Liao Susan, Xu Guofu, Wang Wei, Watari Fumio, Cui Fuzhai, Ramakrishna Seeram, Chan Casey K
Nanoscience and Nanotechnology Initiative, Division of Bioengineering, Faculty of Engineering, National University of Singapore, Singapore 117576, Singapore.
Acta Biomater. 2007 Sep;3(5):669-75. doi: 10.1016/j.actbio.2007.03.007. Epub 2007 May 18.
Inspired by self-assembly of nano-hydroxyapatite (nHA) on collagen associated with the 67nm periodic microstructure of collagen, we used multi-walled carbon nanotubes (MWCNTs) with approximately 40nm bamboo periodic microstructure as a template for nHA deposition to form a nHA-MWCNT composite. The assembled apatite was analyzed by transmission electron microscopy and scanning electron microscopy. Defects that were analogous to edge dislocations along the carbon nanotubes' multi-walled surfaces were the nucleation sites for nHA after these defects had been functionalized principally into carboxylic groups. Spindle-shaped units consisting of an assembly of near parallel, fibril-like nHA polycrystals were formed and oriented at a certain angle to the long axis of the carbon nanotubes, unlike nHA-collagen in which the nHA is oriented along the longitudinal axis of the collagen molecule. One possible explanation for this difference is that there are more bonds for calcium chelation (-COOH, >CO) on the collagen fibril surface than on the surface of MWCNTs. Spindle-shaped units that are detached from the MWCNT template are able to maintain the ordered parallel structure of the nHA polycrystal fibril. We have thus created a self-assembled hydroxyapatite on MWCNTs.
受纳米羟基磷灰石（nHA）在与胶原蛋白67nm周期性微观结构相关的胶原蛋白上自组装的启发，我们使用具有约40nm竹节状周期性微观结构的多壁碳纳米管（MWCNT）作为nHA沉积的模板，以形成nHA-MWCNT复合材料。通过透射电子显微镜和扫描电子显微镜对组装的磷灰石进行了分析。沿着碳纳米管多壁表面类似于边缘位错的缺陷，在这些缺陷主要官能化为羧基后，成为nHA的成核位点。形成了由近乎平行的、原纤维状nHA多晶体组装而成的纺锤形单元，并且该单元相对于碳纳米管的长轴以一定角度取向，这与nHA-胶原蛋白不同，在nHA-胶原蛋白中nHA沿着胶原分子的纵轴取向。这种差异的一种可能解释是，胶原纤维表面上用于钙螯合的键（-COOH，>CO）比MWCNT表面上的更多。从MWCNT模板上脱离的纺锤形单元能够保持nHA多晶体原纤维的有序平行结构。因此，我们在MWCNT上创建了一种自组装的羟基磷灰石。
