New methods to improve the bone response to metallic implants are still emerging, ranging from surface modifications of the metal to coatings and drug delivery. One further development of coatings on implants is to incorporate bioactive ions in order to stimulate the bone response without the need of drug delivery. The aim of the current study is to prepare apatite coatings containing Sr and Si using a solution method, for the purpose of further optimising the bone response to metal implants. Titanium substrates were activated to induce the formation of coatings in modified PBS solutions. Soaking in PBS solutions with different concentrations of strontium and silicate at 37℃ or 60℃ produced coatings with different morphologies, thicknesses and compositions. Ion release experiments showed simultaneous release of Sr and Si from the coatings both in PBS and Tris-HCl. Analysis of the results using the Korsmeyer-Peppas model indicate that the release of ions from the coatings was a combination of Fickian diffusion and degradation of the coatings. This study shows that it is possible to coat Ti substrates with modified apatite with ion release functionality and thereby increase the possibilities for a tailored bone response in vivo.
B. Chou and E. Chang, “Microstructural Characterization of Plasma-Sprayed Hydroxyapatite-10 wt% ZrO2 Composite Coating on Titanium,” Biomaterials, Vol. 20, No. 19, 1999, pp. 1823-1832. doi:10.1016/S0142-9612(99)00078-2
A. Hideki, “Science and Medical Applications of Hydroxyapatite,” Ishiyaku Euroamerica, St. Louis, 1992.
K. Degroot, R. Geesink, C. Klein and P. Serekain, “Plasma Sprayed Coatings of Hydroxyapatite,” Journal of Biomedical Materials Research, Vol. 21, No. 12, 1992, pp. 1375-1381. doi:10.1002/jbm.820211203
W. Jaffe and D. Scott, “Total Hip Arthroplasty with Hydroxyapatite-Coated Prosthesis,” Journal of Bone and Joint Surgery, Vol. 78, No. 12, 1996, pp. 1918-1934.
J. Forsgren, U. Bro-hede and M Str?mme, “Co-Loading of Bisphosphonates and Antibiotics to a Biomimetic Hydroxyapatite Coating,” Biotechnology Letters, Vol. 33, No. 6, 2011, pp. 1265-1268. doi:10.1007/s10529-011-0542-7
M. Vallet-Regi and D. Arcos, “Silicon Substituted Hy- droxyapatites. A Method to Upgrade Calcium Phosphate Based Implants,” Materials Chemistry, Vol. 15, 2005, pp. 1509-1516. doi:10.1039/b414143a
A. Oliveira, R. Reis and P. Li,” Strontium-Substituted Apatite Coating Grown on Ti6Al4V Substrate through Biomimetic Synthesis,” Journal of Biomedical Materials Research Part B, Vol. 83, 2007, pp. 258-265.
S. Cazalbou, C. Combes and C. Rey, “Biomimetic Approach for Strontium Containing Ca-P Bioceramics with Enhanced Biological Activity,” Key Engineering Mate- rials, Vol. 192, 2001, pp. 192-195.
I. Gibson, S. Best and W. Bonfield, “Chemical Characterization of Silicon-Substituted Hy-droxyapatite,” Journal of Biomedical Materials Research, Vol. 44, No. 6, 1999, pp. 422-428. doi:10.1002/(SICI)1097-4636(19990315)44:4 3.0.CO;2-#
M. Vallet-Regi and J. M. Gon-zalez-Calbet, “Calcium Phosphates as Substitution of Bone Tissues,” Progress in Solid State Chemistry, Vol. 32, No. 1-2, 2004, pp. 1-31. doi:10.1016/j.progsolidstchem.2004.07.001
S. V. Dorozhkin and M. Epple, “Biological and Medical Significance of Calcium Phosphates,” Angewandte Chemie International Edition, Vol. 41, No. 17, 2002, pp. 3130-3146. doi:10.1002/1521-3773(20020902)41:17 3.0.CO;2-1
P. Marie, P. Ammann, G. Boivin and C. Rey, “Mechanisms of Action and Therapeutic Potential of Strontium in Bone,” Calcified Tissue International, Vol. 69, No. 3, 2001, pp. 121-129. doi:10.1007/s002230010055
E. Zhang and C. Zou, “Porous Titanium and Silicon- Substituted Hydroxyapatite Biomodification Prepared by a Biomimetic Process: Characterization and in Vivo Evaluation,” Acta Biomate-rialia, Vol. 5, No. 5, 2009, pp. 1732-1741. doi:10.1016/j.actbio.2009.01.014
S. Kannan, A. Rebelo and J. M. F. Ferreira, “Novel Synthesis and Structural Characterization of Fluorine and Chlorine Co-Substituted Hydroxyapatites,” Journal of Inorganic Biochemistry, Vol. 100, No. 10, 2006, pp. 1692-1697. doi:10.1016/j.jinorgbio.2006.06.005
S. Kannan, J. H. G. Rocha and J. M. F. Ferreira, “Synthesis and Thermal Stability of Sodium, Magnesium Co-Substituted Hy-droxyapatites,” Journal of Materials Chemistry, Vol. 16, No. 3, 2006, pp. 286-291. doi:10.1039/b511867k
E. Landi, S. Sprio, M. Sandri, G. Celotti and A. Tampieri, “Development of Sr and CO3 Co-Substituted Hydroxy-apatites for Biomedical Applications,” Acta Biomaterialia, Vol. 4, No. 3, 2008, pp. 656-663. doi:10.1016/j.actbio.2007.10.010
I. Gibson and W. Bonfield, “Preparation and Charac- terization of Magne-sium/Carbonate Co-Substituted Hydroxyapatites,” Journal of Materials Science: Materials in Medicine, Vol. 13, No. 7, 2002, pp. 685-693. doi:10.1023/A:1015793927364
W. Xia, C. Lindahl, J. Lausmaa, P. Borchardt, A. Ballo, P. Thomsen and H. Engqvist, “Biomineralized Strontium- Substituted Apatite/Titanium Dioxide Coating on Titanium Surfaces,” Acta Biomaterialia, Vol. 6, No. 4, 2010, pp. 1591-1600. doi:10.1016/j.actbio.2009.10.030
W. Xia, C. Lindahl, C. Persson, P. Thomsen, J. Lausmaa and H. Engqvist, “Changes of Surface Composition and Morphology after Incorporation of Ions into Biomimetic Apatite Coating,” Journal of Biomaterials and Nanobio- technology, Vol. 1, 2010, pp. 7-16. doi:10.4236/jbnb.2010.11002
E. Zhang, C. Zou and S. Zeng, “Preparation and Characterization of Silicon-Substituted Hydroxyapatite Coating by a Biomimetic Process on Titanium Substrate,” Surface and Coatings Technology, Vol. 203, No. 8, 2009, pp. 1075-1080. doi:10.1016/j.surfcoat.2008.09.038
P. Ritger and N. Peppas, “A Simple Equation for Description of Solute Release I. Fickian and Non-Fickian Release from Non-Swellable Devices in the Form of Slabs, Spheres, Cylinders or Discs,” Journal of Controlled Release, Vol. 5, No. 1, 1987, pp. 23-36. doi:10.1016/0168-3659(87)90034-4
N. Peppas, “Analysis of Fickian and Non-Fickian Drug Release from Polymers,” Pharmaceutica Acta Helvetiae, Vol. 60, 1985, pp. 110-111.
M. Lindgren, M. Astrand, U. Wiklund and H. Engqvist, “Investigation of Boundary Conditions for Biomimetic HA Deposition on Titanium Oxide Surfaces,” Journal of Materials Science: Materials in Medicine, Vol. 20, No. 7, 2009, pp. 1401-1408. doi:10.1007/s10856-009-3709-1
J. E. Ellingsen and S. P. Lyngstadaas, “Bio-Implant Interface: Improving Biomaterials and Tissue Reactions” CRC Press, 2003. doi:10.1201/9780203491430
H. B. Wen, J. R. D. Wijin, F. Z. Cui and K. D. Groot, “Preparation of Calcium Phosphate Coatings on Titanium Implant Materials by Simple Chemistry,” The Journal of Biomedical Materials Research, Vol. 41, No. 2, 1998, pp. 227-236. doi:10.1002/(SICI)1097-4636(199808)41:2 3.0.CO;2-K
J. Forsgren, F. Svahn, T. Jarmar and H. Engqvist, “Formation and Adhesion of Biomimetic Hydroxyapatite Deposited on Titanium Substrates,” Acta Biomaterialia, Vol. 3, No. 6, 2007, pp. 980-984. doi:10.1016/j.actbio.2007.03.006
A. E. Porter, N. Patel, J. N. Skepper, S. M. Best and W. Bonfield, “Comparison of in Vivo Dissolution Processes in Hydroxyapatite and Silicon-Substituted Hydroxyapatite Bioceramics,” Biomaterials, Vol. 24, No. 25, 2003, pp. 4609-4620. doi:10.1016/S0142-9612(03)00355-7