Effect of incubation in simulated body fluid on dielectric and photoluminescence properties of nano-hydroxyapatite ceramic doped with strontium ions
Affiliation(s)
School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded, India. Yeshwant Mahavidyalaya, Nanded, India.
School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded, India. Yeshwant Mahavidyalaya, Nanded, India.
ABSTRACT
This paper reports the dielectric and photoluminescence measurements of ossiointegrated strontium doped hydroxyapatite bioceramic. The study on invitro bioactivity of Sr-HAp is carried out by using modified simulated body fluid. Dielectric properties of these ossiointegrated samples are studied in the frequency range 10 Hz to 1 MHz at room temperature. Dielectric constant is found to be decreasing with increase in incubation period and frequency of applied ac field. Higher the period of incubation and applied ac frequency, higher is the dielectric loss. AC conductivity shows frequency independent behaviour for all samples in lower frequency region and then increases linearly with increase in frequency. Sample incubated for longer duration shows higher conductivity. The optical properties of incubated Sr-HAp samples are also investigated with photoluminescence (PL) technique. The PL study shows the blue emission at around 476 nm when excited at 409 nm. The PL in tensity increases with increase in incubation duration and Sr-substitution.
This paper reports the dielectric and photoluminescence measurements of ossiointegrated strontium doped hydroxyapatite bioceramic. The study on invitro bioactivity of Sr-HAp is carried out by using modified simulated body fluid. Dielectric properties of these ossiointegrated samples are studied in the frequency range 10 Hz to 1 MHz at room temperature. Dielectric constant is found to be decreasing with increase in incubation period and frequency of applied ac field. Higher the period of incubation and applied ac frequency, higher is the dielectric loss. AC conductivity shows frequency independent behaviour for all samples in lower frequency region and then increases linearly with increase in frequency. Sample incubated for longer duration shows higher conductivity. The optical properties of incubated Sr-HAp samples are also investigated with photoluminescence (PL) technique. The PL study shows the blue emission at around 476 nm when excited at 409 nm. The PL in tensity increases with increase in incubation duration and Sr-substitution.
Cite this paper
Mahabole, M. , Bahir, M. , Kalyankar, N. and Khairnar, R. (2012) Effect of incubation in simulated body fluid on dielectric and photoluminescence properties of nano-hydroxyapatite ceramic doped with strontium ions. Journal of Biomedical Science and Engineering, 5, 396-405. doi: 10.4236/jbise.2012.57050.
Mahabole, M. , Bahir, M. , Kalyankar, N. and Khairnar, R. (2012) Effect of incubation in simulated body fluid on dielectric and photoluminescence properties of nano-hydroxyapatite ceramic doped with strontium ions. Journal of Biomedical Science and Engineering, 5, 396-405. doi: 10.4236/jbise.2012.57050.
References
[1] Gu, Y.W., Khor, K.A. and Cheang, P. (2004) Bone-like apatite layer formation on hydroxyapatite prepared by spark plasma sintering (SPS). Biomaterials, 25, 4127–4134. doi: 10.1016/j.biomaterials.2003.11.030 [2] Ni, J. and Wang, M. (2002) In vitro evaluation of hydroxyapatite reinforced polyhydroxybutyrate composite. MaterSciEng C, 20, 101–109. doi: 10.1016/S0928-4931(02)00019-X [3] Sa′nchez-Salcedo, S., Balas, F., Izquierdo-Barba, I. and Vallet-Regi, M. (2009) In vitro structural changes in porous HA/b-TCP scaffolds in simulated body fluid. Acta Biomaterialia, 5, 2738–2751. doi:10.1016/j.actbio.2009.03.025 [4] Pecheva, E.V., Pramatarova, L.D., Maitz, M.F., Pham, M.T. and Kondyuirin, A.V. (2004) Kinetics of hydroxyapatite deposition on solid substrates modified by sequential implantation of Ca and P ions Part II: Morphological, composition and structure study. Applied Surface Science, 235, 170–175. doi:10.1016/j.apsusc.2004.05.178 [5] Chavan, P.N., Bahir, M.M., Mene, R.U., Mahabole, M.P. and Khairnar, R.S. (2010) Study of nanobiomaterial hydroxyapatite in simulated body fluid: formation and growth of apatite. Materials Science and Engineering B, 168, 224–230. doi:10.1016/j.mseb.2009.11.012 [6] Arnich, N., Marie-Claire, L., Laurensot, F., Podor, R. and Montiel, A. (2003) Burnel D. In vitro and in vivo studies of lead immobilization by synthetic hydroxyapatite. Environmental Pollution, 124, 139–149. doi:10.1016/S0269-7491(02)00416-5 [7] Wong, C.T., Lu, W.W., Chan, W.K., Cheung, K.M.C., Luk, K.D.K., Lu, D.S., Rabie, A.B.M., Deng, L.F. and Leong, J.C.Y. (2004) In vivo cancellous bone remodeling on a strontium containing hydroxyapatite (Sr-HA) bioactive cement. JbiomedMatRes A, 68, 513–521. doi:10.1002/jbm.a.20089 [8] Labella, R., Braden, M. and Debt, S. (1994) Novel hydroxyapatite-based dental composites. Biomaterials, 15, 1197-1200. doi: 10.1016/0142-9612(94)90269-0 [9] Werber, R., Klaus-Dieter, Brauer, R.B., Wei?, W. and Becker, K. (2000) Osseous integration of bovine hydroxyapatite ceramic in metaphyseal bone defects of the distal. The Journal of Hand Surgery, 25A, 833-841. doi:org/10.1053/jhsu.2000.16354 [10] Mahabole, M.P., Aiyer, R.C., Ramakrishna, C.V., Sreedhar, B. and Khairnar, R.S. (2005) Synthesis, characterization and gas sensing property of hydroxyapatite ceramic. Bulletin of Materials Science, 28, 535-545. doi:10.1007/BF02706339 [11] Mene, R.U., Mahabole, M.P., Aiyer, R.C. and Khairnar, R.S. (2010) Hydroxyapatite Nano-ceramic thick Film: An efficient CO2 Gas Sensor. The open Applied Physics Journal, 3, 10-16. doi:10.2174/1874183501003010010 [12] Mene, R.U., Mahabole, M.P. and Khairnar, R.S. (2011) Surface Modified Hydroxyapatite Thick Films for CO2 Gas Sensing Application: Effect of Swift Heavy Ion Irradiation. Radiation Physics and Chemistry, 80, 682–687. http://dx.doi.org/10.1016/j.radphyschem.2011.02.002 [13] Furuta, S., Katsuki, H. and Komarneni, S. (2000) Removal of lead ions using porous hydroxyapatite monoliths synthesized from gypsum waste. Journal of Ceramic Society of Japan, 108, 315-317. doi:10.2109/jcersj.108.1255_315 [14] Aizawa, M., Howell, S., Itatani, K., Yokogawa, Y., Nishizawa, K., Toriyama, M. and Kameyama, T. (2000) Fabrication of porous ceramics with well-controlled open pores by sintering of fibrous hydroxyapatite particles. Journal of Ceramic Society of Japan, 108, 249-253. doi:10.2109/jcersj.108.1255_249 [15] Sugiyama, S., Nakanishi, T., Ishimura, T., Moriga, T., Hayashi, H., Shigomoto, N. and Moffat, J.B. (1999) Preparation characterization and thermal stability of lead hydroxyapatite. Journal of Solid State Chemistry, 143, 296-302. doi:10.1006/jssc.1998.8126 [16] Schroder, E., Jonsson, T. and Poole L. (2003) Hydroxyapatite chromatography: altering the phosphate-dependent elution profile of protein as a function of pH. Analytical Biochemistry, 313, 176–178. doi:10.1016/S0003-2697(02)00567-5 [17] Park, Y.S. and Yamazaki, Y. (2005) Novel Nafion/Hydroxyapatite composite membrane with high crystallinity and low methanol crossover for DMFCs. Polymer Bulletin, 53, 181–192. doi:10.1007/s00289-004-0310-0 [18] Quilitz, M., Steingro¨ver, K. and Veith, M. (2010) Effect of the Ca/P ratio on the dielectric properties of nanoscaled sub stoichiometric hydroxyapatite. J Mater Sci: Mater Med, 21, 399–405. doi:10.1007/s10856-009-3875-1 [19] Shi, S.L., Pan, W., Han, R.B. and Wan, C.L. (2006) Electrical and dielectric behaviours of Ti3SiC2/hydroxyapatite composites. Applied Physics Letters, 88, 052903-1-052903-2. doi:10.1063/1.2168684 [20] Gittings, J.P., Bowen, C.R., Dent, A.C.E., Turner, I.G., Baxter, F.R. and Chaudhuri, J.B. (2009) Electrical characterization of hydroxyapatite-based bioceramics. Acta Biomaterialia, 5, 743–754. doi:10.1016/j.actbio.2008.08.012 [21] Silva, C.C., Almeida, A.F.L., De oliveira, R.S., Pinheiro, A.G., Goes, J.C. and Sombra, A.S.B. (2003) Dielectric permittivity and loss of hydroxyapatite screen-printed thick films. Journal of Materials Science, 38, 3713–3720. doi:10.1023/A:1025963728858 [22] Hoepefner, T.P. and Case, E.D. (2002) The porosity dependence of the dielectric constant for sintered hydroxyapatite. JbiomedMatRes A, 60, 643–650. doi:10.1002/jbm.10131 [23] Ikoma, T., Yamazaki, A., Nakamura, S. and Akao, M. (1999) Preparation and dielectric property of sintered monoclinic hydroxyapatite. Journal of Materials Science Letters, 18, 1225–1228. doi:10.1023/A:1006610521173 [24] Laghzizil, A., Elherch, N., Bouhaouss, A., Lorente, G., Coradin, T. and Livage, J. (2001) Electrical behavior of hydroxyapatites M10(PO4)6(OH)2 (M = Ca, Pb, Ba). Materials Research Bulletin, 36, 953–962. doi:10.1016/S0025-5408(01)00576-1 [25] Ni, G.X., Lin, J.H., Chiu, P.K.Y., Li, Z.Y. and Lu, W.W. (2010) Effect of strontium-containing hydroxyapatite bone cement on bone remodeling following hip replacement. J Mater Sci: Mater Med, 21, 377–384. doi:10.1007/s10856-009-3866-2 [26] Saint-Jean, J., Camire, C.L., Nevsten, P., Hansen, S. and Ginebra, M.P. (2005) Study of the reactivity and in vitro bioactivity of sr-substituted α-tcp cements. JMater SciMaterMed, 16, 993–1001. doi:10.1007/s10856-005-4754-z [27] Guo, D., Xu, K., Zhao, X. and Han, Y. (2005) Development of a strontium-containing hydroxyapatite bone cement. Biomaterials, 26, 4073–4083. doi:10.1016/j.biomaterials.2004.10.032 [28] Kanno, T., Horiuchi, J.I., Koba, M., Motogami, Y. and Akazawa, T. (1999) Characteristics of the carbonate ions incorporated into calcium, partially-strontium-substituted and strontium apatites. Journal of Materials Science Letters, 18, 1343–1345. doi: 10.1023/A:1006638416515 [29] Wang, X. and Ye, J. (2008) Variation of crystal structure of hydroxyapatite in calcium phosphate cement by the substitution of strontium ions. JMaterSciMaterMed, 19, 1183–1186. doi:10.1007/s10856-007-3209-0 [30] Bera, J., Kalia, V. and Roy, P.K. (2004) Comparison of electrical properties between Ca and Sr hydroxyapatite materials. International Symposium on Advanced Materials and Processing, 6-8 December (2004), IIT Kharagpur, India, 721 302. http://hdl.handle.net/2080/227 [31] Ternane, R., Trabelsi –Ayedi, M., Kbir-Ariguib, N. and Piriou, B. (1999) Luminescent properties of Eu3+ in calcium hydroxyapatite. Journal of Luminescence, 81, 165-170. doi: 10.1016/S0022-2313(98)00172-0 [32] Chen, F., Zhu, Y.J., Zhang, K.H., Wu, J., Wang, K.W., Tang, Q.L. and Mo, X.M. (2011) Europium-doped amorphous calcium phosphate porous nanospheres: preparation and application as luminescent drug carriers. Nanoscale Research Letters, 6, 67. doi:10.1186/1556-276X-6-67 [33] Chen, F., Huang, P., Zhu, Y.J., Wu, J., Zhang, C.L. and Xiang Cui, D.X. (2011) The photoluminescence, drug delivery and imaging properties of multifunctional Eu3+/Gd3+ dual-doped hydroxyapatite nanorods. Biomaterials, 32, 9031-9039. doi:10.1016/j.biomaterials.2011.08.032 [34] Silva, C.C., Filho, F.P., Sombra, A.S.B., Rosa, I.L.V., Leite, E.R., Longa, E. and Varela, J.A. (2008) Study of structural and photoluminescence properties of Ca8Eu2(PO4)6O2. J Fluorescence, 18, 253-259. doi:10.1007/s10895-007-0242-9 [35] Graeve, O.A., Raghunath, K., Madadi, A., Brandon, C.W. and Glass, K.C. (2010) Luminescence variations in hydroxyapatites doped with Eu2+ and Eu3+ ions. Biomaterials, 31, 4259–4267. doi:10.1016/j.biomaterials.2010.02.009 [36] Zhang, C.M., Yang, J., Quan, Z.W., Yang, P.P., Li, C.X., Hou, Z.Y. and Lin J. (2009) Hydroxyapatite nano and microcrystals with multiform morphologies: controllable synthesis and luminescence properties. Crystal Growth and Design, 9, 2725-2733. doi:10.1021/cg801353n [37] Muller, F.A., Muller, L., Zollfrank, C. and Greil, P. (2006) Inherent luminescence of annealed biomimetic apatites. Engineering Materials, 311, 655-658. doi:10.4028/www.scientific.net/KEM.309-311.655 [38] Chung, R.J., Chin, T.S., Cheng, H.Y., Wen, H.W. and Hsieh, M.F. (2007) Photo-luminescent hydroxyapatite coating through a bio-mimetic process. Biomolecular Engineering, 24(5), 459-461. doi:10.1016/j.bioeng.2007.07.006 [39] Zhang, C., Cheng, Z., Yang, P., Xu, Z., Peng, C., Li, G. and Lin J. (2009) Architectures of strontium hydroxyapatite microspheres: solvothermal Synthesis and Luminescence properties. Langmuir, 25(23), 13591–13598. doi:10.1021/la9019684 [40] Zhang, C., Li, C., Huang, S., Hou, Z., Cheng, Z., Yang, P., Peng, C. and Lin J. (2010) Self-activated luminescent and mesoporous strontium hydroxyapatite nanorods for drug delivery. Biomaterials, 31(12), 3374-3383. doi: 10.1016/j.biomaterials.2010.01.044 [41] Tas, A.C. (2000) Synthesis of biomimetic Ca-hydroxyapatite powders at 370C in synthetic body fluids. Biomaterials, 21, 1429-1438. doi: 10.1016/S0142-9612(00)00019-3 [42] Jalota, S., Bhaduri, S.B. and Tas, A.C. (2008) Using a synthetic body fluid (SBF) solution of 27 mM HCO3- to make bone substitutes more osteointegrative. Material Science and Engineering C, 28, 129-140. doi:10.1016/j.msec.2007.10.058 [43] Gittings, J.P., Bowen, C.R., Turner, I.G., Dent, A.C.E., Baxter, F.R. and Chaudhuri, J.B. (2008) Dielectric Properties of Hydroxyapatite Based Ceramics. In: Dimov S, Menz W, Ed., Multi Material Micro Manufacture, Cardiff UK, 2-5. [44] Gittings, J.P., Bowen, C.R., Turner, I.G., Baxter, F.R. and Chaudhuri, J.B. (2007) Characterization of ferroelectric calcium phosphate composites and ceramics. European Ceramic Society, 27, 4187-4190. doi:10.1016/j.jeurceramsoc.2007.02.120 [45] Silva, C.C., Graca, M.P.F., Sombra, A.S.B. and Valente, M.A. (2009) Structural and electrical study of calcium phosphate obtained by a microwave radiation assisted procedure. Physica B: Condensed Matter, 404, 1503-1508. doi:10.1016/j.physb.2009.01.015 [46] Hyun-Min, K., Teruyuki, H., Kokubo, T. and Takashi, N. (2005) Process and kinetics of bonelike apatite formation on sintered hydroxyapatite in a simulated body fluid. Biomaterials, 26, 4366–4373. doi:10.1016/j.biomaterials.2004.11.022
[1] Gu, Y.W., Khor, K.A. and Cheang, P. (2004) Bone-like apatite layer formation on hydroxyapatite prepared by spark plasma sintering (SPS). Biomaterials, 25, 4127–4134. doi: 10.1016/j.biomaterials.2003.11.030 [2] Ni, J. and Wang, M. (2002) In vitro evaluation of hydroxyapatite reinforced polyhydroxybutyrate composite. MaterSciEng C, 20, 101–109. doi: 10.1016/S0928-4931(02)00019-X [3] Sa′nchez-Salcedo, S., Balas, F., Izquierdo-Barba, I. and Vallet-Regi, M. (2009) In vitro structural changes in porous HA/b-TCP scaffolds in simulated body fluid. Acta Biomaterialia, 5, 2738–2751. doi:10.1016/j.actbio.2009.03.025 [4] Pecheva, E.V., Pramatarova, L.D., Maitz, M.F., Pham, M.T. and Kondyuirin, A.V. (2004) Kinetics of hydroxyapatite deposition on solid substrates modified by sequential implantation of Ca and P ions Part II: Morphological, composition and structure study. Applied Surface Science, 235, 170–175. doi:10.1016/j.apsusc.2004.05.178 [5] Chavan, P.N., Bahir, M.M., Mene, R.U., Mahabole, M.P. and Khairnar, R.S. (2010) Study of nanobiomaterial hydroxyapatite in simulated body fluid: formation and growth of apatite. Materials Science and Engineering B, 168, 224–230. doi:10.1016/j.mseb.2009.11.012 [6] Arnich, N., Marie-Claire, L., Laurensot, F., Podor, R. and Montiel, A. (2003) Burnel D. In vitro and in vivo studies of lead immobilization by synthetic hydroxyapatite. Environmental Pollution, 124, 139–149. doi:10.1016/S0269-7491(02)00416-5 [7] Wong, C.T., Lu, W.W., Chan, W.K., Cheung, K.M.C., Luk, K.D.K., Lu, D.S., Rabie, A.B.M., Deng, L.F. and Leong, J.C.Y. (2004) In vivo cancellous bone remodeling on a strontium containing hydroxyapatite (Sr-HA) bioactive cement. JbiomedMatRes A, 68, 513–521. doi:10.1002/jbm.a.20089 [8] Labella, R., Braden, M. and Debt, S. (1994) Novel hydroxyapatite-based dental composites. Biomaterials, 15, 1197-1200. doi: 10.1016/0142-9612(94)90269-0 [9] Werber, R., Klaus-Dieter, Brauer, R.B., Wei?, W. and Becker, K. (2000) Osseous integration of bovine hydroxyapatite ceramic in metaphyseal bone defects of the distal. The Journal of Hand Surgery, 25A, 833-841. doi:org/10.1053/jhsu.2000.16354 [10] Mahabole, M.P., Aiyer, R.C., Ramakrishna, C.V., Sreedhar, B. and Khairnar, R.S. (2005) Synthesis, characterization and gas sensing property of hydroxyapatite ceramic. Bulletin of Materials Science, 28, 535-545. doi:10.1007/BF02706339 [11] Mene, R.U., Mahabole, M.P., Aiyer, R.C. and Khairnar, R.S. (2010) Hydroxyapatite Nano-ceramic thick Film: An efficient CO2 Gas Sensor. The open Applied Physics Journal, 3, 10-16. doi:10.2174/1874183501003010010 [12] Mene, R.U., Mahabole, M.P. and Khairnar, R.S. (2011) Surface Modified Hydroxyapatite Thick Films for CO2 Gas Sensing Application: Effect of Swift Heavy Ion Irradiation. Radiation Physics and Chemistry, 80, 682–687. http://dx.doi.org/10.1016/j.radphyschem.2011.02.002 [13] Furuta, S., Katsuki, H. and Komarneni, S. (2000) Removal of lead ions using porous hydroxyapatite monoliths synthesized from gypsum waste. Journal of Ceramic Society of Japan, 108, 315-317. doi:10.2109/jcersj.108.1255_315 [14] Aizawa, M., Howell, S., Itatani, K., Yokogawa, Y., Nishizawa, K., Toriyama, M. and Kameyama, T. (2000) Fabrication of porous ceramics with well-controlled open pores by sintering of fibrous hydroxyapatite particles. Journal of Ceramic Society of Japan, 108, 249-253. doi:10.2109/jcersj.108.1255_249 [15] Sugiyama, S., Nakanishi, T., Ishimura, T., Moriga, T., Hayashi, H., Shigomoto, N. and Moffat, J.B. (1999) Preparation characterization and thermal stability of lead hydroxyapatite. Journal of Solid State Chemistry, 143, 296-302. doi:10.1006/jssc.1998.8126 [16] Schroder, E., Jonsson, T. and Poole L. (2003) Hydroxyapatite chromatography: altering the phosphate-dependent elution profile of protein as a function of pH. Analytical Biochemistry, 313, 176–178. doi:10.1016/S0003-2697(02)00567-5 [17] Park, Y.S. and Yamazaki, Y. (2005) Novel Nafion/Hydroxyapatite composite membrane with high crystallinity and low methanol crossover for DMFCs. Polymer Bulletin, 53, 181–192. doi:10.1007/s00289-004-0310-0 [18] Quilitz, M., Steingro¨ver, K. and Veith, M. (2010) Effect of the Ca/P ratio on the dielectric properties of nanoscaled sub stoichiometric hydroxyapatite. J Mater Sci: Mater Med, 21, 399–405. doi:10.1007/s10856-009-3875-1 [19] Shi, S.L., Pan, W., Han, R.B. and Wan, C.L. (2006) Electrical and dielectric behaviours of Ti3SiC2/hydroxyapatite composites. Applied Physics Letters, 88, 052903-1-052903-2. doi:10.1063/1.2168684 [20] Gittings, J.P., Bowen, C.R., Dent, A.C.E., Turner, I.G., Baxter, F.R. and Chaudhuri, J.B. (2009) Electrical characterization of hydroxyapatite-based bioceramics. Acta Biomaterialia, 5, 743–754. doi:10.1016/j.actbio.2008.08.012 [21] Silva, C.C., Almeida, A.F.L., De oliveira, R.S., Pinheiro, A.G., Goes, J.C. and Sombra, A.S.B. (2003) Dielectric permittivity and loss of hydroxyapatite screen-printed thick films. Journal of Materials Science, 38, 3713–3720. doi:10.1023/A:1025963728858 [22] Hoepefner, T.P. and Case, E.D. (2002) The porosity dependence of the dielectric constant for sintered hydroxyapatite. JbiomedMatRes A, 60, 643–650. doi:10.1002/jbm.10131 [23] Ikoma, T., Yamazaki, A., Nakamura, S. and Akao, M. (1999) Preparation and dielectric property of sintered monoclinic hydroxyapatite. Journal of Materials Science Letters, 18, 1225–1228. doi:10.1023/A:1006610521173 [24] Laghzizil, A., Elherch, N., Bouhaouss, A., Lorente, G., Coradin, T. and Livage, J. (2001) Electrical behavior of hydroxyapatites M10(PO4)6(OH)2 (M = Ca, Pb, Ba). Materials Research Bulletin, 36, 953–962. doi:10.1016/S0025-5408(01)00576-1 [25] Ni, G.X., Lin, J.H., Chiu, P.K.Y., Li, Z.Y. and Lu, W.W. (2010) Effect of strontium-containing hydroxyapatite bone cement on bone remodeling following hip replacement. J Mater Sci: Mater Med, 21, 377–384. doi:10.1007/s10856-009-3866-2 [26] Saint-Jean, J., Camire, C.L., Nevsten, P., Hansen, S. and Ginebra, M.P. (2005) Study of the reactivity and in vitro bioactivity of sr-substituted α-tcp cements. JMater SciMaterMed, 16, 993–1001. doi:10.1007/s10856-005-4754-z [27] Guo, D., Xu, K., Zhao, X. and Han, Y. (2005) Development of a strontium-containing hydroxyapatite bone cement. Biomaterials, 26, 4073–4083. doi:10.1016/j.biomaterials.2004.10.032 [28] Kanno, T., Horiuchi, J.I., Koba, M., Motogami, Y. and Akazawa, T. (1999) Characteristics of the carbonate ions incorporated into calcium, partially-strontium-substituted and strontium apatites. Journal of Materials Science Letters, 18, 1343–1345. doi: 10.1023/A:1006638416515 [29] Wang, X. and Ye, J. (2008) Variation of crystal structure of hydroxyapatite in calcium phosphate cement by the substitution of strontium ions. JMaterSciMaterMed, 19, 1183–1186. doi:10.1007/s10856-007-3209-0 [30] Bera, J., Kalia, V. and Roy, P.K. (2004) Comparison of electrical properties between Ca and Sr hydroxyapatite materials. International Symposium on Advanced Materials and Processing, 6-8 December (2004), IIT Kharagpur, India, 721 302. http://hdl.handle.net/2080/227 [31] Ternane, R., Trabelsi –Ayedi, M., Kbir-Ariguib, N. and Piriou, B. (1999) Luminescent properties of Eu3+ in calcium hydroxyapatite. Journal of Luminescence, 81, 165-170. doi: 10.1016/S0022-2313(98)00172-0 [32] Chen, F., Zhu, Y.J., Zhang, K.H., Wu, J., Wang, K.W., Tang, Q.L. and Mo, X.M. (2011) Europium-doped amorphous calcium phosphate porous nanospheres: preparation and application as luminescent drug carriers. Nanoscale Research Letters, 6, 67. doi:10.1186/1556-276X-6-67 [33] Chen, F., Huang, P., Zhu, Y.J., Wu, J., Zhang, C.L. and Xiang Cui, D.X. (2011) The photoluminescence, drug delivery and imaging properties of multifunctional Eu3+/Gd3+ dual-doped hydroxyapatite nanorods. Biomaterials, 32, 9031-9039. doi:10.1016/j.biomaterials.2011.08.032 [34] Silva, C.C., Filho, F.P., Sombra, A.S.B., Rosa, I.L.V., Leite, E.R., Longa, E. and Varela, J.A. (2008) Study of structural and photoluminescence properties of Ca8Eu2(PO4)6O2. J Fluorescence, 18, 253-259. doi:10.1007/s10895-007-0242-9 [35] Graeve, O.A., Raghunath, K., Madadi, A., Brandon, C.W. and Glass, K.C. (2010) Luminescence variations in hydroxyapatites doped with Eu2+ and Eu3+ ions. Biomaterials, 31, 4259–4267. doi:10.1016/j.biomaterials.2010.02.009 [36] Zhang, C.M., Yang, J., Quan, Z.W., Yang, P.P., Li, C.X., Hou, Z.Y. and Lin J. (2009) Hydroxyapatite nano and microcrystals with multiform morphologies: controllable synthesis and luminescence properties. Crystal Growth and Design, 9, 2725-2733. doi:10.1021/cg801353n [37] Muller, F.A., Muller, L., Zollfrank, C. and Greil, P. (2006) Inherent luminescence of annealed biomimetic apatites. Engineering Materials, 311, 655-658. doi:10.4028/www.scientific.net/KEM.309-311.655 [38] Chung, R.J., Chin, T.S., Cheng, H.Y., Wen, H.W. and Hsieh, M.F. (2007) Photo-luminescent hydroxyapatite coating through a bio-mimetic process. Biomolecular Engineering, 24(5), 459-461. doi:10.1016/j.bioeng.2007.07.006 [39] Zhang, C., Cheng, Z., Yang, P., Xu, Z., Peng, C., Li, G. and Lin J. (2009) Architectures of strontium hydroxyapatite microspheres: solvothermal Synthesis and Luminescence properties. Langmuir, 25(23), 13591–13598. doi:10.1021/la9019684 [40] Zhang, C., Li, C., Huang, S., Hou, Z., Cheng, Z., Yang, P., Peng, C. and Lin J. (2010) Self-activated luminescent and mesoporous strontium hydroxyapatite nanorods for drug delivery. Biomaterials, 31(12), 3374-3383. doi: 10.1016/j.biomaterials.2010.01.044 [41] Tas, A.C. (2000) Synthesis of biomimetic Ca-hydroxyapatite powders at 370C in synthetic body fluids. Biomaterials, 21, 1429-1438. doi: 10.1016/S0142-9612(00)00019-3 [42] Jalota, S., Bhaduri, S.B. and Tas, A.C. (2008) Using a synthetic body fluid (SBF) solution of 27 mM HCO3- to make bone substitutes more osteointegrative. Material Science and Engineering C, 28, 129-140. doi:10.1016/j.msec.2007.10.058 [43] Gittings, J.P., Bowen, C.R., Turner, I.G., Dent, A.C.E., Baxter, F.R. and Chaudhuri, J.B. (2008) Dielectric Properties of Hydroxyapatite Based Ceramics. In: Dimov S, Menz W, Ed., Multi Material Micro Manufacture, Cardiff UK, 2-5. [44] Gittings, J.P., Bowen, C.R., Turner, I.G., Baxter, F.R. and Chaudhuri, J.B. (2007) Characterization of ferroelectric calcium phosphate composites and ceramics. European Ceramic Society, 27, 4187-4190. doi:10.1016/j.jeurceramsoc.2007.02.120 [45] Silva, C.C., Graca, M.P.F., Sombra, A.S.B. and Valente, M.A. (2009) Structural and electrical study of calcium phosphate obtained by a microwave radiation assisted procedure. Physica B: Condensed Matter, 404, 1503-1508. doi:10.1016/j.physb.2009.01.015 [46] Hyun-Min, K., Teruyuki, H., Kokubo, T. and Takashi, N. (2005) Process and kinetics of bonelike apatite formation on sintered hydroxyapatite in a simulated body fluid. Biomaterials, 26, 4366–4373. doi:10.1016/j.biomaterials.2004.11.022