MODELING AND COMPUTATION OF HYDROXYAPATITE NANOSTRUCTURES AND PROPERTIES

1. European Commission PROJECT NMP3-CT-2003-504937 “Multifunctional percolated nanostructured ceramics fabricated from hydroxylapatyte”  Volume V [Å3] and squareS [Å2] of Van der Waals surface of HAp cell in P63/mandP21/b phases (WebLab Viewer Lite) Unit cell parameters a,b,c[Å] HApin hexagonal P63/m and monoclinic P21/b phase V. BYSTROV1), N.BYSTROVA2), E. PARAMONOVA1), A.. SAPRONOVA1), S. FILIPPOV1), 1)Institute of Mathematical Problems of Byology of RAS; 2)Institute of Theoretical and Experimental Biophysics of RAS, Pushchino, 142290, Moscow region, Russia E-mail:bystrov@impb.psn.ruvsbys@yahoo.co.ukhttp://home.impb.psn.ru (OPIT Home Page) MODELING AND COMPUTATION OF HYDROXYAPATITE NANOSTRUCTURES AND PROPERTIES Hydroxyapatite (Ca5(PO4)3 OH) (HAp) is a crystal structural and compositional analogue to calcified tissues of vertebrates. The biomedical significance of HAp is its bioactivity – HAp ceramics conduct the formation of new bone on their surface. HAp properties are ascribed to the characteristic surface structure of HAp, while the detailed mechanism is still unknown. Hydroxyapaptite can occur in a monoclinic phase (space group P21/b) or in the hexagonal system (P63/m).In the monoclinic phase, all of the dipols in all of the tunnels lying in the same plane parallel to the a,c plane must be either all up or all down and those in the next plane b/2 away must be oriented oppositely. We have used data from CIF (Crystallographic Information File) lybrary [8] which were edited with enCIFer 1.1[7]and spg[6]. Then in Web Lab Viewer Lite [1] the structures of both modification of HAp were created from CIF. Then obtained data were processed by Hyper Chem: OH positions were optimized. Also in Web Lab Viewer Lite H-bonds and Van der Waals surfaces were plot. OH- dipols form so-called “OH- ion channels” along c direction. These channels are bounded within each unit cell be two triangular arrays of Ca2+ ions and by four triangular arrays of O2- ions, belonging to PO43- groups References: 1. N. Hitmi, D. Chatain, C. LaCabanne, J. Dugas, J.C.Trombe, C. Rey and G. Montel, Solid StateCommunications, Vol. 33, pp. 1003-1004, 1980. 2. N. Hitmi, C. LaCabanne and R.A. Young, J.Phys. Chem. Solids Vol. 47, No6, pp533-546, 1986. 3. Nakamura, Nakeda and Yamashita, J. Appl. Phys.,Vol.89, No.10,15 May 2001. Proton transport polarization and depolarization of hydroxyapatite ceramics 4. G.C. Maiti, F.Freund. Influence of fluorine substitution on the proton conductivity of hydroxyapatite. J.Chem.Soc. Dalton, pp.949-955, 1981 5. http://www.msi.com/viewer 6.http://www.calidris-em.com/archive.htm 7. http://www.ccdc.cam.ac.uk/free_services/encifer 8. ftp://ftp.geo.arizona.edu/pub/xtal/data/CIFfiles/