10 - SiO2-CaO-Na2O-P2O5 bioglasses prepared via sol gel method - reduite

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Rémy Catteaux Laboratoire des Matériaux, Céramiques et Procédés Associés Maubeuge
BCerS Mons 2011
SiO2-CaO-Na2O-P2O5 bioglasses prepared via sol gel method Fields of use : - Bones Subtitutes - Surgery
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Plan Bioactivity definition Advantages of the Sol-Gel way Aim Bioglass Synthesis Characterizations Results and perspectives
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Allow intimate chemical bond with living tissues Stable anchoring of the implant Similar to bones mineral phase
bioglass
Carbonated Hydroxyapatite (HCA)
Bioactivity definition
Calcium + Phosphorus In vitro : Simulated Body Fluid In vivo
Bioactivity definition Advantages Aim Synthesis Results & perspectives Characterizatio n
3 Advantages of the Sol-Gel way
Greater rates of resorption and bone formation.
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Bioactivity definition Advantages Aim Synthesis Results & perspectives Characterizatio n
Classical synthesis of glasses by melting glassceramics during the quench bioactivity less interesting low Si ratio high P ratio SOL-GEL WAY ADVANTAGE S
Soft chemical, low temperature Larger composition areas Higher surface area, rich in reactive silanol groups. Faster release of soluble silica. More bioactive, form the HCA layer faster.
TO REPLACE SYNTHESIS BY MELTING

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Bioactivity definition Advantages Aim Synthesis Results & perspectives Characterizatio n
Aim 5 Synthesize bioglass by sol-gel way Control the resorption of the glass
&
the sodium ratio is modulated Slightly soluble ternary compound SiO2 - CaO - P2O5 More soluble quaternary compound SiO2 - CaO - Na2O -P2O5 High melting temperature 1600°C : preparation by traditional method is more difficult. The sodium replaces a part of calcium Sol-gel way possibilities
Sol Gel
Impregnating a porous substrate
Macroporous or composite with controlled porosity
Deposition on a substrate
Film Monolith
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Bioactivity definition Advantages Aim Synthesis Results & perspectives Characterizatio n

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Acid way Basic way
Sol-Gel synthesis:
System Composition Way Notation Ternary 47SiO2 48CaO 5P2O5 Acid 47SiP5T Quaternary 47SiO2 26,5CaO 21,5Na2O 5P2O5 Basic 47SiP5Q
Bioactivity definition Advantages Aim Synthesis Results & perspectives Characterizatio n
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-It’s difficult for quaternary composition to include modifiers elements
without crystallization during the drying acid process.
-After drying process (130°C - 24h), an aging thermal treatment permits
to obtain the glass (temperature giving by TGA/DTA analysis)
H O
+
R
Si
O
R
O
R
O R
H2O
H+
+ ROH + H+ + ROH
Acid hydrolysis reaction : 8 - Average stability of the positive intermediate, which implies that the raw materials are never fully hydrolysed
Bioactivity definition Advantages Aim Synthesis Results & perspectives Characterizatio n

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Basic hydrolysis reaction:
OH- + RO-
O
Si
O
R
O
R
O R O
R H
-
-Hydroxide ion replaces water as the nucleophile. It is more
reactive, hydrolysis is accelerated. - Good stability of the negative reactional intermediate, the hydrolysis reaction is rapid and complete.
Bioactivity definition Advantages Aim Synthesis Results & perspectives Characterizatio n
9 Condensation reactions (valid for both ways):
Si
O
R
O
R
O R O
Si
O
R
O
R
O
R
+ H2O
And alcoxolation reaction:
+ ROH
10 Oxolation reaction:
Bioactivity definition Advantages Aim Synthesis Results & perspectives Characterizatio n

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Specific condensation reaction for ternary system in acid way (in investigation): Condensation reaction in for quaternary system in basic way:
TEOS &Calcium alcoxide inserting calcium in the grid
Ca
O
R
O
R
+ + ROH
Glycerol can make complexes with calcium ions, and can condense with the amorphous silicium grid in formation.
+ + H2O
Bioactivity definition Advantages Aim Synthesis Results & perspectives Characterizatio n
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Thermogravimetric analysis: departure of water, methanol and ethanol
Characterization by Thermal Analysis TGA TDA
Thermal differential analysis: glass transition temperature and crystallization temperature Aging of ternary gel over Tg (800°C) Glass
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Glass transition temperature Tg Crystallization temperature Tc
TDA/TGA on 47SiP5T
For quaternary gel, the TGA and DTA graphs are similar. To obtain the glass, the gel must be heated at about 550°C.
Bioactivity definition Advantages Aim Synthesis Results & perspectives Characterizatio n
E n d o th e rm ic
DTA TGA

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Characterization by X-ray diffraction 13
130°C 600°C 700°C 800°C 900°C 1000°C Wollastonite X-ray diffraction results on 47SiP5T
- The drying gel is amorphous. -The crystalline phase is wollastonite (CaSiO3). To retain the amorphous nature
of the composition the gel heat treatment must not overtop 800°C. - In case of quaternary composition, the gel treatment must not exceed 550°C.
Bioactivity definition Advantages Aim Synthesis Results & perspectives Characterizatio n
Characterization by FTIR
- The spectrum of dried gel at 130°C is similar to that of a conventional silica gel. - After treatment at 800°C, the appearance of a Si-O 2 NBO stretching vibration band 915 cm-1 as well as the widening of the Si-O-Si angular bending band at 475 cm-1 show the passage of the gel to a stabilized glass.
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800°C 130°C
ν Si-O 2NBO δ Si-O-Si
FTIR analysis on 47SiP5T
Bioactivity definition Advantages Aim Synthesis Results & perspectives Characterizatio n

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FTIR analysis on 47SiP5Q
130°C 550°C
δ Si-O-Si ν SiO 2NBO
Fusion at 1400°C
Bioactivity definition Advantages Aim Synthesis Results & perspectives Characterizatio n
-The intensification of the ν SiO 2 NBO band at 917 cm-1 and the widening of
the δ Si-O-Si band at 445 cm-1 point out that the thermal treatment of the gel at 550°C gives a glass.
-The infrared spectrum of this glass corresponds to that of the same
composition, obtained by melting at 1400°C.
15 Characterization of bioactivity
Bioactivity definition Advantages Aim Synthesis Results & perspectives Characterizatio n
- Observation of the HCA after 3 hours of immersion in SBF. - The IR spectra exhibit the characteristic bands of the HCA at 3h. This ternary glass is bioactive. - Results for quaternary system are quite the same.
Infra-Red spectra of bioglass Si47P5T surface versus immersion duration in SBF before immersion 3 hours 24 hours
δ O-P-O crystallised
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Actual results : - Preparation of two glasses has been successful. - Dip coating on classical glass with basic process. - Control of the drying process - Control of the thickness of the layer - Cytotoxicity of glass obtained by basic process. - Incorporation of more phosphorus Perspectives : -Impregnation of dense HA substrates -Impregnation of porous HA substrates -Study of the formed layer -Study of the penetration and resorption 17 Composite or macroporous
Bioactivity definition Advantages Aim Synthesis Results & perspectives Characterizatio n
Thank you for attention