title: Synthesis and characterization of strontium-substituted hydroxyapatite nanoparticles for bone regeneration.
abstract: The production of stable suspensions of strontium-substituted hydroxyapatite (Sr-HA) nanopowders, as Sr ions vector for bone tissue regeneration, was carried out in the present work. Sr-HA nanopowders were synthesized via aqueous precipitation methods using Sr2+amount from 0 to 100mol% and were characterized by several complementary techniques such as solid-state Nuclear Magnetic Resonance spectroscopy, X-ray diffraction, Infrared spectroscopy, N2physisorption and Transmission Electron Microscopy. The substitution of Ca2+with Sr2+in HA is always isomorphic with gradual evolution between the two limit compositions (containing 100% Ca and 100% Sr), this pointing out the homogeneity of the synthesized nanopowders and the complete solubility of strontium in HA lattice. Strontium addition is responsible for an increasing c/a ratio in the triclinic unit cell. A significant variation of the nanopowders shape and dimension is also observed, a preferential growth along the c-axis direction being evident at higher strontium loads. Modifications in the local chemical environment of phosphate and hydroxyl groups in the apatite lattice are also observed. Stable suspensions were produced by dispersing the synthesized nanopowders in bovine serum albumin. Characterization by Dynamic Light Scattering and ζ-potential determination allowed to show that Ca2+→Sr2+substitution influences the hydrodynamic diameter, which is always twice the particles size determined by TEM, the nanoparticles being always negatively charged as a result from the albumin rearrangement upon the interaction with nanoparticles surface. The biocompatibility of the suspensions was studied in terms of cell viability, apoptosis, proliferation and morphology, using osteosarcoma cell line SAOS-2. The data pointed out an increased cell proliferation for HA nanoparticles containing larger Sr2+load, the cells morphology remaining essentially unaffected.
authors.affiliation: Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123 Trento, Italy; INSTM Research Unit, Via G. Giusti 9, 50123 Firenze, Italy. Electronic address: matteo.frasnelli@unitn.it.
authors.forename: Matteo
authors.initials: M
authors.lastname: Frasnelli
authors.affiliation: Department of Molecular Medicine, Center for Health Technologies (CHT), University of Pavia, Viale Taramelli 3/b, 27100 Pavia, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Cristofaro
authors.affiliation: Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123 Trento, Italy; INSTM Research Unit, Via G. Giusti 9, 50123 Firenze, Italy.
authors.forename: Vincenzo M
authors.initials: VM
authors.lastname: Sglavo
authors.affiliation: Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123 Trento, Italy; "Klaus Müller" NMR Laboratory, Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123 Trento, Italy.
authors.forename: Sandra
authors.initials: S
authors.lastname: Dirè
authors.affiliation: Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123 Trento, Italy; "Klaus Müller" NMR Laboratory, Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123 Trento, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Callone
authors.affiliation: Department of Industrial Engineering, University of Trento, Via Sommarive 9, 38123 Trento, Italy.
authors.forename: Riccardo
authors.initials: R
authors.lastname: Ceccato
authors.affiliation: Department of Chemistry, Physical-Chemistry Section, University of Pavia, Viale Taramelli 16, 27100 Pavia (PV), Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Bruni
authors.affiliation: Department of Experimental Medicine, Faculty of Medicine, University of Pavia, Italy.
authors.forename: Antonia Icaro
authors.initials: AI
authors.lastname: Cornaglia
authors.affiliation: Department of Molecular Medicine, Center for Health Technologies (CHT), University of Pavia, Viale Taramelli 3/b, 27100 Pavia, Italy; Department of Occupational Medicine, Toxicology and Environmental Risks, S. Maugeri Foundation, IRCCS, Via S. Boezio, 28, 27100 Pavia (PV), Italy.
authors.forename: Livia
authors.initials: L
authors.lastname: Visai
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001861:Bone Regeneration / Q000187:drug effects*; D002417:Cattle; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D017886:Durapatite / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D053758:Nanoparticles / Q000737:chemistry*; D013324:Strontium / Q000737:chemistry / Q000494:pharmacology
chemical_list: D017886:Durapatite; D013324:Strontium
keywords: Bone regeneration; Nanoparticles; Osteoblast; Solid state (31)P NMR; Strontium hydroxyapatite; Suspensions