title: Hydroxyapatite-collagen composites. Part I: can the decrease of the interactions between the two components be a physicochemical component of osteoporosis in aged bone?
abstract: The interactions of Type I acid soluble collagen (Col) with both carbonate-free hydroxyapatite (HA(1100)) and carbonate-rich one (CHA) were investigated. The aim was to ascertain whether the increase of bone CO(3) (2-) with ageing could relate to the disease known as osteoporosis. HA(1100)-Col and CHA-Col composites with various ratios were prepared and examined. Scanning electron microscopy and differential scanning calorimetry showed a stronger adhesion of the Col matrix to the granules of HA(1100) than to those of CHA. FT-IR spectroscopy showed that with HA(1100) both multiple hydrogen bonds of Col peptide -NH groups with HA PO(4) (3-), and electrochemical interactions between Col peptide -C=O groups and HA Ca(2+) were present. In the presence of CO(3) (2-), the interactions between -NH and phosphate were diminished, and Ca(2+) interacted more strongly with CO(3) (2-) than with peptide -C=O, so causing a separation between the two components of the bone extra-cellular matrix. The results obtained strengthen the hypothesis that the substitution of PO(4) (3-) ions by CO(3) (2-) ions in the HA lattice might be a significant component of osteoporosis, although further investigation is needed.
authors.affiliation: Dipartimento di Ingegneria Chimica, Chimica Industriale e Scienza dei Materiali, Università di Pisa, Largo Lucio Lazzarino, 56122, Pisa, Italy.
authors.forename: Niccoletta
authors.initials: N
authors.lastname: Barbani
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Rosellini
authors.forename: Caterina
authors.initials: C
authors.lastname: Cristallini
authors.forename: Giulio D
authors.initials: GD
authors.lastname: Guerra
authors.forename: Adriano
authors.initials: A
authors.lastname: Krajewski
authors.forename: Mauro
authors.initials: M
authors.lastname: Mazzocchi
mesh_terms: D000375:Aging; D001842:Bone and Bones / Q000473:pathology*; D002152:Calorimetry, Differential Scanning / Q000379:methods; D002627:Chemistry, Physical / Q000379:methods; D017886:Durapatite / Q000737:chemistry*; D005109:Extracellular Matrix / Q000473:pathology; D006801:Humans; D006860:Hydrogen Bonding; D007477:Ions; D008855:Microscopy, Electron, Scanning / Q000379:methods; D008956:Models, Chemical; D010024:Osteoporosis / Q000378:metabolism*; D013055:Spectrophotometry, Infrared / Q000379:methods; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013314:Stress, Mechanical; D013696:Temperature
chemical_list: D007477:Ions; D017886:Durapatite