title: Local structures of mesoporous bioactive glasses and their surface alterations in vitro: inferences from solid-state nuclear magnetic resonance.
abstract: We review the benefits of using (29)Si and (1)H magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy for probing the local structures of both bulk and surface portions of mesoporous bioactive glasses (MBGs) of the CaO-SiO(2)-(P(2)O(5)) system. These mesoporous materials exhibit an ordered pore arrangement, and are promising candidates for improved bone and tooth implants. We discuss experimental MAS NMR results from three MBGs displaying different Ca, Si and P contents: the (29)Si NMR spectra were recorded either directly by employing radio-frequency pulses to (29)Si, or by magnetization transfers from neighbouring protons using cross polarization, thereby providing quantitative information about the silicate speciation present in the pore wall and at the MBG surface, respectively. The surface modifications were monitored for the three MBGs during their immersion in a simulated body fluid (SBF) for intervals between 30 min and one week. The results were formulated as a reaction sequence describing the interconversions between the distinct silicate species. We generally observed a depletion of Ca(2+) ions at the MBG surface, and a minor condensation of the silicate-surface network over one week of SBF soaking.
authors.affiliation: Physical Chemistry Division, Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm, Sweden.
authors.forename: Philips N
authors.initials: PN
authors.lastname: Gunawidjaja
authors.forename: Renny
authors.initials: R
authors.lastname: Mathew
authors.forename: Andy Y H
authors.initials: AY
authors.lastname: Lo
authors.forename: Isabel
authors.initials: I
authors.lastname: Izquierdo-Barba
authors.forename: Ana
authors.initials: A
authors.lastname: García
authors.forename: Daniel
authors.initials: D
authors.lastname: Arcos
authors.forename: María
authors.initials: M
authors.lastname: Vallet-Regí
authors.forename: Mattias
authors.initials: M
authors.lastname: Edén
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D002516:Ceramics / Q000737:chemistry*; D005898:Glass / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008422:Materials Testing / Q000379:methods*; D016062:Porosity; D011208:Powders; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D011208:Powders