Sol-gel synthesis and structure of cordierite/tialite glass-ceramics

In the present work the results of the research on the sol-gel synthesis and structure of cordierite (2MgO·2Al2O3·5SiO2), tialite (Al2O3·TiO2) and cordierite/tialite glass-ceramics as well cordierite containing 2 wt.% of Co and Co+Cu have been described and discussed. The sol-gel synthesis was carried out using different kind of precursors as follows: Al(NO3)×9H2O, Si(OC2H5)4 , Ti(OC4H9)4 , Mg(NO3)2×6H2O, chlorides or nitrates of corresponding metals, H2O, C2H5OH, Aqua Regia, NH4F and PEG. The synthesized gels were dried and thermally treated in the temperature range from 800°C to 1200°C. The sol-gel processes and structure of the cordierite, tialite and cordierite/tialite glass-ceramics have been investigated by means of XRD, FTIR, TEM, SEM and EPMA

In vitro bioactivity of biphasic calcium phosphate silicate glassceramic in CaO-SiO2-P2O5 system

The main purpose of the paper is the evaluation of the influence of chemical composition of the gel of the synthesized 15CaO·0.5P2O5·6SiO2 glass-ceramic on the structure, crystallization behaviour and in vitro bioactivity in static conditions for different periods of time - 3, 9 and 30 days in 1.5SBF. The obtained glass-ceramic was synthesized via polystep sol-gel technique. The structure of the prepared and the one thermally treated at 1200°C for 2 h powder was studied by XRD, 29Si MAS NMR, FTIR and SEM

Density Functional Theory Investigation of Bis(Benzimidazole) Silver (I) Nitrate

International audienceThe geometry, chemical reactivity and electronic structure of a bis(benzimidazole)silver (I) nitrate ([Ag(benzimidazole) 2 ] + [NO 3 ] –) were discussed on the basis of Density Functional Theory calculations using B3LYP/6-31G(d,p) and LANL2DZ for silver atom. The calculations indicated that [Ag(benzimidazole) 2 ] + [NO 3 ] – exists in the form of an ion pair. A large electropositive potential was found on the benzimidazole ligands, while the regions of a negative electrostatic potential is linked with the lone pair of electronegative oxygen atoms in nitrate anion ([NO 3 ] –). The natural bond orbital theory was using to describe electron transfer both within the anion, and between the anion and cation of an ion pair. The energy values of –5.1508 and –2.0907 eV were calculated to HOMO and LUMO orbitals, respectively

In Vitro Bioactivity of Silver-Containing Sol-Gel Glasses: FTIR Analysis

Introduction: The sol-gel glasses (BG) have been used for various biomedical applications, such as orthopedic, dental grafting and tissue engineering. The main purpose of the presented article is the preparation and evaluation of carbonate apatite formation on the BG in SiO2-CaO-P2O5-xAg2O system, where x=0,1,2 and 4wt.% Ag2O (BG/Ag), after soaking in a simulated body fluid (1.5 SBF) for 12 days in static conditions.Materials and Methods: BG/Ag were synthesized from tetraethyl orthosilicate (TEOS), calcium oxide (CaO), phosphoric acid (H3PO4) and silver nitrate (AgNO3) as sources. TEOS was stirred into the mixed solvent of C2H5OH and H2O with a very small amount of HCl in the volume ratio TEOS:C2H5OH:H2O:HCl=1:1:1:0.01. The mixture of calcium phosphate (CP) and appropriate amount of AgNO3 was added to SiO2 sol under stirring for 20h. The mixed sol obtained was gelated at 120oC for 12h and 600oC for 6h.Results: X-ray powder diffraction (XRD) of the synthesized samples showed that the presence of some crystalline phases is dependent on the gel composition. XRD proved the presence of CaCO3, wollastonite, HA and metallic Ag in accordance with gel compositions. Fourier transform infrared spectroscopy (FTIR) of the prepared BG showed the presence of basic absorption bands, corresponding to the different chemical bands and crystalline phases, in agreement with XRD results. FTIR of the examined samples, after soaking in 1.5 SBF solution for 12 days, confirmed that B-type carbonate apatite was formed preferentially on the soaked surface.Conclusions: BG in SiO2-CaO-P2O5-xAg2O system (x=0,1,2 and 4wt.% Ag2O) were synthesized via a polystep sol-gel method. After immersion of the studied BG in 1.5 SBF solutions for 12 days in static conditions, FTIR revealed the presence of some CO32- bands, i.e. after soaking carbonate apatite (CO3HA) may be formed on the surface of the prepared sol-gel glasses. On the basis of FTIR results, we can assume that B-type CO3HA preferentially formed on the soaked samples

Carbonate apatite formation on novel multiphase CaO-SiO2-P2O5-MgO glass-ceramics in TRIS-HCl buffer

The main purpose of the presented article is the preparation of novel glass-ceramics in CaO-SiO2-P2O5-MgO system and evaluation of carbonate apatite formation after soaking in TRIS-HCl buffer solution for 14 days. The investigated samples were prepared via sol-gel method and structure of the obtained samples was studied using XRD, FTIR, SEM, XPS and ICP-AES. XRD of the thermally treated samples showed that the presence of some crystalline phases is depended on the gel composition. FTIR revealed the existence of all characteristic bands for the observed crystalline phases. SEM monitored the presence of particles with different morphology. After soaking in TRIS-HCl solution, FTIR confirmed that carbonate apatite was formed on the soaked surface. The obtained data are in a good agreement with XPS analysis. The change of ions concentrations in TRIS-HCl buffer solution after immersion of the prepared glass-ceramics was recorded by ICP-AES measurements

In vitro bioactivity of glass-ceramic/fibroin composites

Bioactive composite materials were prepared by mixing 20 wt.% of silk fibroin (SF) and 80 wt.% of glassceramics from CaO-SiO2-P2O5-MgO system. In vitro bioactivity of the prepared composites was evaluated in 1.5 simulated body fluid (1.5 SBF) in static conditions. The obtained samples before and after in vitro tests were characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The changes in 1.5 SBF solutions after soaking the samples were evaluated by inductively coupled plasma atomic emission spectroscopy (ICP-AES). MG63 osteosarcoma cells were used for the biological experiments. The obtained experimental data proved that the synthesized composites exhibit excellent in vitro bioactivity

Silk Fibroin/Calcium Phosphate Silicate Composites: In vitro Bioactivity

Abstract Co mposite materials of Silk Fib roin (SF) and Calciu m Phosphate Silicate (CPS) ceramic in the 15CaO-6SiO 2 -0.5P 2 O 5 system were prepared by method of mixing d ifferent percentage of component weight. The structure was characterized before and after in vitro test by FTIR, SEM. The concentration of Ca, Si and P after in vit ro test was analysed by ICP-A ES. FTIR of the composites before in vitro test depicts that random coil and β-sheet structures co-exist in the co mposites. CPS ceramic has a significant effect on the secondary structure of SF. SEM observed that CPS particles uniformly dispersed in SF matrix. FTIR of the composites after in vitro test revealed that carbonate containing hydroxyapatite (CO 3 HA) was formed on the surface. B-type CO 3 HA preferentially formed in the samp le with 75 wt. % CPS ceramic. SEM proved that hydroxyapatite (HA) fo rmed in a high level. ICP-A ES showed that HA precipitation were similar fo r the three composites. Based of these results, it can be concluded that the incorporation of CPS ceramic powder enhanced the in vitro bioactivity

Carbonate-apatite forming ability of polyphase glass-ceramics in the CaO - MgO - SiO2 system

Several types of glass-ceramics in the CaO - MgO - SiO 2 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.2SiO 2 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

Collagen/silicocarnotite composites, cross-linked with chondroitin sulphate: in vitro bioactivity

In this work we present the experimental results on synthesis, structure evolution and in vitro bioactivity of collagen-silicocarnotite-chondroitin sulphate composites. The obtained samples were synthesised by mixing collagen (C) and silicocarnotite (S) powder with C:S ratio of 75:25 and 25:75 wt.% in the presence of chondroitin sulphate (ChS). Collagen was diluted in 5M CH3COOH before mixing. The obtained materials were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) before and after in vitro test in 1.5 simulated body fluid. XRD of synthesized samples showed that before immersion carbonate containing hydroxyapatite (CO3HA) were formed in situ in the composites. FTIR depicts the presence of HPO42– and the “red shift” of COO– and SO3– from ChS was also observed. This “red shift” could be attributed that the ChS prefers to chelate Ca2+ from partially dissolved S powder. SEM of the prepared samples show the presence of nanosized hydroxyapatite (HA) whiskers and flower-like HA assemblies. After in vitro test, XRD proved the presence of HA with well-defined crystallinity. According to the FTIR results B-type CO3HA can be observed. SEM of the precipitated layers show the presence of HA spheres. Inductively coupled plasma atomic emission spectroscopy results lead to a conclusion that after in vitro test of the prepared composites silicon containing carbonate substituted hydroxyapatite (Si-CO3HA) may be formed on the surface of the immersed samples

Sol-gel synthesis and structure of La2O3–CoO–SiO2 powders

LaCoO3 powders are studied because they exhibit interesting electrical, magnetic and catalytic properties. In this paper, new synthesized La2O3-CoO-SiO2 powders with different quantity of silica were prepared via solgel method in aqua media, starting from metal nitrates with different chelating agents. The relation between the reaction in solution, crystallization pathway and morphology were discussed. In LaCoO3-SiO2 powders, depending on the content of SiO2 and the treatment temperature (700–1100°C), different crystalline phases (LaCoO3, Co2SiO4 and La9.31(SiO4)6O2) were observed with the crystallite sizes ranging from 50 to 100 nm. It was proved that chemical composition and nature of used additives has influence on the phase formation and structure of obtained nanomaterials