BIOMATERIAUX 16 heures - Université Paris-Sud · BIOMATERIAUX 16 heures ... Chapitre 2.1c Implants dentaires Chapitre 2.2 Métallurgie Chapitre 2.2a La raideur des alliages

Cours Polytech Orsay Chapitre 2 Prothèse – TiO2 07/10/2010 - 1 -

BIOMATERIAUX

16 heures

Chapitre 2 L’oxyde de Titane TiO2

D. Bazin

Laboratoire de Physique des Solides UMR 2502,

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

Cours Polytech Orsay Chapitre 2 Prothèse – TiO2 07/10/2010 2

PLAN

Chapitre 0 Introduction

Chapitre 1 Sondes & Polymères

Chapitre 2 Prothèse en alliage à base de titane

Chapitre 2.1 Aspect médical Chapitre 2.1a La prothèse de Hanche

Chapitre 2.1b Les cages rigides

Chapitre 2.1c Implants dentaires

Chapitre 2.2 Métallurgie Chapitre 2.2a La raideur des alliages

Chapitre 2.2b La résistance à la fatigue

Chapitre 2.3 Surface d’une prothèse en titane

Chapitre 2.3a Nature de la surface, présence de lacunes oxygène et de groupes

hydroxyles

Chapitre 2.3b la structure de l’oxyde TiO2, analyse fine des diagrammes de diffraction

Chapitre 2.3c Taille et stabilité des particules de TiO2, déformation structurales

observées lors de la transition de phase, mécanisme de croissance et inhibition de la

transformation de phase par passivation

Chapitre 2.4 Revêtement d’apatite Chapitre 2.4a Mécanismes de formation de l’apatite (pH, taille, épaisseur),

Optimisation de la couche de TiO2 (précurseur, Température,

Chapitre 2.4b Composition chimique de l’interface Ti/HA

Chapitre 2.4e Influence de la taille des cristallites

Chapitre 2.4g Modification de la morphologie des cristaux d’apatites déposés

Chapitre 2.15 greffage à la surface de prothèse en titane

Chapitre 2.16 Traitement de surface d’une prothèse en titane

Chapitre 2.5 Etude de la surface d’un implant réel

Chapitre 2.6 Autres applications Chapitre 2.6a TiO2 comme agent anticancéreux

Chapitre 2.6b TiO2 comme agent antibactérien (Ag/TiO2)

Chapitre 2.6c TiO2 comme microfabricated medical device

Chapitre 2.7 Toxicité des nanoparticules de TiO2

Chapitre 2.7a Réponse cellulaire

Chapitre 2.7b Par inhalation

Chapitre 2.7c A travers la peau


Chapitre 2.4 Revêtement d’apatite

Chapitre 2.4a Mécanismes de formation de l’apatite1

Apatite formation induced by negatively charged nanocrystalline TiO2

coatings soaked in simulated body fluid (SBF) is affecting by factors such as

- pH,

- size of TiO2 particles

- thickness of TiO2 coatings,

1. Yang et al., Mechanism and kinetics of apatite formation on nanocrystalline TiO2 coatings:

A quartz crystal microbalance study, Acta Biomaterialia 4 (2008) 560–568


Two different stages were clearly observed in the process of apatite

precipitation, indicating two different kinetic processes.

At the first stage, the Ca2+

ions in SBF were initially attracted to the

negatively charged TiO2 surface,

and then the calcium titanate formed at the interface combined with

phosphate ions, consequently forming apatite nuclei.

After the nucleation, the calcium ions, phosphate ions and other

minor ions (i.e. CO2-3

and Mg2+

) in supersaturated SBF deposited spontaneously

on the original apatite coatings to form apatite precipitates.


Optimisation de la couche de TiO2 (Température) 2

TiO2 thin films were prepared on NiTi surgical alloy by sol–gel method.

Tetrabutyl titanate (Ti(C4H9)4, or Ti(OBu)4, from Zhejiang, China) was used as

TiO2 precursor.

The forming process, surface morphology and structure of the films were

studied by X-ray diffraction and atomic force microscopy.

2. Liu et al., Sol–gel deposited TiO2 film on NiTi surgical alloy for biocompatibility

improvement, Thin Solid Films 429 (2003) 225–230


The results showed that nm-scale TiO2 particles were embedded in the

film of 205 nm thickness. The film existed mainly in the form of anatase, and

the film was compact and smooth. The electrochemical corrosion measurement

indicated that TiO2 thin film, as a protective layer, was effective for improving

corrosion resistance of NiTi alloy. Additionally, in vitro blood compatibility of

the film and NiTi alloy was evaluated by dynamic clotting time and blood

platelets adhesion tests. The results showed that NiTi alloy coated

with TiO2 film had improved blood compatibility.


Chapitre 2.10 Influence de l’épaisseur de la couche de

TiO23

To improve the implant-tissue osteointegration, much effort has gone into

the modification of the Ti surface4,5,6. Among the various attempts

which have been made to improve the osseointegration, hydroxyapatite (HA,

Ca10(PO4)6(OH)2) coatings on Ti implants have shown good fixation to the host

bone and increased bone ingrowth to the implant. The improved

biocompatibility provided by the HA coatings is due to the chemical and

biological similarity of HA to hard tissues, and its consequent direct bonding to

host bones.

Parallel with this development, titania (TiO2) coatings on Ti have been

used to improve the corrosion resistance of Ti, which otherwise restricted its

usage in load-bearing implants over a prolonged period of time.

In practice, the very thin (at most several tens of nanometers) oxide

film on the Ti surface, which is formed in an aqueous environment, plays a

decisive role in determining the biocompatibility and corrosion behaviour of the

Ti implant. Since the corrosion resistance is known to increase with the

thickness of the oxide layer, many attempts have been made to form a thick

3. H.W. Kim et al., Hydroxyapatite coating on titanium substrate with titania buffer

layer processed by sol–gel method Biomaterials 25 (2004) 2533–2538.

4. Ratner BD. New ideas in biomaterials science-a path to engineered biomaterials. J Biomed

Mater Res 1993;27:837–50.

5. Block MS, Finger IM, Fontenot MG, Kent JN. Loaded hydroxyapatite-coated and grit-

blasted titanium implants in dogs. Int J Oral Maxillofac Implants 1989;4:219–25.

6. Nanci A, Wuest JD, Peru L, Brunet P, Sharma V, Zalzal S, et al. Chemical modification of

titanium surfaces for covalent attachment of biologica l molecules. J Biomed Mater Res

1998;40:324–35.


TiO2 layer on the Ti substrate using various methods, such as anodization,

thermal oxidation, and the sol–gel process.

Fig. 1 shows the XRD patterns of the HA layer deposited on a Ti substrate

after heat treatment at various temperatures for 1 h. Prior to HA coating, the

TiO2 was pre-coated onto the Ti substrate at 500°C f or 1 h. When the HA was

heat-treated at 400°C, small apatite peaks began to appear (Fig. 1(A)). When the

heat treatment temperature was increased to 450°C and 500°C (Figs. 1(B) and

(C), respectively), the apatite peak intensities increased, indicating that there

was an improvement in crystallization.

Only the HA, TiO2, and Ti peaks were detected, regardless of

the heat treatment temperature, suggesting the absence of any

chemical reaction between the different components.


SEM morphologies of the HA/ TiO2 double layer coating on the Ti substrate.

SEM images ofthe various coating systems deposited onto Ti: (A) TiO2 coating

surface; (B) HA/TiO2 double layer coating surface; and (C) HA/TiO2 double

layer coating cross sectional views. The heat treatment for each coating was

performed at 500°C for 1 h in air.

The thicknesses of the HA and TiO2 layers were approximately 200 and

200 nm, respectively. Each layer bonded firmly and had a uniform thickness

throughout on the Ti surface. Moreover, there were no delaminations or cracks

at either of the interfaces, suggesting that the bonding capability of both the

HA/TiO2 and TiO2/Ti interfaces was quite good.


Le SEM ne permet pas de mettre en évidence des différences lorsque l’on

procède à des cultures cellulaires. The cellular response to the HA/TiO2 double

layer coating system was assessed by an in vitro culture method using osteoblast

cells. - (A) The cells spread and grew in intimate contact with the bare Ti surface.

- (B) On the Ti substrate coated with TiO2, the cells grew in a similar fashion to those

on the bare Ti.

(C) Also on the HA/TiO2 double-layer coated sample, the cells grew in a similar

fashion, but a little more actively compared to those on the bare Ti and TiO2 coated Ti.


The cellular response to the specimen was assessed in terms of the cell

proliferation and the cell differentiation by measuring the alkaline Phosphatase

(ALP) activity.

Fig. 5. Proliferation number and ALP activity of osteoblate cells cultured on

each sample for periods of 5 and 10 days, respectively. The heat treatment for

each coating was performed at 500°C for 1 h in air.

The cell proliferation number and ALP level on the bare Ti substrate were

larger than those on the plastic control. Moreover, the cells on the coated

samples (both TiO2 coated- and HA/TiO2 double layer coated-Ti) proliferated

more and expressed higher ALP levels compared to those on the bare Ti

substrate. There was little difference between the TiO2 coated- and the HA/TiO2

double layer coated-Ti samples in terms of proliferation. However, the ALP

expression level of the cells on the HA/TiO2 double-layer coated Ti substrate

was higher than that on the TiO2 coated Ti substrate.


Chapitre 2.4b Composition chimique de l’interface Ti/HA7

The sol gel technique employed in this work is based on hydrolysis and

condensation of metal alkoxides such Ti(OR) where R is an organic ligand.

The XRD technique was used to follow the crystallisation of the

produced compounds : TiO2, CaTiO3 and HA.TiO2 was crystallized in

the single phase of anatase at T= 550°C whereas rutile was the

predominant phase at T=750°C.

7. Kaciulis et al., Surface analysis of biocompatible coatings on titanium, J. of electron

Spectroscopy 95 (1998)61-69.


The best quality (homogeneity and stoichiometry) of HA

coating was achieved when the substrate was first coated with

an intermediate layer of CaTiO3.


Chapitre 2.12 taille des cristallites et porosité8

Titanium (Ti) and some of its alloys have been extensively applied as

orthopaedic implant materials under load-bearing conditions due to their

outstanding mechanical properties and biocompatibility9,10

.

However, the mismatch of Young’s modulus between Ti and its

alloys (90–110 GPa) and bones (0.3–30 GPa) causes severe ‘‘stress shielding”,

leading to bone resorption11

.

One way to solve this problem is to reduce the Young’s modulus of Ti-

based biomaterials by introducing a porous structure, thereby minimizing

or eliminating the stress-shielding to the tissues adjacent to the implant materials

and eventually prolonging the implant lifetime12

.

8. Xiao-Bo Chen, The importance of particle size in porous titanium and nonporous

counterparts for surface energy and its impact on apatite formation Acta Biomaterialia 5

(2009) 2290–2302

9. Brunette DM, Tengvall P, Textor M, Thomsen P. Titanium in medicine. Heidelberg:

Springer-Verlag; 2001.

10. Long M, Rack HJ. Titanium alloys in total joint replacement—a materials science

perspective. Biomaterials 1998;19:1621–39.

11. Uhthoff HK, Finneagan M. The effects of metal plates on posttraumatic remodelling and

bone mass. J Bone Joint Surg Br 1983;65:66–71.

12. Gibson LJ, Ashby MF. Cellular solid: structure and properties. Cambridge: Cambridge

University Press; 1997.


13

A porous structure encourages osteointegration and prevents

implantation failure by providing spaces for bone cells, vascular and bone tissue

in growth to form mechanical interlocking14

. It has been proposed that the

optimal pore size for the cell attachment, differentiation and ingrowth of

osteoblasts and vascularization is approximately 200–500 µm15.

Using a special powder metallurgy technique, Wen et al.16

,17

successfully

fabricated a porous Ti with a porosity of 72% and a low Young’s

modulus (5.3 GPa) that exhibited a unique open-cellular porous structure.

13. http://www.covalent.co.jp/eng/rd/new_technologies/bio.html 14. Park JB, Lakes RS. Biomaterials: an introduction. New York: Plenum; 1992.

15. Clemow AJT, Weinstein AM, Klawitter JJ, Koeneman J, Anderson J. Interface mechanics

of porous titanium implants. J Biomed Mater Res 1981;15:73–82.

16. Wen CE, Mabuchi M, Yamada Y, Shimojima K, Chino Y, Asahina T. Processing of

biocompatible porous Ti and Mg. Scripta Mater 2001;45:1147–53.

17. Wen CE, Yamada Y, Shimojima K, Chino Y, Hosokawa H, Mabuchi M. Novel titanium

foam for bone tissue engineering. J Mater Res 2002;17:2633–9.


Early and stable osteointegration at the interface between Ti-based

bone implant materials and a bony site is one of the most important

indicators of clinical success (new bone formation)18

. It has been reported that

excellent osteointegration can be achieved on ceramic implants through a

bioactive calcium phosphate (CaP) apatite layer formed at the bone-

implant interface19

,20

.

An apatite coating is favourable for fast bony adaptation, the absence of

fibrous tissue seams, a reduction in the healing time and an increase in the

tolerance of surgical inaccuracies21

. Moreover, apatite formation in a biological

environment also depends on the surface characteristics of

biomaterials22.

One of the most important surface properties of implants is the surface

energy, which presents the surface wettability. The wettability of an

implant material influences the degree of the contact and interaction between the

implant and the biological environment23

.

Influences of the surface energy on protein adsorption, osteoblast

adhesion, spreading and proliferation have been extensively studied24

. However,

there are still very few studies on the effect of the surface energy of metallic

substrates on bioactive apatite formation25

.

Question : Quelle est la relation entre l’énergie

de surface & taille des particules ?

18. Branemark PI, Hansson BO, Adell R, Breine U, Lindstro¨m J, Hallen O, et al.

Osseointegrated implants in the treatment of edentulous jaw. Experience from a 10-year

period. Scand J Plast Reconst Surg Hand Surg 1977;11(Suppl. 16):1–132.

19. Ohtsuki C, Kushitani H, Kokubo T, Kotani S, Yamamuro T. Apatite formation on the

surface of ceravital-type glass–ceramic in the body. J Biomed Mater Res 1991;25:1363–70.

20. Ho¨land W, Vogel W, Naumann K, Gummel J. Interface reaction between machinable

bioactive glass–ceramics and bone. J Biomed Mater Res 1985;19:303–12.

21. Kay JE. Designing to counteract the effects of initial device instability: mineral and

engineering. J Biomed Mater Res 1988;22:1127–35.

22. Chen XB, Nouri A, Li YC, Lin JG, Hodgson PD, Wen CE. Effect of surface roughness of

Ti, Zr and TiZr on apatite precipitation from simulated body fluid. Biotechnol Bioeng

2008;101:378–87.

23. Baier RE, Shafrin EG, Zisman WA. Adhesion: mechanisms that assist or impede it.

Science 1968;162:1360–8.

24. Kennedy SB, Washburn NR, Simon Jr CG, Amis EJ. Combinational screen of the effect

of surface energy on fibronectin-mediated osteoblast adhesion, spreading and proliferation.

Biomaterials 2006;27:3817–24.

25. Wang XJ, Li YC, Lin JG, Hodgson PD, Wen CE. Apatite-inducing ability of titanium

oxide layer on titanium surface: the effect of surface energy. J Mater Res 2008;23:1682–8.


L’étude va porter sur différents échantillons:


One of the most important surface properties of implants is the surface

energy, which presents the surface wettability. The wettability of an

implant material influences the degree of the contact and interaction between the

implant and the biological environment26

.

26. Baier RE, Shafrin EG, Zisman WA. Adhesion: mechanisms that assist or impede it.

Science 1968;162:1360–8.


Chapitre 2.13 Optimisation de la couche

d’apatite27

Titanium is the most commonly used metallic material in the manufacture

of orthopedic implants, and hydroxyapatite (HA) is bioactive and biocompatible

when used as bone substitutes. To achieve better biocompatibility and excellent

mechanical performance of prostheses, coating calcium phosphates, especially

- hydroxyapatite (HA)

- silicate glass

on tough biocompatible metallic substrates has received considerable

attention28

,29

.

Li30

reported that bone-bonding strength to HA coated titanium rods was

1.0, 1.5, 2.0 and 2.5 MPa after 1, 2, 3 and 4 weeks implantation, respectively, as

determined by pull-out tests. These values were over twice that of the uncoated

titanium rods at 1–4 weeks after implantation.

Il est possible de modifier les caractéristiques structurales de la couche

d’apatite en choisissant des précurseurs différents:

The present study used dip-coating techniques to fabricate HA coating of

- organic sol–gel of Ca(NO3)2 4H2O and PO(CH3)3 ,

- inorganic sol of Ca(NO3)2 4H2O and (NH4)2 HPO4.

Scanning electron microscopy (SEM) and grazing-incidence X-ray diffraction

(XRD) have been used to characterize the morphology and the distributions of

crystallite size and micro-strains of the coatings.

27. L. Guo et al., Fabrication and characterization of thin nano-hydroxyapatite coatings on

titanium Surface & Coatings Technology 185 (2004) 268– 274.

28. D.B. Haddow, P.F. James, R. van Noort, Sol –gel derived calcium phosphate coatings for

biomedical applications, J. Sol–gel Sci. Technol. 13 (1998) 261– 265.

29. E. Saiz, M. Goldman, J.M. Gomez-Vega, A.P. Tomsia, G.W. Marshall, S.J. Marshall, In

vitro behavior of silicate glass coatings on Ti –6Al –4V, Biomaterials 23 (2002) 3749– 3756.

30. T. Li, J. Lee, T. Kobayashi, H. Aoki, Hydroxyapatite coating by dipping method, and

bone bonding strength, J. Mater. Sci. Mater. In Med. 7 (1996) 355– 357.


On remarque par SEM des différences importantes de la surface

Fig. 1. Morphology of thin nano-HA coatings fired at 400 °C

for 2 h

- Haut: Organic sol– gel coating,

- Bas: Inorganic sol coating.


Fig. 3 exhibits the grazing-incidence XRD patterns of both HA

coatings on titanium by firing at 400 °C for 2 h.

From the XRD pattern, CaTiO3 did not form on Ti surface or the

interface after firing at 400–600 °C.

For all coatings after firing over 400 °C, the main crystalline

phase of coatings was calcium phosphate with apatite structure, and

no obvious tricalcium phosphate (-TCP and -TCP) and calcium

oxide were found in the XRD patterns.

Taille des cristalites : Precursor types of HA coating significantly

affected the aggregating size of particles of nano-HA coatings, which

were 25–40 nm for organic sol–gel and approximately 100 nm for

inorganic sol.


Distribution de taille de cristallites


SEM micrograph show the morphology of Sectioned interface

between coating and titanium fired at 400 °C for 2 h

- Haut: Organic sol –gel coating

- Bas: Inorganic sol coating.

Reste à effectuer une étude sur la biocompatibilité


Chapitre 2.14 Modification de la morphologie des

cristaux d’apatites déposés31

Hydroxyapatite (HA) coatings were deposited on commercially pure

titanium plates using a hydrothermal–electrochemical deposition method in an

electrolyte containing calcium and phosphate ions. The deposition conditions

used in this study were the followings: electrolyte temperature (33–20 °C),

current density (1–2 mA/cm2), and deposition time (10–120 min).

Needle-like and granular crystals of apatite coating were created

with different concentrations of calcium (0.0021–0.042 M) and phosphate

(0.00125–0.025 M) salts.

The size of HA crystals of the coating was considerably changed with

different concentration of calcium and phosphate salts, temperature of the

electrolyte, and deposition time.

31. Yousefpour et al., Nano-crystalline growth of electrochemically deposited apatite coating

on pure titanium, Journal of Electroanalytical Chemistry 589 (2006) 96–105


Chapitre 2.15 greffage à la surface de

prothèse en titane32

Pratique médicale & Contamination : Once manufactured,

prostheses are not generally hermetically sealed during shipping, and directions

to the surgeon indicate they should only be autoclaved prior to insertion; this

does not remove the surface contamination. This surface contaminant,

containing principally carbon and oxygen (in the form of native oxide and

partially oxidized hydrocarbon), also contains trace impurity ions, as shown in

the present study.

While the contaminant layer appears to be well tolerated by the

body33,34,35

, there is abundant evidence that it adheres poorly to human hard

tissue, as in the case of dental implants36

.

32. Poulin et al., The cleaning and thiolation of commercial titanium for use in dental

prostheses, Applied Surface Science 143 (1999) 238-244.

33. T. Albrektsson, Crit. Rev. Biocompat. 1 (1984) 53. 34. B. Kasemo, J. Lausmaa, Crit. Rev. Biocompat. 2 (1986) 335.

35. J. Lausmaa, J. Electron Spectrosc. Rel. Phenom. 81 _1996.343.

36. P. Ducheyne, K.E. Healy, in: B.D. Ratner _Ed.., Surface Characterization of Biomaterials,

Elsevier, New York, 1988, p. 175.


An ideal situation would be one in which chemical bonding is established

across the prosthesis hard tissue interface, from titanium to bone, using an

adhesion promoter. This requires several steps, including

1. the efficient cleaning of the as-received implant to expose the reactive

titanium surface,

2. the bonding of one end of a bifunctional adhesion promoter to the

reactive surface

3. the incorporation of the other function into the hard tissue.

To clean the polycrystalline commercial titanium in the present study, we

chose to use potentiostatic anodic (rather than cathodic) polarization because

anodic reactions lead to a more efficient removal of titanium oxide, a major

surface contaminant. Surfaces cleaned in this manner were thiolated with

octadecyl thiol, C12H37SH, a simple thiol having no other reactive groups.


Chapitre 2.16 Traitement de surface

d’une prothèse en titane37

Surface modification of titanium implants by introducing a titania layer on

their surface is an effective approach to provide bioinert titanium with

bioactivity, i.e., the ability to bond directly and tightly to the surrounding hard

tissue through the formation of a thin layer of apatite after implantation in the

human body.

The crystalline structure and abundance of Ti–OH functional groups have

been found to contribute to the ability of TiO2 gel to initiate apatite deposition

on titanium in human physiological fluid.

First step : In the current investigation, an amorphous TiO2 gel was

firstly introduced on titanium surface by oxidizing the titanium substrate with

hydrogen peroxide.

Second step : Well-crystallized anatase TiO2films incorporated with

abundant Ti–OH groups were then produced simply through a subsequent hot

water aging of the amorphous titania TiO2 gel.

Results obtained in this investigation suggested that the low-temperature

crystallization of titania proceeded in a dissolution–precipitation process.

Titanium treated by the present low-temperature chemical modification

technique induced significant apatite deposition within 24 h in a simulated body

fluid.

37. Wu et al., Crystallization of amorphous titania gel by hot water aging and induction of in

vitro apatite formation by crystallized titania, Surface & Coatings Technology 201 (2006)

755–761


Surface morphology of CPTi oxidized by H2O2 solution at 20 °C for 2

h (a, b), followed by hot water aging at 20 °C for 72 h (c, d).

Figs. 1–3 show surface morphologies of CPTi after soaking in the H2O2 solution

at 20 °C for 2, 2 and 72 h, before and after hot water aging.

Oxidizing CPTi for 2 h in the H2O2 solution resulted in a porous titania gel layer

with cracks on the surface (Fig. 1a). The wall of the pores appeared to be

smooth at a high magnification (×40,000) (Fig. 1b).

After hot water aging, cracks disappeared (Fig. 1c), the porous network

collapsed, and the layer consisted mainly of tiny particles having sizes of tens of

nanometers (Fig. 1d).


Surface morphology of CPTi oxidized by H2O2 solution at 20 °C for 2 h and

aged in hot water at 20 °C for 72 h, followed by SBF-soaking for a) 24 h and b)

42 h.

Well-crystallized anatase thin films with excellent in vitro bioactivity

could be produced on titanium surfaces by soaking the titanium substrate in 30

mass% H2O2 solution at 20 °C for 2 to 72 h, followed by a hot water aging at 20

°C for 72 h. During hot water aging, the amorphous titania gel produced by

H2O2 oxidation hydrolyzed and re-precipitated back to the substrate to form

anatase nanocrystals. Titanium treated by the present low temperature chemical

modification technique could induce apatite formation in the simulated body

fluid within 24 h.


Chapitre 2.17 Processus d’interaction

possible entre le titane et l’apatite

The electronic structure of Ti-substituted hydroxyapatite is investigated

using density functional theory within a periodic slab model. Two sorption

mechanisms have been considered: i.e., Ti4+

and Ti(OH)22+

as the likely species

to exchange with Ca2+

.

Ti4+

has a small ionic radius compared to Ca2+

and can dope into both

distinct sites, showing no site preference; however, when two H were removed

from the OH channel to obtain charge compensation, preferential site II

substitution appears, accompanied with a large O shift forming a strong Ti–O

bond.


The species Ti(OH)2

2+ displays a strong site preference:

substitution by Ti(OH)22+

on the hydroxyl channel (site II) is exothermic and

favored strongly over the Ca column (site I). Ti(OH)22+

substitution for Ca2+

induces a large geometry relaxation and distortion, especially within the OH

channel and Ca2+

column, with a considerable shift of Ti compared to the Ca

sites in pure HA. These results are consistent with the experimental observation

that material synthesis with high Ti doping (atomic ratio 4 0.1) shows irregular

particles formation with reduced crystallinity. The calculated cell shape and

volume relaxations indicate that the volume and cell parameters both expand in

all the substituted HA models. The site preference and volume expansion

differences found are attributed to the metal ion shift caused in meeting th

erequirement of strong Ti–O coordination in site I and site II polyhedra.


Chapitre 2.12 Etude de la surface d’un

implant réel38

Due to a too complicated implant geometry (Fig. 1) to perform a

quantitative adhesion test and in order to test the adhesion of the BAG-coating

in a representative way, a simplified geometry for the adhesion test samples

(Fig. 2A), based on that of the oral implant (Fig. 1), is chosen. The oral and test

substrate have the same thermal mass to guarantee that both substrates will have

a comparable coating when using identical spraying parameters.

38. Schrooten et al., Adhesion of bioactive glass coating to Ti6Al4V oral implant,

Biomaterials 21 (2000) 1461-1469.


BAG-coated Ti6Al4V test rod (A), shear test sample (B) and moment

test sample (C).


SEM-micrograph of the coating cross-section of a BAG-

coated moment test sample, tested beyond its functionality.

SEM-micrograph of the BAG}Ti6Al4V interface after

adhesion testing.


Chapitre 2.6 Autres applications

Chapitre 2.6a TiO2 comme agent anticancéreux39

The photocatalytic properties of TiO2-mediated toxicity have been shown

to eradicate cancer cells40,41

. It is now well established that TiO2 particles,

on exposure to ultraviolet (UV) light, produce electrons and holes leading

subsequently to the formation of reactive oxygen species ROS such as

hydrogen peroxide, hydroxyl radicals, and superoxides42

.

These oxygen species are highly reactive with cell membranes and the

cell interior, with damaged areas depending on particle location upon excitation.

Such oxidative reactions affect cell rigidity and chemical arrangement of surface

structures, leading to cell toxicity43.

Despite promising outcomes in killing cancer cells, such treatments would

be difficult to implement in clinical settings for the following reasons.

- First, UV light cannot penetrate deeply into human tissues,

thus limiting this technique to superficial tumors44

.

- Second, UV-mediated production of ROS has a very short life span

and thus would not be able to provide a continuous prolonged cancer-killing

effect.

39. Thevenot et al., Surface chemistry influences cancer killing effect of TiO2 nanoparticles,

Nanomedicine: Nanotechnology, Biology, and Medicine 4 (2008) 226–236

40. Huang N-P, Xu M-H, Yuan C-W, Yu R-R. The study of the photokilling effect and

mechanism of ultrafine TiO2 particles on U937 cells. J Photochem Photobiol A: Chem

1997;108(2-3):229-33.

41. Zhang AP, Sun YP. Photocatalytic killing effect of TiO2 nanoparticles on LS-174-T

human colon cancer cells. World J Gastroenterol 2004; 10(21):3191-3.

42. Ogino C, Farshbaf Dadjour M, Takaki K, Shimizu N. Enhancement of sonocatalytic cell

lysis of Escherichia coli in the presence of TiO2. Biochem Eng J 2006;32(2):100-5.

43. Blake DM, Maness P-C, Huang Z,Wolfrum EJ, Huang J. Application of the photocatalytic

chemistry of titanium dioxide to disinfection and the killing of cancer cells. Sep Purif

Methods 1999;28(1):1-50.

44. Cai R, Kubota Y, Shuin T, Sakai H, Hashimoto K, Fujishima A. Induction of cytotoxicity

by photoexcited TiO2 particles. Cancer Res 1992;52(8):2346-8.


In the present study the nonphotocatalyic anticancer effect of surface-

functionalized TiO2 was examined. Nanoparticles bearing -OH, -NH2, or

-COOH surface groups were tested for their effect on in vitro survival of

several cancer and control cell lines.

High-resolution TEM picture of a 5-nm plasma-generated film deposited on a

25-nm nanoparticle, illustrating the uniform and highly conformal aspect of the

coating.


Visualization of the interaction between TiO2 particles (0.01 mg/mL) and 3T3

cells. Cells were imaged using phase contrast after 3 hours of exposure.

(A) Nonexposed cells appear normal,

(B) exposed cells show collection of particles on the cell membrane.


TiO2 particles were covered with thin polymer films of di (ethylene glycol) vinyl

ether (EO2V, -OH), allyamine (AA, -NH2), and vinyl acetic acid (VAA, -

COOH).


Conclusion : Cell viability was observed to depend on particle

concentrations, cell types, and surface chemistry. Specifically, -NH2

(AA) and -OH (EO2V) groups showed significantly higher toxicity than –

COOH (VAA).

Microscopic and spectrophotometric studies revealed nanoparticle-

mediated cell membrane disruption leading to cell death.

The results suggest that functionalized TiO2, and presumably other

nanoparticles, can be surface engineered for targeted cancer therapy.


Chapitre 2.6b TiO2 comme agent antibactérien45

TiO2 nanoparticles containing Ag+ have been widely used as a filler in the

manufacture of antibacterial plastics, coatings, functional fibers, dishware and

medical facilities, because Ag+ has a strong antibacterial activity against many

kinds of bacteria even at lower concentrations46,47

. However, their agglomeration

and incompatibility with organic matrix can result in the deterioration of their

mechanical properties and decrease their antibacterial property, which limits

their efficient use in antibacterial materials. Fortunately, these drawbacks could

be suppressed by surface modification of inorganic nanoparticles.

The basic material used for this study – antibacterial TiO2/Ag+

nanoparticles – is a commercial product (Shanghai Weilai Company, China)

with the primary particle size of about 70 nm and the Ag+ content approximately

0.4% by weight. Silane coupling agent, g-aminopropyltriethoxysilane (APS)

was obtained from Nanjing Shuguang Chemical Works, China.

For the preparation of composite, PVC powder (WS-1000S) was

purchased from Shanghai Chlor-Alkali Chemical Co., China. Other chemicals

used were of analytical reagent grade. Water used in this investigation was de-

ionized.

45. Cheng et al., Surface-modified antibacterial TiO2/Ag+ nanoparticles: Preparation and

properties, Applied Surface Science 252 (2006) 4154–4160

46. N. Edwards, S.B. Mitchell, A. Pratt, European Patent Application EOS251.783 (1987).

47. M. Kawashita, S. Tsuneyama, F. Miyaji, et al. Biomaterials 21 (2000) 393.


The morphology of modified nanoparticles was determined by Transmission

electron microscopy (TEM). It is obvious that the particles without

modification easily agglomerate (a) whereas the modified type is

well-dispersed (b), with the particle size of approximately 70 nm.

Unmodified particles create aggregates of the size of thousands of

nanometers, and distinct particles can hardly be observed. The treated

particles, on the other hand, are apart, which proves the positive effect of

surface treatment on the particle dispersion.


The bacteriostatic ratio of composites with 1.5 phr modified TiO2/Ag+

nanoparticles to bacteria was also examined. The data in Table 3 shows that the

composites have higher bacteriostatic ratio to Staphylococci (ATCC6532) than

to Escherichia coli (2099). The results further suggest that the composites have

good antibacterial properties.

Conclusions Grafted antibacterial TiO2/Ag

+ nanoparticles were prepared and tested by

various methods with the following conclusions:

(1) APS is chemically bonded on the surface of inorganic particles, the

layer thickness being ca. 25 nm.

(2) Surface treatment of the particles does not deteriorate

antibacterial properties of TiO2/Ag+ nanoparticles.

(3) Surface modification can assure better affinity of the particles to

organic matrix, in our case PVC.

These facts indicate that polymer composites with APS-grafted TiO2/Ag+

nanoparticles could be used for the manufacturing of products with antibacterial

properties in various areas (medicine, food packaging, etc.). Determination of

mechanical and other properties of the composites, however, is a research task

for the future.


Chapitre 2.6c TiO2 comme microfabricated

medical device48

The use of cluster-assembled TiO2 films as cell culture substrates is of

particular interest for the coupling of cultured cells on microfabricated devices,

since it is fully compatible with planar microfabrication technologies49,50

and

it allows the deposition of patterns with submicrometric lateral resolution51

,52

.

This material can be a very interesting substrate for different applications

requiring the integration of cell cultures on micro- and nano devices and arrays.

Cluster-assembled TiO2 thin films are optically transparent and free of

defects causing visible light scattering. Therefore, they are also particularly

suited for high resolution and confocal microscopy characterizations.

TEM micrograph of a region of a cluster-assembled TiO2 film. The film is

mainly amorphous, with nanocrystalline inclusions whose size ranges from 50 to

100nm to less than 10 nm. Both rutile and anatase nanocrystals are observed.

48. Carbon et al., Biocompatibility of cluster-assembled nanostructured TiO2 with primary

and cancer cells, Biomaterials 27 (2006) 3221–3229.

49. Shin H, Jo S, Mikos A. Biomimetic materials for tissue engineering. Biomaterials

2003;24(24):4353–64.

50. Hubbell J. Materials as morphogenetic guides in tissue engineering. Curr Opin Biotechnol

2003;14(5):551–8.

51. Mazza T, Barborini E, Kholmanov IN, Piseri P, Bongiorno G, Vinati S, et al. Libraries of

cluster-assembled titania films for chemical sensing. Appl Phys Lett 2005;87:103–8.

52. Barborini E, Piseri P, Podesta A, Milani P. Cluster beam microfabrication of patterns of

three-dimensional nanostructured objects. Appl Phys Lett 2000;77:1059–61.


This new biomaterial supports normal growth and adhesion of primary

and cancer cells with no need for coating with ECM proteins.


Chapitre 2.6d TiO2 comme désinfectant53

Particularly in microbiological laboratories and areas of intensive medical

use, regular and thorough disinfection of surfaces is required in order to reduce

the numbers of bacteria and to prevent bacterial transmission.

Conventional methods of manual disinfection with wiping are not

effective in the longer term, cannot be standardized, and are time-intensive and

staff-intensive. In addition, there are problems associated with the use of

aggressive chemicals54

.

A potential alternative may be provided by substrates made of light-

guiding materials, coated with specific semiconductors and stimulated by

indirect mild ultraviolet A (UVA) light (320–400 nm). This method shows

oxidative and disinfectant activity. The semiconducting materials about which

most information is available is titanium dioxide (TiO2).

53. Kuhn et al., Disinfection of surfaces by photocatalytic oxidation with titanium dioxide and

UVA light, Chemosphere 53 (2003) 71–77

54. Hahn, A., Michalak, H., Bergemann, K., Heinemeyer, G., Gundert-Remy, U., 1997.

AArtzliche Mitteilungen bei Vergiftungen nach x 16e Chemikaliengesetz 1997.

Dokumentations- und Bewertungsstelle f€ur Vergiftungen im bgvv.



Chapitre 2.6e TiO2 pour stopper des

hémorragies55

Blood is a fluid that can flow out of an injured vessel and so be lost. To

provide sustained hemostasis, or tissue sealing, blood clots must possess

mechanical properties capable of resisting forces, such as shear, that might

otherwise break or tear the clot.

The ability to rapidly stem hemorrhage in trauma patients significantly

impacts their chances of survival, and hence is a subject of ongoing interest in

the medical community. Herein, we report on the effect of biocompatible TiO2

nanotubes on the clotting kinetics of whole blood.

55. Roy et al., The effect of TiO2 nanotubes in the enhancement of blood clotting for the

control of hemorrhage, Biomaterials 28 (2007) 4667–4672


FESEM images of a 10 mm long TiO2 nanotube array achieved by

anodization of a Ti foil sample in a 2% HF in dimethyl sulfoxide

(DMSO) electrolyte; shown are cross-section, top, and bottom. The

DMSO fabricated tubes are loosely bound, and could be separated by

sonication of the sample (ethanol–water mixture) for approximately

10 s.

Figure (lower right) shows some dispersed tubes.


Magnetoelastic sensors were used to quantify the blood clotting56

. Briefly,

magnetoelastic sensors are rectangular strips of ferromagnetic amorphous alloys,

which generate longitudinal elastic waves when exposed to a time varying

magnetic field57

. The frequency and amplitude of these waves at resonance

depends on the viscosity (liquid) or elasticity (solid) of the medium surrounding

the sensor58

.

Time variation in sensor resonance amplitude when immersed in pure blood, nanoparticle

containing blood, and blood containing nanotubes of varying concentrations. A 5% of the data

points are shown. Similar results are obtained for blood in contact with a nanotube/particle

decorated gauze bandage.

The TiO2 nanotubes appear to act as a scaffold, facilitating fibrin formation. Our

results suggest that application of a TiO2 nanotube functionalized bandage could

be used to help stem or stop hemorrhage.

56. Grimes CA, Ong KG, Loiselle K, Stoyanov PG, Kouzoudis D, Liu Y, et al.

Magnetoelastic sensors for remote query environmental monitoring. J Smart Mater Struct

1999;8:639–46.

57. de Lacheisserie E duT. Magnetostriction: theory and applications of magnetoelasticity. In:

Handbook of chemistry and physics. New York: CRC Press; 1993.

58. Grimes CA, Ong KG, Loiselle K, Stoyanov PG, Kouzoudis D, Liu Y, et al.

Magnetoelastic sensors for remote query environmental monitoring. J Smart Mater Struct

1999;8:639–46.


Chapitre 2.7 Toxicité des

nanoparticules de TiO259,60

Recently, the potential impacts of nanomaterials on human and the

environment have attracted great attention of scientists, industries and regulatory

issues of governments 61,62,63,64

.

Some pioneering work has explored the adverse health effects of ultrafine

and fine TiO2 particles. They revealed the increased neutrophils and phagocytes

in bronchoalveolar lavage (BAL) fluid and lactate dehydrogenase (LDH)

leakage in the lung of rats and mice after exposure to TiO2 particles6566

, the

sunlight-illuminated TiO2 catalyzed DNA damage in vitro67

.

59. C. Vamanu et al., Induction of cell death by TiO2 nanoparticles: Studies on a human

monoblastoid cell line Toxicology in Vitro 22 (2008) 1689–1696.

60. Wang et al., Potential neurological lesion after nasal instillation of TiO2 nanoparticles in

the anatase and rutile crystal phases, Toxicology Letters 183 (2008) 72–80.

61. Colvin, V.L., 2003. The potential environmental impact of engineered nanomaterials. Nat.

Biotechnol. 21 (10), 1166–1170.

62. Donaldson, K., Stone, V., Tran, C.L., Kreyling,W., Borm, P.J.A., 2004. Nanotoxicology:

a new frontier in particle toxicology relevant to both the workplace and general environment

and to consumer safety. Occup. Environ. Med. 61, 727–728.

63. Nel, A., Xia, T., Mädler, L., Li, N., 2006. Toxic potential of materials at the nanolevel.

Science 311 (3), 622–627.

64. Oberdörster, G., Utell, M.J., 2002. Ultrafine particles in the urban air: to the respiratory

tract and beyond? Environ. Health Perspect. 110A, 440–441.

65. Oberdörster, G., Ferin, J., Gelein, R., Soderholm, S.C., Finkelstein, J., 1992. Role of the

alveolar macrophage in lung injury: studies with ultrafine particles. Environ. Health Perspect.

97, 193–199.

66. Bermudez, E., Mangum, J.B., Wong, B.A., Asgharian, B., Hext, P.M., Warheit, D.B.,

Everitt, J.I., 2004. Pulmonary responses of mice, rats, and hamsters to subchronic inhalation

of ultrafine titanium dioxide particles. Toxicol. Sci. 77, 347–357.

67. Wamer,W.G., Yin, J.,Wei, R., 1997. Oxidative damage to nucleic acids photosensitized

by titanium dioxide. Free Radic. Biol. Med. 23, 851–858.


Prothesis

Titanium either pure or in alloys is extensively used for a wide range of

implanted medical devices, such as

dental implants,

joint replacements,

cardiovascular stents,

spinal fixation devices,

due to its advantageous combination of physico-chemical and biological

properties.

However, under mechanical stress or altered physiological

conditions such as low pH, Ti-based implants can release large

amounts of particle debris, both in the micrometer and nanometer

size range 68, 69,70

.

68. Brien, W.W., Salvati, E.A., Betts, F., Bullough, P., Wright, T., Rimnac, C., Buly, R.,

Garvin, K., 1992. Metal levels in cemented total hip arthroplasty. A comparison of well-fixed

and loose implants. Clinical Orthopaedics and Related Research, 66–74.

69. Buly, R.L., Huo, M.H., Salvati, E., Brien, W., Bansal, M., 1992. Titanium wear debris in

failed cemented total hip arthroplasty. An analysis of 71 cases. The Journal of Arthroplasty 7,

315–323.

70. Arys, A., Philippart, C., Dourov, N., He, Y., Le, Q.T., Pireaux, J.J., 1998. Analysis of

titanium dental implants after failure of osseointegration: combined

histological, electron microscopy, and X-ray photoelectron spectroscopy approach. Journal of

Biomedical Materials Research 43, 300–312.


Chapitre 2.7a Toxicité des nanoparticules de TiO2 – Réponse cellulaire

The cellular responses to degradation products from titanium (Ti) implants are

important indicators for the biocompatibility of these widely used implantable

medical devices. The potential toxicity of nanoparticulate matter released from

implants has been scarcely studied.

The aim of this study was to investigate the potential of TiO2 nanoparticles

to induce modifications characteristic for death by apoptosis and/or necrosis in

U937 human monoblastoid cells.

Electron micrographs of U937 cells after 42 h exposure to (A) 4 mg/ml nano-

TiO2 – note pseudopodia (black arrow) embracing small nano-TiO2 aggregates

(white arrow), (B) 2 mg/ml nano-TiO2 – note cell with vacuole containing small

nano-TiO2 aggregates and (C) the same vacuole at higher magnification – note

presence of nano-TiO2 inside the vacuole and outside the cell (arrows).


Scanning transmission electron microscopy of cells after 42 h exposure to 2

mg/ml nano-TiO2. (A) Apoptotic cell with nano-TiO2 (arrow), (B) higher

magnification of (A), (C), (D) single nanoparticles inside cytoplasm. Particles

(arrow) are not present in a vacuole. All particles were confirmed to consist of

Ti by spot energy-dispersive X-ray analyses, indicated by a white cross on A, B,

and C.

TiO2 nanoparticles induced both apoptotic and necrotic

modifications in U937 cells.


Chapitre 2.7b Par inhalation71

This study was designed to determine whether ultrafine-TiO2 particles

impart significant toxicity in the lungs of rats, and more importantly, how the

activity of different TiO2 formulations compares with other reference particulate

materials, such as anatase/rutile ultrafine-TiO2 particles.

Thus, the aim was to assess in rats, using a well-developed short-term

pulmonary bioassay, the pulmonary toxicity effects of two intratracheally

instilled, ultrafine-TiO2 particle samples and to compare the lung toxicity

responses of these samples with

71. Warheit et al., Pulmonary toxicity study in rats with three forms of ultrafine-TiO2

particles: Differential responses related to surface properties, Toxicology 230 (2007) 90–104



The responses to uf-1, uf-2 or F-1 TiO2 particles were substantially less active in

terms of inflammation, cytotoxicity, and fibrogenic effects when compared to

the quartz, or to the uf-3 TiO2 particles.


Chapitre 2.7c A travers la peau72

Skin is the largest organ of the body and serves as a primary outer layer of

environmental and/or occupational exposure. It is also an important route of

entry for foreign articles including nanomaterials into the body.

The exposure of nanoscale TiO2 to the skin can be either intentional or

accidental.

For example, in certain lotions or creams, nanoscale TiO2 is

incorporated as a sunscreen component or used to coat fibrous materials and

enhance water or as a stain repellent property. Therefore the application of the

nanoparticles to human skin is intentional.

On the other hand, dermal contact with anthropomorphic

substances during nanomaterial manufacture or combustion can be accidental.

Due to the extremely small size of nanoparticles, assessment of health risks and

toxicity of nanoscale TiO2, in particular, following a long term dermal exposure,

is a key area of study in nanotechnology.

Control des tailles par TEM

72. Wu et al.,Toxicity and penetration of TiO2 nanoparticles in hairless mice and porcine skin

after subchronic dermal exposure, Toxicology Letters 191 (2009) 1–8


TEM image of nano-TiO2 particles.

(A) TiO2 10 nm;

(B) TiO2 25 nm;

(C) TiO2 60 nm.


Histopathological evaluation of the organ of hairless mice after dermal exposure

to different sized TiO2 nanoparticles for 60 days. Samples were stained with

hematoxilin and eosin (H&E) and observed at 100×. The arrows points at

pathological changes in various tissue sections.

Documents

BIOMATERIAUX 16 heures - Université Paris-Sud · BIOMATERIAUX 16 heures ... Chapitre 2.1c Implants dentaires Chapitre 2.2 Métallurgie Chapitre 2.2a La raideur des alliages