorus and often effectively achieve phosphorus targets versus calcium salts, with sevelamer having a positive effect on bone disease, vascular calcification, and patient-level outcomes in dialysis patients in several trials. There is also evidence that lanthanum carbonate can improve bone health, but data are limited to its effects to vascular calcification or patient-level outcomes. Magnesium salts have also been shown to reduce serum phosphorus levels, but clear evidence is lacking on bone, vascular, or clinical outcomes. It also remains to be established whether long-term systemic accumulation of lanthanum and magnesium, in tissues including bone, has clinically relevant toxic effects. This review summarises the evidence of efficacy and safety for newer calcium-free phosphate binders in CKD-MBD management. PMID:22555359

Frazão, João M; Adragão, Teresa

2012-01-01

206

Steel corrosion protection by means of alkyd paints pigmented with calcium acid phosphate  

SciTech Connect

The use of classic anticorrosive pigments is becoming more and more restricted by increasing environmental concerns; they are gradually being replaced by zinc phosphate and related compounds. Other anticorrosive pigments such as surface-exchanged silicas were also proposed. The object of this research is to study the anticorrosive properties of calcium acid phosphate as an inhibitive pigment, introducing a careful selection of complementary pigments in order to achieve an efficient anticorrosive protection. Several alkyd paints were prepared and evaluated through accelerated and electrochemical tests. The nature of the passive film formed was also studied. Paint containing zinc oxide and calcium carbonate (50/50) as complementary pigments showed the best performance in the salt spray test. Zinc oxide and calcium carbonate decreased film permeability and improved steel passivation. The passive film was composed of ferric oxyhydroxide, the pores of which became plugged by ferric phosphate.

Amo, B. del; Romagnoli, R.; Vetere, V.F. [CIC-CONICET, La Plata (Argentina)

1999-06-01

207

The use of calcium phosphate cement in vertebroplasty of the base of odontoid process.  

PubMed

The authors describe the use of bone cement containing calcium phosphate for vertebroplasty of the cavity in the base of odontoid process. A 23-year-old female patient was operated on by incision in lateral cervical area (anterior open access). After a blunt dissection, the working cannula (Kyphon) was introduced under fluoroscopic guidance through the C2 vertebral body to the cavity in the base of the odontoid process. Intraoperatively, biopsy of the lesion was taken and histo-pathological examination excluded the presence of neoplasm. The cavity, presumably haemangioma, was successfully filled with calcium phosphate bone cement KyphOsTM FS (Ky-phon). The proper filling without paravertebral cement leak was confirmed by postoperative computed tomography (CT). The CT and magnetic resonance imaging performed 9 months after the procedure showed that cement was still present in the cavity. This is the first use of calcium phosphate cement to conduct the vertebroplasty of C2 vertebra. PMID:24375006

Zapa?owicz, Krzysztof; Wojdyn, Maciej; Zieli?ski, Krzysztof W?odzimierz; Snopkowska-Wiaderna, Dorota

2013-01-01

208

Solubilization of calcium phosphate as a consequence of carbon translocation by Rhizoctonia solani.  

PubMed

A model system based on arrays of three concentric rings of discrete agar droplets is described which allowed study of fungal growth in vitro in nutritionally-heterogeneous conditions. Droplets containing different combinations of glucose and calcium phosphate were used to study the consequences of spatially separating these components in relation to metal phosphate solubilization by Rhizoctonia solani. A pH indicator, bromocresol purple, was added to the agar to visualise the localised production of acidity by the fungus. In the presence of the fungus, solubilization of calcium phosphate on homogeneous agar plates only occurred when glucose was present in the underlying medium. However, solubilization occurred in droplets containing calcium phosphate, but no glucose, when glucose was present in other droplets within the tessellation and where fungal hyphae spanned the droplets. This demonstrates that substrate was transported via mycelia from glucose-containing domains, with the functional consequence of metal phosphate solubilization. In another design, where the inner ring of droplets contained glucose and the outer ring contained only calcium phosphate, acidification of all droplets in the outer ring was observed when the inner droplets contained glucose. However, solubilization of calcium phosphate only occurred when the concentration of glucose in the inner droplets was greater than 2% (w/v). This indicated that a threshold concentration of carbon source may be required before such mechanisms of solubilization are invoked. There was also evidence for reverse translocation of substrate from newly colonised glucose-containing droplets in the outer ring to the central droplets, where fungal growth had originated. PMID:19709212

Jacobs, Helen; Boswell, Graeme P; Ritz, Karl; Davidson, Fordyce A; Gadd, Geoffrey M

2002-04-01

209

Setting time and formability of calcium phosphate cements prepared using modified dicalcium phosphate anhydrous powders.  

PubMed

Calcium phosphate cements (CPCs) were prepared using Ca4(PO4)2O (TeCP) and modified CaHPO4 (DCPA) to evaluate the effects of the powder properties for DCPA particles on the setting time and formability of the resulting CPCs. Two types of modified DCPA were prepared by milling commercially available DCPA with ethanol (to produce E-DCPA) or distilled water (to produce W-DCPA). The E-DCPA samples consisted of well-dispersed, fine primary particles, while the W-DCPA samples contained agglomerated particles, and had a smaller specific surface area. The mean particle size decreased with increased milling time in both cases. The raw CPC powders prepared using W-DCPA had a higher packing density than those prepared using E-DCPA, regardless of the mean particle size. The setting time of the CPC paste after mixing with distilled water decreased with decreases in the mean particle size and specific surface area, for both types of DCPA. The CPCs prepared using W-DCPA showed larger plasticity values compared with those prepared using E-DCPA, which contributed to the superior formability of the W-DCPA samples. The CPCs prepared using W-DCPA showed a short setting time and large plasticity values, despite the fact that only a small amount of liquid was used for the mixing of the raw CPC powders (a liquid-to-powder ratio of 0.25 g g(-1) was used). It is likely that the higher packing density of the raw CPC powders prepared using W-DCPA was responsible for the higher performance of the resulting CPCs. PMID:24715331

Sawamura, Takenori; Mizutani, Yoichiro; Okuyama, Masahiko; Kasuga, Toshihiro

2014-07-01

210

Anticariogenicity of Calcium Phosphate Complexes of Tryptic Casein Phosphopeptides in the Rat  

Microsoft Academic Search

Casein phosphopeptides (CPP) stabilize calcium phosphate through the formation of casein-phosphopeptide amorphous calcium-phosphate complexes (CPP-CP). The ability of CPP-CP to reduce caries activity was investigated by use of specific-pathogen-free rats inoculated with Streptococcus sobrinus. The animals consumed a defined cariogenic diet free of dairy products. Solutions (100 pL) of the CPP-CP (0.1, 0.2, 0.5, 1.0% w\\/v) were applied to the

E. C. Reynolds; C. J. Cain; EL Webber; C. L. Black; P. F. Riley; I. H. Johnson; J. W. Perich

1995-01-01

211

Carboxymethyl cellulose/silica hybrids as templates for calcium phosphate biomimetic mineralization.  

PubMed

Multiphase hybrid materials were synthesized using carboxymethyl cellulose (CMC) as bioactive polymer, silica gel as matrix assisted networks and calcium phosphate as inorganic mineral phase. These hybrids were investigated with infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. Biomimetic crystal growth nucleated from the CMC/silica hybrids was suggested as amorphous calcium phosphate with an evidence that hydroxyapatite, the mineralized component of bone, may be formed at high CMC content. This study provides an efficient approach toward bone-like hybrids with potential bone healing applications. PMID:25526694

Salama, Ahmed; Abou-Zeid, Ragab E; El-Sakhawy, Mohamed; El-Gendy, Ahmed

2015-03-01

212

Theoretical and practical experience of calcium phosphate inhibition in RO waters  

Microsoft Academic Search

The increasing trend over the last ten years to use waste water as a feed source for reverse osmosis membrane plant has resulted in an increase in calcium phosphate scaling on membrane surfaces. This is due to much higher levels of phosphate in waste water typically 10-30 mg\\/l as compared with a groundwater source which may have only 1-5 mg\\/l

S. P. Chesters; F. del Vigo; E. G. Darton

213

Simulations of inositol phosphate metabolism and its interaction with InsP(3)-mediated calcium release.  

PubMed Central

Inositol phosphates function as second messengers for a variety of extracellular signals. Ins(1,4,5)P(3) generated by phospholipase C-mediated hydrolysis of phosphatidylinositol bisphosphate, triggers numerous cellular processes by regulating calcium release from internal stores. The Ins(1,4,5)P(3) signal is coupled to a complex metabolic cascade involving a series of phosphatases and kinases. These enzymes generate a range of inositol phosphate derivatives, many of which have signaling roles of their own. We have integrated published biochemical data to build a mass action model for InsP(3) metabolism. The model includes most inositol phosphates that are currently known to interact with each other. We have used this model to study the effects of a G-protein coupled receptor stimulus that activates phospholipase C on the inositol phosphates. We have also monitored how the metabolic cascade interacts with Ins(1,4,5)P(3)-mediated calcium release. We find temporal dynamics of most inositol phosphates to be strongly influenced by the elaborate networking. We also show that Ins(1,3,4,5)P(4) plays a key role in InsP(3) dynamics and allows for paired pulse facilitation of calcium release. Calcium oscillations produce oscillatory responses in parts of the metabolic network and are in turn temporally modulated by the metabolism of InsP(3). PMID:12202356

Mishra, Jyoti; Bhalla, Upinder S

2002-01-01

214

Biomimetic Nanocomposites of Calcium Phosphate and Self-Assembling Triblock and Pentablock Copolymers  

SciTech Connect

In an effort to mimic the growth of natural bone, self-assembling, micelle and gel-forming copolymers were used as a template for calcium phosphate precipitation. Because of the cationic characteristics imparted by PDEAEM end group additions to commercially available Pluronic{reg_sign} Fl27, a direct ionic attraction mechanism was utilized and a polymer-brushite nanocomposite spheres were produced. Brushite coated spherical micelles with diameters of {approx}40 nm, and agglomerates of these particles (on the order of 0.5 {mu}m) were obtained. Thickness and durability of the calcium phosphate coating, and the extent of agglomeration were studied. The coating has been shown to be robust enough to retain its integrity even below polymer critical micelle concentration and/or temperature. Calcium phosphate-polymer gel nanocomposites were also prepared. Gel samples appeared as a single phase network of agglomerated spherical micelles, and had a final calcium phosphate concentration of up to 15 wt%. Analysis with x-ray diffraction and NMR indicated a disordered brushite phase with the phosphate groups linking inorganic phase to the polymer.

Drew Lenzen Enlow

2006-08-09

215

Probability-Based Compatibility Curves for Calcium and Phosphates in Parenteral Nutrition Formulations.  

PubMed

Background: The information content of the calcium phosphate compatibility curves for adult parenteral nutrition (PN) solutions may benefit from a more sophisticated statistical treatment. Binary logistic regression analyses were evaluated as part of an alternate method for generating formulation compatibility curves. Materials and Methods: A commercial PN solution was challenged with a systematic array of calcium and phosphate concentrations. These formulations were then characterized for particulates by visual inspection, light obscuration, and filtration followed by optical microscopy. Logistic regression analyses of the data were compared with traditional treatments for generating compatibility curves. Results: Assay-dependent differences were observed in the compatibility curves and associated probability contours; the microscopic method of precipitate detection generated the most robust results. Calcium and phosphate compatibility data generated from small-volume glass containers reasonably predicted the observed compatibility of clinically relevant flexible containers. Conclusions: The published methods for creating calcium and phosphate compatibility curves via connecting the highest passing or lowest failing calcium concentrations should be augmented or replaced by probability contours of the entire experimental design to determine zones of formulation incompatibilities. We recommend researchers evaluate their data with logistic regression analysis to help build a more comprehensive probabilistic database of compatibility information. PMID:23894169

Gonyon, Thomas; Carter, Phillip W; Phillips, Gerald; Owen, Heather; Patel, Dipa; Kotha, Priyanka; Green, John-Bruce D

2013-07-26

216

Effects of additives on the rheological properties and injectability of a calcium phosphate bone substitute material.  

PubMed

An injectable calcium phosphate bone substitute material has been prepared by mixing amorphous calcium phosphate (ACP) and dicalcium phosphate dihydrate (DCPD) for use in noninvasive surgery, and the influence of additives, such as disodium hydrogen phosphate, polyethylene glycol (PEG), glycerin, and citric acid, on the rheological properties and injectability of the ACP + DCPD cement system have been studied in this work. Novel approach of thixotropy measurement has been used to characterize the stability of the pastes. The results show that the injectability and the setting time can be augmented by the addition of disodium phosphate solution to the paste but reduced by the addition of PEG 200, glycerin, or citric acid to the paste. This study suggests that the injectability and the setting time of the ACP + DCPD bone substitute material can be balanced, and the injectable calcium phosphate bone substitute material with satisfied fluidity and injectability for clinical operation can be prepared by optimizing the additives and their concentrations, according to different clinical requirements. PMID:16362962

Wang, Xiupeng; Ye, Jiandong; Wang, Hai

2006-08-01

217

Effect of rapidly resorbable calcium phosphates and a calcium phosphate bone cement on the expression of bone-related genes and proteins in vitro.  

PubMed

The use of biodegradable bone substitutes is advantageous for alveolar ridge augmentation because it avoids second-site surgery for autograft harvesting. This study examines the effect of novel, rapidly resorbable calcium phosphates and a calcium phosphate bone cement on the expression of bone-related genes and proteins by human bone-derived cells (HBDCs) and compares this behavior to that of tricalciumphosphate (TCP). Test materials were alpha-TCP, two materials with a crystalline phase Ca(2)KNa(PO(4))(2) and with a small amorphous portion containing either magnesium potassium phosphate (material denominated GB14) or silica phosphate (material denominated GB9), and a calcium phosphate bone cement (material denominated Biocement D). HBDCs were grown on the substrata for 3, 7, 14, and 21 days, counted, and probed for various mRNAs and proteins (type I collagen, osteocalcin, osteopontin, osteonectin, alkaline phosphatase, and bone sialoprotein). All substrates supported continuous cellular growth for 21 days. In the presence of GB14 and Biocement D specimens cell proliferation was reduced and cell differentiation increased. At day 21, the greatest number of cells was found on GB9 expressing significantly higher levels of bone-related proteins than cells grown on all other surfaces. Because all novel materials facilitated the expression of the osteoblastic phenotype at least as much as TCP and the polystyrene control, these biomaterials can be regarded as excellent candidate bone substitute materials. GB9 induced the highest proliferation and cellular differentiation after 21 days of incubation, suggesting that this material may possess a higher potency for enhancing osteogenesis than TCP. PMID:14999762

Knabe, C; Berger, G; Gildenhaar, R; Meyer, J; Howlett, C R; Markovic, B; Zreiqat, H

2004-04-01

218

Prevalence and possible pathological significance of calcium phosphate salt accumulation in tendon matrix degeneration.  

PubMed Central

OBJECTIVES: To investigate the prevalence of calcium phosphate mineral salt accumulation in degenerative supraspinatus 'tendinitis' compared with a normal sample of human tendons, and to determine whether there is an association of calcium salt deposition with pathological changes in the tendon extracellular matrix. METHODS: Cadaver tendons (supraspinatus and common biceps tendons, n = 96) and fragments of supraspinatus tendons obtained during shoulder surgery (n = 31) were analysed for calcium content by atomic absorption spectroscopy, phosphorous content using a spectrophotometric assay, and matrix composition (collagen, glycosaminoglycans and DNA) using standard biochemical techniques. RESULTS: We established baseline values of calcium concentration in macroscopically normal cadaver tendons (mean 1.1 (SD 0.35) micrograms/mg dry wt, n = 60) and found that 33% (nine of 27) of ruptured tendons from patients with 'degenerative tendinitis' contained an excess of calcium (more than 2SD greater than the normal sample mean). Five of these specimens had increased concentrations of phosphorous and calcium:phosphorous (molar) ratios consistent with a variety of possible calcium crystals, including calcium pyrophosphate, hydroxyapatite, and tricalcium phosphate, in addition to mixed or amorphous calcium phosphate deposits. Four of these specimens contained normal concentrations of phosphorous, consistent with deposits of calcium oxalate or calcium carbonate, although this was not confirmed biochemically. In contrast, surgical specimens (n = 4) from patients with 'calcifying tendinitis' (radiographically detected calcium deposits) all contained salts with a mineral composition consistent with hydroxyapatite. The presence and identity of crystal deposits was subsequently confirmed in five specimens by radiographic microanalysis. Analysis of the tendon matrix demonstrated a number of significant differences between normal and degenerate (ruptured) tendons, including a reduction in collagen content, an increase in sulphated glycosaminoglycans (predominantly dermatan sulphate) and an increase in DNA (cellular) content. However, there were no significant differences between degenerate tendons that were 'calcified' and those degenerate specimens that contained normal concentrations of calcium. CONCLUSIONS: Although there was a relatively high prevalence of calcium salts in degenerate tendons, which might contribute to the pathological process (such as increased matrix collagen degradation), these data are consistent with the hypothesis that 'dystrophic calcification' of degenerate tendon matrix is a pathological entity distinct from cell mediated 'calcifying tendinitis'. Calcification is probably one possible outcome (or end point) of chronic tendon injury, although the possibility exists that in many cases, the presence of calcium salts may contribute to the tendon matrix degeneration. PMID:8712860

Riley, G P; Harrall, R L; Constant, C R; Cawston, T E; Hazleman, B L

1996-01-01

219

Competitive adsorption of bovine serum albumin and lysozyme on characterized calcium phosphates by polyacrylamide gel electrophoresis method.  

PubMed

Characterizations of hydroxyapatite (HA), biphasic calcium phosphate (BCP) and beta tricalcium phosphate (beta-TCP) ceramic particles were carried out using X-ray diffusion (XRD), Scanning electron micrograph (SEM), Particle Sizer and Zeta potential analyzer. Competitive adsorption of bovine serum albumin (BSA) and lysozyme (LSZ) on the three calcium phosphates were investigated by polyacrylamide gel electrophoresis (PAGE) method. The results showed that HA, BCP and beta-TCP ceramic particles with irregular shapes and similar size distributions all had negative surface net charges in pH7.4 phosphate buffered saline (PBS) solution and exhibited alike behaviors of BSA and LSZ adsorption. LSZ had higher affinity for calcium phosphate ceramics than BSA and its adsorption on them didn't be almost influenced by the increasing of BSA concentration in the solution. Electrostatic interaction played an important role on the competitive adsorption of BSA and LSZ on the surface of calcium phosphate ceramic particles. PMID:17619993

Zhu, X D; Fan, H S; Zhao, C Y; Lu, J; Ikoma, T; Tanaka, J; Zhang, X D

2007-11-01

220

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

PubMed

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 T B; Min, Young K; Lee, Byong-Taek

2014-10-01

221

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

EDUARDO A SLATOPOLSKY; STEVEN K BURKE; MAUREEN A DILLON

1999-01-01

222

SOILS, SEC 1 SOIL ORGANIC MATTER DYNAMICS & NUTRIENT CYCLING RESEARCH ARTICLE Biogenic calcium phosphate transformation in soils  

E-print Network

phosphate transformation in soils over millennial time scales Shinjiro Sato & Eduardo G. Neves & Dawit calcium phosphate (Ca-P). However, very little is known about long-term changes of biogenic Ca-P in soil­1,000 years, -tricalcium phosphate increased to 16% of total P after 900­1,100 years, after which both Ca

Lehmann, Johannes

223

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

1956-01-01

224

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

Technology Transfer Automated Retrieval System (TEKTRAN)

The adjuvant activity of chitosan and calcium phosphate-particles (CAP) was studied following intranasal coadministration of commercial chickens with inactivated Newcastle disease virus (NDV) vaccine. After three vaccinations with inactivated NDV in combination with chitosan or CAP an increase in an...

225

Effect of different calcium phosphate scaffold ratios on odontogenic differentiation of human dental pulp cells.  

PubMed

Calcium phosphate (CaP) scaffolds have been widely and successfully used with osteoblast cells for bone tissue regeneration. However, it is necessary to investigate the effects of these scaffolds on odontoblast cells' proliferation and differentiation for dentin tissue regeneration. In this study, three different hydroxyapatite (HA) to beta tricalcium phosphate (?-TCP) ratios of biphasic calcium phosphate (BCP) scaffolds, BCP20, BCP50, and BCP80, with a mean pore size of 300?m and 65% porosity were prepared from phosphoric acid (H2PO4) and calcium carbonate (CaCO3) sintered at 1000°C for 2h. The extracts of these scaffolds were assessed with regard to cell viability and differentiation of odontoblasts. The high alkalinity, more calcium, and phosphate ions released that were exhibited by BCP20 decreased the viability of human dental pulp cells (HDPCs) as compared to BCP50 and BCP80. However, the cells cultured with BCP20 extract expressed high alkaline phosphatase activity and high expression level of bone sialoprotein (BSP), dental matrix protein-1 (DMP-1), and dentin sialophosphoprotein (DSPP) genes as compared to that cultured with BCP50 and BCP80 extracts. The results highlighted the effect of different scaffold ratios on the cell microenvironment and demonstrated that BCP20 scaffold can support HDPC differentiation for dentin tissue regeneration. PMID:25686943

AbdulQader, Sarah Talib; Kannan, Thirumulu Ponnuraj; Rahman, Ismail Ab; Ismail, Hanafi; Mahmood, Zuliani

2015-04-01

226

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

227

Initial deposition of calcium phosphate ceramic on polystyrene and polytetrafluoroethylene by rf magnetron sputtering deposition  

Microsoft Academic Search

Calcium phosphate (CaP) coatings can be applied to improve the biological performance of polymeric medical implants. A strong interfacial bond between ceramic and polymer is required for clinical applications. Because the chemical structure of an interface plays an important role in the adhesion of a coating, we studied the formation of the interface between CaP and polystyrene (PS) and polytetrafluoroethylene

B. Feddes; J. G. C. Wolke; J. A. Jansen; A. M. Vredenberg

2003-01-01

228

Enamel subsurface lesion remineralisation with casein phosphopeptide stabilised solutions of calcium, phosphate and fluoride.  

PubMed

Casein phosphopeptide stabilised amorphous calcium phosphate (CPP-ACP) and amorphous calcium fluoride phosphate (CPP-ACFP) solutions have been shown to remineralise enamel subsurface lesions. The aim of this study was to determine the effect of ion composition of CPP-ACP and CPP-ACFP solutions on enamel subsurface lesion remineralisation in vitro. CPP-bound and free calcium, phosphate and fluoride ion concentrations in the solutions were determined after ultrafiltration. The ion activities of the free ion species present were calculated using an iterative computational program. The mineral deposited in the subsurface lesions was analysed using transverse microradiography and electron microprobe. CPP was found to stabilise high concentrations of calcium, phosphate and fluoride ions at all pH values (7.0-4.5). Remineralisation of the subsurface lesions was observed at all pH values tested with a maximum at pH 5.5. The CPP-ACFP solutions produced greater remineralisation than the CPP-ACP solutions at pH 5.5 and below. The mineral formed in the subsurface lesions was consistent with hydroxyapatite and fluorapatite for remineralisation with CPP-ACP and CPP-ACFP, respectively. The activity gradient of the neutral ion pair CaHPO(4)(0) into the lesion was significantly correlated with remineralisation and together with HF(0) were identified as important species for diffusion. PMID:18204252

Cochrane, N J; Saranathan, S; Cai, F; Cross, K J; Reynolds, E C

2008-01-01

229

Calcium Phosphate Nanoparticles Induce Mucosal Immunity and Protection against Herpes Simplex Virus Type 2  

Microsoft Academic Search

Previously we reported that calcium phosphate nanoparticles (CAP) represented a superior alternative to alum adjuvants in mice immunized with viral protein. Additionally, we showed that CAP was safe and elicited no detectable immunoglobulin E (IgE) response. In this study, we demonstrated that following mucosal delivery of herpes simplex virus type 2 (HSV-2) antigen with CAP, CAP adjuvant enhanced protective systemic

Qing He; Alaina Mitchell; Tulin Morcol; Steve J. D. Bell

2002-01-01

230

Inflammatory cytokine response to titanium chemical composition and nanoscale calcium phosphate surface modification  

Microsoft Academic Search

Nanoscale surface modification of titanium dental implants with calcium phosphate (CaP) has been shown to achieve superior bone wound healing and osseointegration compared with smooth or microrough titanium surfaces alone. As bone healing has been shown to be influenced by the action of cytokines, this study examined whether changes in cytokine gene expression from RAW 264.7 cells cultured on commercially

Stephen Hamlet; Saso Ivanovski

2011-01-01

231

Lead Retention in a Calcareous Soil Influenced by Calcium and Phosphate Amendments  

EPA Science Inventory

Phosphate amendments in calcareous lead (Pb)-contaminated soils to immobilize Pb may be hindered due to competition of Pb with calcium (Ca) that may inhibit the retention of Pb as a precipitation mechanism. This study explored the retention of Pb in a calcareous soil spiked and ...

232

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

2013-01-01

233

Transformation of Amorphous Calcium Phosphate to Crystalline Dahllite in the Radular Teeth of Chitons  

Microsoft Academic Search

A comparison of infrared spectra from individual teeth along the radula of a chiton (Polyplacophora, Mollusca) shows that the first-formed calcium phosphate mineral is amorphous. Over a period of weeks the mineral transforms to dahllite. The c axes of the dahllite crystals are aligned approximately perpendicular to the tooth surface.

H. A. Lowenstam; S. Weiner

1985-01-01

234

Osteoblast proliferation on neat and apatite-like calcium phosphate-coated titanium foam scaffolds  

E-print Network

Osteoblast proliferation on neat and apatite-like calcium phosphate-coated titanium foam scaffolds-bearing ability of lightweight titanium made it possible to be used as a biomaterial, especially in hip revision and fixation surgery. It was initially shown that sand-blasted or surface-roughened titanium implants had

Tas, A. Cuneyt

235

Sedimentation Study of Biphasic Calcium Phosphate Particles A. Fatimi1,a  

E-print Network

is an aqueous polymer solution (hydroxypropylmethylcellulose (HPMC) or sodium carboxymethylcellulose (CMC in orthopedic and dental surgery. The IBS considered of a polymer solution mixed with biphasic calcium phosphate was 40%. This study investigated the influence of polymer solution on the BCP particles stability

Paris-Sud XI, Université de

236

Calcium phosphate bone cements, functionalized with VEGF: Release kinetics and biological activity  

Microsoft Academic Search

Calcium phosphate bone cements are of great interest for bone replacement since the nanocrystalline structure allows their remodelling into native bone tissue. A strategy to accelerate vascularization of the implant region is the functionalization with vascular endothelial growth factor (VEGF), which is known to mediate angio- genesis in vivo. In this study, the release of recombinant human VEGF (rhVEGF165) following

A. Lode; C. Wolf-Brandstetter; A. Reinstorf; A. Bernhardt; U. König; W. Pompe; M. Gelinsky

2007-01-01

237

Dietary and Pharmacological Control of Calcium and Phosphate Metabolism in Dialysis Patients  

Microsoft Academic Search

Chronic kidney disease-mineral and bone disorder is a new term defining a complex syndrome which underlines the need of a systemic approach to disturbances of calcium and phosphate metabolism in patients with renal failure. In recent years, the availability of new phosphorus binders and the appearance of new selective vitamin D receptor activators and calcimimetics have increased our current armamentarium

J. Bover; E. Andrés; M. J. Lloret; A. Aguilar; J. Ballarín

2009-01-01

238

Silicon-stabilized ?-tricalcium phosphate and its use in a calcium phosphate cement: characterization and cell response.  

PubMed

?-Tricalcium phosphate (?-TCP) is widely used as a reactant in calcium phosphate cements. This work aims at doping ?-TCP with silicon with a twofold objective. On the one hand, to study the effect of Si addition on the stability and reactivity of this polymorph. On the other, to develop Si-doped cements and to evaluate the effect of Si on their in vitro cell response. For this purpose a calcium-deficient hydroxyapatite was sintered at 1250°C with different amounts of silicon oxide. The high temperature polymorph ?-TCP was stabilized by the presence of silicon, which inhibited reversion of the ??? transformation, whereas in the Si-free sample ?-TCP completely reverted to the ?-polymorph. However, the ?-? transformation temperature was not affected by the presence of Si. Si-?-TCP and its Si-free counterpart were used as reactants for a calcium phosphate cement. While Si-?-TCP showed faster hydrolysis to calcium-deficient hydroxyapatite, upon complete reaction the crystalline phases, morphology and mechanical properties of both cements were similar. An in vitro cell culture study, in which osteoblast-like cells were exposed to the ions released by both materials, showed a delay in cell proliferation in both cases and stimulation of cell differentiation, more marked for the Si-containing cement. These results can be attributed to strong modification of the ionic concentrations in the culture medium by both materials. Ca-depletion from the medium was observed for both cements, whereas continuous Si release was detected for the Si-containing cement. PMID:22154863

Mestres, Gemma; Le Van, Clemence; Ginebra, Maria-Pau

2012-03-01

239

Gas phase laser synthesis and processing of calcium phosphate nanoparticles for biomedical applications  

NASA Astrophysics Data System (ADS)

Biochemical processes make pervasive use of calcium and phosphate ions. Calcium phosphate salts that are naturally nontoxic and bioactive have been used for several medical applications in form of coatings and micropowders. Nanoparticle-based calcium phosphates have been shown to be internalized by living cells and be effective in DNA transfection, drug delivery, and transport of fluorophores for imaging of intracellular processes. They are also expected to interact strongly with cell adhesive proteins and are therefore promising elements in approaches to mimic the complex environment of the extra cellular matrix of bone. Harnessing this biomedical potential requires the ability to control the numerous characteristics of nanophase calcium phosphates that affect biological response, including nanoparticle chemical composition, crystal phase, crystallinity, crystallographic orientation of exposed faces, size, shape, surface area, number concentration, and degree of aggregation. This dissertation focuses on the use of laser-induced gas-phase synthesis for creation of calcium phosphate nanoparticles, and corresponding nanoparticle-based substrates that could offer new opportunities for guiding biological responses through well-controlled biochemical and topological cues. Gas-phase synthesis of nanoparticles has several characteristics that could enhance control over particle morphology, crystallinity, and surface area, compared to liquid-phase techniques. Synthesis from gas-phase precursors can be carried out at high temperatures and in high-purity inert or reactive gas backgrounds, enabling good control of chemistry, crystal structure, and purity. Moreover, the particle mean free path and number concentration can be controlled independently. This allows regulation of interparticle collision rates, which can be adjusted to limit aggregation. High-temperature synthesis of well-separated particles is therefore possible. In this work high power lasers are employed to vaporize microcrystalline calcium phosphate materials to generate an aerosol of nanoparticles which is further processed and deposited using principles of aerosol mechanics. Particles and resulting particle-based systems are analyzed by transmission electron microscopy, atomic force microscopy, X-ray diffraction, and optical absorption. Obtained substrates are functionalized with cell adhesive peptides. Findings show that laser-induced gas-phase synthesis provides attractive new dimensions in the controlled fabrication of calcium phosphate nanoparticles, including manipulation not only of size and chemical composition, but also crystal phase make-up, fractal structure, and nanotopography of derived substrates.

Bapat, Parimal V.

240

Accurate coronary calcium phosphate mass measurements from electron beam computed tomograms.  

PubMed

Precipitates of calcium phosphate in coronary arteries always indicate the presence of atherosclerosis. The mass of these precipitates is related to the severity of atherosclerosis. To determine the accuracy of electron beam computed tomographic (CT) mass estimates, we imaged 21 human hearts inside an anthropomorphic chest phantom using an Imatron C-100 electron beam CT scanner (Imatron, San Francisco, CA). We then incinerated the 63 imaged coronary arteries and weighed the mineral ash. We calculated the mass estimates from the images using an algorithm derived from a model that assumes simple radiographic properties of the coronary arteries. We also calculated the currently used coronary calcium score for each artery. Although both the mass estimates and the scores correlated with the actual mass of the incinerated specimens (r = .97 and r = .93), the correlation with the mass estimates was better (P = .02; William's test). The regression equation relating the actual mass to the mass estimates was y = 1.37 x + 14, indicating that the CT mass estimates consistently underestimate actual coronary calcium phosphate mass. We conclude that relative mass estimates using electron beam CT scanning are accurate and that both these and the currently employed calcium scores reflect the actual mass of precipitated calcium phosphate in diseased coronary arteries. PMID:7549356

Detrano, R; Tang, W; Kang, X; Mahaisavariya, P; McCrae, M; Garner, D; Peng, S K; Measham, C; Molloi, S; Gutfinger, D

1995-07-01

241

The role of intracellular calcium phosphate in osteoblast-mediated bone apatite formation  

PubMed Central

Mineralization is a ubiquitous process in the animal kingdom and is fundamental to human development and health. Dysfunctional or aberrant mineralization leads to a variety of medical problems, and so an understanding of these processes is essential to their mitigation. Osteoblasts create the nano-composite structure of bone by secreting a collagenous extracellular matrix (ECM) on which apatite crystals subsequently form. However, despite their requisite function in building bone and decades of observations describing intracellular calcium phosphate, the precise role osteoblasts play in mediating bone apatite formation remains largely unknown. To better understand the relationship between intracellular and extracellular mineralization, we combined a sample-preparation method that simultaneously preserved mineral, ions, and ECM with nano-analytical electron microscopy techniques to examine osteoblasts in an in vitro model of bone formation. We identified calcium phosphate both within osteoblast mitochondrial granules and intracellular vesicles that transported material to the ECM. Moreover, we observed calcium-containing vesicles conjoining mitochondria, which also contained calcium, suggesting a storage and transport mechanism. Our observations further highlight the important relationship between intracellular calcium phosphate in osteoblasts and their role in mineralizing the ECM. These observations may have important implications in deciphering both how normal bone forms and in understanding pathological mineralization. PMID:22879397

Boonrungsiman, Suwimon; Gentleman, Eileen; Carzaniga, Raffaella; Evans, Nicholas D.; McComb, David W.; Porter, Alexandra E.; Stevens, Molly M.

2012-01-01

242

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

PubMed

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

2013-04-01

243

Nanocrystalline biphasic resorbable calcium phosphate (HAp/?-TCP) thin film prepared by electron beam evaporation technique  

NASA Astrophysics Data System (ADS)

Biphasic calcium phosphate (BCP) thin film having resorbable ?-tricalcium phosphate (?-TCP) and non-resorbable hydroxyapatite (HAp) phases having enhanced bioactivity was synthesized by electron beam evaporation technique. Nanosized BCP was deposited as a layer (500 nm) on (0 0 1) silicon substrate by electron beam evaporation and crystalline phase of samples were found to improve on annealing at 700 °C. Uniform deposition of calcium phosphate on silicon substrate was verified from elemental mapping using scanning electron microscope (SEM-EDX). Annealing of the samples led to a decrease in surface roughness, hydrophobicity and dissolution of the coating layer. Amoxicillin loaded thin films exhibited significant bacterial resistance. In addition, BCP thin films did not exhibit any cytotoxicity. Antibiotics incorporated BCP coated implants might prevent the post-surgical infections and could promote bone-bonding of orthopedic devices.

Elayaraja, K.; Chandra, V. Sarath; Joshy, M. I. Ahymah; Suganthi, R. V.; Asokan, K.; Kalkura, S. Narayana

2013-06-01

244

Microbial phytase-induced calcium-phosphate precipitation--a potential soil stabilization method.  

PubMed

Two hypotheses were tested: (1) microbial dephosphorylation of phytate in the presence of Ca²+ ions will result in the precipitation of hydroxyapatite-like crystals and (2) precipitation of calcium-phosphate crystals on and between sand-like particles can cause cementation. A growing culture of the dimorphic phytase-active yeast Arxula adeninivorans was introduced into a column filled with quartz particles and subsequently a liquid growth medium amended with calcium phytate was pumped through the column resulting in increased strength and stiffness of the quartz particle matrix. Environmental scanning electron microscope analysis combined with energy-dispersive X-ray measurement revealed cementation of the quartz particles by calcium-phosphate crystals. This microbial mineralization process could provide a novel approach to improving the mechanical properties like strength and stiffness of sandy soils. PMID:21253909

Roeselers, G; Van Loosdrecht, M C M

2010-11-01

245

Procedure for the study of acidic calcium phosphate precursor phases in enamel mineral formation.  

PubMed

Considerable evidence suggests that an acidic calcium phosphate, such as octacalcium phosphate (OCP) or brushite, is involved as a precursor in enamel and other hard tissue formation. Additionally, there is in vitro evidence suggesting that fluoride accelerates and magnesium inhibits the hydrolysis of OCP to hydroxyapatite (OHAp). As the amount of OCP or brushite in enamel cannot be measured directly in the presence of an excess of hydroxyapatite, a procedure was developed that allows for their indirect in vivo quantification as pyrophosphate. This permits study of the effects of fluoride and magnesium ions on enamel mineral synthesis. Rat incisor calcium phosphate was labeled by intraperitoneal injection of NaH2(32)PO4. The rats were then subjected to various fluoride and magnesium treatments with subcutaneous implanted osmotic pumps. They were then killed at predetermined intervals; the nascent sections of the incisors were collected, cleaned, and pyrolyzed at 500 degrees C for 48 hours to convert acidic calcium phosphates to calcium pyrophosphate; the pyrophosphate was separated from orthophosphate by anion-exchange chromatography; and the resulting fractions were counted by liquid scintillation spectrometry. The activities of the pyro- and orthophosphate fractions were used to calculate the amount of acidic calcium phosphate present in the nascent mineral. The results demonstrated that the percentage of radioactive pyrophosphate in nascent incisors decreased with time, with increasing serum F- concentration, and with decreasing serum magnesium content. The technique described here should prove to be a powerful new tool for studying the effects of various agents on biological mineral formation. PMID:1315187

Siew, C; Gruninger, S E; Chow, L C; Brown, W E

1992-02-01

246

Crystallized nano-sized alpha-tricalcium phosphate from amorphous calcium phosphate: microstructure, cementation and cell response.  

PubMed

New insight on the conversion of amorphous calcium phosphate (ACP) to nano-sized alpha tricalcium phosphate (?-TCP) provides a faster pathway to calcium phosphate bone cements. In this work, synthesized ACP powders were treated with either water or ethanol, dried, crystallized between 700 and 800?°C, and then cooled at different cooling rates. Particle size was measured in a scanning electron microscope, but crystallite size calculated by Rietveld analysis. Phase composition and bonding in the crystallized powder was assessed by x-ray diffraction and Fourier-transform infrared spectroscopy. Results showed that 50?nm sized ?-TCP formed after crystallization of lyophilized powders. Water treated ACP retained an unstable state that may allow ordering to nanoapatite, and further transition to ?-TCP after crystallization and subsequent decomposition. Powders treated with ethanol, favoured the formation of pure ?-TCP. Faster cooling limited the growth of ?-TCP. Both the initial contact with water and the cooling rate after crystallization dictated ?-TCP formation. Nano-sized ?-TCP reacted faster with water to an apatite bone cement than conventionally prepared ?-TCP. Water treated and freeze-dried powders showed faster apatite cement formation compared to ethanol treated powders. Good biocompatibility was found in pure ?-TCP nanoparticles made from ethanol treatment and with a larger crystallite size. This is the first report of pure ?-TCP nanoparticles with a reactivity that has not required additional milling to cause cementation. PMID:25886478

Vecbiskena, Linda; Gross, Karlis Agris; Riekstina, Una; Yang, Thomas Chung-Kuang

2015-01-01

247

Relationship between iron, calcium and phosphate during experimental cutaneous calcinosis  

Microsoft Academic Search

Calcification of the skin (calciphylaxis) induced by the subcutaneous administration of iron chloride to dihydrotachysterol (DHT)-sensitized rats is preceded by the selective deposition of iron (visible with electron microscopic techniques) on the surface of collagen fibrils. Electron probe X-ray microanalysis indicates that the injectionof iron alone suffices to increase local concentrations of calcium and phosphorus; however, apatite formation occurs only

G. Gabbiani; M. C. Badonnel; C. A. Baud

1969-01-01

248

The nucleation and growth of calcium phosphate onto self-assembled monolayers  

NASA Astrophysics Data System (ADS)

The nucleation and growth of calcium phosphate is of great importance to the formation of mammalian hard tissue structures such as bone and teeth and for unwanted, ectopic calcium phosphate deposition on arteries and implants. In spite of its importance, the mechanisms of nucleation and growth of calcium phosphate are not well known, but are believed to involve an organic template. The nucleation and growth of calcium phosphate was studied onto model nucleation templates composed of alkanethiol self-assembled monolayers on gold that were developed and tailored to have various surface functionalities, various surface site densities composed of mixtures of two thiols, and various degrees of conformational disorder composed of mixtures of SAMs of various chain lengths. The quartz crystal microbalance was developed as an in-situ technique to study the nucleation and growth kinetics and ex-situ techniques such as X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy were used to assess adsorbate molecular chemistry in the initial stages of deposition. Significant nucleation and growth of calcium phosphate onto SAMs involved the adsorption of solution-formed critical nuclei. This mechanism is in contrast to heterogeneous nucleation and may have important implications for bone formation. An initial slow growth region occurred which involved the adsorption and assembly of solution-formed nanometer-sized particles. A second fast growth period occurred which involved the adsorption and growth of solution-formed critical nuclei or the assembly of supercritical particles. There was evidence for the heterogeneous nucleation of a very low density of crystals at low solution supersaturation. Heterogeneous nucleation may be limited due to the use of planar surfaces and to limits on phosphate adsorption due to electrostatic double layer anisotropy at the charged interfaces. Surface selective deposition was found in the initial slow growth region with growth promoted onto charged SAMs such as carboxylic acid in contrast to hydroxyl, methyl ester, and methyl. The nanoparticle assembly growth mechanism was used to form ultrathin films of calcium phosphate which have not been formed previously. The micron-sized and ultrathin films are of interest as biosensors, bioelectronic devices, and bioactive coatings on implants.

Tarasevich, Barbara J.

249

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

2013-11-01

250

Adsorption of levofloxacin onto goethite: effects of pH, calcium and phosphate.  

PubMed

Adsorption of levofloxacin (LEV), one of the extensively used antibiotics, onto goethite was investigated using batch experiments. The adsorption of LEV on goethite was pH-dependent. A maximum adsorption was reached at pH 6. Above or below pH 6, the adsorption decreased. In the presence of calcium (Ca(2+)), a decrease in adsorption was observed, due to probably formation of Ca(2+)-LEV complexes in solutions. Phosphate also showed a significant inhibition on LEV adsorption over a pH range of 3-10. Phosphate competed with LEV for binding sites on the surface of goethite, and the electrostatic competition between LEV and phosphate on goethite surface might be another reason for the decrease in adsorption. These results indicated that Ca(2+) and phosphate have a great influence on the distribution of LEV in soils and waters, which will eventually affect its antibacterial activity in the environment. PMID:24269055

Qin, Xiaopeng; Liu, Fei; Wang, Guangcai; Weng, Liping; Li, Lu

2014-04-01

251

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

1998-01-01

252

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

PubMed

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

2013-07-01

253

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

2014-01-01

254

FGF23 and Klotho: the new cornerstones of phosphate/calcium metabolism  

PubMed Central

Since its first description as a phosphaturic agent in the early 2000’s, the Fibroblast Growth Factor 23 (FGF23) has rapidly become the third key player of phosphate/calcium metabolism with the two ‘old’ PTH and vitamin D. FGF23 is a protein synthesized by osteocytes that acts mainly as a phosphaturic factor and a suppressor of 1? hydroxylase activity in the kidney. It inhibits the expression of type IIa and IIc sodium-phosphate cotransporters on the apical membrane of proximal tubular cells, thus leading to an inhibition of phosphate reabsorption. Moreover, it also inhibits the 1? hydroxylase activity. These two renal pathways account together for the hypophosphatemic effect of FGF23, but FGF23 has also been recently described as an inhibiting factor for PTH synthesis. Its exact role in bone remains to be defined. A transmembrane protein, Klotho, is an essential cofactor for FGF23 biological activity, but it can also act by itself for calcium and PTH regulation. This paper gives an overview of these recent data of phosphate/calcium physiology, as well as a description of clinical conditions associated with FGF23 deregulation (genetic diseases and chronic kidney disease). As a conclusion, future therapeutic consequences of the FGF23/Klotho axis are discussed. PMID:21497493

Bacchetta, Justine; Cochat, Pierre; Salusky, Isidro B

2014-01-01

255

Synthesis, characterization and cation adsorption of p-aminobenzoic acid intercalated on calcium phosphate  

SciTech Connect

Graphical abstract: Scanning electron microscopy photographs of calcium phosphate (a) and intercalated with p-aminobenzoic acid (b). Highlights: ? Calcium phosphate was intercalated with p-aminobenzoic acid. ? Guest molecule contains nitrogen and oxygen atoms from amine and carboxylic groups. ? These basic centers are potentially useful for cation coordination in ethanol solution. ? Crystal morphology of compounds is lamellar, it agrees with expected structural characteristics. -- Abstract: Crystalline lamellar calcium phosphate retained 4-aminobenzoic acid inside its cavity without leaching. The intense infrared bands in the 1033 and 1010 cm{sup ?1} interval confirmed the presence of the phosphonate groups attached to the inorganic layer, with sharp and intense peaks in X-ray diffraction patterns, which gave basal distances of 712 and 1578 pm for the original and the intercalated compounds, respectively. Solid-state {sup 31}P nuclear magnetic resonance spectra presented only one peak for the phosphate groups attached to the main inorganic polymeric structure near ?2.4 ppm. The adsorption isotherms from ethanol gave the maximum adsorption capacities of 6.44 and 3.34 mmol g{sup ?1} for nickel and cobalt, respectively, which stability constant and distribution coefficient followed Co > Ni.

Silva, Camila F.N. [Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR (Brazil)] [Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR (Brazil); Lazarin, Angélica M., E-mail: amlazarin2@uem.br [Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR (Brazil); Sernaglia, Rosana L.; Andreotti, Elza I.S. [Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR (Brazil)] [Departamento de Química, Universidade Estadual de Maringá, Av. Colombo, 5790, 87020-900 Maringá, PR (Brazil)

2012-06-15

256

Dissolution control and cellular responses of calcium phosphate coatings on zirconia porous scaffold.  

PubMed

Different types of calcium phosphates [hydroxyapatite (HA), fluorapatite (FA), tricalcium phosphate (TCP), and their composites (HA + FA, HA + TCP)] were coated on a zirconia (ZrO(2)) porous scaffold using a powder slurry method. The ZrO(2) porous scaffold was intended for a load-bearing implant, and the apatite layers were coated to improve osteoconductivity. The insertion of an FA intermediate layer between the coating layer and ZrO(2) scaffold effectively suppressed the reaction between the calcium phosphate and ZrO(2) and maintained the coating layer at the initial powder composition. The obtained coating layer, of a thickness of approximately 30 microm, was relatively microporous and firmly adherent to the ZrO(2) scaffold. Dissolution tests in physiological solution showed typical differences depending on the coating layers, with the dissolution rate increasing in the order TCP > HA + TCP > HA > HA + FA > FA. This result suggests the functional coating of the calcium phosphates in view of tailoring the solubility. Osteoblast-like cells, MG63 and HOS, responded similarly in terms of cell growth, morphology, and proliferation rate regardless of the coating types, indicating favorable and comparable cell viability. However, the alkaline phosphatase (ALP) activity of the cells on the pure HA and HA composite coatings (HA + FA and HA + TCP) expressed at higher levels compared to those on pure FA and pure TCP coatings for both MG63 and HOS cells, suggesting a selective cell activity depending on the coating types. All the calcium phosphate-coated-ZrO(2) scaffolds showed higher ALP levels compared to pure ZrO(2) scaffold. PMID:14762932

Kim, Hae-Won; Kim, Hyoun-Ee; Salih, Vehid; Knowles, Jonathan C

2004-03-01

257

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

E-print Network

minerals. The calcium encapsulation efficiency was found to depend upon a number of factors that included. Calcium ion release and mineral formation was activated by a bilayer-to-micelle mesophase transformation intrinsic factors such as the nature of the lipid headgroup, the length and degree of unsaturation

258

Oral phosphate binders: phosphate binding capacity of iron (III) hydroxide complexes containing saccharides and their effect on the urinary excretion of calcium and phosphate in rats.  

PubMed

Phosphate binders that contain aluminum or calcium are frequently prescribed to treat hyperphosphatemia in patients with end-stage renal disease (ESRD), but an accumulation of aluminum can lead to encephalopathy, aluminum-related bone disease (ARBD) such as osteomalacia, anaemia, and resistance to erythropoietin, and calcium accumulation can lead to hypercalcaemia. High phosphate concentrations are reduced in vitro and in vivo by a phosphate adsorption pill, which is synthesized by hydrolyzing ferrous sulfate in the presence of saccharides, to form an iron (III)-saccharide complex that is acid resistant and binds phosphate greater than iron (III) hydroxide alone. Under in vitro conditions, containing 3.26 mg P/dL, the iron (III)-sucrose complex showed the highest phosphate adsorption capacity at pH 2 with artificial gastric juice, 58.9 mg P/g binder. For the 7 day in vivo study, 0% (Group 1), 1% (Group 2), 4% (Group 3), and 8% (Group 4) iron (III)-sucrose complex was admixed into the rodent chow by weight and fed to 15 male Wistar rats. The weight and volume of the feces and urine, and the calcium, iron, and phosphorus excretions in the feces and urine samples were monitored for any signs of irregularity. Total urine outflow was collected during a 24-h period to determine the amount of phosphate recovered, which indicates the ability of the phosphate binder to reduce gastrointestinal phosphate absorption. The fecal iron excretion was significantly effected by the amount of binder ingested throughout the study for Group 2 (p < 0.001), Group 3 (p < 0.01), and Group 4 (p < 0.001). The urinary calcium excretion (mg/rat/24-h) significantly increased by the 7th day for Group 2 (p < 0.05) and Group 4 (p < 0.01) in comparison to the control. Finally, after 7 days, there was a significant drop in the urinary phosphorus levels (mg P/rat/24-h) in a dose dependent manner for Group 2: from 7.82 +/- 1.46 to 1.98 +/- 0.10 mg P/rat/24-h (102 mg P/dL/24-h; p < 0.05); Group 3: from 6.70 +/- 1.14 to 0.16 +/- 0.09 mg P/rat/24-h (6.0 mg P/dL/24-h; p < 0.01); and Group 4: from 8.25 +/- 0.67 to 0.04 +/- 0.01 mg P/rat/24-h (0.9 mg P/dL/24-h; p < 0.01). The results show that this new adsorbent might provide an alternative to conventional aluminum and calcium containing phosphate-binding agents for combating hyperphosphataemia. PMID:10516989

Yamaguchi, T; Baxter, J G; Maebashi, N; Asano, T

1999-09-01

259

The progress of early phase bone healing using porous granules produced from calcium phosphate cement  

PubMed Central

Objective Bone grafting is a vital component in many surgical procedures to facilitate the repair of bone defects or fusions. Autologous bone has been the gold standard to date in spite of associated donor-site morbidity and the limited amount of available donor bone. The aim of this study was to investigate the progress of bone regeneration and material degradation of calcium phosphate granules (CPG) produced from a calcium phosphate self-setting cement powder compared to the use of autologous bone grafting in the treatment of "critical size defects" on load-bearing long bones of minipigs. Methods A critical size defect in the tibial metaphysis of 16 mini-pigs was filled either with autologous cancellous graft or with micro- and macroporous carbonated, apatic calcium phosphate granules (CPG) produced from a calcium phosphate self-setting cement powder. After 6 weeks, the specimens were assessed by X-ray and histological evaluation. The amount of new bone formation was analysed histomorphometrically. Results The semi-quantitative analysis of the radiological results showed a complete osseous bridging of the defect in three cases for the autograft group. In the same group five animals showed a beginning, but still incomplete bridging of the defect, whereas in the CPG group just two animals developed this. All other animals of the CPG group showed only a still discontinuous new bone formation. Altogether, radiologically a better osseous bridging was observed in the autograft group compared to the CPG group. Histomorphometrical analysis after six weeks of healing revealed that the area of new bone was significantly greater in the autograft group concerning the central area of the defect zone (p < 0.001) as well as the cortical defect zone (p < 0.002). All defects showed new bone formation, but only in the autograft group defects regenerated entirely Conclusions Within the limits of the present study it could be demonstrated that autologous cancellous grafts lead to a significantly better bone regeneration compared to the application of calcium phosphate granules (CPG) produced from a calcium phosphate self-setting cement powder after 6 weeks. In the early phase of bone-healing, the sole application of CPG appears to be inferior to the autologous cancellous grafts in an in vivo critical size defect on load-bearing long bones of mini-pigs. PMID:20562058

2010-01-01

260

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

2008-01-01

261

Calcium thorium phosphate (Whitlockite-type mineral). Synthesis and structure refinement  

SciTech Connect

The crystal structure of a new calcium thorium phosphate has been refined by the full-profile Rietveld method using X-ray powder diffraction data. The sample has been synthesized by the sol-gel technique. The phosphate has been identified by X-ray powder diffraction and IR spectroscopy. The refined composition is represented by the formula Ca{sub 10.26}Th{sub 0.12}(PO{sub 4}){sub 7}. The CaO{sub n} and PO{sub 4} polyhedra are distorted compared to the corresponding polyhedra in the basic compound {beta}-Ca{sub 3}(PO{sub 4}){sub 2}.

Orlova, A. I., E-mail: oai@uic.nnov.ru [Lobachevsky State University of Nizhni Novgorod (Russian Federation); Khainakov, S. A. [University of Oviedo (Spain); Loginova, E. E.; Oleneva, T. A. [Lobachevsky State University of Nizhni Novgorod (Russian Federation); Garcia Granda, S. [University of Oviedo (Spain); Kurazhkovskaya, V. S. [Moscow State University (Russian Federation)

2009-07-15

262

Calcium thorium phosphate (Whitlockite-type mineral). Synthesis and structure refinement  

NASA Astrophysics Data System (ADS)

The crystal structure of a new calcium thorium phosphate has been refined by the full-profile Rietveld method using X-ray powder diffraction data. The sample has been synthesized by the sol-gel technique. The phosphate has been identified by X-ray powder diffraction and IR spectroscopy. The refined composition is represented by the formula Ca10.26Th0.12(PO4)7. The CaO n and PO4 polyhedra are distorted compared to the corresponding polyhedra in the basic compound ?-Ca3(PO4)2.

Orlova, A. I.; Kha?nakov, S. A.; Loginova, E. E.; Oleneva, T. A.; Granda, S. Garcia; Kurazhkovskaya, V. S.

2009-07-01

263

Hereditary deafness with hydrops and anomalous calcium phosphate deposits  

SciTech Connect

The temporal bones from a 58-year-old white woman who had had hereditary congenital deafness were examined with the techniques of microdissection and surface preparations followed by sectioning of the modiolus. There was bilateral, almost total sensorineural degeneration, which also involved the saccule. The degeneration of the distal processes of the cochlear neurons in the osseous spiral lamina was almost complete, whereas numerous ganglion cells and proximal processes remained in the modiolus and the internal auditory canal. Severe cochleo-saccular hydrops was present in the left ear with Reissner's membrane bulging into the horizontal canal. X-ray diffraction and electron probe analysis were used to study the abnormal crystalline deposits in both ears. On the left side the saccular otoconia were composed of calcite, but the utricular macula was covered by a crust of apatite spherulites. More apatite occurred around the maculae and in the scala media. The cupulae were composed of apatite and octacalcium phosphate. On the right side the utricular otoconia were of normal calcite, but there was a deposit of apatite on the macula sacculi. The upper part of the scala media was completely filled by a deposit of apatite and octacalcium phosphate.

Johnsson, L.G.; Rouse, R.C.; Hawkins, J.E. Jr.; Kingsley, T.C.; Wright, C.G.

1981-11-01

264

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.

2006-08-01

265

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

Microsoft Academic Search

The effects of solid state synthesis process parameters and primary calcium precursor on the cement-type hydration efficiency\\u000a (at 37°C) of ?-tricalcium phosphate (Ca3(PO4)2 or ?-TCP) into hydroxyapatite (Ca10?xHPO4(PO4)6?x(OH)2?x x = 0–1, or HAp) have been investigated. ?-TCP was synthesized by firing of stoichiometric amount of calcium carbonate (CaCO3) and monetite (CaHPO4) at 1150–1350°C for 2 h. Three commercial grade CaCO3 powders of different

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

2011-01-01

266

Fabrication and mechanical testing of porous calcium phosphate bioceramic granules.  

PubMed

Porous hydroxyapatite/tricalcium phosphate (HA/TCP) granules were fabricated by a novel technique of vacuum impregnation of reticulated polyurethane (PU) foams with ceramic slip. The resultant granules had 5-10% interconnected porosity with controlled pore sizes necessary to allow bone ingrowth combined with good mechanical properties. Using PU foams with a different number of pores per inch (ppi), porous HA/TCP granules in the size range of 2-8 mm were successfully manufactured. Dieplunger tests were used to compare the compression and relaxation properties of the granules with those of a commercially available bone graft product, BoneSave. The results of the die-plunger testing showed that the experimental granules were stiffer than the BoneSave materials and had less of a tendency to crumble to powder after testing. This therefore suggests that these experimental granules would be useful for impaction grafting and space filling applications. PMID:17554596

Hsu, Y H; Turner, I G; Miles, A W

2007-10-01

267

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

2014-06-01

268

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

E-print Network

A new approach in biomimetic synthesis of calcium phosphate coatings using lactic acid­Na lactate-SBF) contained appropriate amounts of sodium lactate (NaL) and lactic acid (HL), as well as all the other ionic

Tas, A. Cuneyt

269

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

2010-04-01

270

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

PubMed Central

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. PMID:20671783

2010-01-01

271

Recurrent calcium phosphate urolithiasis in a black-and-white ruffed lemur (Varecia variegata).  

PubMed

An adult intact male black-and-white ruffed lemur (Varecia variegata) suffered recurrent bouts of urethral blockage over a 3-yr period caused by calcium phosphate (apatite form) uroliths. Surgical intervention was required in two of the three instances. Various attempts at medical management failed to control formation of the stones, and the underlying etiology remains unclear. In addition, there have been consistent, multiple, unchanging renal mineralizations over the course of the case. Medical management failed to significantly alter the urinary pH; although, to date, no further problems have been noted. To the authors' knowledge, this is the first known report of calcium phosphate stones in a prosimian species. PMID:24712174

Cushing, Andrew C; Kollias, George; Knafo, S Emmanuelle; Streeter, Renee; Ahou-Madi, Noha

2014-03-01

272

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.

2011-01-01

273

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

PubMed

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

2014-11-26

274

Engineering of polarized tubular structures in a microfluidic device to study calcium phosphate stone formation†  

PubMed Central

This communication describes the formation of tubular structures with a circular cross-section by growing epithelial cells in a microfluidic (MF) device. Here we show for the first time that it is possible to form a monolayer of polarized cells, embedded within the MF device which can function as an in vivo epithelia. We showed: i) the overexpression of specific protein(s) of interest (i.e., ion channel and transport proteins) is feasible inside tubular structures in MFs; ii) the functional kinetic information of Ca2+ in cells can be measured by microflurometry using cell permeable Ca2+ probe under confocal microscope; and iii) calcium phosphate stones can be produced in real time in MFs with Ca2+ transporting epithelia. These data suggest that tubular structures inside this MF platform can be used as a suitable model to understand the molecular and pharmacological basis of calcium phosphate stone formation in the epithelial or other similar cellular micro environments. PMID:22960772

Wei, Zengjiang; Amponsah, Prince K.; Al-Shatti, Mariyam

2012-01-01

275

Calcium phosphate materials containing alumina: Raman spectroscopical, histological, and ultrastructural study.  

PubMed

Variable alumina quantities were added to two types of calcium phosphate materials-hydroxyapatite ceramics with Ca/P = 1.67 and calcium metaphosphate glass with Ca/P = 1--in order to increase their mechanical properties. Raman spectroscopy shows that alumina interacts with the phosphate group of these materials, while thermomechanical analysis shows that their elastic modulus has a value similar to that of bone. Histological sections demonstrate that the surface in close contact with ceramic materials shows a good integration between bone and biomaterial. All ceramic specimens are penetrated by well-stained, presumably glycoprotein, matrix, that consistently forms a thin network in close contact with the implant. After 6 weeks bone growing on both ceramic and glass shows signs of maturation with a lamellar structure and an apparently normal mineralization. In the case of the glass, inside this newly formed bone, were often observed two layers, the internal one showing a well defined lamellar structure. PMID:2019610

Bertoluzza, A; Simoni, R; Tinti, A; Morocutti, M; Ottani, V; Ruggeri, A

1991-01-01

276

Regularities of Forming Calcium Phosphate Coatings on Zirconium from Electrolytes Based on Synthesized and Biological Hydroxyapatite  

NASA Astrophysics Data System (ADS)

Physical-chemical and mechanical properties of calcium phosphate coating formed by microarc oxidation method on the zirconium surface were investigated. Two types of electrolytes based on synthesized and biological hydroxyapatite (HA) were used to form the coatings. Deposition of the coating based on synthesized hydroxyapatite lead to an increase in functional properties of coatings (adhesion strength, Ca/P ratio) in comparison with the calcium phosphate coating deposited using biological hydroxyapatite. The x-ray phase analysis and TEM of coatings showed that the coatings have submicrocrystalline structure containing both stoichiometric and non-stoichiometric phases CaZr4(PO4)6, ?-Ca2P2O7, ?-CaP2O6, ZrP2O7, ZrO2, Zr3O1-x, and Zr.

Sharkeev, Yu. P.; Kulyashova, K. S.

2014-02-01

277

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

2011-01-01

278

Microbial phytase-induced calcium-phosphate precipitation: a potential soil stabilization method  

Microsoft Academic Search

Two hypotheses were tested: (1) microbial dephosphorylation of phytate in the presence of Ca2+ ions will result in the precipitation of hydroxyapatite-like crystals and (2) precipitation of calcium-phosphate crystals on and between sand-like particles can cause cementation. A growing culture of the dimorphic phytase-active yeast Arxula adeninivorans was introduced into a column filled with quartz particles and subsequently a liquid

G. Roeselers; M. C. M. Van Loosdrecht

2011-01-01

279

Microbial phytase-induced calcium-phosphate precipitation — a potential soil stabilization method  

Microsoft Academic Search

Two hypotheses were tested: (1) microbial dephosphorylation of phytate in the presence of Ca2+ ions will result in the precipitation of hydroxyapatite-like crystals and (2) precipitation of calcium-phosphate crystals on and between sand-like particles can cause cementation. A growing culture\\u000a of the dimorphic phytase-active yeast Arxula adeninivorans was introduced into a column filled with quartz particles and subsequently a liquid

G. Roeselers; M. C. M. Van Loosdrecht

2010-01-01

280

An oscillating mechanism in the synthesis of doped nanocrystalline calcium carbonate phosphates  

Microsoft Academic Search

A mechanism of the synthesis reactions of doped nanocrystalline calcium carbonate phosphates is considered, and an oscillating\\u000a type of model is proposed for these reactions. The system is oscillatory in nature and can be represented as a brusselator\\u000a of the simplest implementation of cubic nonlinearity. Biomaterial obtaining highly active resorption and the transdermal ability\\u000a to activate the processes of osteogenesis

L. F. Koroleva

2010-01-01

281

The deposition of calcium pyrophosphate and phosphate by matrix vesicles isolated from fetal bovine epiphyseal cartilage  

Microsoft Academic Search

Summary  Since calcium (Ca) deposition by isolated fetal bovine matrix vesicles is selectively supported by nucleoside triphosphate,\\u000a and since the Ca deposits appear to be amorphous by transmission electron microscopy [1], attempts were made to study further\\u000a the nature of these Ca deposits. Calcification of isolated matrix vesicles was allowed to occur in a calcifying medium in\\u000a which either inorganic phosphate

Howard H. T. Hsu; H. Clarke Anderson

1984-01-01

282

Diphosphonates Inhibit Formation of Calcium Phosphate Crystals in vitro and Pathological Calcification in vivo  

Microsoft Academic Search

Two diphosphonates containing the P-C-P bond, CH3C(OH)(PO3HNa)2 and H2C(PO3HNa)2, inhibit the crystallization of calcium phosphate in vitro and prevent aortic calcification of rats given large amounts of vitamin D3. The diphosphonates therefore have effects similar to those described for compounds containing the P-O-P bond but are active when administered orally.

Marion D. Francis; R. Graham G. Russell; Herbert Fleisch

1969-01-01

283

Effect of Microstructural Evolution on Wettability of Laser Coated Calcium Phosphate on Titanium Alloy  

SciTech Connect

Surface engineering of synthetic implant materials provides an exciting opportunity to mimic natural biomaterials. Surface that are bioactive and textured at multi scale have the potential for easier osseointegration. Ti alloy surfaces known for their biocompatibility are coated with bioactive Calcium Phosphate using a laser source at multiple processing speeds. The resulting surface has multiscale morphology and multi-phase chemical nature. Faster processing speeds showed improved wettability to water along with higher degree of crystallinity in the phases present.

Kurella, Anil K [ORNL; Hu, Michael Z. [ORNL; Dahotre, Narendra B [ORNL

2008-01-01

284

Bone response to fast-degrading, injectable calcium phosphate cements containing PLGA microparticles  

Microsoft Academic Search

Apatitic calcium phosphate cements (CPC) are frequently used to fill bone defects due to their favourable clinical handling and excellent bone response, but their lack of degradability inhibits complete bone regeneration. In order to render these injectable CaP cements biodegradable, hollow microspheres made of poly (d,l-lactic-co-glycolic) acid (PLGA) have been previously used as porogen since these microspheres were shown to

Rosa P. Félix Lanao; Sander C. G. Leeuwenburgh; Joop G. C. Wolke; John A. Jansen

2011-01-01

285

Biocompatibility and degradation of poly(DL-lactic-co-glycolic acid)\\/calcium phosphate cement composites  

Microsoft Academic Search

Injectable calcium phosphate (Ca-P) cement materials exhibit favorable osteocompatible behavior but are resorbed slowly because of a lack of a bone ingrowth-enabling macroporosity. In this study, poly(DL-lactic-co-glycolic acid) (PLGA) microparticles (average size 66 +\\/- 25 microm) were incorporated into Ca-P cement to obtain a macroporous Ca-P cement scaffold after PLGA hydrolysis in vivo. Preset PLGA\\/Ca-P cement composite discs of various

P. Quinten Ruhé; Elizabeth L. Hedberg; Nestor Torio Padron; Paul H. M. Spauwen; John A. Jansen; Antonios G. Mikos

2005-01-01

286

Formation of Calcium Phosphate Whiskers in Hydrogen Peroxide (H2O2) Solutions at 901C  

E-print Network

Formation of Calcium Phosphate Whiskers in Hydrogen Peroxide (H2O2) Solutions at 901C A. Cuneyt Tas-pot technique to syn- thesize CaP whiskers, with a Ca/P molar ratio r1.50, in 30% hydrogen peroxide solutions hydroxyapatite powders by using Ca(NO3)2 Á 4H2O and (NH4)2HPO4 was the only appearance of hydrogen peroxide in Ca

Tas, A. Cuneyt

287

Controlled formation of calcium-phosphate-based hybrid mesocrystals by organic-inorganic co-assembly  

NASA Astrophysics Data System (ADS)

An understanding of controlled formation of biomimetic mesocrystals is of great importance in materials chemistry and engineering. Here we report that organic-inorganic hybrid plates and even mesocrystals can be conveniently synthesized using a one-pot reaction in a mixed system of protein (bovine serum albumin (BSA)), surfactant (sodium bis(2-ethylhexyl) sulfosuccinate (AOT)) and supersaturated calcium phosphate solution. The morphologies of calcium-phosphate-based products are analogous to the general inorganic crystals but they have abnormal and interesting substructures. The hybrids are constructed by the alternate stacking of organic layer (thickness of 1.31 nm) and well-crystallized inorganic mineral layer (thickness of 2.13 nm) at the nanoscale. Their morphologies (spindle, rhomboid and round) and sizes (200 nm-2 ?m) can be tuned gradually by changing BSA, AOT and calcium phosphate concentrations. This modulation effect can be explained by a competition between the anisotropic and isotropic assembly of the ultrathin plate-like units. The anisotropic assembly confers mesocrystal characteristics on the hybrids while the round ones are the results of isotropic assembly. However, the basic lamellar organic-inorganic substructure remains unchanged during the hybrid formation, which is a key factor to ensure the self-assembly from molecule to micrometre scale. A morphological ternary diagram of BSA-AOT-calcium phosphate is used to describe this controlled formation process, providing a feasible strategy to prepare the required materials. This study highlights the cooperative effect of macromolecule (frame structure), small biomolecule (binding sites) and mineral phase (main component) on the generation and regulation of biomimetic hybrid mesocrystals.

Zhai, Halei; Chu, Xiaobin; Li, Li; Xu, Xurong; Tang, Ruikang

2010-11-01

288

Calcium phosphate thin films enhance the response of human mesenchymal stem cells to nanostructured titanium surfaces.  

PubMed

The development of biomaterial surfaces possessing the topographical cues that can promote mesenchymal stem cell recruitment and, in particular, those capable of subsequently directing osteogenic differentiation is of increasing importance for the advancement of tissue engineering. While it is accepted that it is the interaction with specific nanoscale topography that induces mesenchymal stem cell differentiation, the potential for an attendant bioactive chemistry working in tandem with such nanoscale features to enhance this effect has not been considered to any great extent. This article presents a study of mesenchymal stem cell response to conformal bioactive calcium phosphate thin films sputter deposited onto a polycrystalline titanium nanostructured surface with proven capability to directly induce osteogenic differentiation in human bone marrow-derived mesenchymal stem cells. The sputter deposited surfaces supported high levels of human bone marrow-derived mesenchymal stem cell adherence and proliferation, as determined by DNA quantification. Furthermore, they were also found to be capable of directly promoting significant levels of osteogenic differentiation. Specifically, alkaline phosphatase activity, gene expression and immunocytochemical localisation of key osteogenic markers revealed that the nanostructured titanium surfaces and the bioactive calcium phosphate coatings could direct the differentiation towards an osteogenic lineage. Moreover, the addition of the calcium phosphate chemistry to the topographical profile of the titanium was found to induce increased human bone marrow-derived mesenchymal stem cell differentiation compared to that observed for either the titanium or calcium phosphate coating without an underlying nanostructure. Hence, the results presented here highlight that a clear benefit can be achieved from a surface engineering strategy that combines a defined surface topography with an attendant, conformal bioactive chemistry to enhance the direct osteogenic differentiation of human bone marrow-derived mesenchymal stem cells. PMID:24904730

McCafferty, Mura M; Burke, George A; Meenan, Brian J

2014-01-01

289

Treatment of periodontal defects in dogs using an injectable composite hydrogel\\/biphasic calcium phosphate  

Microsoft Academic Search

An injectable composite silanized hydroxypropyl methyl cellulose\\/biphasic calcium phosphate (Si-HPMC\\/BCP) has been investigated\\u000a in humans with promising results. The aim of this study was to evaluate his efficacy for treating periodontal defects (canine\\u000a fenestration and premolar furcation) in dog models. At 3 months, we observed that bone formation around BCP particles in furcation\\u000a model is more discernible but not statistically significant

Xavier StruillouHerveBoutignyZahi; Hervé Boutigny; Zahi Badran; Borhane H. Fellah; Olivier Gauthier; Sophie Sourice; Paul Pilet; Thierry Rouillon; Pierre Layrolle; Pierre Weiss; Assem Soueidan

2011-01-01

290

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

Microsoft Academic Search

Urethane dimethacrylate (UDMA), an oligomeric poly(ethylene glycol) extended UDMA (PEG-U) and a blend of UDMA\\/PEG-U were chosen\\u000a as model systems for introducing both hydrophobic and hydrophilic segments and a range of compliances in their derived polymers.\\u000a Experimental composites based on these three resins with amorphous calcium phosphate (ACP) as the filler phase were polymerized\\u000a and evaluated for mechanical strength and

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

2008-01-01

291

Calcium phosphate-bearing matrices induce osteogenic differentiation of stem cells through adenosine signaling  

PubMed Central

Synthetic matrices emulating the physicochemical properties of tissue-specific ECMs are being developed at a rapid pace to regulate stem cell fate. Biomaterials containing calcium phosphate (CaP) moieties have been shown to support osteogenic differentiation of stem and progenitor cells and bone tissue formation. By using a mineralized synthetic matrix mimicking a CaP-rich bone microenvironment, we examine a molecular mechanism through which CaP minerals induce osteogenesis of human mesenchymal stem cells with an emphasis on phosphate metabolism. Our studies show that extracellular phosphate uptake through solute carrier family 20 (phosphate transporter), member 1 (SLC20a1) supports osteogenic differentiation of human mesenchymal stem cells via adenosine, an ATP metabolite, which acts as an autocrine/paracrine signaling molecule through A2b adenosine receptor. Perturbation of SLC20a1 abrogates osteogenic differentiation by decreasing intramitochondrial phosphate and ATP synthesis. Collectively, this study offers the demonstration of a previously unknown mechanism for the beneficial role of CaP biomaterials in bone repair and the role of phosphate ions in bone physiology and regeneration. These findings also begin to shed light on the role of ATP metabolism in bone homeostasis, which may be exploited to treat bone metabolic diseases. PMID:24395775

Shih, Yu-Ru V.; Hwang, YongSung; Phadke, Ameya; Kang, Heemin; Hwang, Nathaniel S.; Caro, Eduardo J.; Nguyen, Steven; Siu, Michael; Theodorakis, Emmanuel A.; Gianneschi, Nathan C.; Vecchio, Kenneth S.; Chien, Shu; Lee, Oscar K.; Varghese, Shyni

2014-01-01

292

3D printing of composite calcium phosphate and collagen scaffolds for bone regeneration.  

PubMed

Low temperature 3D printing of calcium phosphate scaffolds holds great promise for fabricating synthetic bone graft substitutes with enhanced performance over traditional techniques. Many design parameters, such as the binder solution properties, have yet to be optimized to ensure maximal biocompatibility and osteoconductivity with sufficient mechanical properties. This study tailored the phosphoric acid-based binder solution concentration to 8.75 wt% to maximize cytocompatibility and mechanical strength, with a supplementation of Tween 80 to improve printing. To further enhance the formulation, collagen was dissolved into the binder solution to fabricate collagen-calcium phosphate composites. Reducing the viscosity and surface tension through a physiologic heat treatment and Tween 80, respectively, enabled reliable thermal inkjet printing of the collagen solutions. Supplementing the binder solution with 1-2 wt% collagen significantly improved maximum flexural strength and cell viability. To assess the bone healing performance, we implanted 3D printed scaffolds into a critically sized murine femoral defect for 9 weeks. The implants were confirmed to be osteoconductive, with new bone growth incorporating the degrading scaffold materials. In conclusion, this study demonstrates optimization of material parameters for 3D printed calcium phosphate scaffolds and enhancement of material properties by volumetric collagen incorporation via inkjet printing. PMID:24529628

Inzana, Jason A; Olvera, Diana; Fuller, Seth M; Kelly, James P; Graeve, Olivia A; Schwarz, Edward M; Kates, Stephen L; Awad, Hani A

2014-04-01

293

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

PubMed Central

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. PMID:21711603

2011-01-01

294

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

2011-12-01

295

Resorbable bioceramics based on stabilized calcium phosphates. Part I: rational design, sample preparation and material characterization.  

PubMed

It has long been the goal of biomaterials research in the field of orthopedics to develop synthetic structures exhibiting comprehensive bioactivity. In particular, an ideal bone-biomaterial would support the activity of osteoblasts in the development of new bone, while simultaneously being resorbed by osteoclasts as part of the lifelong orderly process of bone remodelling. Such resorbable calcium phosphate-based thin films and bulk ceramics have now been created by the high-temperature processing of a fine precipitate, formed from a colloidal sol and stabilized using an additive such as silicon. The materials have two characteristic features: a phase composition which is a mixture of calcium hydroxyapatite and a silicon stabilized tricalcium phosphate, and a microporous morphology based on inter-connected particles (0.2-1 microm in diameter). X-ray diffraction, infrared spectroscopy, nuclear magnetic resonance spectroscopy, and light scattering experiments indicate that the characteristic phase composition arises during sintering through substitution reactions where silicon enters the calcium phosphate lattice under conditions of high chemical reactivity. The crystallographic features are linked through the glaserite form of the apatite structure. PMID:10503974

Langstaff, S; Sayer, M; Smith, T J; Pugh, S M; Hesp, S A; Thompson, W T

1999-09-01

296

Effects of silica on the bioactivity of calcium phosphate composites in vitro.  

PubMed

In the present study, silica-calcium phosphate composites (SiO(2)-CaP composites) were developed by mixing the starting materials (SiO(2) and CaHPO(4)) in different ratios with the addition of 0.1% w/v NaOH solution. The phase composition of the SiO(2)-CaP composites was determined by XRD and FTIR. After thermal treatment at 350 degrees C/1 h and at 1000 degrees C/3.5 h; all SiO(2)-CaP composites composed of beta-quartz, alpha-cristobalite and beta-Ca2P2O7. The presence of calcium phosphate enhanced the transformation of beta-quartz into alpha-cristobalite at 1000 degrees C. SEM observation indicated favorable attachment and spreading of neonatal rat calvaria osteoblasts onto the surface of silica-rich SiO(2)-CaP composites. After attachment, these cells produced significantly higher amount of protein and expressed higher AP activity than cells attached to silica-poor samples. Results of the study suggested that the silica-based composites are more bioactive than calcium phosphate-based composites. Silica promoted the expression of osteoblast phenotype by both solution-mediated effect and direct interaction with the surface of the substrate. PMID:15803281

Ning, C Q; Mehta, J; El-Ghannam, A

2005-04-01

297

3D Printing of Composite Calcium Phosphate and Collagen Scaffolds for Bone Regeneration  

PubMed Central

Low temperature 3D printing of calcium phosphate scaffolds holds great promise for fabricating synthetic bone graft substitutes with enhanced performance over traditional techniques. Many design parameters, such as the binder solution properties, have yet to be optimized to ensure maximal biocompatibility and osteoconductivity with sufficient mechanical properties. This study tailored the phosphoric acid-based binder solution concentration to 8.75 wt% to maximize cytocompatibility and mechanical strength, with a supplementation of Tween 80 to improve printing. To further enhance the formulation, collagen was dissolved into the binder solution to fabricate collagen-calcium phosphate composites. Reducing the viscosity and surface tension through a physiologic heat treatment and Tween 80, respectively, enabled reliable thermal inkjet printing of the collagen solutions. Supplementing the binder solution with 1–2 wt% collagen significantly improved maximum flexural strength and cell viability. To assess the bone healing performance, we implanted 3D printed scaffolds into a critically sized murine femoral defect for 9 weeks. The implants were confirmed to be osteoconductive, with new bone growth incorporating the degrading scaffold materials. In conclusion, this study demonstrates optimization of material parameters for 3D printed calcium phosphate scaffolds and enhancement of material properties by volumetric collagen incorporation via inkjet printing. PMID:24529628

Inzana, Jason A.; Olvera, Diana; Fuller, Seth M.; Kelly, James P.; Graeve, Olivia A.; Schwarz, Edward M.; Kates, Stephen L.; Awad, Hani A.

2014-01-01

298

Calcium phosphate cement - gelatin powder composite testing in canine models: Clinical implications for treatment of bone defects.  

PubMed

Previous studies have reported the excellent biocompatibility of calcium phosphate cement. However, calcium phosphate cement needs further improvement in order for it to promote bone replacement and eventual bone substitution, as it exhibits slow biodegradability and thus remains in the body over an extended period of time. In this study, we mixed calcium phosphate cement with gelatin powder in order to create a composite containing macropores with interconnectivity, and we then implanted it into canine femurs from the diaphysis to the distal metaphysis. Eight dogs were divided into the sham group, the control (C0) group with 100 wt% calcium phosphate cement, the C10 group with 90 wt% calcium phosphate cement and 10 wt% gelatin powder, and the C15 group with 85 wt% calcium phosphate cement and 15 wt% gelatin powder. Bone replaceability in C10 and C15 at 3 and 6 months was evaluated by radiography, micro-CT, histomorphometry, and mineral apposition rate. New bone formation was seen in C10 and C15 although that was not seen in C0 at six months. The mineral apposition rate was significantly higher in C15 than in C10 in both the diaphysis and metaphysis, and the composite was found to have excellent biodegradability and bone replaceability in canine subjects. As the composite is easily and rapidly prepared, it is likely to become a new bone substitute for use in clinical settings. PMID:25550332

Yomoda, Mitsuhiro; Sobajima, Satoshi; Kasuya, Akihiro; Neo, Masashi

2015-05-01

299

Parameters influencing ciprofloxacin, ofloxacin, amoxicillin and sulfamethoxazole retention by natural and converted calcium phosphates.  

PubMed

The retention of four antibiotics, ciprofloxacin, ofloxacin, amoxicillin and sulfamethoxazole by a natural phosphate rock (francolite) was studied and compared with a converted hydroxyapatite powder. The maximum sorption capacities were found to correlate with the molecular weight of the molecules. The mechanisms of sorption depended mostly on the charge of the antibiotic whereas the kinetics of the process was sensitive to their hydrophobic/hydrophilic character. The two materials showed slightly distinct affinities for the various antibiotics but exhibited similar maximum sorption capacities despite different specific surface areas. This was mainly attributed to the more pronounced hydrophobic character of the francolite phase constituting the natural phosphate. These data enlighten that the retention properties of these mineral phases depend on a complex interplay between the inter-molecular and molecule-solid interactions. These findings are relevant to understand better the contribution of calcium phosphates in the fate and retention of antibiotics in soils. PMID:25749000

Bouyarmane, H; El Hanbali, I; El Karbane, M; Rami, A; Saoiabi, A; Saoiabi, S; Masse, S; Coradin, T; Laghzizil, A

2015-06-30

300

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: rumigg@yahoo.com; Tepavitcharova, S., E-mail: rumigg@yahoo.com; Rabadjieva, D., E-mail: rumigg@yahoo.com; Sezanova, K., E-mail: rumigg@yahoo.com; Ilieva, R., E-mail: rumigg@yahoo.com [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)

2013-12-16

301

Surface controlled calcium phosphate formation on three-dimensional bacterial cellulose-based nanofibers.  

PubMed

Studies on the early calcium phosphate (Ca-P) formation on nanosized substrates may allow us to understand the biomineralization mechanisms at the molecular level. In this work, in situ formation of Ca-P minerals on bacterial cellulose (BC)-based nanofibers was investigated, for the first time, using the X-ray absorption near-edge structure (XANES) spectroscopy. In addition, the influence of the surface coating of nanofibers on the formation of Ca-P minerals was determined. Combined with XRD analysis, XANES results revealed that the nascent precursor was ACP (amorphous calcium phosphate) which was converted to TCP (?-tricalcium phosphate), then OCP (octacalcium phosphate), and finally to HAP (hydroxyapatite) when phosphorylated BC nanofibers were the templates. However, the formation of nascent precursor and its transformation process varied depending on the nature of the coating material on nanofibrous templates. These results provide new insights into basic mechanisms of mineralization and can lead to the development of novel bioinspired nanostructured materials. PMID:25686980

Luo, Honglin; Xiong, Guangyao; Zhang, Chen; Li, Deying; Zhu, Yong; Guo, Ruisong; Wan, Yizao

2015-04-01

302

Characterization of a novel calcium phosphate composite bone cement: flow, setting, and aging properties.  

PubMed

The flow, setting, and aging characteristics of a newly developed calcium phosphate/calcium aluminate composite orthopaedic cement were studied. The effect of vibration on the flow of the cement paste was studied and found to greatly enhance placement. The setting times of this cement were dependent on temperature and decreased with increasing temperatures. At 37 degrees C, the working and setting times were 6.3 +/- 0.3 and 12.8 +/- 0.4 minutes, respectively. Hydration and conversion of the cement phases continued while specimens were stored under simulated, physiological conditions. A cumulative increase in mass of 8.23 +/- 0.65% was observed over a 14 month test period. During this time, the cement was found to expand slightly, 0.71 +/- 0.39%. X-ray diffraction was used to characterize the crystalline phases present during hydration and conversion. The calcium aluminate in the cement hydrated and formed calcium aluminate chloride hydrates, while no changes were observed in the beta-tricalcium phosphate during the testing period. PMID:17122927

Roemhildt, M L; Wagner, S D; McGee, T D

2006-11-01

303

New macroporous calcium phosphate glass ceramic for guided bone regeneration.  

PubMed

This work describes a method to obtain macroporous resorbable glass and glass ceramic scaffolds with controlled biodegradability for tissue engineering applications. The constructs consisted of glass and glass ceramics in the system P(2)O(5)-CaO-Na(2)O-TiO(2) and they were prepared by foaming a slurry of glass particles by addition of a H(2)O(2) solution, and subsequent sintering of the porous structures obtained. Different thermal treatments were applied to control the degree of devitrification of the glass. The resultant materials showed a porosity percentage between 40% and 55% with a wide variety of pores ranging from 20 to 500 microm in diameter as determined by SEM and Image Analysis. The resulting constructs were predominantly formed by a vitreous phase, although small amounts of calcium metaphosphate and pyrophosphates were detected by X-ray diffraction and Raman spectroscopy after the sintering process. The biological response was also evaluated by means of the MTT test, the material showed a non-cytotoxic effect. PMID:15046913

Navarro, Melba; del Valle, Sergio; Martínez, Salvador; Zeppetelli, Stefania; Ambrosio, Luigi; Planell, Josep Anton; Ginebra, Maria Pau

2004-08-01

304

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

1998-01-01

305

Modulation of porosity in apatitic cements by the use of ?-tricalcium phosphate—calcium sulphate dihydrate mixtures  

Microsoft Academic Search

Calcium phosphate bone cements are injectable biomaterials that are being used in dental and orthopaedic applications through minimally invasive surgery techniques. Nowadays, apatitic bone cements based on ?-tricalcium phosphate (?-TCP) are of special interest due to their self-setting behaviour when mixed with an aqueous liquid phase. In this study, a new method to improve osteointegration of ?-TCP-based cements is presented.

Enrique Fernández; Maria Daniela Vlad; Maria Montserrat Gel; Jose López; Ricardo Torres; Juan V. Cauich; Marc Bohner

2005-01-01

306

Transmission electron microscopy observations at the interface of bone and four types of calcium phosphate ceramics with different calcium/phosphorus molar ratios.  

PubMed

Four kinds of calcium phosphate ceramics, beta-calcium pyrophosphate (Ca2P2O7), beta-tricalcium phosphate (Ca3(PO4)2), hydroxyapatite (Ca10(PO4)6(OH)2) and tetracalcium phosphate (Ca4(PO4)2O), were prepared. The calcium/phosphorus molar ratios were 1, 1.5, 1.66 and 2, respectively. Particles (150-300 microns) of these ceramics were packed into holes (diameter 2.5 mm) made in the tibial metaphysis of mature male rats. At 2 weeks, 4 weeks, 8 weeks and 6 months after the operation, undecalcified specimens were prepared. Transmission electron microscopy showed that the bone-bonding behaviour of calcium phosphate ceramics at the interface with bone did not vary with the calcium/phosphate molar ratio. Amorphous substances or needle-like microcrystals were observed on the surface of the ceramics at 2 weeks after implantation. The ceramics showed direct continuity with small crystallites of bone tissue at 4 weeks, 8 weeks and 6 months after implantation. The ceramics appeared to be getting smaller with time. Collagen fibres were not observed at the bone/ceramic interface. Neither chemical bonding nor mechanical bonding by interlocking between bone and ceramics was described by morphological observation using transmission electron microscopy. PMID:8519932

Kitsugi, T; Yamamuro, T; Nakamura, T; Oka, M

1995-09-01

307

Sphingosine1-phosphate Mobilizes Intracellular Calcium and Activates Transcription Factor NF-?B in U937 Cells  

Microsoft Academic Search

Sphingosine-1-phosphate (SPP), a metabolite of sphingolipids, has been implicated as a second messenger in cell growth regulation and signal transduction via calcium mobilization from internal stores. This study shows that SPP mobilizes intracellular calcium in U937 cells and demonstrates for the first time the ability of SPP to activate the transcription factor NF-?B in these cells. Furthermore, calcium release from

Vladimir A. Shatrov; Volker Lehmann; Salem Chouaib

1997-01-01

308

Calcium phosphate flocs and the clarification of sugar cane juice from whole of crop harvesting.  

PubMed

Sugar cane biomass is one of the most viable feedstocks for the production of renewable fuels and chemicals. Therefore, processing the whole of crop (WC) (i.e., stalk and trash, instead of stalk only) will increase the amount of available biomass for this purpose. However, effective clarification of juice expressed from WC for raw sugar manufacture is a major challenge because of the amounts and types of non-sucrose impurities (e.g., polysaccharides, inorganics, proteins, etc.) present. Calcium phosphate flocs are important during sugar cane juice clarification because they are responsible for the removal of impurities. Therefore, to gain a better understanding of the role of calcium phosphate flocs during the juice clarification process, the effects of impurities on the physicochemical properties of calcium phosphate flocs were examined using small-angle laser light scattering technique, attenuated total reflectance Fourier transformed infrared spectroscopy, and X-ray powder diffraction. Results on synthetic sugar juice solutions showed that the presence of SiO2 and Na(+) ions affected floc size and floc structure. Starch and phosphate ions did not affect the floc structure; however, the former reduced the floc size, whereas the latter increased the floc size. The study revealed that high levels of Na(+) ions would negatively affect the clarification process the most, as they would reduce the amount of suspended particles trapped by the flocs. A complementary study on prepared WC juice using cold and cold/intermediate liming techniques was conducted. The study demonstrated that, in comparison to the one-stage (i.e., conventional) clarification process, a two-stage clarification process using cold liming removed more polysaccharides (?19%), proteins (?82%), phosphorus (?53%), and SiO2 (?23%) in WC juice but increased Ca(2+) (?136%) and sulfur (?200%). PMID:25574835

Thai, Caroline C D; Moghaddam, Lalehvash; Doherty, William O S

2015-02-11

309

Hollow calcium phosphate microcarriers for bone regeneration: in vitro osteoproduction and ex vivo mechanical assessment.  

PubMed

Synthetic grafting materials, such as calcium phosphates (hydroxyapatite, HA; tricalcium phosphate, TCP), polymers, or composites thereof, can be used as osteoconductive scaffolds and delivery vehicles for osteoinductive growth factors. Carrier materials must be engineered to deliver these factors in a controlled fashion at a rate and dose consistent with the biological need and responsiveness of the system to optimize bone formation and ingrowth. They should also simultaneously provide mechanical support and slowly resorb as new bone is formed. This investigation assessed the elution characteristics of BMP-7 (OP-1) from hollow calcium phosphate spheres of varying chemical composition (HA/beta-TCP) and porosity (dense/porous). The pharmacokinetics indicated a bimodal trend of protein release with protein elution peaking between fifteen and thirty minutes in solution (bolus release) and continuing through the eight-week time point (sustained release). Eluted OP-1 bioactivity was characterized over a three-week period using mesenchymal stem cell (MSC) cultures and included assessment of the protein's differential, proliferative, and calcified nodule forming abilities. Alkaline phosphatase enzyme (ALP) activity in MSCs peaked between 12 and 16 days post-OP-1 exposure. Elutant from the HA dense treatment group induced the highest degree of ALP expression while elutant from the beta-TCP treatment groups induced the formation of significantly higher numbers of calcified nodules in culture. The aggregate modulus of a clinically relevant 2 cc dose of carriers was quantified using custom designed testing fixtures to investigate the effects of carrier size, porosity, chemical composition, and the presence of a central hole on mechanical integrity. Significant increases in moduli were noted for carrier size and chemical composition (HA>beta-TCP). These preliminary in vitro and ex vivo results indicate the clinical potential of the hollow calcium phosphate carriers as successful load-bearing delivery vehicles for OP-1. PMID:17851170

Santoni, Brandon G; Pluhar, G Elizabeth; Motta, Tatiana; Wheeler, Donna L

2007-01-01

310

Umbilical Cord Stem Cell Seeding on Fast-Resorbable Calcium Phosphate Bone Cement  

PubMed Central

Tissue engineering offers immense promise for bone regeneration. Human umbilical cord mesenchymal stem cells (hUCMSCs) can be collected without invasive procedures required for bone marrow MSCs. The objective of this study was to investigate the physical properties and the differentiation capacity of hUCMSCs on calcium phosphate cement (CPC) scaffolds with improved dissolution/resorption rates. CPC consisted of tetracalcium phosphate and dicalcium phosphate anhydrous, with various tetracalcium phosphate/dicalcium phosphate anhydrous ratios. At 1/3 ratio, CPC had a dissolution rate 40% faster than CPC control at 1/1. The faster-resorbable CPC had strength and modulus similar to CPC control. Their strength and modulus exceeded the reported values for cancellous bone, and were much higher than those of hydrogels and injectable polymers for cell delivery. hUCMSCs attached to the nano-apatitic CPC and proliferated rapidly. hUCMSCs differentiated into the osteogenic lineage, with significant increases in alkaline phosphatase activity, osteocalcin, collagen I, and osterix gene expression. In conclusion, in this study we reported that hUCMSCs attaching to CPC with high dissolution/resorption rate showed excellent proliferation and osteogenic differentiation. hUCMSCs delivered via high-strength CPC have the potential to be an inexhaustible and low-cost alternative to the gold-standard human bone marrow mesenchymal stem cells. These results may broadly impact stem-cell-based tissue engineering. PMID:20388037

Zhao, Liang; Detamore, Michael S.; Takagi, Shozo; Chow, Laurence C.

2010-01-01

311

Molecular mechanism of crystallization impacting calcium phosphate cements  

SciTech Connect

In summary, SPM data has shown that (1) Mg inhibits growth on all steps but relatively high Mg/Ca ratios are needed. Extracting the mechanism of interaction requires more modeling of the kinetic data, but step morphology is consistent with incorporation. (2) Citrate has several effects depending on the citrate/Ca ratio. At the lowest concentrations, citrate increases the step free energy without altering the step kinetics; at higher concentrations, the polar step is slowed. (3) Oxalate also slows the polar step but additionally stabilizes a new facet, with a [100]{sub Cc} step. (4) Etidronate has the greatest kinetic impact of the molecules studied. At 7{micro}M concentrations, the polar step slows by 60% and a new polar step appears. However, at the same time the [10-1]{sub Cc} increases by 67%. It should be noted that all of these molecules complex calcium and can effect kinetics by altering the solution supersaturation or the Ca to HPO{sub 4}{sup 2-} ratio. For the SPM data shown, this effect was corrected for to distinguish the effect of the molecule at the crystal surface from the effect of the molecule on the solution speciation. The goal of this paper is to draw connections between fundamental studies of atomic step motion and potential strategies for materials processing. It is not our intent to promote the utility of SPM for investigating processes in cement dynamics. The conditions are spectacularly different in many ways. The data shown in this paper are fairly close to equilibrium (S=1.6) whereas the nucleation of cements is initiated at supersaturation ratios in the thousands to millions. Of course, after the initial nucleation phase, the growth will occur at more modest supersaturations and as the cement evolves towards equilibrium certainly some of the growth will occur in regimes such as shown here. In addition to the difference in supersaturation, cements tend to have lower additive to calcium ratios. As an example, the additive to Ca ratio is {approx}10{sup -3} to 10{sup -4} for a pyrophosphate based cement (Grover et al., 2006). Where the in situ SPM approach provides unique insights is in providing details of where and how molecules inhibit or accelerate kinetics. This has the potential to aid in designing molecules to target specific steps and to guide synergistic combinations of additives. For example, it is unlikely that bulk techniques could deduce the simultaneous acceleration and inhibition effects of etidronate; or that citrate reduced growth rate by altering step density rather than step speed. In addition, SPM data translates to tractable questions for modelers. The questions changes from 'How does etidronate inhibit brushite growth?' to 'Why does etidronate bind strongly to the [101]{sub Cc} step while it doesn't to the [10-1]{sub Cc} step?' This is still a challenging question but it is far better defined. Given that step chemistries are generally different, it seems reasonable to expect that the greatest inhibition will be achieved not with one, but with several synergistically chosen additives. For example, the most effective growth inhibitors for brushite would target the two fast steps, namely the non-polar, [10-1]{sub Cc} and the polar, [101]{sub Cc} steps. Several molecules have been shown to slow the polar step, with etidronate as the most dramatic example. By contrast, only Mg was observed to slow the [10-1]{sub Cc} step. Thus, a combination of high concentrations of Mg to target the [10-1]{sub Cc} step with low concentrations of etidronate to target the polar steps, should be a more effective combination than either alone. However Mg is not a particularly good inhibitor in the sense that high concentrations are needed, and it is not specific. More ideally, an inhibitor would be designed to interact specifically with the [10-1] step, which would allow the two steps to be independently modified. Again, this provides an opportunity for tighter coupling with theoretical modeling. The question changes from 'What types of molecules will inhibit brushite growth' to 'What type of molecule

Giocondi, J L; El-Dasher, B S; Nancollas, G H; Orme, C A

2009-05-31

312

Investigation by infrared absorption spectroscopy into the chemical mechanisms of the wet process synthesis of some calcium phosphates  

NASA Astrophysics Data System (ADS)

The present work describes the reactions of wet process synthesis, of some calcium phosphates, such as tricalcium phosphate (Ca{3}(PO{4})2) and hydroxyapatite (Ca{10}(PO{4})6(OH){2}). These reactions of synthesis are acido-basic reactions between the phosphoric acid (H{3}PO{4}) and calcium carbonates (CaCO{3}).The evolution of these reactions (and the concerned chemical mechanisms) were followed by mid infrared spectroscopy absorption. Indeed, in the first stage of these three reactions in which the medium is strongly acidic, favours the formation of a stable intermediate compound, which is the brushite.During the reaction, the concentration of phosphoric acid decreases, the pH increases and the brushite becomes unstable, thus it evolves to a more stable calcium phosphate under these new pH conditions. This later product was either the tricalcium phosphate or hydroxyapatite, according to the pH solution.

Essaddek, A.; Elgadi, M.; Mejdoubi, E.; Elansari, L. L.; Moradi, K.; Karroua, M.

2005-03-01

313

New chemolysis for urological calcium phosphate calculi – a study in vitro  

PubMed Central

Background Advances in techniques have left very few indications for open surgical extraction of urinary stones currently. These advances notwithstanding, the search continues for medical approaches to urinary stone management. In this study, we perform an in vitro study analyzing the efficiency and prospect of two new complex solutions in urological calcium phosphate calculi dissolution. Methods Eighteen stones composed mainly of calcium phosphates were taken from patients who underwent kidney stone surgery. These stones were large enough (weight range 0.514–0.928 g) to be fragmented and matched equally into six groups. Chemolysis of phosphate stones was done with six different solvents and was repeated 3 times with 6 stones for each solution. At 24, 48 and 72 h, reduction in weight, percentage weight change, and dissolution rate; the dissolution rates at pH 5.0, 7.0 and 8.5 for each solution, using different cations (Na+, K+ or Ca2+), according to different dilutions (1:1, 1:2, 1:3, 1:4) of S1 and S2 were simultaneously determined. Results Calcium phosphate calculi were poorly dissolved by Phys and Art, and they had a low dissolution rate in pH 8.5 EDTA. The most effective solutions were S1, S2 and R, with 72 h mean dissolution rates: 5.75 ± 0.44 mg/hr (S1), 5.2 ± 0.63 mg/hr (S2), 4.55 ± 0.46 mg/hr (R) ( ± s, p < 0.01 R, S1 and S2 vs Phys, Art and EDTA; p < 0.05, S1 vs R, LSD-test). The mean percentage weight loss at 72 h was: 52.1 ± 15.75 % (S1), 44.4 ± 7.37 % (S2) and 40.5 ± 3.67 % (R) ( ± s, p < 0.01 R, S1 and S2 vs Phys, Art and EDTA, LSD-test). Diluted twice, S1 and S2 had even better effectiveness than their initial solution. The additive of Na+, K+ or Ca2+ greatly reduced the dissolution rates of S1, S2. Conclusion Our data indicate that test solutions S1 and S2 are effective solvents in the chemolysis of calcium phosphate stones. At twice dilutions, these solutions are even more useful in the treatment of stone disease. PMID:15907215

Xiang-bo, Zhang; Zhi-ping, Wang; Jian-min, Duan; Jian-zhong, Lu; Bao-liang, Ma

2005-01-01

314

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: jcalder@cinvestav.mx

2006-01-15

315

Preparation of spherical calcium phosphate granulates suitable for the biofunctionalization of active brazed titanium alloy coatings.  

PubMed

Titanium-based alloys can be actively brazed onto bio-inert ceramics and potentially be used as biocompatible coatings. To further improve their bioactivity in vivo, introduction of calcium phosphate (CaP)-based granulates onto their surface layer is possible. For this, mechanically stable CaP-based granulates need to be able to withstand the demand of the brazing process. In this study, spherical granulates, made of a calcium phosphate composite composed primarily of ?-tricalcium phosphate and hydroxyapatite, a bioactive glass, and a mixture of the previous two, were manufactured by spray drying. The influence of organic additives (Dolapix CE64, trisodium citrate) and solids content (30-80 wt%) in the slurry on the physical characteristics of granulates was investigated. X-ray diffraction, Brunauer, Emmett, Teller specific surface area standard method, scanning electron microscopy, granulate size analysis, and single granule strength were performed. Our results showed that trisodium citrate permitted the production of granulates with regular morphology, high density, and increased failure stress values. The strong granules also withstood the brazing process. These results show that CaP bioactive agents can be generated and be integrated during the demanding metallurgical processes, allowing for one-step bioactivation of metal brazes. PMID:25389977

Schickle, Karolina; Gerardo-Nava, Jose L; Puidokas, Sabrina; Anavar, Sharareh Samadian; Bergmann, Christian; Gingter, Philipp; Schickle, Benjamin; Bobzin, Kirsten; Fischer, Horst

2015-04-01

316

Controlled crystal growth of calcium phosphate on titanium surface by NaOH-treatment  

NASA Astrophysics Data System (ADS)

A simple supersaturated calcification solution (SCS) was used to deposit calcium phosphate (Ca-P) on the surface of NaOH-treated titanium (NaOH-Ti), in order to study the corresponding deposition mechanism of calcium phosphate (Ca-P). No Ca-P coating from SCS was found on titanium without NaOH-treatment, while NaOH-Ti possessed the capability to induce a Ca-P coating on the titanium surface. Octacalcium phosphate (OCP) crystals were first grown on an NaOH-Ti surface, followed by hydroxyapatite (HA) with a [0 0 1] preferential orientation on OCP. It is found that two factors controlled the growth of Ca-P crystals on NaOH-Ti from SCS. First, the surface morphology of NaOH-Ti characterized with crevices seems to be beneficial for inducing a Ca-P coating from SCS; second, the basic hydroxyl, Ti-OH, radical has increased in NaOH-Ti with the increase of treating time and concentration, which facilitate the nucleation of Ca-P crystals.

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

1999-04-01

317

Some studies on calcium phosphate embedded in polyvinyl alcohol matrix before and after ?-irradiation  

NASA Astrophysics Data System (ADS)

The Ca-P ratio in polymer matrix was adjusted to 1.67 as in hydroxyapatite. The complexed polyvinyl alcohol (PVA) materials exhibit the characteristic absorption bands of phosphate at 601 and 962 cm -1 indicating the presence of (HPO 4) -1 anions in the structure. The X-ray diffraction (XRD) revealed that the reaction between Ca and P ions in the PVA medium has a great effect on polymeric matrix crystallization. After irradiation, XRD results for sample c showed more sharp peaks indicating that irradiation can break the principal chemical bonds and favoring additional crystallization processes and therefore the crystallinity increases. An improvement in the thermal stability of PVA doped with calcium phosphate could be seen with the increase of calcium phosphate intercalated with PVA. The surfaces of films were analyzed by scanning electron microscope (SEM) before and after ?-irradiation. The formation of hydroxyapatite is confirmed by energy dispersive X-ray spectroscopy (EDX analysis). The electric conduction data were interpreted on the basis of an intrachain one-dimensional interpolaron hopping model of Kuivalainen.

Abdelrazek, E. M.; El Damrawi, G.; Al-Shahawy, A.

2010-02-01

318

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

319

Renal transport of bisphosphonates: accumulation by renal cortical slices enhanced by calcium phosphate ions.  

PubMed

Bisphosphonates have been recognized as useful therapeutic agents in metabolic bone disease. Earlier studies showed a net renal secretion of 1-hydroxy-ethylidene-1,1-bisphosphonate (HEBP). They suggested a renal cellular uptake of this compound. We further studied this concept by investigating the uptake in vitro of 14C-HEBP by rat renal cortex slices. HEBP was accumulated against a concentration gradient, a process that was dependent on time, temperature, and substrate concentration. Unlike that of 3H-p-aminohippurate, the uptake was not affected by change in medium Na+ or glucose and acetate concentration, or by anoxia and various metabolic inhibitors. It was, however, markedly increased by raising the medium calcium and inorganic phosphate concentration. Equilibrium dialysis with renal cortex homogenates suggests that HEBP binds to a cytosolic macromolecule through a process that exhibits saturability and calcium dependency. In conclusion, the results suggest that the bisphosphonate HEBP can penetrate kidney cells by a process that does not appear to be energy dependent, but is markedly influenced by the extracellular calcium-phosphate concentration. PMID:3925057

Troehler, U; Bonjour, J P; Fleisch, H

1985-07-01

320

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

2013-01-01

321

Identification of proteins extracted from calcium oxalate and calcium phosphate crystals induced in the urine of healthy and stone forming subjects  

Microsoft Academic Search

The purpose of our study was to identify the proteins and investigate the differences, if any, between protein components\\u000a of the matrices of calcium oxalate (CaOx) and calcium phosphate (CaP) crystals induced in?vitro in whole human urine of healthy\\u000a individuals and kidney stone patients. In addition, preliminary studies were performed to understand the effect of centrifugation\\u000a and filtration of urine

Fouad Atmani; Patricia A. Glenton; Saeed R. Khan

1998-01-01

322

Direct 3D powder printing of biphasic calcium phosphate scaffolds for substitution of complex bone defects.  

PubMed

The 3D printing technique based on cement powders is an excellent method for the fabrication of individual and complex bone substitutes even in the case of large defects. The outstanding bone remodeling capacity of biphasic calcium phosphates (BCPs) containing hydroxyapatite (HA) as well as tricalcium phosphate (TCP) in varying ratios makes the adaption of powder systems resulting in BCP materials to this fabrication technique a desirable aim. This study presents the synthesis and characterization of a novel powder system for the 3D printing process, intended for the production of complexly shaped BCP scaffolds by a hydraulic setting reaction of calcium carbonate and TCP with phosphoric acid. The HA/TCP ratio in the specimens could be tailored by the calcium/phosphate ratio of the starting powder. The scaffolds could be fabricated with a dimensional accuracy of >96.5% and a minimal macro pore size of 300 µm. Independent of the phase composition the printed specimens showed a microporosity of approximately 68%, while the compressive strength strongly depended on the chemical composition and increased with rising TCP content in the scaffolds to a maximum of 1.81 MPa. Post-treatment of the scaffolds with a polylactic-co-glycolic acid-solution enhanced the mechanical properties by a factor of 8. In vitro studies showed that all BCP scaffolds were cytocompatible and enhanced the cell viability as well as the cell proliferation, as compared with pure TCP. Cell proliferation is even better on BCP when compared to HA and cell viability is in a similar range on these materials. PMID:24429776

Castilho, Miguel; Moseke, Claus; Ewald, Andrea; Gbureck, Uwe; Groll, Jürgen; Pires, Inês; Teßmar, Jörg; Vorndran, Elke

2014-03-01

323

Antibacterial amorphous calcium phosphate nanocomposites with a quaternary ammonium dimethacrylate and silver nanoparticles  

PubMed Central

Objectives Calcium and phosphate ion-releasing resin composites are promising for remineralization. However, there has been no report on incorporating antibacterial agents to these composites. The objective of this study was to develop antibacterial and mechanically-strong nanocomposites incorporating a quaternary ammonium dimethacrylate (QADM), nanoparticles of silver (NAg), and nanoparticles of amorphous calcium phosphate (NACP). Methods The QADM, bis(2-methacryloyloxyethyl) dimethylammonium bromide (ionic dimethacrylate-1), was synthesized from 2-(N,N-dimethylamino)ethyl methacrylate and 2-bromoethyl methacrylate. Ng was synthesized by dissolving Ag 2-ethylhexanoate salt in 2-(tertbutylamino)ethyl methacrylate. Mechanical properties were measured in three-point flexure with bars of 2×2×25 mm (n = 6). Composite disks (diameter = 9 mm, thickness = 2 mm) were inoculated with Streptococcus mutans. The metabolic activity and lactic acid production of biofilms were measured (n = 6). Two commercial composites were used as controls. Results Flexural strength and elastic modulus of NACP+QADM, NACP+NAg, and NACP+QADM+NAg matched those of commercial composites with no antibacterial property (p > 0.1). The NACP+QADM+NAg composite decreased the titer counts of adherent S. mutans biofilms by an order of magnitude, compared to the commercial composites (p < 0.05). The metabolic activity and lactic acid production of biofilms on NACP+QADM+NAg composite were much less than those on commercial composites (p < 0.05). Combining QADM and NAg rendered the nanocomposite more strongly antibacterial than either agent alone (p < 0.05). Significance QADM and NAg were incorporated into calcium phosphate composite for the first time. NACP+QADM+NAg was strongly-antibacterial and greatly reduced the titer counts, metabolic activity, and acid production of S. mutans biofilms, while possessing mechanical properties similar to commercial composites. These nanocomposites are promising to have the double benefits of remineralization and antibacterial capabilities to inhibit dental caries. PMID:22305716

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

2012-01-01

324

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

PubMed

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

2013-09-01

325

Injectable and fast resorbable calcium phosphate cement for body-setting bone grafts.  

PubMed

In this work a calcium phosphate (CPC)/polymer blend was developed with the advantage of being moldable and capable of in situ setting to form calcium deficient hydroxyapatite under physiological conditions in an aqueous environment at body temperature. The CPC paste consists in a mix of R cement, glycerol as a liquid phase carrier and a biodegradable hydrogel such as Polyvinyl alcohol, which acts as a binder. Microstructure and mechanical analysis shows that the CPC blend can be used as an injectable implant for low loaded applications and fast adsorption requirements. The storage for commercial distribution was also evaluated and the properties of the materials obtained do not significantly change during storage at -18 degrees C. PMID:20386961

Rajzer, I; Castaño, O; Engel, E; Planell, J A

2010-07-01

326

Regulation of calcium phosphate sedimentation in biological fluids through post-nucleation shielding  

E-print Network

In vertebrates, insufficient availability of calcium and phosphate ions in extracellular fluids leads to loss of bone density and neuronal hyper-excitability. To counteract this problem, calcium ions are present at high concentrations throughout body fluids -- at concentrations exceeding the saturation point. This situation leads to the opposite situation where unwanted mineral sedimentation may occur. Remarkably, ectopic or out-of-place sedimentation into soft tissues is rare, in spite of the thermodynamic driving factors. This fortunate fact is due to the presence of auto-regulatory proteins that are found in abundance in bodily fluids. Yet, many important inflammatory disorders such as atherosclerosis and osteoarthritis are associated with this undesired calcification. Hence, it is important to gain an understanding of the regulatory process and the conditions under which it can go awry. In this Letter, we use ideas from mean-field classical nucleation theory to study the regulation of sedimentation of cal...

Chang, Joshua C

2015-01-01

327

Direct growth of human enamel-like calcium phosphate microstructures on human tooth.  

PubMed

Dental Enamel is the hardest mineralized tissue in the human body which is comprised of nanorod-like hydroxyapatite crystals arranged into a highly organized micro-architectural unit called an enamel prism. In this paper the direct growth of human enamel-like structures on human tooth using fluorapatite/phosphoric acid pastes is explored. SEM images show that the newly formed calcium phosphate crystals can be self-assembled into a similar ordered microstructure as those seen in human enamel. The mechanism of how these structures form is discussed. This work demonstrates the potential of applying nanotechnology to regenerate dental enamel clinically without cells. PMID:19441525

Wang, Xiaokun; Xia, Chunjie; Zhang, Zhouhao; Deng, Xuliang; Wei, Shicheng; Zheng, Gang; Chen, Haifeng

2009-02-01

328

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. PMID:25247137

Salama, Ahmed; Neumann, Mike; Günter, Christina

2014-01-01

329

Hydroxyapatite forming ability of electrostatic spray pyrolysis derived calcium phosphate nano powder.  

PubMed

A novel fabrication technique, i.e., electrostatic spray pyrolysis (ESP), has been used in this study to prepare calcium phosphate nano powders. Final annealing was done at 400 degrees C for 30 min in air. The hydroxyapatite-forming ability of the annealed powder has been investigated in Eagle's minimum essential medium solution. X-ray diffracton, field emission scanning electron microscope, energy dispersive X-ray spectroscope, and Fourier transform infrared spectroscope were employed to characterize the annealed powders after immersion. The powder with an amorphous structure induced hydroxyapatite formation on their surfaces after immersion for 15 days. PMID:17546422

Hwang, Kyu-Seog; Jeon, Kyung-Ok; Jeon, Young-Sun; Kim, Byung-Hoon

2007-04-01

330

Development of a novel fluorapatite-forming calcium phosphate cement with calcium silicate: In vitro and in vivo characteristics.  

PubMed

Aim of this study was to develop a novel fluorapatite-forming calcium phosphate cement (FA-CPC) with tricalcium silicate (TCS) for endodontic applications and to examine its in vitro and in vivo characteristics. The FA-CPC powder consisted of 62.8% CaHPO4, 30.8% CaCO3, and 6.4% NaF. One part of TCS was combined with 9 parts of FA-CPC powder (FA-CPC with TCS). A 1.5 M phosphate solution was used as cement liquid. Setting time (ST), diametral tensile strength (DTS), phase composition by X-ray diffraction (XRD), and cement alkalinity were analyzed. Cement biocompatibility was assessed using rat subcutaneous model. Cement ST was 10.3±0.6 min and DTS was 3.89±0.76 MPa. XRD patterns showed that highly crystalline apatitic material was the only significant phase present and pH value was approximate 11.0. FA-CPC with TCS demonstrated similar biocompatibility as that of mineral trioxide aggregate control. These results suggest that FA-CPC with TCS may be useful for endodontic applications. PMID:25740309

Suzuki, Yusuke; Hayashi, Makoto; Yasukawa, Takuya; Kobayashi, Hiroshi; Makino, Kosuke; Hirano, Yoriyuki; Takagi, Shozo; C Chow, Laurence; Ogiso, Bunnai

2015-04-01

331

Elucidating the individual effects of calcium and phosphate ions on hMSCs by using composite materials.  

PubMed

The biological performance of bone graft substitutes based on calcium phosphate bioceramics is dependent on a number of properties including chemical composition, porosity and surface micro- and nanoscale structure. However, in contemporary bioceramics these properties are interlinked, therefore making it difficult to investigate the individual effects of each property on cell behavior. In this study we have attempted to investigate the effects of calcium and inorganic phosphate ions independent from one another by preparing composite materials with polylactic acid (PLA) as a polymeric matrix and calcium carbonate or sodium phosphate salts as fillers. Clinically relevant bone marrow derived human mesenchymal stromal cells (hMSCs) were cultured on these composites and proliferation, osteogenic differentiation and ECM mineralization were investigated with time and were compared to plain PLA control particles. In parallel, cells were also cultured on conventional cell culture plates in media supplemented with calcium or inorganic phosphate to study the effect of these ions independent of the 3D environment created by the particles. Calcium was shown to increase proliferation of cells, whereas both calcium and phosphate positively affected alkaline phosphatase enzyme production. QPCR analysis revealed positive effects of calcium and of inorganic phosphate on the expression of osteogenic markers, in particular bone morphogenetic protein-2 and osteopontin. Higher levels of mineralization were also observed upon exposure to either ion. Effects were similar for cells cultured on composite materials and those cultured in supplemented media, although ion concentrations in the composite cultures were lower. The approach presented here may be a valuable tool for studying the individual effects of a variety of soluble compounds, including bioinorganics, without interference from other material properties. PMID:25676583

Danoux, Charlène B S S; Bassett, David C; Othman, Ziryan; Rodrigues, Ana I; Reis, Rui L; Barralet, Jake E; van Blitterswijk, Clemens A; Habibovic, Pamela

2015-04-15

332

VS-501: a novel, nonabsorbed, calcium- and aluminum-free, highly effective phosphate binder derived from natural plant polymer  

PubMed Central

Inadequate control of serum phosphate in chronic kidney disease can lead to pathologies of clinical importance. Effectiveness of on-market phosphate binders is limited by safety concerns and low compliance due to high pill size/burden and gastrointestinal (GI) discomfort. VS-501 is a nonabsorbed, calcium- and aluminum-free, chemically modified, plant-derived polymer. In vitro studies show that VS-501 has a high density and a low swell volume when exposed to simulated gastric fluid (vs. sevelamer). When male Sprague–Dawley (SD) rats on normal diet were treated with VS-501 or sevelamer, serum phosphate was not significantly altered, but urinary phosphate levels decreased by >90%. VS-501 had no effect on serum calcium (Ca) or urinary Ca, while 3% sevelamer significantly increased serum and urine Ca. In 5/6 nephrectomized (NX) uremic SD rats on high-phosphate diet, increasing dietary phosphate led to an increase in serum and urine phosphate, which was prevented in rats treated with VS-501 or sevelamer (0.2–5% in food). High-phosphate diet also increased serum fibroblast growth factor-23 and parathyroid hormone in 5/6 NX rats that was prevented by VS-501 or sevelamer. VS-501 or sevelamer increased fecal phosphate in a dose-dependent manner. More aortic calcification was observed in 5/6 NX rats treated with 5% sevelamer, while VS-501 and sevelamer did not show significant effects on cardiac parameters, fibrosis, intestine histology, and intestinal sodium-dependent phosphate cotransporter gene expression. These results suggest that VS-501 is effective in binding phosphate with no effects on calcium homeostasis, and may have improved pill burden and GI side effects. PMID:25197556

Wu-Wong, J Ruth; Chen, Yung-wu; Gaffin, Robert; Hall, Andy; Wong, Jonathan T; Xiong, Joseph; Wessale, Jerry L

2014-01-01

333

Preparation and characterization of biphasic calcium phosphate ceramics of desired composition.  

PubMed

A modified processing route for fabricating dense and porous biphasic calcium phosphate (BCP) ceramics of desired and reproducible phase composition (hydroxyapatite (HA)/beta-tricalcium phosphate (beta-TCP) ratio) has been developed. The principal idea of the route was combining a precipitation and a solid phase methods. First, a nonstoichiometric (slightly carbonated calcium-deficient) HA (CdHA) precipitate was synthesized by mixing a calcium carbonate (CaCO(3)) water suspension with an orthophosphoric acid (H(3)PO(4)) solution in abundance (related to the amount resulting in a stoichiometric HA) under definite conditions, and a powder of the precipitate was prepared and calcinated in air (860 degrees C, 1.5 h). In the second stage, a BCP ceramics of the composition determined by the calcium-deficiency in a calcinated powder (the acid abundance in a mixture) was processed by sintering powder compacts with or without a porosizer under appropriate conditions (1,200 degrees C, 2h). A calibrating dependence of the HA/beta-TCP ratio in the ceramics on the acid abundance has been plotted which enabled a controlled preparation of BCP ceramics. A correlation based on unresolved bands in nu(4)-PO (4) (3-) domain in IR-spectra of nanostructured BCP materials was found. Using the correlation, the process of CdHA --> beta-TCP transformation could be easily monitored. The density and microhardness of the BCP ceramics neglectly depended on the composition, however, the compressive strength did: the lower the HA/beta-TCP ratio, the higher the strength in the dense materials. PMID:18322781

Zyman, Z Z; Tkachenko, M V; Polevodin, D V

2008-08-01

334

Effects of novel calcium phosphate cements on human bone marrow fibroblastic cells.  

PubMed

The identification and characterization of biocompatible materials that augment bone cell proliferation and osteogenic activity have important therapeutic implications in skeletal reconstruction and joint replacement. In the present study, we have examined the effects of three biocements, biocement H, calcium-deficient apatite; biocement F, apatite + CaHPO(4); biocement D, carbonated apatite + CaHPO(4) + CaCO(3) and an amorphous calcium phosphate (ACP) proposed as implant fixing materials, on the growth, differentiation, and cell surface interaction of human bone marrow fibroblastic cells. These cells are known to be progenitors of osteoblasts, chondroblasts, adipocytes, myoblasts, and reticulocytes. Alkaline phosphatase enzyme activity, a marker of the osteoblast phenotype, was increased by a factor of two- to sixfold on carbonated apatite, one- to sixfold on apatite and three- to 10-fold on calcium-deficient apatite, over levels observed on plastic. Cell proliferation was significantly reduced. Photomicroscopic examination indicated high biocompatibility with close adhesion of the bone marrow fibroblastic cells to composites D, F, and H. Longer term marrow cultures (15 days) confirmed the stimulation of cell differentiation, as assessed by collagen production, over cell proliferation, of cells grown on carbonated apatite. Enhanced osteoblastic differentiation was observed on a 70% carbonated apatite, which has a composition similar to bone mineral, whereas cell toxicity was observed on cells grown on amorphous calcium phosphate. This in vitro human bone marrow fibroblast culture system provides a simple and effective method for the evaluation of new biomaterials. The development of these novel cements may be of potential use in orthopedic implants. PMID:9836792

Oreffo, R O; Driessens, F C; Planell, J A; Triffitt, J T

1998-01-01

335

Experimental synovitis induced by aluminium phosphate in rabbits. Comparison of the changes produced in synovial tissue and in articular cartilage by aluminium phosphate, carrageenin, calcium hydrogen phosphate dihydrate, and natural diamond powder.  

PubMed

The goal of this experimental study was to examine the effect on articular tissue of tribasic aluminium phosphate (crystalline and amorphous forms) after intraarticular injection in rabbit and to compare it with that of various phlogistic compounds such as carrageenin, calcium hydrogen phosphate dihydrate and diamond powder, as a control. Synovium and cartilage were studied with light microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive micro-analysis (EDM). Crystalline and amorphous aluminium phosphate could induce a synovitis with articular effusion in rabbits. With TEM, lysosomal inclusions of phagocytosed material were observed. Through SEM coupled with EDM, aluminium associated with phosphate was found in cellular elements. PMID:6087947

Delongeas, J L; Netter, P; Boz, P; Faure, G; Royer, R J; Gaucher, A

1984-01-01

336

Structural, morphological and surface characteristics of two types of octacalcium phosphate-derived fluoride-containing apatitic calcium phosphates.  

PubMed

Octacalcium phosphate (OCP) has been reported to stimulate bone regeneration during hydrolysis into hydroxyapatite (HA). The present study was designed to characterize structural, morphological and surface properties of fluoride-containing apatitic calcium phosphates (CaP) obtained through OCP hydrolysis or direct precipitation of OCP in the presence of 12-230ppm of fluoride (F). The products were characterized by chemical analysis, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and Fourier transform infrared spectroscopy (FTIR) as well as measurements of surface area, solubility, osteoblastic activities and bovine serum albumin (BSA) adsorption. XRD analysis re-confirmed that both preparations yielded more apatitic CaP with a higher concentration of F. However, the co-precipitated products (CF-CaP) maintained the properties of OCP, in particular the solubility, whereas the hydrolysis products (HF-CaP) had the characteristics of fluoridated apatite. The crystals of plate-like OCP were changed to the crystals of rod-like CF-CaP and small irregular HF-CaP with the advance of the hydrolysis. The SAED analysis detected both OCP and apatite crystals even in the most hydrolyzed CF-CaP. Mouse bone marrow stromal ST-2 cells grew better on CF-CaP compared with HF-CaP. BSA adsorption was inhibited on HF-CaP more than on CF-CaP. These results show that OCP produces physicochemically distinct apatitic fluoridated CaP during hydrolysis, regarding the structure, the crystal morphology and the protein adsorption, depending on the fluoride introduction route, which provides biologically interesting material. PMID:22868193

Shiwaku, Y; Anada, T; Yamazaki, H; Honda, Y; Morimoto, S; Sasaki, K; Suzuki, O

2012-12-01

337

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

2014-08-01

338

Effect of increased strut porosity of calcium phosphate bone graft substitute biomaterials on osteoinduction.  

PubMed

The effect of increasing strut porosity on the osteoinductivity of porous calcium phosphate (CaP) and silicate-substituted calcium phosphate (SiCaP) bone substitute materials was investigated in an ovine ectopic model. One to two millimeter-sized granules or block implants with strut porosities of 10, 20, or 30% were inserted into the left and right paraspinalis muscle. At 12 weeks, histological sections were prepared through the center of each implant and bone contact, bone area and implant area quantified. Backscattered scanning electron microscopy (bSEM) was used to visualize bone within small pores in the struts of the scaffolds. Increased bone formation was measured in the SiCaP with 30% strut porosity (5.482% ± 1.546%) when compared with the nonsilicate CaP with the same morphology (1.160% ± 0.502%, p = 0.02), indicating that silicate substitution may increase osteoinduction. Greater bone formation was seen in scaffolds with increased strut porosity. No bone growth was found in any of the SiCaP scaffold with 10% porosity. There was no significant difference between block and granule specimens. Scanning electron microscopy and EDX in combination with histology demonstrated bone formation within pores <5 ?m in size. The use of silicate-substituted CaP material with increased strut porosity may further augment repair and regeneration in bony sites. PMID:22419568

Coathup, Melanie J; Hing, Karin A; Samizadeh, Sorousheh; Chan, Oliver; Fang, Yvette S; Campion, Charlie; Buckland, Thomas; Blunn, Gordon W

2012-06-01

339

siRNA transfection with calcium phosphate nanoparticles stabilized with PEGylated chelators.  

PubMed

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

2013-01-01

340

Fatigue Behavior of Ti-6-4 Alloy with Application of Calcium Phosphate  

NASA Astrophysics Data System (ADS)

It is key to consider a material's mechanical properties when determining its use for any given application, including biomaterial implantations. One such characteristic includes the fatigue life, which is determined by repeatedly cycling specified amounts of load on any given material. The fatigue life is then measured according to how many cycles of load the material can undergo before fracture. When a material is introduced to the human body it is usually expected that the life of the material will not match that of the patient. It is crucial to understand the fatigue life of the material before implantation to pre-diagnose how often and when the implant will need to be replaced. The purpose of this project is to help determine and compare the fatigue behaviors of a commonly used biocompatible coating on Titanium 6-4 metal alloy. The comparison will help identify how the material properties vary with the addition of calcium phosphate when compared to the bare alloy itself. Multiple, small rectangular samples were cut by electrical discharge machining (EDM) of which half were covered with calcium phosphate coating. Fatigue crack initiations and propagation would then be analyzed using scanning electron microscopy (SEM) to help determine the nature of the damage processes. It was found that the fatigue life of the coated samples varied at different stresses but was greater than the bare samples, and particularly high in the 900 MPa - 1000 MPa stress range.

Kamboj, Jaspal Singh

341

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.

2013-03-01

342

Chapter 9: Model Systems for Formation and Dissolution of Calcium Phosphate Minerals  

SciTech Connect

Calcium phosphates are the mineral component of bones and teeth. As such there is great interest in understanding the physical mechanisms that underlie their growth, dissolution, and phase stability. Control is often achieved at the cellular level by the manipulation of solution states and the use of crystal growth modulators such as peptides or other organic molecules. This chapter begins with a discussion of solution speciation in body fluids and relates this to important crystal growth parameters such as the supersaturation, pH, ionic strength and the ratio of calcium to phosphate activities. We then discuss the use of scanning probe microscopy as a tool to measure surface kinetics of mineral surfaces evolving in simplified solutions. The two primary themes that we will touch on are the use of microenvironments that temporally evolve the solution state to control growth and dissolution; and the use of various growth modifiers that interact with the solution species or with mineral surfaces to shift growth away from the lowest energy facetted forms. The study of synthetic minerals in simplified solution lays the foundation for understand mineralization process in more complex environments found in the body.

Orme, C A; Giocondi, J L

2006-07-29

343

Factors affecting the structure and properties of an injectable self-setting calcium phosphate foam.  

PubMed

One of the main challenges in the investigation on calcium phosphate cements (CPC) lies in the introduction of macroporosity, without loosing the self-setting ability and injectability, characteristic of the cement-type materials. The benefits of macroporosity are related to the enhancement of bone regeneration mechanisms, such as angiogenesis and tissue ingrowth. In this work, the feasibility to obtain self-setting injectable macroporous hydroxyapatite foams by the incorporation of a protein-based foaming agent to a CPC is demonstrated. Albumen is combined with an alpha-tricalcium phosphate [Ca3(PO4)2, alpha-TCP] paste, which hydrolyzes to a calcium deficient hydroxyapatite during the setting reaction. A systematic study is presented, where the effect of different processing parameters is analyzed in terms of porosity, setting properties, injectability, and compressive strength. Self-setting foams with porosities up to 70%, which maintain their porous structure after injection, are obtained. These injectable foams can be used both for direct in vivo applications and for the fabrication of low temperature tissue engineering scaffolds. PMID:17001653

Ginebra, Maria-Pau; Delgado, José-Angel; Harr, Ingela; Almirall, Amisel; Del Valle, Sergio; Planell, Josep A

2007-02-01

344

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

PubMed Central

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, W.F.; Icenogle, T.B.; Antonucci, J.M.; Skrtic, D.

2008-01-01

345

Importance of FTIR Spectra Deconvolution for the Analysis of Amorphous Calcium Phosphates  

NASA Astrophysics Data System (ADS)

This work will consider Fourier transform infrared spectroscopy – diffuse reflectance infrared reflection (FTIR-DRIFT) for collecting the spectra and deconvolution to identify changes in bonding as a means of more powerful detection. Spectra were recorded from amorphous calcium phosphate synthesized by wet precipitation, and from bone. FTIR-DRIFT was used to study the chemical environments of PO4, CO3 and amide. Deconvolution of spectra separated overlapping bands in the ?4PO4, ?2CO3, ?3CO3 and amide region allowing a more detailed analysis of changes at the atomic level. Amorphous calcium phosphate dried at 80 oC, despite showing an X-ray diffraction amorphous structure, displayed carbonate in positions resembling a carbonated hydroxyapatite. Additional peaks were designated as A1 type, A2 type or B type. Deconvolution allowed the separation of CO3 positions in bone from amide peaks. FTIR-DRIFT spectrometry in combination with deconvolution offers an advanced tool for qualitative and quantitative determination of CO3, PO4 and HPO4 and shows promise to measure the degree of order.

Brangule, Agnese; Agris Gross, Karlis

2015-03-01

346

Effects of Calcium Phosphate Nanocrystals on Osseointegration of Titanium Implant in Irradiated Bone  

PubMed Central

Radiotherapy may compromise the integration of implant and cause implant loss. Implant surface modifications have the possibility of promoting cell attachment, cell growth, and bone formation which ultimately enhance the osseointegration process. The present study aimed to investigate the effects of calcium phosphate nanocrystals on implant osseointegration in irradiated bone. Sixteen rabbits were randomly assigned into control and nano-CaP groups, receiving implants with dual acid-etched surface or dual acid-etched surface discretely deposited of nanoscale calcium-phosphate crystals, respectively. The left leg of all the rabbits received 15?Gy radiation, followed by implants placement one week after. Four animals in each group were sacrificed after 4 and 12 weeks, respectively. Implant stability quotient (ISQ), ratio of bone volume to total volume (BV/TV), bone growth rate, and bone-to-implant contact (BIC) were evaluated. The nano-CaP group showed significantly higher ISQ (week 12, P = 0.031) and bone growth rate (week 6, P = 0.021; week 9, P = 0.001) than that in control group. No significant differences in BV/TV and BIC were found between two groups. Titanium implant surface modified with CaP nanocrystals provides a potential alternative to improve bone healing around implant in irradiated bone. PMID:25685809

Li, Jun Yuan; Pow, Edmond Ho Nang; Kwong, Dora Lai Wan; Cheung, Lim Kwong

2015-01-01

347

Effects of trabecular calcium phosphate scaffolds on stress-signaling in osteoblast precursor cells  

PubMed Central

The objective of this research was to investigate stress-signaling patterns in response to two dimensional (2-D) and three dimensional (3-D) calcium phosphate (CP) materials using human embryonic palatal mesenchyme cells (HEPM, CRL-1486, ATCC, Manassas, VA), an osteoblast precursor cell line. Control discs and scaffolds were fabricated from hydroxyapatite (HA) and ? tri-calcium phosphate (TCP) ceramics. Phospho-specific antibody cell-based ELISA (PACE) technique was utilized on members of the mitogen-activated protein kinase (MAPK) cascade including; the extracellular signal-regulated kinases (ERK1/2), p38, c-Jun N-terminal kinase (JNK), and the anti-apoptosis mediator protein kinase B (AKT). Quantification of these signals was evaluated during the early attachment phase of osteoblast precursor cells. In this study, it was observed that 3-D CP scaffolds significantly activated the stress mediators p38 and JNK but not ERK1/2. This signal trend was matched with an up-regulation in AKT, suggesting the ability of cells to manage high stress signals in response to 3-D CP architecture and that 3-D CP scaffolds are necessary for studies simulating a natural trabecular bone organization. The absence of these signals in 2-D CP surfaces indicated the importance of local architecture conditions on cell stress response. It was concluded from this study that osteoblast precursor cells cultured in 3-D CP scaffolds experience greater stress-signaling patterns when compared to 2-D CP surfaces. PMID:17350089

Appleford, Mark R.; Oh, Sunho; Cole, Judith A.; Carnes, David L.; Lee, Myunghyun; Bumgardner, Joel D.; Haggard, Warren O.; Ong, Joo L.

2007-01-01

348

Limited compliance of some apatitic calcium phosphate bone cements with clinical requirements.  

PubMed

Clinical requirements for calcium phosphate bone cements were formulated in terms of the initial setting time, the final setting time, the cohesion time and the ultimate compressive strength. Two cements were tested. Biocement H was made of a powder containing alpha-tertiary calcium phosphate and precipitated hydroxyapatite. Biocement F was made of a powder containing, in addition, some monetite. The liquid/powder (L/P) ratio was varied over the range 0.30-0.40 ml g(-1), whereas the accelerator concentration in the liquid was varied from 0%-4% Na2HPO4 in water. For Biocement H there was no combination L/P ratio and % Na2HPO4 for which all clinical requirements were satisfied. However, Biocement F had a certain area where this was the case. Therefore, it is expected that Biocement F can be applied in clinical situations such as orthopaedics, plastic and reconstructive surgery and oral and maxillofacial surgery, even when early contact with blood is inevitable. PMID:15348685

Khairoun, I; Boltong, M G; Driessens, F C; Planell, J A

1998-11-01

349

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

E-print Network

(0.14 g if using dihydrate; [phosphate] must be 1.5 mM) 6.5 g HEPES pH to 7.0 and bring up to 500 ml with distilled water. Re-pH at this point because it can change. Aliquot and store at ­20°C. 2M CaCl2 87.6 g CaCalcium Phosphate Transfection Works very well for 293 cells (up to 95% transfection efficiencies

Lamond, Angus I.

350

Variation in crystallinity of hydroxyapatite and the related calcium phosphates by mechanical grinding and subsequent heat treatment  

Microsoft Academic Search

The crystallinity of hydroxyapatite (HAp) and the related calcium phosphates for regenerating hard tissues was controlled\\u000a by the mechanical grinding (MG) method and subsequent heat treatment. The HAp, carbonate-apatite (CO3Ap), fluorapatite (FAp), and ?- and ?-tricalcium phosphates (?-TCP and ?-TCP, respectively) and tetracalcium diphosphate monoxide (TTCP) were used as initial materials. Variations in crystallinity\\u000a and crystal structure were examined by

Takayoshi Nakano; Yukichi Umakoshi; Atsuyuki Tokumura

2002-01-01

351

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

2007-01-01

352

Osteogenicity of biphasic calcium phosphate ceramics and bone autograft in a goat model.  

PubMed

The aim of this work was to compare the osteogenicity of calcium phosphate ceramic granules with autologous bone graft in ectopic and orthotopic sites. Biphasic calcium phosphate (BCP) granules composed of hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP) in a 60/40 ratio were sintered at 1050, 1125 and 1200 degrees C, producing different microporosities. Either BCP ceramic granules or autologous bone chips (n=7) were implanted into paraspinal muscles. Osteoinduction was not observed in either the BCP implants or autologous bone chips after 6 or 12 weeks in the ectopic sites. Hollow and bored polytetrafluoroethylene (PTFE) cylinders were filled with autologous bone, BCP granules or left empty, then implanted into critical-sized defects in femoral epiphyses. The PTFE cylinders left empty contained marrow and blood vessels but not mineralized bone, indicating that this model prevented bone ingrowth (0.56+/-0.43% at 12 weeks). Bone formation was observed in contact with the BCP1050 and BCP1125 granules in the femoral sites after 6 weeks. The amount of bone after 12 weeks was 5.6+/-7.3 and 9.6+/-6.6% for BCP1050 and BCP1125, respectively. Very little bone formation was observed with the BCP1200 implants (1.5+/-1.3% at 12 weeks). In both the ectopic and orthotopic sites, autologous bone chips were drastically resorbed (from 19.4+/-3.7% initially to 1.7+/-1.2% at 12 weeks). This study shows that synthetic bone substitutes may have superior stability and osteogenic properties than autologous bone grafts in critical-sized bone defects. PMID:18093645

Fellah, Borhane H; Gauthier, Olivier; Weiss, Pierre; Chappard, Daniel; Layrolle, Pierre

2008-03-01

353

Hierarchically microporous/macroporous scaffold of magnesium-calcium phosphate for bone tissue regeneration.  

PubMed

Hierarchically 3D microporous/macroporous magnesium-calcium phosphate (micro/ma-MCP) scaffolds containing magnesium ammonium phosphate hexahydrate [NH(4)MgPO(4).6H(2)O] and hydroxyapatite [Ca(10)(PO(4))(6)(OH)(2)] were fabricated from cement utilizing leaching method in the presence of sodium chloride (NaCl) particles and NaCl saturated water solution. NaCl particles produced macroporosity, and NaCl solution acted as both cement liquid and porogens, inducing the formation of microporosity. The micro/ma-MCP scaffolds with porosities varied from 52 to 78% showed well interconnected and open macropores with the sizes of 400-500 microm, and degradation of the scaffolds was significantly enhanced in Tris-HCl solution compared with macroporous MCP (ma-MCP) and corresponding calcium phosphate cement (CPC) scaffolds. Cell attachment and proliferation of MG(63) on micro/ma-MCP were significantly better than ma-MCP and CPC scaffolds because of the presence of microporosity, which enhanced the surface area of the scaffolds. Moreover, the alkaline phosphatase (ALP) activity of the MG(63) cells on micro/ma-MCP was significantly higher than ma-MCP and CPC scaffolds at 7 days, and the MG(63) cells with normal phenotype spread well and formed confluent layers across the macroporous walls of the micro/ma-MCP scaffolds. Histological evaluation confirmed that the micro/ma-MCP scaffolds improved the efficiency of new bone regeneration, and exhibited excellent biocompatibility, biodegradability and faster and more effective osteogenesis in vivo. PMID:19931903

Wei, Jie; Jia, Junfeng; Wu, Fan; Wei, Shicheng; Zhou, Huanjun; Zhang, Hongbo; Shin, Jung-Woog; Liu, Changsheng

2010-02-01

354

Crystallization behavior of silica-calcium phosphate biocomposites: XRD and FTIR studies.  

PubMed

Silica and calcium phosphates (CaP) are the most important ingredients in bioactive materials that bond to bone and enhance bone tissue formation. In this study, silica-calcium phosphate (SiO2-CaP) composites were developed by powder metallurgy method, using silica (SiO2) and anhydrous dicalcium phosphate (CaHPO4) powders (CaP) in the ratios (wt%): 20/80, 40/60, 60/40 and 80/20. The effects of temperature and chemical composition on crystallization and phase transformation of the SiO2-CaP composites were evaluated by XRD and FTIR. Thermal treatment of the starting material suggested that CaHPO4 transforms into: gamma-Ca2P2O7 at 800 degrees C; beta-Ca2P2O7 at 1000 degrees C and alpha-Ca2P2O7 at 1200 degrees C. On the other hand, beta-quartz was the only detected phase after thermal treatment of silica in the temperature range 800-1200 degrees C. For all SiO2-CaP composites, SiO2 and CaP did not modify the crystallization behavior of each other when sintered in the temperature range 800-1000 degrees C. However, at 1200 degrees C, CaP promoted the transformation of gamma-quartz into alpha-cristobalite. Moreover, SiO2 stabilized beta-Ca2P2O7. The modifications in the crystallization behavior were related to ion substitution and formation of solid solutions. PMID:15880933

Ning, C Q; Greish, Y; El-Ghannam, A

2004-11-01

355

Structure and formation mechanism of calcium phosphate concretions formed in simulated body fluid.  

PubMed

Synthetic calcium phosphate (CaP) concretions in the form of hemispheres formed under carefully controlled conditions (pH 7.4, 37 °C, no evaporation) from stagnant simulated body fluid on anionic polymeric substrate (laminin) were observed by scanning and transmission electron microscopy and atomic force microscopy. The hemispheres with diameter between approximately 50 and 200 ?m were composed of closely connected round spherical and elliptical objects of diameter varying from 70 to 120 nm with surface layer composed of tightly packed spherical objects of diameter 25-30 nm. The phase composition of concretions consisting of amorphous material was uniform. The concretions were formed by aggregation of CaP clusters (Posner's clusters Ca9(PO4)3 or [Ca3(PO4)2] n ) generated in the solution by perikinetic coagulation, their settling onto a substrate and subsequent accumulation through surface migration (surface nucleation) followed by accretion of nanoparticles arriving from surrounding solution. The similarity of ultrafine structures of these synthetic CaP concretions and the compact phosphatic phase appearing in some phosphate calculi indicates that analogous mechanisms could be active at the formation of the latter in the kidneys. PMID:24132583

Grases, Felix; Zelenková, Markéta; Söhnel, Otakar

2014-02-01

356

Ultrasound effect on osteoblast precursor cells in trabecular calcium phosphate scaffolds  

PubMed Central

This study investigated the in vitro effect of low intensity pulsed ultrasound (LIPUS) on human embryonic palatal mesenchyme cells (HEPM, CRL-1486, ATCC, Manassas, VA), an osteoblast precursor cell line, during early adhesion to calcium phosphate scaffolds. Hydroxyapatite (HA) and ?-tricalcium phosphate (TCP) ceramic scaffolds were produced by a template coating method. Phospho-specific antibody cell-based ELISA (PACE) technique was utilized on stress activation proteins including; the extracellular signal-regulated kinase (ERK1/2), P38, c-Jun N-terminal kinase (JNK) and the anti-apoptosis mediator protein kinase B (PKB/AKT). Cell-based ELISA’s were also performed on the membrane anchoring protein vinculin and ?6?4 integrin. LIPUS stimulated activation of ERK 1/2, JNK, P38 and vinculin in traditional 2 dimension (2-D) culture. Calcium release from the scaffolds was partially involved in the activation of ERK 1/2 when cell response was compared between culture on 2-D surfaces and 3 dimension (3-D) HA and TCP scaffolds. Effects of calcium extracted media from scaffolds alone could not account for the full activation of JNK, P38, AKT, vinculin and ?6?4 integrin. LIPUS stimulation further increased ERK activity on TCP scaffolds corresponding with an increase in both vinculin and ?6?4 integrin levels. It was concluded from this study that LIPUS treatment can significantly affect stress signaling mediators and adhesion proteins in osteoblast precursor cells during the early cell-attachment phase to trabecular patterned scaffolds. PMID:17706764

Appleford, Mark R.; Oh, Sunho; Cole, Judith A.; Protivínský, Jiri; Ong, Joo L.

2007-01-01

357

In situ synthesis of magnesium-substituted biphasic calcium phosphate and in vitro biodegradation  

SciTech Connect

Highlights: ? Mg–BCP were successfully prepared through in situ aqueous co-precipitation method. ? The amount of ?-TCP phase was changed with the magnesium substitution level. ? The substitution of magnesium led to a decrease in the unit cell volume. ? Mg–BCP could be able to develop a new apatite phase on the surface faster than BCP. -- Abstract: In situ preparation of magnesium (Mg) substituted biphasic calcium phosphate (BCP) of hydroxyapatite (HAp)/?-tricalcium phosphate (?-TCP) were carried out through aqueous co-precipitation method. The concentrations of added magnesium were varied with the calcium in order to obtain constant (Ca + Mg)/P ratios of 1.602. X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) spectroscopy were used to characterize the structure of synthesized magnesium substituted BCP powders. The results have shown that substitution of magnesium in the calcium deficient apatites revealed the formation of biphasic mixtures of different HAp/?-TCP ratios after heating at 1000 °C. The ratios of the formation of phase mixtures were dependent on the content of magnesium. After immersing in Hanks’ balanced salt solution (HBSS) for 1 week, 1 wt% magnesium substituted BCP powders were degraded and precipitation started to be formed with small granules consisting of number of flake-like crystal onto the surface of synthesized powders. On the other hand, in the case of pure BCP powders, the formation of new precipitates was detected after immersion in HBSS for 2 weeks. On the basis of these results, magnesium substituted BCP could be able to develop a new apatite phase on the surface in contact with physiological fluids faster than BCP does. In addition, the retention time to produce the new apatite phase in implantation operation for the BCP powder could be controlled by the amount of magnesium substitution.

Kim, Tae-Wan; Lee, Hyeong-Shin; Kim, Dong-Hyun; Jin, Hyeong-Ho [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)] [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Hwang, Kyu-Hong [School of Nano and Advanced Materials, Gyeongsang National University, Jinju, Kyungnam 660-701 (Korea, Republic of)] [School of Nano and Advanced Materials, Gyeongsang National University, Jinju, Kyungnam 660-701 (Korea, Republic of); Lee, Jong Kook [Department of Advanced Materials Engineering, Chosun University, Gwangju 501-759 (Korea, Republic of)] [Department of Advanced Materials Engineering, Chosun University, Gwangju 501-759 (Korea, Republic of); Park, Hong-Chae [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)] [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Yoon, Seog-Young, E-mail: syy3@pusan.ac.kr [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)] [School of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)

2012-09-15

358

Accelerating calcium phosphate growth on NaOH-treated poly-(lactic- co-glycolic acid) by evaporation-induced surface crystallization  

Microsoft Academic Search

Poly(lactic-co-glycolic acid) (PLGA) is a promising material for the regeneration of bone tissue, but its surface properties are not optimal for the application. Coating the surface of PLGA with a continuous layer of calcium phosphate is an effective approach to address the limitation. Current coating techniques for PLGA require immersion in supersaturated calcium phosphate solutions for days to weeks. In

K. Duan; Allen Tang; Rizhi Wang

2008-01-01

359

Preparation of amorphous calcium-magnesium phosphates at pH 7 and characterization by x-ray absorption and fourier transform infrared spectroscopy  

Microsoft Academic Search

Amorphous calcium-magnesium phosphates were prepared by precipitation from moderately supersaturated aqueous solutions at pH 7. Chemical analysis of the samples by ion chromatography showed that up to about 50% of the phosphate ions were protonated, the proportion increasing with the magnesium to calcium ion activity ratio in the solution. When left it contact with the supernatant, the amorphous precipitates matured

C. Holt; M. J. J. M. van Kemenade; J. E. Harries; L. S. Nelson; R. T. Bailey; D. W. L. Hukins; S. S. Hasnain; P. L. de Bruyn

1988-01-01

360

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

PubMed Central

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

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

2013-01-01

361

Enhancement of intracellular sphingosine-1-phosphate production by inositol 1,4,5-trisphosphate-evoked calcium mobilisation in HEK-293 cells: endogenous sphingosine-1-phosphate as a modulator of the calcium response.  

PubMed

Sphingosine-1-phosphate (S1P) regulates many cellular functions, such as migration, differentiation and growth. The effects of S1P are thought to be primarily mediated by G-protein coupled receptors, but an intracellular function as a calcium releasing second messenger has also been proposed. Here we show that in HEK-293 cells, exogenous S1P mobilises sequestered calcium by a mechanism primarily dependent on the phospholipase C (PLC)/inositol 1,4,5-trisphosphate (IP3) pathway, and secondarily on the subsequent synthesis of intracellular S1P. Stimulating HEK-293 cells exogenously with S1P increased the production of both inositol phosphates and intracellular S1P. The calcium response was inhibited in cells treated with 2-APB, caffeine or U73122, showing that the PLC/IP3 pathway for calcium release is activated in response to exogenous S1P. The calcium response was partially inhibited in cells treated with the sphingosine kinase inhibitor DMS and in cells expressing a catalytically inactive sphingosine kinase, showing that endogenously produced S1P is also involved. Importantly, 2-APB and U73122 inhibited the S1P-evoked production of intracellular S1P. S1P is therefore not likely a major calcium releasing second messenger in HEK-293 cells, but rather a secondary regulator of calcium mobilisation. PMID:15763425

Blom, Tomas; Slotte, J Peter; Pitson, Stuart M; Törnquist, Kid

2005-07-01

362

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

PubMed Central

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.

2013-01-01

363

Novel tea polyphenol-modified calcium phosphate nanoparticle and its remineralization potential.  

PubMed

Tea polyphenols (TP) are not only potent antimicrobial and antioxidant agents but also effective modifiers in the formation of nanosized crystals. Since nano-hydroxyapatite (n-HA) is known to enhance remineralization of dental hard tissue, our aims were to synthesize nanosized calcium phosphate particles incorporating TP and to test their potential as caries preventive agent. An ammonia water diffusion method was used to synthesize nanosized calcium phosphate particles (TP-CaP) in the presence of various amounts of TP. The resultant products were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The remineralization potential of the nano TP-CaP was then investigated in a 12-day pH-cycling model. Nano TP-CaP slurries, at pH 7.0 and pH 5.5, were applied onto preformed enamel lesions 4 × 3 min per day. n-HA slurries at pH 7.0 and pH 5.5 were used as positive controls, and deionized water was served as a negative control. SEM showed nanosized particles were only formed at 27 mg/mL of TP. Further characterization of the nanosized particles revealed the components were amorphous calcium phosphate, HA, and TP. Both surface microhardness and transverse microradiography analyses showed that nano TP-CaP at pH 5.5, but not at pH 7.0, significantly enhanced remineralization, to the same extent as the n-HA controls. Furthermore, significantly higher amount of TP was found in the supernatant of TP-CaP at pH 5.5 than those at pH 7.0. Since TP can inhibit bacterial growth and enzyme activities, the novel nanosized TP-CaP particle, at low pH, is a potential dual-functional-remineralization and antibacteria-product. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2014. PMID:25470574

He, Libang; Deng, Dongmei; Zhou, Xuedong; Cheng, Lei; Ten Cate, Jacob M; Li, Jiyao; Li, Xudong; Crielaard, Wim

2014-12-01

364

Dental plaque microcosm biofilm behavior on calcium phosphate nanocomposite with quaternary ammonium  

PubMed Central

Objectives Half of dental restorations fail in 10 years, with secondary caries as the main reason. Calcium phosphate composites could remineralize tooth lesions. The objectives of this study were to: (1) Impart antibacterial activity to a composite with nanoparticles of amorphous calcium phosphate (NACP); and (2) investigate the effect of quaternary ammonium dimethacrylate (QADM) on mechanical and dental plaque microcosm biofilm properties for the first time. Methods The NACP and glass particles were filled into a dental resin that contained bis(2-methacryloyloxy-ethyl) dimethyl-ammonium bromide, the QADM. NACP nanocomposites containing 0%, 7%, 14%, and 17.5% of QADM by mass, respectively, were photo-cured. A commercial composite with no antibacterial activity was used as control. Mechanical properties were measured in three-point flexure. A human saliva microcosm model was used to grow biofilms on composites. Live/dead assay, metabolic activity, colony-forming unit (CFU) counts, and lactic acid production of biofilms on the composites were measured. Results Increasing QADM mass fraction monotonically reduced the biofilm viability, CFU and lactic acid. Biofilms on NACP nanocomposite with 17.5% QADM had metabolic activity that was 30% that on a commercial composite control (p<0.05). Total microorganisms, total streptococci, and mutans streptococci CFU counts (mean±sd; n=6) on composite control was 6-fold those on NACP+17.5% QADM nanocomposite. Composite control had long strings of cells with normal short-rod shapes, while some cells on NACP-QADM nanocomposites disintegrated into pieces. Adding QADM to NACP did not decrease the strength and elastic modulus, which matched (p>0.1) those of a commercial composite without Ca-PO4 or antibacterial activity. Significance A dental plaque microcosm model was used to evaluate the novel NACP-QADM nanocomposite. The nanocomposite greatly reduced the biofilm viability, metabolic activity and lactic acid, while its mechanical properties matched those of a commercial composite. NACP-QADM nanocomposite with calcium phosphate fillers, good mechanical properties and a strong antibacterial activity may have potential for anti-biofilm and anti-caries restorations. PMID:22578992

Cheng, Lei; Weir, Michael D.; Zhang, Ke; Wu, Eric; Xu, Sarah M.; Zhou, Xuedong; Xu, Hockin H. K.

2012-01-01

365

The Calcium Phosphate Matrix of FGF-2-Apatite Composite Layers Contributes to Their Biological Effects  

PubMed Central

The purpose of the present study was to fabricate fibroblast growth factor (FGF)-2-apatite composite layers on titanium (Ti) pins in one step at 25 °C using a supersaturated calcium phosphate (CaP) solution, and to evaluate the physicochemical characteristics and biological effects of the coated Ti pins compared with coated Ti pins fabricated at 37 °C. Ti pins were immersed in a supersaturated CaP solution containing 0.5, 1.0, or 2.0 µg/mL FGF-2 at 25 °C for 24 h (25F0.5, 25F1.0, and 25F2.0) or containing 4.0 µg/mL FGF-2 at 37 °C for 48 h (37F4.0). Except for the 25F0.5, the chemical compositions and the mitogenic activity levels of FGF-2 of the composite layers formed by these two methods were similar, except for the Ca/P molar ratio, which was markedly smaller at 25 °C (1.55–1.56 ± 0.01–0.02, p = 0.0008–0.0045) than at 37 °C (1.67 ± 0.11). Thus, either the apatite was less mature or the amount of amorphous calcium phosphate was higher in the composite layer formed at 25 °C. In vivo, the pin tract infection rate by visual inspection for 37F4.0 (45%) was lower than that for 25F1.0 (80%, p = 0.0213), and the rate of osteomyelitis for 37F4.0 (35%) was lower than that for 25F0.5 (75%, p = 0.0341). The extraction torque for 37F4.0 (0.276 ± 0.117 Nm) was higher than that for 25F0.5 (0.192 ± 0.117 Nm, p = 0.0142) and that for 25F1.0 (0.176 ± 0.133 Nm, p = 0.0079). The invasion rate of S. aureus for 37F4.0 (35%) was lower than that for 25F0.5 (75%, p = 0.0110). On the whole, the FGF-2-apatite composite layer formed at 25 °C tended to be less effective at improving fixation strength in the bone-pin interface and resisting pin tract infections. These results suggest that the chemistry of the calcium phosphate matrix that embeds FGF-2, in addition to FGF-2 content and activity, has a significant impact on composite infection resistance and fixation strength. PMID:24918287

Mutsuzaki, Hirotaka; Ito, Atsuo; Sogo, Yu; Sakane, Masataka; Oyane, Ayako; Yamazaki, Masashi

2014-01-01

366

Comparison of the adjuvant activity of aluminum hydroxide and calcium phosphate on the antibody response towards Bothrops asper snake venom.  

PubMed

The adjuvanticity of aluminum hydroxide and calcium phosphate on the antibody response in mice towards the venom of the snake Bothrops asper was studied. It was found that, in vitro, most of the venom proteins are similarly adsorbed by both mineral salts, with the exception of some basic phospholipases A2, which are better adsorbed by calcium phosphate. After injection, the adjuvants promoted a slow release of the venom, as judged by the lack of acute toxicity when lethal doses of venom were administered to mice. Leukocyte recruitment induced by the venom was enhanced when it was adsorbed on both mineral salts; however, venom adsorbed on calcium phosphate induced a higher antibody response towards all tested HPLC fractions of the venom. On the other hand, co-precipitation of venom with calcium phosphate was the best strategy for increasing: (1) the capacity of the salt to couple venom proteins in vitro; (2) the venom ability to induce leukocyte recruitment; (3) phagocytosis by macrophages; and (4) a host antibody response. These findings suggest that the chemical nature is not the only one determining factor of the adjuvant activity of mineral salts. PMID:23506358

Olmedo, Hidekel; Herrera, María; Rojas, Leonardo; Villalta, Mauren; Vargas, Mariángela; Leiguez, Elbio; Teixeira, Catarina; Estrada, Ricardo; Gutiérrez, José María; León, Guillermo; Montero, Mavis L

2014-01-01

367

Mechanical and rheological properties and injectability of calcium phosphate cement containing poly (lactic-co-glycolic acid) microspheres  

Microsoft Academic Search

To enhance tissue ingrowth and promote rapid resorption, efforts were made to build macropores into calcium phosphate cement (CPC); however, this led to a decrease in its mechanical properties. In this study, poly (lactic-co-glycolic acid) (PLGA) microspheres were incorporated into CPC to impart macroporosity and maintain early strength. The influences of the content of PLGA microspheres on the mechanical strength,

Xiaopeng Qi; Jiandong Ye

2009-01-01

368

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

2000-01-01

369

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

2003-01-01

370

Preparation and Characterization of Electrodeposited Calcium Phosphate\\/Chitosan Coating on Ti6Al4V Plates  

Microsoft Academic Search

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

J. Wang; J. de Boer; K. de Groot

2004-01-01

371

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

PubMed

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

2014-05-01

372

Numerical investigation of heat-mass transfer of calcium phosphates at crystal growth for normal and microgravity conditions  

NASA Astrophysics Data System (ADS)

Numerical modeling of heat and mass transfer at growth of crystals octacalcium phosphate Ca8H2(PO4)6 and hydroxyapatite Ca10(OH)2(PO4)6 from mixture CaCl2 and KH2PO4+ K2HPO4 in a solution KCl for terrestrial conditions and microgravity environment is devoted. Mathematical modeling is performed on the basis of a solution of nonstationary Navier-Stokes equations for incompressible fluid flows and heat/mass transfer equations. The results of mathematical modeling, showing possible convective mechanisms of transfer the components are submitted. The influence thermal convection and two mechanisms of concentration convection (separately and jointly) on carry a component and formation of calcium phosphates is considered. The results of parametric calculations for various values of thermal and solutes Grashof numbers are presented. The influences of gravitation on character of transfer the component of reaction and formation calcium phosphates are investigated. The influence of gravitational conditions on dynamics and character of formation of calcium phosphates for conditions of experiments before spent on the Earth and in space under the program EURECA (crystallization of octacalcium phosphate from solution is shown. Also the possible reasons of formation of different sizes of ground and space crystals are discussed.

Fedyushkin, A. I.; Suvorova, E. I.

373

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

PubMed

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

2014-03-01

374

The final phases of calcium and magnesium phosphates precipitated from solutions of high to medium concentration  

NASA Astrophysics Data System (ADS)

The phases of calcium and magnesium phosphates, which are obtained by evolution at 25°C of the first precipitates in their mother solutions, are described in terms of pH and composition of solutions. The initial conditions were: 0.050M ? [P] ? 0.500M; [P] = [Ca] + [Mg]; 0 ? [Mg]/[Ca] ? 1. The most abundant final phases are brushite, CaHPO 4·2H 2O; monetite, CaHPO 4; newberyite, MgHPO 4·3H 2O and struvite, MgNH 4PO 4·6H 2O. At low concentration whitlockite, Ca 9MgH(PO 4) 7, occurs with the amorphous phase previously precipitated, Ca 3(PO 4) 2·nH 2O. The conditions for stability are discussed and the changes observed are interpreted.

Abbona, Francesco; Lundager Madsen, Hans Erik; Boistelle, Roland

1988-07-01

375

ILLUMINATING THE ROLE OF AGGLOMERATES ON CRITICAL PHYSICOCHEMICAL PROPERTIES OF AMORPHOUS CALCIUM PHOSPHATE COMPOSITES  

PubMed Central

Water sorption (WS), mechanical strength, and ion release of polymeric composites formulated with 40 % as-made or milled amorphous calcium phosphate (ACP) are compared after 1, 2 and 3 months of aqueous exposure. Ethoxylated bisphenol A dimethacrylate, triethylene glycol dimethacrylate, 2-hydroxyethyl methacrylate and methacryloxyethyl phthalate comprised the resin. The WS (mass %) peaked at 3 months. WS of as-made ACP composites was significantly higher than WS of milled ACP composites and copolymers. Both composite groups experienced decreases in biaxial flexural strength (BFS) with water aging, with milled ACP composites retaining a significantly higher BFS throughout immersion. Ion release was moderately reduced in milled ACP composites, though they remained superior to as-made ACP composites due to significantly lower WS and higher BFS after prolonged aqueous exposure. PMID:19774100

O’Donnell, J.N.R.; Antonucci, J.M.; Skrtic, D.

2009-01-01

376

Self-healing hybrid nanocomposites consisting of bisphosphonated hyaluronan and calcium phosphate nanoparticles.  

PubMed

Non-covalent interactions are often regarded as insufficient to construct macroscopic materials of substantial integrity and cohesion. However, the low binding energy of such reversible interactions can be compensated by increasing their number to work in concert to create strong materials. Here we present the successful development of an injectable, cohesive nanocomposite hydrogel based on reversible bonds between calcium phosphate nanoparticles and bisphosphonate-functionalized hyaluronic acid. These nanocomposites display a capacity for self-healing as well as adhesiveness to mineral surfaces such as enamel and hydroxyapatite. Most importantly, these non-covalently cross-linked composites are surprisingly robust yet biodegradable upon extensive in vitro and in vivo testing and show bone interactive capacity evidenced by bone ingrowth into material remnants. The herein presented method provides a new methodology for constructing nanoscale composites for biomedical applications, which owe their integrity to reversible bonds. PMID:24862440

Nejadnik, M Reza; Yang, Xia; Bongio, Matilde; Alghamdi, Hamdan S; van den Beucken, Jeroen J J P; Huysmans, Marie C; Jansen, John A; Hilborn, Jöns; Ossipov, Dmitri; Leeuwenburgh, Sander C G

2014-08-01

377

Effect of anion substitution on the electron spin resonance of Cr5 + in calcium phosphate apatite  

NASA Astrophysics Data System (ADS)

Electron spin resonance studies have been made at 4.2 K of CrO3-4 substituted for PO3-4 in three calcium phosphate apatites. The hydroxyapatite studied has a hexagonal structure stabilized by Cl- impurities. The fluorapatite is confirmed by the ESR to undergo a phase transition involving small structural changes to a noncentrosymmetric phase. But the ESR shows that the distortion of the PO3-4 tetrahedra is remarkably similar to that of the hydroxyapatite. Chlorapatite has a centrosymmetric monoclinic structure and has a considerably more distorted PO3-4 tetrahedron. Comparison of the results with previously studied hexagonal barium and strontium apatites shows that cation substitution has a much stronger effect on the PO3-4 structure than does anion substitution.

Pifer, J. H.; Ziemski, S.; Greenblatt, M.

1983-06-01

378

In Vitro and in Vivo Characteristics of Fluorapatite-Forming Calcium Phosphate Cements  

PubMed Central

This study reports for the first time in vitro and in vivo properties of fluorapatite (FA)-forming calcium phosphate cements (CPCs). The experimental cements contained from (0 to 3.1) mass % of F, corresponding to presence of FA at levels of approximately (0 to 87) mass %. The crystallinity of the apatitic cement product increased greatly with the FA content. When implanted subcutaneously in rats, the in vivo resorption rate decreased significantly with increasing FA content. The cement with the highest FA content was not resorbed in soft tissue, making it the first known biocompatible and bioinert CPC. These bioinert CPCs might be useful for applications where slow or no resorption of the implant is required to achieve the desired clinical outcome. PMID:21479080

Takagi, Shozo; Frukhtbeyn, Stan; Chow, Laurence C.; Sugawara, Akiyoshi; Fujikawa, Kenji; Ogata, Hidehiro; Hayashi, Makoto; Ogiso, Binnai

2010-01-01

379

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: hcheung@med.miami.edu

2005-05-13

380

Polymerization shrinkage and stress development in amorphous calcium phosphate/urethane dimethacrylate polymeric composites  

PubMed Central

This study explores how substituting a new high molecular mass oligomeric poly(ethylene glycol) extended urethane dimethacrylate (PEG-U) for 2-hydroxyethyl methacrylate (HEMA) in photo-activated urethane dimethacrylate (UDMA) resins affects degree of vinyl conversion (DC), polymerization shrinkage (PS), stress development (PSSD) and biaxial flexure strength (BFS) of their amorphous calcium phosphate (ACP) composites. The composites were prepared from four types of resins (UDMA, PEG-U, UDMA/HEMA and UDMA/PEG-U) and zirconia-hybridized ACP. Introducing PEG-U improved DC while not adversely affecting PS, PSSD and the BFS of composites. This improvement in DC is attributed to the long, more flexible structure between the vinyl groups of PEG-U and its higher molecular mass compared to poly(HEMA). The results imply that PEG-U has the potential to serve as an alternative to HEMA in dental and other biomedical applications. PMID:20169007

Antonucci, J.M.; Regnault, W. F.; Skrtic, D.

2010-01-01

381

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

2013-01-01

382

Enzyme-assisted calcium phosphate biomineralization on an inert alumina surface.  

PubMed

In this study a bioinspired approach to induce self-mineralization of bone-like material on alumina surfaces is presented. The mineralizing enzyme alkaline phosphatase (ALP) is covalently immobilized by a carbodiimide-mediated chemoligation method. The enzymatic activity of immobilized ALP and its mineralization capability are investigated under acellular conditions as well as in the presence of human bone cells. Analytical, biochemical and immunohistochemical characterization show that ALP is efficiently immobilized, retains its activity and can trigger calcium phosphate mineralization on alumina at acellular conditions. In vitro cell tests demonstrate that ALP-functionalized alumina clearly boosts and enhances bone cell mineralization. Our results underpin the great potential of ALP-functionalized alumina for the development of bioactive surfaces for applications such as orthopaedic and dental implants, enabling a fast and firm implant osseointegration. PMID:25462843

Aminian, Alieh; Pardun, Karoline; Volkmann, Eike; Li Destri, Giovanni; Marletta, Giovanni; Treccani, Laura; Rezwan, Kurosch

2015-02-01

383

Solution combustion synthesis of calcium phosphate particles for controlled release of bovine serum albumin.  

PubMed

Four different phase compositions of calcium phosphate (CaP) particles were prepared via a solution combustion method. X-ray diffraction (XRD) and Rietveld analysis results revealed that the variations in the nominal Ca/P (molar) ratios were found to provide a favorable control in the different proportions of CaP materials. Bovine serum albumin (BSA) was used as a model protein to study the loading and release behavior. The release profile indicated that the BSA release rates depended on the phase compositions of the CaP particles, and showed an order of TCP-BSA>BCP-1-BSA>BCP-2-BSA>HA-BSA. The results suggested that the BSA protein release rate can be controlled by varying the phase compositions of CaP carriers. Moreover, the release process involved two stages: firstly surface diffusion via ion exchange and secondly intraparticle diffusion. PMID:25746262

Zhao, Junfeng; Zhao, Junjie; Qian, Yu; Zhang, Xiali; Zhou, Feifei; Zhang, Hong; Lu, Hongbin; Chen, JianHua; Wang, XuHong; Yu, Wencong

2015-05-01

384

An improvement in sintering property of beta-tricalcium phosphate by addition of calcium pyrophosphate.  

PubMed

The sintering behavior of calcium pyrophosphate (CPP, Ca2P2O7)-doped beta-tricalcium phosphate [TCP, Ca3(PO4)2], prepared by solid state reaction, was investigated in-situ, using dilatometry. Pure beta-TCP undergoes phase transition to alpha-TCP at about 1200 degrees C; hence pure beta-TCP ceramics should be sintered bclow 1200 degrees C. Pure beta-TCP sintered body can achieve a relative density of only 86% when sintered at 1150 degrees C. However, the addition of CPP in the range of 0.5-3 wt% delays phasc transition of beta-TCP and enables sintering of beta-TCP at 1200 degrees C without a phase transformation to alpha-TCP. Due to this effect of CPP added to TCP, CPP-doped beta-TCP ceramics with relative density over 95% could be obtained when sintered at 1200 degrees C for 2 h. PMID:11771710

Ryu, Hyun-Seung; Youn, Hyuk-Joon; Hong, Kug Sun; Chang, Bong-Sun; Lee, Choon-Ki; Chung, Sung-Soo

2002-02-01

385

Preparation and osteogenic properties of magnesium calcium phosphate biocement scaffolds for bone regeneration  

NASA Astrophysics Data System (ADS)

The regenerative treatment of large osseous defects remains a formidable challenge in today. In the present study, we have synthesized biodegradable magnesium calcium phosphate biocement (MCPB) scaffolds with interconnected macroporous structure (100-600 ?m), as well as good bioactivity, biocompatibility and proper degradatibility. The results revealed that the porosity increased from 52% to 80% of MCPB scaffolds while the compressive strength decreased from 6.1 MPa to 1.2 MPa. We further assessed the effects of scaffolds on the rabbit femur cavity defect model in vivo by using synchrotron radiation X-ray microCT and microCT imaging, indicating that the MCPB scaffolds underwent gradually degradation and promoted the extensive neo-bone formation.

Li, X.; Niu, Y.; Guo, H.; Chen, H.; Li, F.; Zhang, J.; Chen, W.; Wu, Z.; Deng, Y.; Wei, J.; Liu, C.

2013-07-01

386

Injection of calcium phosphate pastes: prediction of injection force and comparison with experiments.  

PubMed

Calcium phosphate ceramics suspensions (ICPCS) are used in bone and dental surgery as injectable bone substitutes. This ICPCS biomaterial associates biphasic calcium phosphate (BCP) granules with hydroxypropylmethylcellulose (HPMC) polymer. Different ICPCS were prepared and their rheological properties were evaluated in parallel disks geometry as a function of the BCP weight ratio (35, 40, 45 and 50 %). The suspensions show a strongly increased viscosity as compared to the suspending fluid and the high shear rate part of the flow curve can be fitted with a power law model (Ostwald-de Waele model). The fitting parameters depend on the composition of the suspension. A simple device has been used to characterize extrusion of the paste using a disposable syringe fitted with a needle. The injection pressure of four ICPCS formulations was studied under various conditions (needle length and radius and volumetric flow rate), yielding an important set of data. A theoretical approach based on the capillary flow of non-Newtonian fluids was used to predict the necessary pressure for injection, on the basis of flow curves and extrusion conditions. The extrusion pressure calculated from rheological data shows a quantitative agreement with the experimental one for model fluids (Newtonian and HPMC solution) but also for the suspension, when needles with sufficiently large diameters as compared to the size of particles, are used. Depletion and possibly wall slip is encountered in the suspensions when narrower diameters are used, so that the injection pressure is less than that anticipated. However a constant proportionality factor exists between theory and injection experiments. The approach developed in this study can be used to correlate the rheological parameters to the necessary pressure for injection and defines the pertinent experimental conditions to obtain a quantitative agreement between theory and experiments. PMID:22528073

Fatimi, Ahmed; Tassin, Jean-François; Bosco, Julia; Deterre, Rémi; Axelos, Monique A V; Weiss, Pierre

2012-07-01

387

Human umbilical cord stem cell encapsulation in calcium phosphate scaffolds for bone engineering  

PubMed Central

Human bone marrow mesenchymal stem cells (hBMSCs) require an invasive procedure to harvest, and have lower self-renewal potential with aging. Umbilical cord mesenchymal stem cells (hUCMSCs) are a relatively new stem cell source; this study reveals a self-setting and load-bearing calcium phosphate construct that encapsulates these stem cells. The flexural strength (mean ± sd; n = 5) of the hUCMSC-encapsulating calcium phosphate cement (CPC) increased from (3.5 ± 1.1) MPa without polyglactin fibers, to (11.7 ± 2.1) MPa with 20% of polyglactin fibers (p < 0.05). hUCMSCs attached to the bone mineral-mimicking scaffold in the osteogenic media and differentiated down the osteogenic lineage, yielding elevated alkaline phosphatase (ALP) and osteocalcin (OC) gene expressions. ALP and OC on the CPC-fiber scaffold was 2-fold those on CPC control without fibers. hUCMSCs encapsulated inside the scaffolds retained excellent viability and cell density. The encapsulated hUCMSCs inside four different constructs successfully differentiated down the osteogenic lineage and synthesized bone minerals, as confirmed by mineral staining, SEM, and XRD. The percentage of mineral area synthesized by the encapsulated hUCMSCs increased from about 3% at day-7, to 12% at day-21 (p < 0.05). In conclusion, this study demonstrated that hUCMSCs encapsulated in the bioengineered scaffolds osteo-differentiated and synthesized bone minerals. The self-setting CPC–chitosan–fiber scaffold supported the viability and osteogenic differentiation of the encapsulated hUCMSCs, and had mechanical strength matching that of cancellous bone. PMID:20149437

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

2010-01-01

388

In vitro biodegradation of three brushite calcium phosphate cements by a macrophage cell-line.  

PubMed

Depending upon local conditions, brushite (CaHPO4 x 2 H2O) cements may be largely resorbed or (following hydrolysis to hydroxyapatite) remain stable in vivo. To determine which factors influence cement resorption, previous studies have investigated the solution-driven degradation of brushite cements in vitro in the absence of any cells. However, the mechanism of cell-mediated biodegradation of the brushite cement is still unknown. The aim of the current study was to observe the cell-mediated biodegradation of brushite cement formulations in vitro. The cements were aged in the presence of a murine cell line (RAW264.7), which had the potential to form osteoclasts in the presence of the receptor for nuclear factor kappa B ligand (RANKL) in vitro, independently of macrophage colony stimulating factor (M-CSF). The cytotoxicity of the cements on RAW264.7 cells and the calcium and phosphate released from materials to the culture media were analysed. Scanning electron microscopy (SEM) and focused ion beam (FIB) microscopy were used to characterise the ultrastructure of the cells. The results showed that the RAW264.7 cell line formed multinucleated TRAP positive osteoclast-like cells, capable of ruffled border formation and lacunar resorption on the brushite calcium phosphate cement in vitro. In the osteoclast-like cell cultures, ultrastructural analysis by SEM revealed phenotypic characteristics of osteoclasts including formation of a sealing zone and ruffled border. Penetration of the surface of the cement, was demonstrated using FIB, and this showed the potential demineralising effect of the cells on the cements. This study has set up a useful model to investigate the cell-mediated cement degradation in vitro. PMID:16720039

Xia, Zhidao; Grover, Liam Michael; Huang, Yizhong; Adamopoulos, Iannis E; Gbureck, Uwe; Triffitt, James T; Shelton, Richard M; Barralet, Jake E

2006-09-01

389

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.

2012-01-01

390

Structure-Composition-Property Relationships in Polymeric Amorphous Calcium Phosphate-Based Dental Composites†  

PubMed Central

Our studies of amorphous calcium phosphate (ACP)-based materials over the last decade have yielded bioactive polymeric composites capable of protecting teeth from demineralization or even regenerating lost tooth mineral. The anti-cariogenic/re-mineralizing potential of these ACP composites originates from their propensity, when exposed to the oral environment, to release in a sustained manner sufficient levels of mineral-forming calcium and phosphate ions to promote formation of stable apatitic tooth mineral. However, the less than optimal ACP filler/resin matrix cohesion, excessive polymerization shrinkage and water sorption of these experimental materials can adversely affect their physicochemical and mechanical properties, and, ultimately, limit their lifespan. This study demonstrates the effects of chemical structure and composition of the methacrylate monomers used to form the matrix phase of composites on degree of vinyl conversion (DVC) and water sorption of both copolymers and composites and the release of mineral ions from the composites. Modification of ACP surface via introducing cations and/or polymers ab initio during filler synthesis failed to yield mechanically improved composites. However, moderate improvement in composite’s mechanical stability without compromising its remineralization potential was achieved by silanization and/or milling of ACP filler. Using ethoxylated bisphenol A dimethacrylate or urethane dimethacrylate as base monomers and adding moderate amounts of hydrophilic 2-hydroxyethyl methacrylate or its isomer ethyl-?-hydroxymethacrylate appears to be a promising route to maximize the remineralizing ability of the filler while maintaining high DVC. Exploration of the structure/composition/property relationships of ACP fillers and polymer matrices is complex but essential for achieving a better understanding of the fundamental mechanisms that govern dissolution/re-precipitation of bioactive ACP fillers, and, ultimately, the suitability of the composites for clinical evaluation. PMID:21966588

O’Donnell, Justin N.R.; Schumacher, Gary E.; Antonucci, Joseph M.; Skrtic, Drago

2009-01-01

391

Bioactive ceramics prepared by sintering and crystallization of calcium phosphate invert glasses.  

PubMed

Novel glass-ceramics were synthesized via sintering and crystallization by heating powder compacts of SiO2-free calcium phosphate invert glasses of 60CaO x 30P2O5 x 7Na2O x 3TiO2 or 60CaO x 30P2O5 x 7Na2O x 3MgO at 800-850 degrees C in air. The glass-ceramics were relatively dense materials consisting of crystalline phases such as beta-Ca3(PO4)2 and beta-Ca2P2O7 with glassy phases. The compacts were densified by the viscous flow of the glassy phases while heating. By soaking in simulated body fluid at 37 degrees C, a calcium phosphate phase was formed newly on the surface of the glass-ceramic derived from 60CaO x 30P2O5 x 7Na2O x 3TiO2 glass, while the phase was not formed on that derived from 60CaO x 30P2O5 x 7Na2O x 3MgO glass: the former was implied to show bioactivity. Composition of the glassy phase as the matrix varies with the additives such as TiO2 and MgO, and the chemical properties of the phase influence the bioactivity of the glass-ceramics. The glass-ceramic derived from 60CaO x 30P2O5 x 7Na2O x 3TiO2 glass has relatively high fracture toughness of K(IC) approximately 2 MPa m(0.5) and bending strength of 100-120 MPa. PMID:10454013

Kasuga, T; Sawada, M; Nogami, M; Abe, Y

1999-08-01

392

Bioactive polymethylmethacrylate bone cement modified with combinations of phosphate group-containing monomers and calcium acetate.  

PubMed

Bone cement from polymethylmethacrylate powder and methylmethacrylate liquid has been successfully demonstrated as artificial material to anchor joint replacements in bone. However, it lacks the capability to bond directly to bone, so long-term implantation leads to an increased risk of loosening. Bioactive materials show better performance in fixation to bone, and the chemical bonding depends on bone-like apatite formation. This is triggered by surface reactions with body fluid. For these reactions, superficial functional groups like silanol (Si-OH) are ideal sites to induce apatite nucleation and the release of Ca(2+) ions accelerates the apatite growth. Therefore, incorporation of materials containing these key components may provide the cement with apatite-forming ability. In this study, phosphoric acid 2-hydroxyethyl methacrylate ester or bis[2-(methacryloyloxy)ethyl] phosphate supplying a phosphate group (PO4H2) was added into methylmethacrylate liquid, while calcium acetate as a source of Ca(2+) ions was mixed into polymethylmethacrylate powder. The influences of the combinations on the setting time and compressive strength were also investigated. Apatite was formed on the cements modified with 30 mass% of phosphoric acid 2-hydroxyethyl methacrylate ester or bis[2-(methacryloyloxy)ethyl] phosphate. The induction period was shortened with increased amounts of Ca(CH3COO)2. The setting time could be controlled by the Ca(CH3COO)2/monomer mass ratio. Faster setting was achieved at a ratio close to the mixing ratio of the powder/liquid (2:1), and both increases and decreases in the amount of Ca(CH3COO)2 prolonged the setting time based on this ratio. The highest compressive strength was 88.8?±?2.6?MPa, higher than the lowest limit of ISO 5833 but was lower than that of the simulated body fluid-soaked reference. The increase of additives caused the decline in compressive strength. In view of balancing apatite formation and clinical standard, bis[2-(methacryloyloxy)ethyl] phosphate is more suitable as an additive, and the optimal modification is a combination of 30 mass% of bis[2-(methacryloyloxy)ethyl] phosphate and 20 mass% of Ca(CH3COO)2. PMID:25568169

Liu, Jinkun; Shirosaki, Yuki; Miyazaki, Toshiki

2015-04-01

393

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

2010-01-01

394

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

2012-01-01

395

Calcium phosphate based three-dimensional cold plotted bone scaffolds for critical size bone defects.  

PubMed

Bone substitutes, like calcium phosphate, are implemented more frequently in orthopaedic surgery to reconstruct critical size defects, since autograft often results in donor site morbidity and allograft can transmit diseases. A novel bone cement, based on ?-tricalcium phosphate, polyethylene glycol, and trisodium citrate, was developed to allow the rapid manufacturing of scaffolds, by extrusion freeform fabrication, at room temperature. The cement composition exhibits good resorption properties and serves as a basis for customised (e.g., drug or growth factor loaded) scaffolds for critical size bone defects. In vitro toxicity tests confirmed proliferation and differentiation of ATDC5 cells in scaffold-conditioned culture medium. Implantation of scaffolds in the iliac wing of sheep showed bone remodelling throughout the defects, outperforming the empty defects on both mineral volume and density present in the defect after 12 weeks. Both scaffolds outperformed the autograft filled defects on mineral density, while the mineral volume present in the scaffold treated defects was at least equal to the mineral volume present in the autograft treated defects. We conclude that the formulated bone cement composition is suitable for scaffold production at room temperature and that the established scaffold material can serve as a basis for future bone substitutes to enhance de novo bone formation in critical size defects. PMID:24719891

Bergmann, Christian J D; Odekerken, Jim C E; Welting, Tim J M; Jungwirth, Franz; Devine, Declan; Bouré, Ludovic; Zeiter, Stephan; van Rhijn, Lodewijk W; Telle, Rainer; Fischer, Horst; Emans, Pieter J

2014-01-01

396

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: Frank.Mueller@ww.uni-erlangen.de

2007-06-05

397

Human bone marrow stem cell-encapsulating calcium phosphate scaffolds for bone repair  

PubMed Central

Due to its injectability and excellent osteoconductivity, calcium phosphate cement (CPC) is highly promising for orthopedic applications. However, a literature search revealed no report on human bone marrow mesenchymal stem cell (hBMSC) encapsulation in CPC for bone tissue engineering. The aim of this study was to encapsulate hBMSCs in alginate hydrogel beads and then incorporate them into CPC, CPC–chitosan and CPC–chitosan–fiber scaffolds. Chitosan and degradable fibers were used to mechanically reinforce the scaffolds. After 21 days, that the percentage of live cells and the cell density of hBMSCs inside CPC-based constructs matched those in alginate without CPC, indicating that the CPC setting reaction did not harm the hBMSCs. Alkaline phosphate activity increased by 8-fold after 14 days. Mineral staining, scanning electron microscopy and X-ray diffraction confirmed that apatitic mineral was deposited by the cells. The amount of hBMSC-synthesized mineral in CPC–chitosan–fiber matched that in CPC without chitosan and fibers. Hence, adding chitosan and fibers, which reinforced the CPC, did not compromise hBMSC osteodifferentiation and mineral synthesis. In conclusion, hBMSCs were encapsulated in CPC and CPC–chitosan–fiber scaffolds for the first time. The encapsulated cells remained viable, osteodifferentiated and synthesized bone minerals. These self-setting, hBMSC-encapsulating CPC-based constructs may be promising for bone tissue engineering applications. PMID:20451676

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

2010-01-01

398

Investigation of silicon complexes in Si-doped calcium phosphate bioceramics  

NASA Astrophysics Data System (ADS)

Silicon doped calcium phosphate materials have drawn great interest as bioceramics for bone repair due to their enhanced bioactivity. However, the low level of doping in these materials, generally ˜1 wt.%, makes it difficult to determine the effects the silicon has on the structure of these materials. In this study, silicon substituted hydroxyapatite (Si-HA), silicon stabilized alpha tricalcium phosphate (Si-TCP), and a multi-phase mixture consisting of approximately 75% Si-TCP with the remainder being mainly Si-HA have been synthesized using isotopically enriched silica containing ^29Si. ^29Si magic-angle spinning nuclear magnetic resonance spectroscopy (MAS-NMR) has been used to examine the silicon complexes within these materials resulting from the substitution of SiO4^4- for PO4^3- and the required charge compensation mechanism needed to achieve this. Previous ab initio studies on these materials have investigated charge compensation mechanisms to suggest possible silicon complexes and these serve as a basis for interpreting the NMR results.

Gillespie, P.; Stott, M. J.; Sayer, M.; Wu, G.

2007-03-01

399

In situ synthesis of silicon-substituted biphasic calcium phosphate and their performance in vitro  

NASA Astrophysics Data System (ADS)

In situ preparation of silicon (Si) substituted biphasic calcium phosphate (BCP) of hydroxyapatite (HAp)/ ?-tricalcium phosphate (?-TCP) were carried out through aqueous co-precipitation method. The concentrations of added silicon were varied with the phosphor in order to obtain constant Ca/(P+Si) ratios of 1.602. X-ray diffraction (XRD) and Fourier transformed infrared (FTIR) spectroscopy were used to characterize the structure of synthesized silicon substituted BCP powders. The characterization revealed that the formation of biphasic mixtures of different HAp/ ?-TCP ratios was dependent on the content of silicon. After immersing in Hanks' balanced salt solution (HBSS) for 1 week, 3 wt% silicon substituted BCP powders were degraded and precipitation started to be formed with small granules consisting of number of flake-like crystal onto the surface of synthesized powders. In the case of 1 wt% silicon substituted BCP powders, the degradation behavior was detected after immersion in HBSS for 3 weeks. On the other hand, silicon unsubtituted BCP powders were not degraded even after that duration. On the basis of these results, silicon substituted BCP is able to develop a new apatite phase on the surface in contact with physiological fluids faster than BCP does. This enhanced reactivity resulted in reduction for the stability of the ?-TCP structure due to SiO4 tetrahedral distortion and disorder at the hydroxyl site when silicon incorporates into BCP.

Song, Chang-Weon; Kim, Tae-Wan; Kim, Dong-Hyun; Jin, Hyeong-Ho; Hwang, Kyu-Hong; Lee, Jong Kook; Park, Hong-Chae; Yoon, Seog-Young

2012-01-01

400

Bacterially produced calcium phosphate nanobiominerals: sorption capacity, site preferences, and stability of captured radionuclides.  

PubMed

A Serratia sp. bacterium manufactures amorphous calcium phosphate nanominerals (BHAP); this material has shown increased sorption capacity for divalent radionuclide capture. When heat-treated (?450 °C) the cell biomass is removed and the biominerals are transformed to hydroxyapatite (HAP). Using a multimethod approach, we have elucidated both the site preferences and stability of analogue radionuclide incorporation for Sr, Co, Eu, and U. Strontium incorporates within the bulk amorphous inorganic phase of BHAP; however, once temperature modified to crystalline HAP, bonding was consistent with Sr substitution at the Ca(1) and/or Ca(2) sites. Cobalt incorporation occurs within the bulk inorganic amorphous phase of BHAP and within the amorphous grain boundaries of HAP. Europium (an analogue for trivalent actinides) substituted at the Ca(2) and/or the Ca(3) position of tricalcium phosphate, a known component of HAP grain boundaries. Uranium was surface complexed with no secondary minerals detected. With multiple sites for targeted radionuclide incorporation, high loadings, and good stability against remobilization, BHAP is shown to be a potential material for the remediation of aqueous radionuclide in groundwater. PMID:24823240

Handley-Sidhu, S; Hriljac, J A; Cuthbert, M O; Renshaw, J C; Pattrick, R A D; Charnock, J M; Stolpe, B; Lead, J R; Baker, S; Macaskie, L E

2014-06-17

401

Calcium Phosphate Based Three-Dimensional Cold Plotted Bone Scaffolds for Critical Size Bone Defects  

PubMed Central

Bone substitutes, like calcium phosphate, are implemented more frequently in orthopaedic surgery to reconstruct critical size defects, since autograft often results in donor site morbidity and allograft can transmit diseases. A novel bone cement, based on ?-tricalcium phosphate, polyethylene glycol, and trisodium citrate, was developed to allow the rapid manufacturing of scaffolds, by extrusion freeform fabrication, at room temperature. The cement composition exhibits good resorption properties and serves as a basis for customised (e.g., drug or growth factor loaded) scaffolds for critical size bone defects. In vitro toxicity tests confirmed proliferation and differentiation of ATDC5 cells in scaffold-conditioned culture medium. Implantation of scaffolds in the iliac wing of sheep showed bone remodelling throughout the defects, outperforming the empty defects on both mineral volume and density present in the defect after 12 weeks. Both scaffolds outperformed the autograft filled defects on mineral density, while the mineral volume present in the scaffold treated defects was at least equal to the mineral volume present in the autograft treated defects. We conclude that the formulated bone cement composition is suitable for scaffold production at room temperature and that the established scaffold material can serve as a basis for future bone substitutes to enhance de novo bone formation in critical size defects. PMID:24719891

Bergmann, Christian J. D.; Odekerken, Jim C. E.; Welting, Tim J. M.; Jungwirth, Franz; Devine, Declan; Bouré, Ludovic; Zeiter, Stephan; van Rhijn, Lodewijk W.; Telle, Rainer; Fischer, Horst; Emans, Pieter J.

2014-01-01

402

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

PubMed

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

2009-04-15

403

Injectable Calcium Phosphate Cement: Effects of Powder-to-Liquid Ratio and Needle Size  

PubMed Central

Calcium phosphate cement (CPC) sets in situ and forms apatite with excellent osteoconductivity and bone-replacement capability. The objectives of this study were to formulate an injectable tetracalcium phosphate-dicalcium phosphate cement (CPCD), and investigate the powder/liquid ratio and needle-size effects. The injection force (mean ± SD; n = 4) to extrude the paste increased from (8 ± 2) N using a 10-gauge needle to (144 ± 17) N using a 21-gauge needle (p < 0.05). With the 10-gauge needle, the mass percentage of extruded paste was (95 ± 4)% at a powder/liquid ratio of 3; it decreased to (70 ± 12)% at powder/liquid = 3.5 (p < 0.05). A relationship was established between injection force, F, and needle lumen cross-sectional area, A: F = 5.0 + 38.7/A0.8. Flexural strength, S, (mean ± SD; n = 5) increased from (5.3 ± 0.8) MPa at powder/liquid = 2 to (11.0 ± 0.8) MPa at powder/liquid = 3.5 (p < 0.05). Pore volume fraction, P, ranged from 62.4% to 47.9%. A relationship was established: S = 47.7 × (1 - P)2.3. The strength of the injectable CPCD matched/exceeded the reported strengths of sintered porous hydroxyapatite implants that required machining. The novel injectable CPCD with a relatively high strength may be useful in filling defects with limited accessibility such as periodontal repair and tooth root-canal fillings, and in minimally-invasive techniques such as percutaneous vertebroplasty to fill the lesions and to strengthen the osteoporotic bone. PMID:17635038

Burguera, Elena F.; Sun, Limin

2009-01-01

404

Synthesis, characterization and antimicrobial activity of the micro/nano structured biogenic silver doped calcium phosphate  

NASA Astrophysics Data System (ADS)

Scale formation in PVC pipelines reduces the water flow efficiency and enhances microbial contamination. A bio-based composite material comprising of silver doped calcium phosphate (Cp-Ag) was synthesized using a simple technique (photo catalysis) and herein, we report for the first time on preparation and evaluation of the antimicrobial efficacy of silver doped calcite extracted from the scale in drinking water pipe lines. Five concentrations of silver doped calcite materials viz,5, 10, 15, 20 and 25 ppm were prepared using chemical ammonia mediated synthetic method. The material Cp-Ag was characterized by using the techniques UV-Visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Scanning electron microscopy, Raman spectroscopy, Thermo gravimetric analysis, X-ray photo electron spectroscopy (XPS), Nuclear magnetic resonance spectrometer and X-ray flouresence microscopy (XRF). Typical rhombohedral structure of the silver doped calcite was observed. XRF and XPS studies confirmed the presence of both calcium and silver in the composite material (Cp-Ag). The silver doped calcite material exhibited enhanced inhibition against Escherichia coli and staphylococcus aureus (Kirby-Bauer discs diffusion assay) which is also dependent on the concentration of the Cp-Ag material.

Supraja, N.; Prasad, T. N. V. K. V.; David, Ernest

2015-02-01

405

Odontogenic Differentiation of Human Dental Pulp Stem Cells Stimulated by the Calcium Phosphate Porous Granules  

PubMed Central

Effects of three-dimensional (3D) calcium phosphate (CaP) porous granules on the growth and odontogenic differentiation of human dental pulp stem cells (hDPSCs) were examined for dental tissue engineering. hDPSCs isolated from adult human dental pulps were cultured for 3-4 passages, and populated on porous granules. Cell growth on the culture dish showed an ongoing increase for up to 21 days, whereas the growth on the 3D granules decreased after 14 days. This reduction in proliferative potential on the 3D granules was more conspicuous under the osteogenic medium conditions, indicating that the 3D granules may induce the odontogenic differentiation of hDPSCs. Differentiation behavior on the 3D granules was confirmed by the increased alkaline phosphatase activity, up-regulation of odontoblast-specific genes, including dentin sialophosphoprotein (DSPP) and dentin matrix protein 1 (DMP1) by quantitative polymerase chain reaction, and greater level of dentin sialoprotein synthesis by western blot. Moreover, the cellular mineralization, as assessed by Alizarin red S and calcium quantification, was significantly higher in the 3D CaP granules than in the culture dish. Taken all, the 3D CaP porous granules should be useful for dental tissue engineering in combination with hDPSCs by providing favorable 3D substrate conditions for cell growth and odontogenic development. PMID:21772958

Nam, Sunyoung; Won, Jong-Eun; Kim, Cheol-Hwan; Kim, Hae-Won

2011-01-01

406

Initial deposition of calcium phosphate ceramic on polystyrene and polytetrafluoroethylene by rf magnetron sputtering deposition  

NASA Astrophysics Data System (ADS)

Calcium phosphate (CaP) coatings can be applied to improve the biological performance of polymeric medical implants. A strong interfacial bond between ceramic and polymer is required for clinical applications. Because the chemical structure of an interface plays an important role in the adhesion of a coating, we studied the formation of the interface between CaP and polystyrene (PS) and polytetrafluoroethylene (PTFE). The coating was deposited in a radio frequency (rf) magnetron sputtering deposition system. Prior to the deposition, some samples received an oxygen plasma pretreatment. We found that the two substrates show a strongly different reactivity towards CaP. On PS a phosphorus and oxygen enrichment is present at the interface. This is understood from POx complexes that are able to bind to the PS. The effects of the plasma pretreatment are overruled by the deposition process itself. On PTFE, a calcium enrichment and an absence of phosphorus is found at the interface. The former is the result of CaF2-like material being formed at the interface. The latter may be the result of phosphorus reacting with escaping fluorine to a PF3 molecule, which than escapes from the material as a gas molecule. We found that the final structure of the interface is mostly controlled by the bombardment of energetic particles escaping either from the plasma or from the sputtering target. The work described here can be used to understand and improve the adhesion of CaP coatings deposited on medical substrates.

Feddes, B.; Wolke, J. G. C.; Jansen, J. A.; Vredenberg, A. M.

2003-03-01

407

Incorporation of biphasic calcium phosphate microparticles in injectable thermoresponsive hydrogel modulates bone cell proliferation and differentiation.  

PubMed

To provide osteoblast cells with a three-dimensional environment closer to bone matrix, an engineered construct mimicking bone components have been designed and evaluated. A biocompatible injectable thermo-responsive hydrogel, hyaluronic acid-g-chitosan-g-poly (N-isopropylacrylamide) (HA-CPN), was used as a biomimetic organic gel matrix while embedded biphasic calcium phosphate (BCP) ceramic micoparticles were used to replace mineralized matrix. The physicochemical properties of HA-CPN/BCP hydrogel composite were characterized by X-ray diffraction, thermogravimeric analysis, differential scanning calorimetric, and Fourier transform infrared spectroscopy. Human fetal osteoblast cells were cultured in vitro in HA-CPN and HA-CPN/BCP scaffold to study cell viability, proliferation, gene expression, and maintenance of their osteoblastic differential potentials. Overall, HA-CPN/BCP can serve as a better injectable carrier for bone cells than HA-CPN with enhanced proliferation rate and alkaline phosphatase activity from biochemical assays, improved calcium deposition and mineralization of extracellular matrix by histological examinations, and elevated gene expression of all essential osteoblastic genes from quantitative real-time PCR, to provide a cell/scaffold construct with higher mechanical strength and elasticity. From in vivo nude mice subcutaneous implantation experiments, the injected cell mass can form ectopic bone tissue in HA-CPN/BCP hydrogel composite. PMID:23711782

Chen, Jyh-Ping; Tsai, Ming-Jin; Liao, Han-Tsung

2013-10-01

408

Dissolution behavior and early bone apposition of calcium phosphate-coated machined implants  

PubMed Central

Purpose Calcium phosphate (CaP)-coated implants promote osseointegration and survival rate. The aim of this study was to (1) analyze the dissolution behavior of the residual CaP particles of removed implants and (2) evaluate bone apposition of CaP-coated machined surface implants at the early healing phase. Methods Mandibular premolars were extracted from five dogs. After eight weeks, the implants were placed according to drilling protocols: a nonmobile implant (NI) group and rotational implant (RI) group. For CaP dissolution behavior analysis, 8 implants were removed after 0, 1, 2, and 4 weeks. The surface morphology and deposition of the coatings were observed. For bone apposition analysis, block sections were obtained after 1-, 2-, and 4-week healing periods and the specimens were analyzed. Results Calcium and phosphorus were detected in the implants that were removed immediately after insertion, and the other implants were composed mainly of titanium. There were no notable differences between the NI and RI groups in terms of the healing process. The bone-to-implant contact and bone density in the RI group showed a remarkable increase after 2 weeks of healing. Conclusions It can be speculated that the CaP coating dissolves early in the healing phase and chemically induces early bone formation regardless of the primary stability. PMID:24455442

Hwang, Ji-Wan; Lee, Eun-Ung; Lee, Jung-Seok; Jung, Ui-Won; Lee, In-Seop

2013-01-01

409

CALCIUM PHOSPHATE GRANULES IN THE HEPATOPANCREAS OF THE BLUE CRAB CALLINECTES SAPIDUS  

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.

1974-01-01

410

Calcium phosphate granules in the hepatopancreas of the blue crab Callinectes sapidus.  

PubMed

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 microg-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 microm 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 degrees C, only 10% more was lost upon dry ashing at 450 degrees 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 microg-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 micromol/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, G L; Chen, C H; Greenawalt, J W; Lehninger, A L

1974-05-01

411

Block copolymer-coated calcium phosphate nanoparticles sensing intracellular environment for oligodeoxynucleotide and siRNA delivery.  

PubMed

The organic-inorganic hybrid nanoparticles entrapping oligodeoxynucleotide (ODN) or siRNA were prepared through the self-associating phenomenon of the block copolymer, poly(ethylene glycol)-block-poly(aspartic acid) (PEG-PAA), with calcium phosphate. The nanoparticles have diameters in the range of several hundreds of nanometers depending on the PEG-PAA concentration and revealed excellent colloidal stability due to the steric repulsion effect of the PEG layer surrounding the calcium phosphate core. The loading capacities of ODN and siRNA were fairly high, reaching almost 100% under optimal conditions. The flowcytometric analysis and confocal microscopy observation indicated that the hybrid nanoparticles loaded with ODN were taken up by the cells through the endocytosis mechanism. Furthermore, the calcium phosphate core dissociates in the intracellular environment with appreciably lowered calcium ion concentration compared to the exterior, allowing the release of the incorporated ODN and siRNA in a controlled manner. Eventually, effective intracellular delivery and nuclear localization of these nucleic acid-based drugs were evidenced through the observation of laser confocal microscopy using FITC-labeled ODN. This smart ion-sensitive characteristic of hybrid nanoparticles was further demonstrated by the appreciable silencing of reporter gene expression by siRNA incorporated in the nanoparticles. PMID:15196761

Kakizawa, Yoshinori; Furukawa, Sanae; Kataoka, Kazunori

2004-06-18

412

An in vitro investigation of the mechanical-chemical and biological properties of calcium phosphate/calcium silicate/bismutite cement for dental pulp capping.  

PubMed

The properties of new calcium phosphate/calcium silicate/bismutite (CPCSBi) cement were compared with those of calcium hydroxide (CH) and Dycal cements in dental pulp-capping applications. CPCSBi is composed of hydroxyapatite, tetracalcium phosphate, bismutite, and calcium silicate, which was analyzed by SEM, FTIR, and XRD. The results of ion release from CPCSBi showed that the concentrations of Bi(3+), Ca(2+), PO4(2-), and Si(4+) increased with time in deionized water solutions. The setting time of CPCSBi and Dycal was 13 min 50 s and 2 min 25 s, respectively. There were no statistical differences in compressive strength and solubility between CPCSBi and Dycal (p > 0.05). The pH of CPCSBi (10.9) was lower than that of CH (11.6) and Dycal (12.5) after immersion for 24 h. Only slight cytotoxicity appeared for CPCSBi, whereas both CH and Dycal produced moderate discoloration and lysis. In antimicrobial tests against Sm, Av, La, and Sa, the antimicrobial potency of the CPCSBi was approximately 5-10 times greater than that of Dycal and CH groups. The dissoluble dentin matrix components (DDMCs) extracted from CPCSBi exposed to dentin powder demonstrated increased expression of dentin sialophosphoprotein (DSPP) and soteocalcin (OCN) dramatically in human pulp cells by RT-PCR. These results suggest that CPCSBi will be a good candidate for use as a dental pulp-capping agent in future. PMID:20524188

Shen, Qingyi; Sun, Jiao; Wu, Jie; Liu, Changsheng; Chen, Fangping

2010-07-01

413

The effect of tri-calcium phosphate (TCP) addition on the degradation of polylactide-co-glycolide (PLGA)  

Microsoft Academic Search

This paper investigates the effects of ?-tri-calcium phosphate (?-TCP) addition on the properties of polylactide-co-glycolide\\u000a (PLGA). Samples with additions of 5, 10, 15, 20, 30 and 40 wt% ?-TCP were prepared via a hotpressing method. Long-term in vitro\\u000a studies (up to 60 days) were carried out in pH 7.4 phosphate-buffered saline (PBS). Degradation properties were investigated\\u000a by monitoring pH, water uptake and mass

Lisa Maria Ehrenfried; Munnawwar H. Patel; Ruth E. Cameron

2008-01-01

414

Prospective study of standalone balloon kyphoplasty with calcium phosphate cement augmentation in traumatic fractures  

PubMed Central

Prospective consecutive series cases study to investigate the clinical and radiological results of standalone balloon kyphoplasty and cement augmentation with calcium phosphate in traumatic fractures. Independent observer evaluation of radiological and computer tomography results, visual analogue scale (VAS), Roland–Morris score and complications with acute traumatic compression fractures type A, treated with a standalone balloon kyphoplasty and cement augmentation with calcium phosphate (Calcibon™); follow-up time at a mean of 30 months (24–37 months). From August 2002 to August 2003, consecutive patients with traumatic compression fractures (Magerl type A) without neurological deficit underwent standalone kyphoplasty with Calcibon. We report here the pre-, post-operative and the follow-up results, applying the VAS (0–10) for pain rating, the Roland–Morris (0–24) disability score, CT-scan examination, detailed radiographic evaluation of vertebral body (VB) deformity and segmental kyphosis measurement. The pre-operative X-ray measurements, VAS and the 7 days Roland–Morris scores are compared with the post-operative and the 30 months follow-up findings. Twenty-eight patients with 33 treated fracture levels were included in this study. The mean initial vertebral deformity (VB kyphosis) was 17°, corrected to a post-operative of 6°. We noted a loss of correction at the follow-up in comparison to the post-operative standing X-ray at 24 h of 3° vertebral deformity and 3° segmental kyphosis. The VAS score demonstrates a decrease over time from a mean of 8.7–3.1 at 7 days and to 0.8 at the last follow-up. The Roland–Morris disability score demonstrates a similar improvement. We noticed no major complications related to the procedure. The mean cement resorption after 1 year was 20.3% (0.3–35.3%) and is related to the individual biological resorption process and is not predictable. All patients with vertebral fractures as sole medical problem were discharged within 48 h. All active patients returned to the same work within 3 months with the same working ability as before the accident. Standalone balloon kyphoplasty is a potential alternative mini-invasive technique to reduce the fractures. However, due to the intrinsic characteristic of calcium phosphate cement (Calcibon) we recommend the application of this biological cement for standalone reduction and stabilisation only in fractures type A1 and A3.1 in young patient. In case of higher destruction levels of the VB, we propose the utilisation of Calcibon associated with posterior instrumentation. Having regard to the pointed out indications, our preliminary results demonstrate a new possibility to treat this kind of fractures, allowing a rapid handling of pain, early discharge and return to normal activities. PMID:17120071

Cremer, Claus; Otten, Philippe; Jakob, Roland Peter

2006-01-01

415

Restoration of parathyroid function after change of phosphate binder from calcium carbonate to lanthanum carbonate in hemodialysis patients with suppressed serum parathyroid hormone.  

PubMed

Control of phosphate is the most critical in the treatment of chronic kidney disease with mineral and bone disorder (CKD-MBD). Because calcium-containing phosphate binder to CKD patients is known to induce adynamic bone disease with ectopic calcification by increasing calcium load, we examined the effect of lanthanum carbonate (LaC), a non-calcium containing phosphate binder, to restore bone turnover in 27 hemodialysis patients with suppressed parathyroid function (serum intact parathyroid hormone [iPTH] ? 150 pg/mL). At the initiation of LaC administration, the dose of calcium-containing phosphate binder calcium carbonate (CaC) was withdrawn or reduced based on serum phosphate. After initiation of LaC administration, serum calcium and phosphate decreased significantly by 4 weeks, whereas whole PTH and iPTH increased. A significant and positive correlation between decreases of serum calcium, but not phosphate, with increases of whole PTH and iPTH, suggested that the decline in serum calcium with reduction of calcium load by LaC might increase parathyroid function. Serum bone resorption markers, such as serum tartrate-resistant acid phosphatase 5b, and N-telopeptide of type I collagen increased significantly by 4 weeks after LaC administration, which was followed by increases of serum bone formation markers including serum bone alkaline phosphatase, intact procollagen N-propeptide, and osteocalcin. Therefore, it was suggested that LaC attenuated CaC-induced suppression of parathyroid function and bone turnover by decreasing calcium load. In conclusion, replacement of CaC with LaC, either partially or totally, could increase parathyroid function and resultant bone turnover in hemodialysis patients with serum iPTH ? 150 pg/mL. PMID:25556148

Inaba, Masaaki; Okuno, Senji; Nagayama, Harumi; Yamada, Shinsuke; Ishimura, Eiji; Imanishi, Yasuo; Shoji, Shigeichi

2015-03-01

416

Casein Phosphopeptide-Amorphous Calcium Phosphate and Shear Bond Strength of Adhesives to Primary Teeth Enamel  

PubMed Central

Background: CPP-ACP (Phosphopeptide-Amorphous Calcium Phosphate) has an important role in caries prevention in pediatric patients. This study was done, because of the great use of CPP-ACP and the need for restoration for teeth treated with CPP-ACP as well as the importance of shear bond strength of adhesives in the success of restorations. Objectives: This study aimed to evaluate the effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on shear bond strength of dental adhesives to enamel of primary teeth molars. Materials and Methods: This in vitro study was conducted on 180 extracted primary molars. They were randomly divided into 6 groups and each group was divided into 2 subgroups (treated with CPP-ACP and untreated). In subgroups with CPP-ACP, enamel was treated with CPP-ACP paste 1 h/d for 5 days. Types of adhesives that were evaluated in this study were Tetric N-Bond, AdheSE, AdheSE One F, single Bond 2, SE Bond, and Adper Prompt L-Pop. Shear bond strength was tested with a universal testing machine and mode of failure was evaluated under stereomicroscope. Data were analyzed by T test, 2-way analysis of variance (ANOVA), Tukey and Fisher exact test using SPSS18. P < 0.05 was considered as significance level. Results: Shear bond strengths of different adhesive systems to enamel of primary teeth treated and untreated with CPP-ACP showed no significant difference (P > 0.05). Mode of failure in all groups regardless of CPP-ACP administration was mainly adhesive type. Our results indicated that CPP-ACP did not affect shear bond strength of studied adhesives to primary teeth enamel. Conclusions: To have a successful and durable composite restoration, having a high strength bonding is essential. Considering the wide use of CPP-ACP in preventing tooth decay and the role of adhesive shear bond strength (SBS) in success of composite restoration, we conducted the present study to evaluate the effect of CPP-ACP on the SBS of adhesives to primary teeth enamel. PMID:25793113

Farokh Gisovar, Elham; Hedayati, Nassim; Shadman, Niloofar; Shafiee, Leila

2015-01-01

417

Reinforcement of a self-setting calcium phosphate cement with different fibers.  

PubMed

A water-based calcium phosphate cement (CPC) has been used in a number of medical and dental procedures due to its excellent osteoconductivity and bone replacement capability. However, the low tensile strength of CPC prohibits its use in many unsupported defects and stress-bearing locations. Little investigation has been carried out on the fiber reinforcement of CPC. The aims of the present study, therefore, were to examine whether fibers would strengthen CPC, and to investigate the effects of fiber type, fiber length, and volume fraction. Four different fibers were used: aramid, carbon, E-glass, and polyglactin. Fiber length ranged from 3-200 mm, and fiber volume fraction ranged from 1.9-9.5%. The fibers were mixed with CPC paste and placed into molds of 3 x 4 x 25 mm. A flexural test was used to fracture the set specimens and to measure the ultimate strength, work-of-fracture, and elastic modulus. Scanning electron microscopy was used to examine specimen fracture surfaces. Fiber type had significant effects on composite properties. The composite ultimate strength in MPa (mean +/- SD; n = 6) was (62+/-16) for aramid, (59+/-11) for carbon, (29+/-8) for E-glass, and (24+/-4) for polyglactin, with 5.7% volume fraction and 75 mm fiber length. In comparison, the strength of unreinforced CPC was (13+/-3). Fiber length also played an important role. For composites containing 5.7% aramid fibers, the ultimate strength was (24+/-3) for 3 mm fibers, (36+/-13) for 8 mm fibers, (48 +/-14) for 25 mm fibers, and (62+/-16) for 75 mm fibers. At 25 mm fiber length, the ultimate strength of CPC composite was found to be linearly proportional to fiber strength. In conclusion, a self-setting calcium phosphate cement was substantially strengthened via fiber reinforcement. Fiber length, fiber volume fraction, and fiber strength were found to be key microstructural parameters that controlled the mechanical properties of CPC composites. PMID:10906680

Xu, H H; Eichmiller, F C; Giuseppetti, A A

2000-10-01

418

EFFECT OF ACTIVE ACCUMULATION OF CALCIUM AND PHOSPHATE IONS ON THE STRUCTURE OF RAT LIVER MITOCHONDRIA.  

PubMed

Rat liver mitochondria allowed to accumulate maximal amounts of Ca(++) and HPO(4) (=) ions from the suspending medium in vitro during respiration have a considerably higher specific gravity than normal mitochondria and may be easily separated from the latter by isopycnic centrifugation in density gradients of sucrose or cesium chloride. When the mitochondria are allowed to accumulate less than maximal amounts of Ca(++) and HPO(4) (=) from the medium, they have intermediate specific gravities which are roughly proportional to their content of calcium phosphate. Maximally "loaded" mitochondria are relatively homogeneous with respect to specific gravity. Correlated biochemical and electron microscopic studies show that Ca(++)-loaded mitochondria contain numerous dense granules, of which some 85 per cent are over 500 A in diameter. These granules are electron-opaque not only following fixation and staining with heavy metal reagents, but also following fixation with formaldehyde, demonstrating that the characteristic granules in Ca(++)-loaded mitochondria have intrinsic electron-opacity. The dense granules are almost always located within the inner compartment of the mitochondria and not in the spac