Nucleation and growth of apatite by a self-assembled polycrystalline bioceramic.
The formation aspects of a polycrystalline self-assembled bioceramic leading to the nucleation of hard-tissue mineral from a supersaturated solution are discussed. Scanning electron imaging and surface-sensitive interrogations of the nucleated mineral indicated the presence of an intermediate amorphous layer encompassing a rather crystalline phase that formed on niobium oxide (Nb(2)O(5)) microstructures. The crystalline phase was identified from Raman spectroscopy as hydroxyapatite (HAP), while the phosphorous-rich amorphous layer is suggested to have the chemical form CaO-P(2)O(5). In addition, the mechanism favoring HAP nucleation is discussed in terms of the (0 0 2) and (0 0 1) diffraction planes of HAP and Nb(2)O(5), respectively. The small mismatch along several lattice dimensions strongly suggests epitaxy as a dominant mode in the heterogeneous nucleation of HAP. Furthermore, the effectiveness of this mode was shown to critically depend on the self-organization of the Nb(2)O(5) microstructures. Because nucleation does not appear to depend solely on the integrity of Nb(2)O(5) crystals, the self-organization of Nb(2)O(5) crystals also contributes significantly to HAP nucleation. Based on our results, we propose the organized arrangement of bioceramic crystals as a new mode for the bioinspiration of hydroxyapatite and other hard-tissue mineral.
Department of Preventive and Community Dentistry, Oral Health Research Institute, Indiana University School of Dentistry, Indianapolis, IN 46202, USA. rkarlins@iupui.edu
Robert L
RL
Karlinsey
Keewook
K
Yi
Clif W
CW
Duhn
D001031:Apatites / Q000737:chemistry*; D040761:Biomimetic Materials / Q000737:chemistry*; D002516:Ceramics / Q000737:chemistry*; D003459:Crystallins / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D008956:Models, Chemical; D009556:Niobium / Q000737:chemistry*; D010084:Oxidation-Reduction; D010087:Oxides / Q000138:chemical synthesis / Q000737:chemistry
D001031:Apatites; D003459:Crystallins; D010087:Oxides; D009556:Niobium; C073337:niobium pentoxide