New Sol-gel Calcium Phosphate Composites for Bone Regeneration

1. New Sol-gel Calcium Phosphate Composites for Bone Regeneration Laura Epure1,2, Fatiha Chellat 1,2, Mariam Zoulgami 1 Nelson Camargo 3, Yahye Merhi 2, L'Hocine Yahia 1 1 Biomedical Engineering Institute, Laboratory for the Inovation and Analysis of Bioperformance, École Polytechnique de Montréal, Canada 2 Laboratory of Experimental Pathology , Montreal Heart Institute , Canada 3Universidade do Estado de Santa Catarina, Centro de Ciencias Tecnologicas, Brezil

2. Introduction Calcium phosphate bioceramics • The most used calcium phosphate-based bioceramics are: • hydroxyapatite [HAp, Ca10(PO4)6(OH)2], and • β-or α- tricalcium phosphate [TCP, Ca3(PO4)2]. • These ceramics are used in porous, granular and denses forms as bone graft substitutes in orthopedics and dental surgery • Poor mechanical properties  limit their application to: small unloaded implant, powder, surface-coating materials and low-loaded implants. • Preparation of calcium phosphate-based ceramic composites can partially solve the problem of these limits.

3. Introduction Sol-gel synthesis • The sol-gel synthesis method is simple, economic, and results in a high quality powder which could be useful for hard tissue reconstruction applications. • Processing of sol-gel TCP usually results in a fine-grain microstructure and crystals, better accepted by the host tissue. The morphology of the gel powders after calcination at 9000C TCP

4. Objective • To investigate the potential use of new calcium phosphate composites obtained by sol-gel method. The study focuseson phase identification, microstructuralexamination, and biocompatibility evaluations of these new materials.

5. SiO2 5 wt%10 wt% 15 wt% + Distilled water CaO + P2O5 (Ca/P=1,67) Stirring (540rpm) 24Hrs Sol-Gel Heating at 700C 4Hrs 9000C 2Hrs OB00 OB1OB3OB5 13000C 2Hrs OB01 OB2OB4 OB6 Materials • Sol-gel method • Reactants for TCP-based ceramic composites: • SiO2n nano particles< 100nm , CaO, P2O5 , CaO: calcination of CaCO3 at 9000C for 2 h • pH permanently adjusted at 7 (Ca:P ratio=1.67)

6. Methods • Phase identifications of the calcined and sintered materials were determined using X-ray diffraction (RDX) method. • Microstructural examinationwas determined by scanning electron microscopy (SEM) • Cell viability was evaluated using MTT (3-(4,5-dimethylthiazole-2yl)-2,5-triphenyl tetrazolium) coloration assay.

7. Indirect cytotoxicity study: • L929 mouse fibroblast cell-line (ATCC) • cell treatment: 24, 48 and 72 h Methods • Cytotoxicity was studied using the material particles extracts. • Material particles extracts: immersion of the composite OB particles • in culture medium (0.1 mg/ml) • at 370C • for a period of 120 h • under permanent shaking at 240 rpm.

8. 9000C 13000C SiO2 5 wt% SiO2 10 wt% SiO2 15 wt% Results XRD-patterns of OB powder samples

9. powder specimens dense bulk specimens powder specimens TCP 1300°C TCP 1300°C TCP 900°C TCP + 15% SiO2 900°C TCP + 15%SiO2 1300°C TCP + 15%SiO2 1300°C Results SEM-microstructural examination

10. Results MTT-cytotoxicity test • exposure of L-929 to TCP-SiO2 composites extracts did not affect cell viability

11. Conclusions • Based on phase identification, microstructural examination and biocompatibility testing: • the new TCP sol-gel composites seem to be good biomaterial candidates; • the results are encouraging but more studies are necessary. Future Work • Further investigations are ongoing : • to study osteoblastic adherence to the tricalcium phosphate sol-gel composites and their behaviour in a simulated physiologic environment.

12. Thank You !