biomat ériaux biomateriaux · 2010. 11. 4. · chapitre3 prothèse de hanche - apatite- 31082010 -...

Chapitre3 Prothèse de hanche - Apatite- 31082010 - 1 -

BIOMATERIAUX

Chapitre 3 – Apatite

Science des mat ériauxTechniques de

caractérisation

Médecine

Biomat ériaux

D. Bazin

Laboratoire de Physique des Solides UMR 8502,

Université Paris Sud, Bât 510 91405 Orsay Cedex, France.

Chapitre3 Prothèse de hanche - Apatite- 31082010

2

Chapitre 3 Apatite

Partie A Quelques généralités sur l’os

Partie B Propriétés physicochimiques

Partie C La diffraction des rayons X

Partie D Les cations

Partie E Quelques études sur des phosphates de calcium proches de

l’apatite p 131 Chapitre 2E.1 Influence des oligoéléments sur les transformations de phase

p 135 Chapitre 2E.2 L’ octacalcium phosphate – OCP

p 138 Chapitre 2E.3 Nouvel OCP ?

p 142 Chapitre 2E.4 nouvelles morphologies pour l’OCP

Partie F Quelques études sur des échantillons biologiques P147 Chapitre 2F.1 Répartition spatiale du strontium dans l’os

P150 Chapitre 2F.2 Répartition du strontium à l’interface os-cartilage

P153 Chapitre 2F.3 Le cas du gallium

P 158 Chapitre 2F.4 Diffraction de neutrons et résorption d’une fracture

Chapitre 2F.5 localisation du zinc dans des apatites biologiques


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Chapitre 2E Les phosphates de calciums proches de l’apatite

Amorphous materials represent about 25% of the minerals formed under

the induction or control of living organisms1. Among these amorphous minerals

are those that have similar chemical composition with different degrees of short-

range order2,3. Amorphous calcium phosphates (ACP) have been widely

regarded as the metastable precursor phase for the subsequent formation of

thermodynamically more stable calcium phosphate phases such as octacalcium

phosphate (OCP) and hydroxyapatite (HAP) depending on the pH value of the

solution4,5,6.

- Le cas du phosphate amorphe de calcium7

- Sr & octacalcium phosphate - OCP8

- Collapsed Octacalcium Phosphate Stabilized by Ionic Substitutions

1. Weiner, S.; Dove, P. M. ReV. Mineral. Geochem. 2003, 54, 1–29.

2. Posner, A. S.; Betts, F. Acc. Chem. Res. 1975, 8, 273–281.

3. Betts, F.; Blumenthal, N. C.; Posner, A. S.; Becker, G. L.; Lehninger, A. L. Proc. Natl.

Acad. Sci. U.S.A. 1975, 72, 2088–2090.

4. Abbona, F.; Baronnet, A. J. Cryst. Growth 1996, 165, 98–105.

5. Tung, M. S.; Brown, W. E. Calcif. Tissue Int. 1983, 35, 783–790.

6. Brecevic, Lj.; F. .uredi-Milhofer, H. Calcif. Tissue Int. 1972, 10, 82–90.

7. Tao al., Evolution of Amorphous Calcium Phosphate to Hydroxyapatite Probed by Gold

Nanoparticles, J. Phys. Chem. C 2008, 112, 14929–14933.

8. K. Matsunaga et al., Sr Substitution in Bioactive Calcium Phosphates : A first principles

study, J. Phys. Chem. B 2009, 113, 3584–3589


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Chapitre 2E.1 Influence des oligoéléments sur les transformations de phase9

Calcium hydrogen phosphate dihydrate, CaHPO4, 2H2O, known as the

rare mineral brushite, is a metastable compound which is normally observed as

the primary crystalline product, when calcium phosphate is precipitated at low

pH and low temperature10

,11

.

Brushite, forming tabular crystals, has been precipitated at 25°C in the

presence of each of 14 different di- and trivalent metal ions. The influence of

these ions at micromolar concentrations on the solvent-mediated phase

transformation of brushite to more basic calcium phosphates has been studied as

well. The effect of additives on brushite crystallization was pH-dependent,

which could be related to the presence or absence of amorphous precipitate. In

the latter case the course of the crystallization process could be followed by

recording pH as function of time.

Most of the ions have a marked effect on the transformation to

octacalcium phosphate (OCP) and hydroxyapatite (HAP) as well.

- Cu(II) and Zn are strong inhibitors,

- whereas Pb(II) is a moderate promotor.

9. H. E. Lundager-Madsen, Influence of foreign metal ions on crystal growth and morphology

of brushite (CaHPO4, 2H2O) and its transformation to octacalcium phosphate and apatiteJ. of

Crystal Growth 310 (2008) 2602-2612.

10. H.E. Lundager Madsen, G. Thorvardarson, J. Crystal Growth 66 (1984) 369.

11. F. Abbona, H.E. Lundager Madsen, R. Boistelle, J. Crystal Growth 74 (1986) 581.


5

Chapitre 2E.2 Le cas du phosphate amorphe de calcium12

Gold nanoparticles are used as ex-situ probes to monitor the detailed

evolution process of ACP in vitro.

12. Tao al., Evolution of Amorphous Calcium Phosphate to Hydroxyapatite Probed by Gold

Nanoparticles, J. Phys. Chem. C 2008, 112, 14929–14933.


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La synthèse est suivie par T.E.M.

Figure 3. TEM images of calcium phosphates at different intervals in the

presence of gold nanoparticles. (A-C) Gold nanoparticles were immersed into

calcium phosphates.

(A) 16 min;

(B) 5 h;

(C) 12 h.

(D-F) Gold nanoparticles were loaded on the surface of ACP

microspheres.

Par comparaison : Clearly, Au NPs hadn’t changed the pathway of

transformation phenomenologically as the morphologies and phases at different

stages were similar in the presence and absence of gold probes.


7

Conclusion :

- The HAP nanoneedles first formed at the ACP-solution interface and

extended outward radially.

- The ACP microsphere provides a template and nutrient for the growth

and assembly of HAP nanoneedles.

This study shows that the involvement of gold nanoparticles can provide a

new strategy to investigate the detailed evolution process of amorphous

materials.


8

Chapitre 2E.2 L’ octacalcium phosphate - OCP13

Regarding the HAp-solution interfaces, it can be expected that HAp

surfaces in contact with aqueous solutions are subjected to hydration by water

molecules.

A number of researchers pointed out the presence of a transition region

between HAp and aqueous solution, which is metastable, as compared to HAp,

and contains water molecules, protonated phosphate ions (HPO42-

), and other

trace elements14

,15

.

13. K. Matsunaga et al., Sr Substitution in Bioactive Calcium Phosphates : A first principles

study, J. Phys. Chem. B 2009, 113, 3584–3589

14. Santos, R. A.; Wind, R. A.; Bronnimann, C. E. J. Magn. Reson. B1994, 105, 183–187.

15. Cazalbou, S.; Eichert, D.; Ranz, X.; Drouet, C.; Combes, C.; Harmand, M. F.; Rey, C. J.

Mater. Sci. 2005, 16, 405–409.


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In this regard, Brown et al. proposed the crystal structure of octacalcium

phosphate [Ca8H2(PO4)6 ·5H2O (OCP)] as a structural model for the interfacial

transition region (see Figure 1)16,17

.

Figure 1. Crystal structures of (a) OCP and (b) HAp viewed along the c axis.

The PO43-

groups are represented by the tetrahedra. These two are arranged to

highlight the similarity in HAp and the apatitic layer of OCP.

16. Brown, W. E. Nature 1962, 196, 1048–1050.

17. Brown, W. E.; Mathew, M.; Tung, M. S. Prog. Crystal. Growth Charact. 1981, 4, 59–87.


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Since it is also thought that OCP is an intermediate phase for nucleation of

HAp crystals during bone mineralization processes18,19,20

, it is reasonable to

consider that OCP is a prototype structure of the interfacial transitional region

between HAp and aqueous solution21

.

In order to investigate possible Sr2+

location in the system of HAp

crystals in contact with aqueous solutions, therefore, the present study attempts

to perform first-principles calculations for Sr2+

ions incorporated into OCP and

HAp by ion exchange with Ca2+

.

Conclusion :

As compared with the Sr substitutions in HAp, the formation energies of

substitutional Sr2+

at a number of Ca sites in OCP were much smaller,

which indicates that Sr2+

ions can be more favorably substituted for Ca2+

in OCP

by ion exchange.

Since OCP is considered as the precursor phase of HAp, it can be

speculated that the Sr2+

incorporation can stabilize the metastable

calcium phosphate phase,

- to prevent apatite resorption

- or to promote apatite nucleation during bone remodeling

processes.

18. Dorozhkin, S. V. J. Mater. Sci. 2007, 42, 1061–1095.

19. Brown, W. E.; Schroeder, L. W.; Ferris, J. S. J. Phys. Chem. 1979,83, 1385–1388.

20. Tseng, Y. H.; Mou, C. Y.; Chen, J. C. C. J. Am. Chem. Soc. 2006, 128, 6909–6918.

21. Tung, M. S.; Skrtic, D. In Octacalcium phosphate; Chow, L. C., Eanes, E. D., Eds.;

Karger: Basel, Switzerland, 2001.


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Chapitre 2E.3 Nouvel OCP ? Collapsed OCP Stabilized by

Ionic Substitutions22

OCP versus HP d’un point de vue structural

The unit cell of OCP consists of “apatitic layers”, where Ca2+

and PO43-

ions occupy the same relative positions as in HA, and of “hydrated layers”,

where Ca2+

and PO43-

ions are more widely spaced, due to the presence of the

interdispersed structural water molecules23

,24

. Apatitic layers (about 1.1 nm

thick) alternate with hydrated layers (about 0.8 nm thick) parallel to the (100)

face.

OCP et les impuretés

However, OCP is less sensitive than HA to the presence of

impurities25

,most likely because of the presence of lattice waterwhich decreases

the adsorption of foreign ions26

. At variance, the results of theoretical studies

based on first principles calculations;with OCP assumed to be a structuralmodel

of the transition region betweenHAand the solution;indicated that substitutional

foreign ions, such as Sr2+

, Mg2+

, and Zn2+

, can be more easily incorporated in

OCP than in HA lattice27

,28

.

22. E. Boanini et al., Crystal growth desigh 2010

23. Brown, W. E.; Smith, J. P.; Lehr, J. R.; Frazier, A. W. Nature 1962, 196, 1048–1055.

24. Mathew, M.; Brown, W. E.; Schroeder, L. W.; Dickens, B. J. Cryst. Spectrosc. Res. 1988,

18, 235–250.

25. Salimi, M. H.; Heughebaert, J. C.; Nancollas, G. H. Langmuir 1985, 1, 119–122.

26. Wang, L.; Nancollas, G. H. Chem. Rev. 2008, 108, 4628–4669. 27. Matsunaga, K. J. Chem. Phys. 2008, 128, 245101245111

28. Matsunaga, K.; Murata, H. J. Phys. Chem. B 2009, 113, 3584–3589.


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Des différences en SEM et DRX importantes en fonction de la nature des substitutions

Figure 1. SEM images of (a) Ca-OCP, (b) Mg10, (c) Sr10, and (d) Mn10

crystals.

Figure 2. Powder X-rays diffraction patterns patterns of (a) Ca-OCP, (b) Mg10,

(c) Sr10, and (d) Mn10 samples.


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Figure 2. Powder X-rays diffraction patterns patterns of (a) Ca-OCP, (b) Mg10,

(c) Sr10, and (d) Mn10 samples.

Plusieurs phases sont synthétisées suite à la substitution


14

Le comportement des phases en température est different suivant la subsitution

Figure 4. –High magnification of the small angle region of the powder XRD

patterns of (a) Ca-OCP, (b) Mg15, and (c) Sr15 samples. The diagrams were

recorded in situ at increasing temperature.

Conclusion : We have explored the possibility of introducing biologically

relevant ions, namely Sr2+

, Mg2+

, and Mn2+

into the structure of octacalcium

phosphate (OCP).

- OCP with partial substitutions of Sr2+

and Mg2+

for Ca2+

up to 7.4 and 1.0

at%, respectively, was successfully synthesized.

- On the contrary, Mn2+

completely inhibits OCP crystallization, and it

promotes the precipitation of brushite.

The incorporation of Sr2+

and Mg2+

disturbs the shape of the crystals and

reduces the stability of OCP structure.

Due to the destabilizing effect of the foreign ions, in the temperature range

of 170-250 °C, Mg- and Sr-OCP contain “collapsed OCP” but no OCP, which

allowed us to calculate the unit cell of this new phase characterized by a slightly

reduced a-axis and a wider γ angle with respect to OCP.


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Chapitre 2E.4 Différentes Morphologies pour l’OCP29

In this study, we hypothesize that the cationic surfactant lamellar

templates may “sandwich” the longitudinal side of the OCP plates and modulate

the nanocrystal growth while its surface remains clear.

Cetyltrimethylammonium bromide (CTAB), which is an extensively applied

structure-directing amphiphilic small molecule, has the potential to form

vesicles over critical micelle concentration (CMC) and transform lamellar

structure with increasing concentration in solution30

,31

.

29. Yang et al., Facile Synthesis of Octacalcium Phosphate Nanobelts: Growth Mechanism

and Surface Adsorption Properties, JPC 2010

30. Lamont, R. E.; Ducker, W. A. J. Am. Chem. Soc. 1998, 120, 7602.

31. Zhao, F.; Du, Y.; Yang, P.; Li, X.; Tang, J. Sci. China, Ser. B: Chem. 2005, 48, 101.


16

(a)

(b)

©

Figure 3. Morphology difference of OCP synthesized with calcium acetate (a),

calcium chloride (b), and calcium nitrate (c) as calcium salt species.


17

Figure 4. Morphology evolution of OCP obtained at different CTAB

concentrations with 1 h of aging time: (a) 0.20, (b) 0.30, (c) 0.40, (d)

0.60, (e) 0.70, and (f) 0.80 mM. The bar is 20 μm.


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Figure 7. Schematic mechanism illustration of OCP nucleation on the CTAB

vesicle preferentially protecting the longitudinal faces of the OCP nanobelts by

CTAB lamellar structure template leaving the belt ends amenable to grow

rapidly in the aqueous solution, without surface contamination.

Conclusions

In summary, the OCP nanobelts without surface contaminants were

synthesized by a new small molecule-assisted wet-chemical method. The

nonabsorbed small molecule surfactant (i.e., CTAB) has a key role in

modulating crystallite anisotropic growth of long belt-like nanostructures.

biomat ériaux biomateriaux · 2010. 11. 4. · chapitre3 prothèse de hanche - apatite- 31082010 -...

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