Browsing by Author "Fernandes M.H.V."

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Carbonate - apatite forming ability of polyphase glass - ceramics in the CaO - MgO - SiO2 system
    (2015-01-01) Mihailova I.; Radev L.; Aleksandrova V.; Colova I.; Salvado I.M.M.; Fernandes M.H.V.
    Several types of glass-ceramics in the CaO - MgO - SiO2 system are shown to be bioactive, biocompatible and exhibiting various advantages for bone regeneration. A polyphase calcium-magnesium-silicate glass-ceramics is prepared by the sol-gel method including a two-step thermal treatment procedure aiming to investigate the effect of its phase composition on the in-vitro bioactivity observed. The dried gels of a chemical composition 3CaO.MgO.2SiO2 corresponding to merwinite are thermally treated at 700°C and 1100°C. The structural behavior of the synthesized samples is examined by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Larnite as the main crystalline phase, accompanied by merwinite, akermanite and periclase are detected after heat treatment at 1100°C. The in-vitro bioactivity of the glass-ceramics is detected by investigating the apatite formation ability in Simulated Body Fluid (SBF) for different times of soaking. The changes on the surface of the immersed samples and the formation of Mg- and Si-substituted carbonated apatites are verified by FTIR, SEM and Energy Dispersive Spectroscopy (EDS) techniques. The dissolution behavior of the glass-ceramics in SBF is also carried out by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The results indicate fast degradation in SBF and high reactivity of the polyphase glass-ceramics. The latter might be used as a bioactive implant material.
  • No Thumbnail Available
    Item
    Methylcellulose/SiO2 hybrids: Sol-gel preparation and characterization by XRD, FTIR and AFM
    (2011-03-21) Rangelova N.; Radev L.; Nenkova S.; Salvado I.M.M.; Fernandes M.H.V.; Herzog M.
    Methylcellulose (MC)/SiO2 organic/inorganic hybrid materials have been prepared from MC and methyltriethoxysilane or ethyltrimethoxysilane, and characterized by XRD, FTIR and AFM. XRD showed peak shifts. FTIR shows intermolecular hydrogen bonding between MC and SiO2. AFM depicts surface roughness which depends on the silica precursor and MC content. © Versita Sp. z o.o.
  • No Thumbnail Available
    Item
    Organic/inorganic bioactive materials part IV: In vitro assessment of bioactivity of gelatin-calcium phosphate silicate/wollastonite hybrids
    (2010-04-01) Radev L.; Hristov V.; Fernandes M.H.V.; Salvado I.M.M.
    Biohybrids consisting of gelatin (G) and calcium phosphate silicate/wollastonite (CPS/W) have not been prepared so far. In this work our results are focused on the possibility of obtaining G-CPS/W bioactive hybrids in vitro. XRD, FTIR, SEM/EDS techniques were employed to characterize the synthesized hybrid materials. FTIR shows that before immersion in 1.5 SBF the ``red shift`` of COO- band for pure G is observed. The presence of this bond could be attributed to the formation of COO-Ca2+ via non-biomimetic route. After immersion in 1.5 SBF, FTIR shows the presence of A- and B-type carbonate containing hydroxyapatite (A/B-CO3HA). ESD and FTIR show that small amount of calcite (CaCO3) are present after in vitro test in 1.5 SBF for 3 days. XRD reveals that CO3HA and small amounts of CaCO3 can be detected after in vitro test. SEM results obtained for immersed samples show that hydroxyapatite (HA) particles fully covered the surface of the hybrids by a layer composed of spherulites. At higher magnification, very small elongated crystallites could be observed. © 2010 Versita Warsaw and Springer-Verlag Wien.