MODELING AND COMPUTATION OF HYDROXYAPATITE NANOSTRUCTURES AND PROPERTIES

MODELING AND COMPUTATION OF HYDROXYAPATITE NANOSTRUCTURES AND PROPERTIES V. BYSTROV 1), N. BYSTROVA 2), E. PARAMONOVA 1) , A. . SAPRONOVA 1), S. FILIPPOV 1), 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. ru vsbys@yahoo. co. uk http: //home. impb. psn. ru (OPIT Home Page) Hydroxyapatite (Ca 5(PO 4)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 P 21/b) or in the hexagonal system (P 63/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. OH- dipols form so-called “OH- ion channels” along c direction. These channels are bounded within each unit cell be two triangular arrays of Ca 2+ ions and by four triangular arrays of O 2 - ions, belonging to PO 43 - groups Unit cell parameters a, b, c [Å] HAp in hexagonal P 63/m and monoclinic P 21/b phase European Commission PROJECT NMP 3 -CT-2003 -504937 “Multifunctional percolated nanostructured ceramics fabricated from hydroxylapatyte” We have used data from CIF (Crystallographic Information File) lybrary [8] which were edited with en. CIFer 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. Volume V [Å3] and square S [Å2] of Van der Waals surface of HAp cell in P 63/m and P 21/b phases (Web. Lab Viewer Lite) References: 1. N. Hitmi, D. Chatain, C. La. Cabanne, J. Dugas, J. C. Trombe, C. Rey and G. Montel, Solid State. Communications, Vol. 33, pp. 10031004, 1980. 2. N. Hitmi, C. La. Cabanne and R. A. Young, J. Phys. Chem. Solids Vol. 47, No 6, pp 533 -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/