title: A solid-state NMR study of selenium substitution into nanocrystalline hydroxyapatite.
abstract: The substitution of selenium oxyanions in the hydroxyapatite structure was examined using multinuclear solid-state resonance spectroscopy (ssNMR). The study was supported by powder X-ray diffractometry (PXRD) and wavelength dispersion X-ray fluorescence (WD-XRF). Samples of pure hydroxyapatite (HA300) and selenate (HA300-1.2SeO4) or selenite (HA300-1.2SeO3) substituted hydroxyapatites were synthesized using the standard wet method and heated at 300 °C to remove loosely bonded water. PXRD data showed that all samples are single-phase, nanocrystalline hydroxyapatite. The incorporation of selenite and selenate ions affected the lattice constants. In selenium-containing samples the concentration of Se was very similar and amounted to 9.55% and 9.64%, for HA300-1.2SeO4 and HA300-1.2SeO3, respectively. PXRD and ssNMR data showed that the selenite doping significantly decreases the crystallite size and crystallinity degree. 31P and 1H NMR experiments demonstrated the developed surface hydrated layer in all samples, especially in HA300-1.2SeO3. 1H NMR studies showed the dehydroxylation of HA during the selenium oxyanions substitution and the existence of hydrogen bonding in structural hydroxyl group channels. 1H→77Se cross polarization NMR experiments indicated that selenites and selenates are located in the crystal lattice and on the crystal surface.
authors.affiliation: Department of Inorganic and Analytical Chemistry, Faculty of Pharmacy with the Laboratory Medicine Division, Medical University of Warsaw, ul. Banacha 1, 02-097 Warsaw, Poland. joanna.kolmas@wum.edu.pl.
authors.forename: Joanna
authors.initials: J
authors.lastname: Kolmas
authors.affiliation: Department of Inorganic and Analytical Chemistry, Faculty of Pharmacy with the Laboratory Medicine Division, Medical University of Warsaw, ul. Banacha 1, 02-097 Warsaw, Poland. marzena.kuras@wum.edu.pl.
authors.forename: Marzena
authors.initials: M
authors.lastname: Kuras
authors.affiliation: Department of Inorganic and Analytical Chemistry, Faculty of Pharmacy with the Laboratory Medicine Division, Medical University of Warsaw, ul. Banacha 1, 02-097 Warsaw, Poland. eoledzka@wum.edu.pl.
authors.forename: Ewa
authors.initials: E
authors.lastname: Oledzka
authors.affiliation: Department of Inorganic and Analytical Chemistry, Faculty of Pharmacy with the Laboratory Medicine Division, Medical University of Warsaw, ul. Banacha 1, 02-097 Warsaw, Poland. marcin.sobczak@wp.pl.
authors.forename: Marcin
authors.initials: M
authors.lastname: Sobczak
mesh_terms: D017886:Durapatite / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D012643:Selenium; D014961:X-Ray Diffraction
chemical_list: D017886:Durapatite; D012643:Selenium
keywords: biomaterials; calcium phosphates; hydroxyapatite; powder diffractometry; selenium oxyanions; solid-state nuclear magnetic resonance