羥基磷灰石(HA)是一種無機的人工合成骨質材料，這種材料通常可在Ti-6Al-4V上成長或幫助修復已被損壞的骨骼。具有生物相容性的PU可塗佈在Ti合金上成為一種具有人體骨骼上的軟性組織，在本研究中，將PU以及複合材料PU/CNTs浸泡於仿生體液(SBF)中數天，羥基磷灰石會在材料表面形成，並探討不同溫度環境的成長情形，而具有奈米碳管的複合材料能幫助HA在材料表面成核、成長。
　　而在本研究的兩種複合材料(PU/RCNTs及PU/FCNTs)中，具有官能機的酸化奈米碳管能較有效的使HA成長於PU/FCNTs複合材料表面。通常島狀HA的在兩種複合材料的高度差異不大(2.9um~3um之間)，然而表面的覆蓋程度卻大為不同，成長在PU/RCNTs表面的HA附著力差，容易因為外力或水的浸泡而脫落，PU/FCNTs複合材料上的HA卻能夠緊密的附著其上，造成此現象是因為FCNT是親水性，能夠吸引仿生流體中的正負離子，使表面形成不平衡的離子濃度，藉由電荷間的吸引力使得HA能穩定附著複合材料表面。高的表面覆蓋率代表HA能穩定成長且較能抵抗施加於表面的外力。而仿生流體的溫度亦是一個重要的成長HA因素，當流體溫度低於正常人體體溫(37度C)時，HA的成長速率將大為下降，隨著溫度的上升，HA的成長速率亦隨之提升。

1.White, A.A., S.M. Best, and I.A. Kinloch, Hydroxyapatite-carbon nanotube composites for biomedical applications: A review. International Journal of Applied Ceramic Technology, 2007. 4(1): p. 1-13.
2.Lahiri, D., S. Ghosh, and A. Agarwal, Carbon nanotube reinforced hydroxyapatite composite for orthopedic application: A review. Materials Science and Engineering: C, 2012. 32(7): p. 1727-1758.
3.Iijima, S., Helical microtubules of graphitic carbon. Nature, 1991. 354(6348): p. 56-58.
4.Yu, M.-F., et al., Tensile loading of ropes of single wall carbon nanotubes and their mechanical properties. Physical review letters, 2000. 84(24): p. 5552-5555.
5.Yu, M.-F., et al., Strength and breaking mechanism of multiwalled carbon nanotubes under tensile load. Science, 2000. 287(5453): p. 637-640.
6.Chen, Y., et al., Wear studies of hydroxyapatite composite coating reinforced by carbon nanotubes. Carbon, 2007. 45(5): p. 998-1004.
7.Johnson, B.B., et al., Wear behavior of Carbon Nanotube/High Density Polyethylene composites. Mechanics of Materials, 2009. 41(10): p. 1108-1115.
8.Chen, W.X., et al., Electroless preparation and tribological properties of Ni-P-Carbon nanotube composite coatings under lubricated condition. Surface and Coatings Technology, 2002. 160(1): p. 68-73.
9.Lim, D.-S., J.-W. An, and H.J. Lee, Effect of carbon nanotube addition on the tribological behavior of carbon/carbon composites. Wear, 2002. 252(5–6): p. 512-517.
10.Benoit, F.M., Degradation of polyurethane foams used in the mêcme breast implant. Journal of Biomedical Materials Research, 1993. 27(10): p. 1341-1348.
11.Zhang, J.Y., et al., A new peptide-based urethane polymer: synthesis, biodegradation, and potential to support cell growth in vitro. Biomaterials, 2000. 21(12): p. 1247-1258.
12.Wang Li, Z.Y., Zou Qin, LI Yu-Bao, Effect of Composition on Physical\|chemical Properties and Biological Properties of Hydroxyapatite/Aliphatic Polyurethane Scaffolds for Bone Tissue Engineering. Chemical Journal of Chinese University, 2011. 32(10): p. 7.
13.Liu, H.S., et al., Hydroxyapatite synthesized by a simplified hydrothermal method. Ceramics International, 1997. 23(1): p. 19-25.
14.Zhou, J., et al., High temperature characteristics of synthetic hydroxyapatite. Journal of Materials Science: Materials in Medicine, 1993. 4(1): p. 83-85.
15.Conz, M.B., J.M. Granjeiro, and G.d.A. Soares, Hydroxyapatite crystallinity does not affect the repair of critical size bone defects. Journal of Applied Oral Science, 2011. 19(4): p. 337-342.
16.Tas, A.C., Synthesis of biomimetic Ca-hydroxyapatite powders at 37 degrees C in synthetic body fluids. Biomaterials, 2000. 21(14): p. 1429-1438.
17.Aryal, S., et al., Carbon nanotubes assisted biomimetic synthesis of hydroxyapatite from simulated body fluid. Materials Science and Engineering: A, 2006. 426(1): p. 202-207.
18.Aryal, S., et al., Synthesis and characterization of hydroxyapatite using carbon nanotubes as a nano-matrix. Scripta Materialia, 2006. 54(2): p. 131-135.
19.Cheng, C., et al., Toxicity and imaging of multi-walled carbon nanotubes in human macrophage cells. Biomaterials, 2009. 30(25): p. 4152-4160.
20.Xu, J.L., et al., Preparation and characterization of a novel hydroxyapatite/carbon nanotubes composite and its interaction with osteoblast-like cells. Materials Science & Engineering C-Biomimetic and Supramolecular Systems, 2009. 29(1): p. 44-49.
21.George, J.H., M.S. Shaffer, and M.M. Stevens, Investigating the cellular response to nanofibrous materials by use of a multi-walled carbon nanotube model. Journal of Experimental Nanoscience, 2006. 1(1): p. 1-12.
22.Kagan, V.E., et al., Carbon nanotubes degraded by neutrophil myeloperoxidase induce less pulmonary inflammation. Nature Nanotechnology, 2010. 5(5): p. 354-359.
23.Li, A., et al., Mechanical properties, microstructure and histocompatibility of MWCNTs/HAp biocomposites. Materials Letters, 2007. 61(8-9): p. 1839-1844.
24.Facca, S., et al., In Vivo Osseointegration of Nano-Designed Composite Coatings on Titanium Implants. Acs Nano, 2011. 5(6): p. 4790-4799.
25.Sakamoto, H., et al., Structure and strength at the bonding interface of a titanium-segmented polyurethane composite through 3-(trimethoxysilyl) propyl methacrylate for artificial organs. Journal of Biomedical Materials Research Part A, 2007. 82A(1): p. 52-61.