tailieunhanh - Advances in Biomimetics Part 14

Tham khảo tài liệu 'advances in biomimetics part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 447 Biomimetic Hydroxyapatite Deposition on Titanium Oxide Surfaces for Biomedical Application soaking medium from plate-like to sphere-like 25 . Ion images obtained from ToF-SIMS analyses show homogeneous Ca and Sr distributions indicating co-localization of the Ca and Sr ions Fig. 18 . Silicon doped hydroxyapatite coating deposited on titanium oxide has been reported by Zhang and Xia et al 71 72 . Similar morphology with biomimetic hydroxyapatite has been observed Fig. 19 . Cracks are also observed due to the dehydration shrinkage. The coating thickness was 5-10pm with a shear strength in the order of 16MPa. The chemical reactions in the solution could be illustrated as following 71 I 2O t sioS -H sioq 1 IhSiOỈ- Hl HSi h P HSiClJ -H I SioJ 3 HPC H 4 H 1 ico - 1bO CŨ2 T 5 lotí 2l 20-4 -y TO txSi 4 tJ OH - Ca1a rOJịị 2 i-4s-sr S O4 í OHẠrl 6 Silicon was confirmed to exist in the form of SiO44- groups in biomimetic SiHA coating. Fig. 19. SEM surface micrographs of biomimetic SiHA coatings obtained from different silicon modified Hank s balanced salt solution a 1mM b 5mM c 100mM. 71 6. Biological response of biomimetic HA coatings Calcium phosphate based coatings on titanium implants are now accepted to be suitable for enhancing bone formation around implants to contribute to cementless fixation and thus to improve clinical success at an early stage after implantation 70 . Narayanan and Kim et al summarized the interface reactions as following five steps 70 . 1. Dissolution of calcium phosphate based coatings 2. Re-precipitation of apatite 3. Ion exchange accompanied by absorption and incorporation of biological molecules 4. Cell attachment proliferation and differentiation 5. Extracellular matrix formation and mineralization. The dissolution of HA coating is a key step to induce the precipitation of bone-like apatite on the implant surface. Because the biomimetic hydroxyapatite coatings have a low degree of crystallinity and porous structure their solubility is .