The main purpose of the presented article is the preparation and evaluation of carbonate apatite ... more The main purpose of the presented article is the preparation and evaluation of carbonate apatite formation on the sol-gel glasses in SiO 2 -CaO-P 2 O 5 -xAg 2 O system, where x=0, 1, 2 and 4 wt.% Ag 2 O, after soaking in 1.5 SBF solutions for 12 days in static conditions. The investigated samples were prepared via the polystep sol-gel method and the structure of the obtained samples was monitored by XRD and FTIR. XRD of the synthesized and thermal treated at 600 o C for 6 hrs. samples showed that the presence of some crystalline phases is depended on the gel composition. FTIR revealed the existence of all the characteristic bands for the observed phases. 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.
Imperial journal of interdisciplinary research, 2017
The main objectives of the presented study is the preparation of 80BG/20G (in wt. %) composites b... more The main objectives of the presented study is the preparation of 80BG/20G (in wt. %) composites between sol-gel glasses (BG) in the SiO 2 -CaO-P 2 O 5 -xAg 2 O (x=0, 1, 2 and 4 wt. %) system and gelatin (G), after soaking in 1.5 SBF solutions for 12 days in static conditions. The structure and in vitro bioactivity of the prepared composites were examined by XRD and FTIR. XRD for the composites, before soaking in 1.5 SBF solutions, revealed the presence of different CaCO 3 crystalline phases, such as aragonite, calcite and vaterite. In the prepared samples, XRD also detected the presence of in situ formed hydroxyapatite, accompanied with Wollastonite phase. FTIR of the studied 80BG/20G composites, after soaking in 1.5 SBF solutions, proved the formation of B-type carbonate contacting hydroxyapatite (bioapatite) on their surface. SEM-EDX results of the soaked samples show the presence of HA aggregates on the soaked surceases. On the bases of results obtained we can conclude that the ...
Imperial journal of interdisciplinary research, 2016
Blends of silk fibroin (SF), Bombyx mori and alginate (SA), in form of films and sponges, were in... more Blends of silk fibroin (SF), Bombyx mori and alginate (SA), in form of films and sponges, were investigated. The films were prepared by drying at room temperature, the sponges – by lyophilization. In vitro behavior test was performed in Simulated Body Fluid media (SBF) for 3, 14 and 25 days. It was found strong effect of biomaterial’s morphological structure on their behavior in 1.5 SBF. The films of SF/SA exhibit bioactivity . The sponges of SF/SA exhibit degradation . Two observed processes - bioactivity and degradation, depending on the ratio of SF and SA of the investigated blends. The changes were confirmed by FTIR, EDX, changes of sample’s mass and SEM. The effect of SA at the conversion of silk I to silk II into the blends was obvious, because the samples were not treated with alcohols. Alginate induced the conformation transition of fibroin’s macromolecules and recrystallization of β-sheets. It was found the interactions between the fibroin’s amido groups and carboxyl groups...
Bioactive glass was first synthesized by L. Hench in 1971. There are many studies on the properti... more Bioactive glass was first synthesized by L. Hench in 1971. There are many studies on the properties of several metals and metal ions dopants used in the SiO 2-CaO-P 2 O 5 system of bioglasses, such as Ag, Cu, Zn, and Fe. A number of authors have carried out research related to the influence of silver oxide on the properties of bioglasses. However, publications on the properties of elastomer-based composites containing bioactive glasses are relatively scarce. We have not found in the literature studies discussing how silver oxide concentration in bioglasses of the CaO-SiO 2-P 2 O 5-Ag 2 O system affects the significant properties of a natural rubber biocomposite. In this regard, the purpose of the present work is to investigate the aforementioned influence on the properties of this type of composites, namely, vulcanization, physicomechanical, thermal, dynamic, dielectric, electric, and thermoconductive characteristics. We have established those parameters of the composites to be impacted considerably by both degree of filling with bioglass and the silver oxide content in the latter. The improvement in the composites thermostability and some of their physicomechanical performance is the most significant. The volume resistance decreases, and the thermal conductivity coefficients increase. Results from scanning electron microscopy and energy-dispersive X-ray (EDX) analyses have confirmed the influence of silver oxide initially on the phase composition of the bioglass, hence on the properties of the biocomposites through changes in the bioglass used as filler. The dielectric characteristics of some of the biocomposites suggest that they can be used as substrates and insulating layers in flexible antennas for short-range wireless communications. KEYWORDS Ag 2 O, bioglasses, dielectric properties, natural rubber composites, physicomechanical properties 1 | INTRODUCTION Bioactive glass (BG) was first synthesized by L. Hench and coworkers in 1971. Ever since, it has been attracting attention because of the properties allowing its medical applications. 1 There are high requirements for BG materials that should be met, especially those concerning minimal risk of developing extra compilations when applied. There are many studies on the antibacterial properties of several metals and metal ion dopants used in the SiO 2-CaO-P 2 O 5 system of BG, such as Ag, 2-10 Cu, 10 Zn, 11 Mn, 12 and Fe. 13 As the colleagues of Hench have suggested,
International Journal of Materials and Chemistry, 2013
Co mposite materials of Silk Fib roin (SF) and Calciu m Phosphate Silicate (CPS) ceramic in the 1... more 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.
Systematic investigations on the isomerization and oxidative transformations of some menthadiens ... more Systematic investigations on the isomerization and oxidative transformations of some menthadiens in the presence of different additives have been carried out. In the obtained reaction masses have been identified hydrocarbons, ketones, alchohols and oxides which are prospective raw materials for aromatic production, perfumery and cosmetics.
The aim of the present study is to synthesize and study calcium-cobalt silicates: Ca 2 CoSi 2 O 7... more The aim of the present study is to synthesize and study calcium-cobalt silicates: Ca 2 CoSi 2 O 7 and CaCoSi 2 O 6 , which are structural analogues of akermanite and diopside minerals in the full substitution of the positions of magnesium with cobalt. The shown phases have been determined in the system CaO–CoO–SiO 2. The chosen crystal phases belong to two main structural silicate types – silicates with diorthogroups of silicon-oxygen tetrahedrons and silicates with chains of silicon-oxygen tetrahedrons. On the basis of each one of them ceramic pigments can be synthesized. The interest towards these syntheses is raised by tracing the influence of structural position of cobalt ions on the coloring. In the selected phases it is expected the cobalt to take different structural positions. In the akermanite structure Ca 2 CoSi 2 O 7 cobalt cations take tetrahedral coordination toward oxygen atoms. In pyroxene structure CaCoSi 2 O 6 the cobalt is in octahedral coordination. The phases are...
Several types of glass-ceramics in the CaO-MgO-SiO 2 system are shown to be bioactive, biocompati... more 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.
The ceramics in the system CaO-MgO-SiO 2 has recently received a great deal of attention because ... more The ceramics in the system CaO-MgO-SiO 2 has recently received a great deal of attention because they exhibit good in vitro bioactivity and have potential use as bone implants. Biphasic calcium-magnesium-silicate ceramics was prepared by a sol-gel method. The dried gel with chemical composition 3CaO.MgO.2SiO 2 was thermally treated at 1300 °C for 2 h. The structural behavior of the synthesized ceramics was examined by means of X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Merwinite, as the main crystalline phase, and akermanite, as the minor phase, were identified. The in vitro bioactivity of the synthesized ceramic samples was recorded in Simulated Body Fluid (SBF) for different times of soaking. The apatite formation on the surface of the immersed samples was detected by FTIR, SEM and Energy Dispersive Spectroscopy (EDS) techniques. The ion concentrations in the SBF solutions after the in vitro test were evaluated by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). On the basis of the results obtained, the ability of the biphasic ceramics to deposit apatite layer was found. The peculiarities of the formation of apatite layer depending on the phase composition were analyzed and discussed.
The main purpose of the paper is the evaluation of the influence of chemical composition of the g... more 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. .
In the present work the results of the research on the sol-gel synthesis and structure of cordier... more 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. .
International Journal of Materials and Chemistry, 2012
In this work we present the experimental results on synthesis structure and in vitro bioactivity ... more In this work we present the experimental results on synthesis structure and in vitro bioactivity of collagen (C)/calcium phosphate silicate (CPS)/chondroitin sulfate (ChS) composites with C/CPS ratio of 25:75 wt. % and 75:25wt. %. The synthesized composites were characterized by XRD, FTIR and SEM/EDS. XRD and FTIR before in vitro test proved that the carbonate containing hydroxyapatite (CO 3 HA) formed in situ. After in vitro test for 3 days in 1.5 SBF, the nucleation of B-type CO 3 HA was estimated on the obtained C/CPS=75:25 wt. % composite with cauliflower-like assembly. On the C/CPS=25:75 wt. % amorphous hydroxyapatite (HA) layer was observed.
In this work we present the experimental results on synthesis, structure evolution and in vitro b... more 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 HPO4 2- 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 prepa...
The 70SiO2-30CaO (wt.%) sol-gel glasses doped with 1, 3 and 5 NbF5 (wt.%) were prepared via polys... more The 70SiO2-30CaO (wt.%) sol-gel glasses doped with 1, 3 and 5 NbF5 (wt.%) were prepared via polystep sol-gel route. The synthesized glasses were characterized by XRD, FTIR and SEM. Changes in 1.5 SBF solutions were measured by ICP-AES. XRD of the glasses stabilized at 700°C for 6 hours proved the presence of niocalite. FTIR was consistent with XRD data. The in vitro bioactivity study of all glasses prepared were carried out by soaking in 1.5 simulated body fluid (1.5 SBF) at 37°C for 6 and 12 days in static conditions. The FTIR reveals the formation of A-type and B-type carbonate containing hydroxyapatite (CO3HA) layer. Changes in 1.5 SBF solutions, after 6 days of soaking, show that the Ca concentration increased significantly, compared to the initial Ca content in the 1.5 SBF solution before in vitro test. After 12 days of immersion, the Ca concentration decreased, i.e., the formation of HA phase consumed Ca from 1.5 SBF solution. For all soaking times, the concentration of P is m...
In this work we present experimental results about synthesis, structure evolution and in vitro bi... more In this work we present experimental results about synthesis, structure evolution and in vitro bioactivity of new calcium phosphate silicate/wollastonite (CPS/W) glass-ceramics. The samples obtained were synthesized via polystep sol-gel process with different Ca/P+Si molar ratio (R). The structure of the materials obtained was studied by XRD, FTIR spectroscopy and SEM. XRD showed the presence of Ca15(PO4)2(SiO4)6, β-CaSiO3 and α-CaSiO3 for the sample with R=1.89 after thermal treatment at 1200°C/2h. The XRD results are in good agreement with FTIR analysis. SEM denotes that apatite formation can be observed after soaking in simulated body fluid (SBF).
In the present work Polyurethane (PU)/Bioglass (BG) composite materials were synthesized with dif... more In the present work Polyurethane (PU)/Bioglass (BG) composite materials were synthesized with different content of BG (10 and 20 mol.%) as filler. The 85S Bioglass was synthesized via polystep sol-gel method. The chemical composition of BG is 85SiO2-10CaO-5P2O5 (wt.%). The synthesis of PU was carried out by a two-step polyaddition reaction. The 85S BG was added in situ during the polymerization reaction. In vitro bioactivity of the prepared composites was examined in the presence of 1.5 SBF for 7 days in static conditions. The structure of synthesized PU/BG composites before and after in vitro test was determined by XRD, FTIR and SEM. XRD of the samples before in vitro test proved that the phase of γCa2P2O7 in the PU/20BG is visible. FTIR revealed the presence of urethane bond between OH-(from BG) and NCO groups (from PU). Based on FTIR results after in vitro test in 1.5 SBF solutions, A/B-carbonate containing hydroxyapatite (CO3HA) was formed. XRD proved that HA was formed on the s...
The silicocarnotite, as an inorganic part of the coatings, has been synthesized using a polystep ... more The silicocarnotite, as an inorganic part of the coatings, has been synthesized using a polystep sol-gel method. The chemical composition of the prepared silicocarnotite sol is described as 58.12 CaO, 29.42 P2O5, 12.45 SiO2 (wt%), where Ca/P+Si = 1,67. The acid soluble type I collagen, as an organic part of the obtained coatings, was mixed with silicocarnotite powder in a weight ratio of 25:75 and 75:25 weight ratio without cross-linkage. The acidity of the obtained mixture was readjust with 25% NH4OH to pH = 9.0. The mixture was then dried at 37°C for 12 h. The growth of B-type carbonate containing hydroxyapatite (B-type CO3HA) in which CO3 2+→PO4 3− on the surface of collagen/silicocarnotite coatings soaked in 1.5 simulated body fluid (1.5 SBF) was observed. The nucleation of B-type CO3HA was estimated on the obtained coatings after 3 days immersion in 1.5 SBF. The negatively charged carboxylate groups from the collagen surface may be responsible for the HA deposition. This was co...
In the present study, novel hybrid materials of Collagen (C) and Calcium Phosphate Silicate/Wolla... more In the present study, novel hybrid materials of Collagen (C) and Calcium Phosphate Silicate/Wollastonite (CPS/W) were synthesized. The CPS/W ceramic was prepared via polystep sol-gel method. The dissolution test of CPS/W ceramic was filled with TRIS-HCl buffer. FTIR depicts that hydroxyl carbonate apatite (OHCO3HA) was observed after 3 days of immersion in TRIS-HCl buffer. Biohybrids of C-CPS/W were produced from diluted hydrochloric acid collagen type I and ceramic powder with different ratios of C and CPS/W equal to 25:75 and 75:25 wt.%. The synthesized hybrids were characterized by FTIR, XRD and SEM. FTIR depicts a “red shift” if amide I could be attributed to the fact that the collagen prefers to chelate Ca2+ from partial dissolution of CPS/W ceramic. The growth of B-type carbonate containing hydroxyapatite (B-CO3HA) on the C-CPS/W hybrids soaked in 1.5SBF was observed. The negatively charged carboxylate groups from the collagen may be responsible for hydroxyapatite (HA) deposit...
The main purpose of the presented article is the preparation and evaluation of carbonate apatite ... more The main purpose of the presented article is the preparation and evaluation of carbonate apatite formation on the sol-gel glasses in SiO 2 -CaO-P 2 O 5 -xAg 2 O system, where x=0, 1, 2 and 4 wt.% Ag 2 O, after soaking in 1.5 SBF solutions for 12 days in static conditions. The investigated samples were prepared via the polystep sol-gel method and the structure of the obtained samples was monitored by XRD and FTIR. XRD of the synthesized and thermal treated at 600 o C for 6 hrs. samples showed that the presence of some crystalline phases is depended on the gel composition. FTIR revealed the existence of all the characteristic bands for the observed phases. 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.
Imperial journal of interdisciplinary research, 2017
The main objectives of the presented study is the preparation of 80BG/20G (in wt. %) composites b... more The main objectives of the presented study is the preparation of 80BG/20G (in wt. %) composites between sol-gel glasses (BG) in the SiO 2 -CaO-P 2 O 5 -xAg 2 O (x=0, 1, 2 and 4 wt. %) system and gelatin (G), after soaking in 1.5 SBF solutions for 12 days in static conditions. The structure and in vitro bioactivity of the prepared composites were examined by XRD and FTIR. XRD for the composites, before soaking in 1.5 SBF solutions, revealed the presence of different CaCO 3 crystalline phases, such as aragonite, calcite and vaterite. In the prepared samples, XRD also detected the presence of in situ formed hydroxyapatite, accompanied with Wollastonite phase. FTIR of the studied 80BG/20G composites, after soaking in 1.5 SBF solutions, proved the formation of B-type carbonate contacting hydroxyapatite (bioapatite) on their surface. SEM-EDX results of the soaked samples show the presence of HA aggregates on the soaked surceases. On the bases of results obtained we can conclude that the ...
Imperial journal of interdisciplinary research, 2016
Blends of silk fibroin (SF), Bombyx mori and alginate (SA), in form of films and sponges, were in... more Blends of silk fibroin (SF), Bombyx mori and alginate (SA), in form of films and sponges, were investigated. The films were prepared by drying at room temperature, the sponges – by lyophilization. In vitro behavior test was performed in Simulated Body Fluid media (SBF) for 3, 14 and 25 days. It was found strong effect of biomaterial’s morphological structure on their behavior in 1.5 SBF. The films of SF/SA exhibit bioactivity . The sponges of SF/SA exhibit degradation . Two observed processes - bioactivity and degradation, depending on the ratio of SF and SA of the investigated blends. The changes were confirmed by FTIR, EDX, changes of sample’s mass and SEM. The effect of SA at the conversion of silk I to silk II into the blends was obvious, because the samples were not treated with alcohols. Alginate induced the conformation transition of fibroin’s macromolecules and recrystallization of β-sheets. It was found the interactions between the fibroin’s amido groups and carboxyl groups...
Bioactive glass was first synthesized by L. Hench in 1971. There are many studies on the properti... more Bioactive glass was first synthesized by L. Hench in 1971. There are many studies on the properties of several metals and metal ions dopants used in the SiO 2-CaO-P 2 O 5 system of bioglasses, such as Ag, Cu, Zn, and Fe. A number of authors have carried out research related to the influence of silver oxide on the properties of bioglasses. However, publications on the properties of elastomer-based composites containing bioactive glasses are relatively scarce. We have not found in the literature studies discussing how silver oxide concentration in bioglasses of the CaO-SiO 2-P 2 O 5-Ag 2 O system affects the significant properties of a natural rubber biocomposite. In this regard, the purpose of the present work is to investigate the aforementioned influence on the properties of this type of composites, namely, vulcanization, physicomechanical, thermal, dynamic, dielectric, electric, and thermoconductive characteristics. We have established those parameters of the composites to be impacted considerably by both degree of filling with bioglass and the silver oxide content in the latter. The improvement in the composites thermostability and some of their physicomechanical performance is the most significant. The volume resistance decreases, and the thermal conductivity coefficients increase. Results from scanning electron microscopy and energy-dispersive X-ray (EDX) analyses have confirmed the influence of silver oxide initially on the phase composition of the bioglass, hence on the properties of the biocomposites through changes in the bioglass used as filler. The dielectric characteristics of some of the biocomposites suggest that they can be used as substrates and insulating layers in flexible antennas for short-range wireless communications. KEYWORDS Ag 2 O, bioglasses, dielectric properties, natural rubber composites, physicomechanical properties 1 | INTRODUCTION Bioactive glass (BG) was first synthesized by L. Hench and coworkers in 1971. Ever since, it has been attracting attention because of the properties allowing its medical applications. 1 There are high requirements for BG materials that should be met, especially those concerning minimal risk of developing extra compilations when applied. There are many studies on the antibacterial properties of several metals and metal ion dopants used in the SiO 2-CaO-P 2 O 5 system of BG, such as Ag, 2-10 Cu, 10 Zn, 11 Mn, 12 and Fe. 13 As the colleagues of Hench have suggested,
International Journal of Materials and Chemistry, 2013
Co mposite materials of Silk Fib roin (SF) and Calciu m Phosphate Silicate (CPS) ceramic in the 1... more 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.
Systematic investigations on the isomerization and oxidative transformations of some menthadiens ... more Systematic investigations on the isomerization and oxidative transformations of some menthadiens in the presence of different additives have been carried out. In the obtained reaction masses have been identified hydrocarbons, ketones, alchohols and oxides which are prospective raw materials for aromatic production, perfumery and cosmetics.
The aim of the present study is to synthesize and study calcium-cobalt silicates: Ca 2 CoSi 2 O 7... more The aim of the present study is to synthesize and study calcium-cobalt silicates: Ca 2 CoSi 2 O 7 and CaCoSi 2 O 6 , which are structural analogues of akermanite and diopside minerals in the full substitution of the positions of magnesium with cobalt. The shown phases have been determined in the system CaO–CoO–SiO 2. The chosen crystal phases belong to two main structural silicate types – silicates with diorthogroups of silicon-oxygen tetrahedrons and silicates with chains of silicon-oxygen tetrahedrons. On the basis of each one of them ceramic pigments can be synthesized. The interest towards these syntheses is raised by tracing the influence of structural position of cobalt ions on the coloring. In the selected phases it is expected the cobalt to take different structural positions. In the akermanite structure Ca 2 CoSi 2 O 7 cobalt cations take tetrahedral coordination toward oxygen atoms. In pyroxene structure CaCoSi 2 O 6 the cobalt is in octahedral coordination. The phases are...
Several types of glass-ceramics in the CaO-MgO-SiO 2 system are shown to be bioactive, biocompati... more 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.
The ceramics in the system CaO-MgO-SiO 2 has recently received a great deal of attention because ... more The ceramics in the system CaO-MgO-SiO 2 has recently received a great deal of attention because they exhibit good in vitro bioactivity and have potential use as bone implants. Biphasic calcium-magnesium-silicate ceramics was prepared by a sol-gel method. The dried gel with chemical composition 3CaO.MgO.2SiO 2 was thermally treated at 1300 °C for 2 h. The structural behavior of the synthesized ceramics was examined by means of X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Merwinite, as the main crystalline phase, and akermanite, as the minor phase, were identified. The in vitro bioactivity of the synthesized ceramic samples was recorded in Simulated Body Fluid (SBF) for different times of soaking. The apatite formation on the surface of the immersed samples was detected by FTIR, SEM and Energy Dispersive Spectroscopy (EDS) techniques. The ion concentrations in the SBF solutions after the in vitro test were evaluated by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). On the basis of the results obtained, the ability of the biphasic ceramics to deposit apatite layer was found. The peculiarities of the formation of apatite layer depending on the phase composition were analyzed and discussed.
The main purpose of the paper is the evaluation of the influence of chemical composition of the g... more 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. .
In the present work the results of the research on the sol-gel synthesis and structure of cordier... more 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. .
International Journal of Materials and Chemistry, 2012
In this work we present the experimental results on synthesis structure and in vitro bioactivity ... more In this work we present the experimental results on synthesis structure and in vitro bioactivity of collagen (C)/calcium phosphate silicate (CPS)/chondroitin sulfate (ChS) composites with C/CPS ratio of 25:75 wt. % and 75:25wt. %. The synthesized composites were characterized by XRD, FTIR and SEM/EDS. XRD and FTIR before in vitro test proved that the carbonate containing hydroxyapatite (CO 3 HA) formed in situ. After in vitro test for 3 days in 1.5 SBF, the nucleation of B-type CO 3 HA was estimated on the obtained C/CPS=75:25 wt. % composite with cauliflower-like assembly. On the C/CPS=25:75 wt. % amorphous hydroxyapatite (HA) layer was observed.
In this work we present the experimental results on synthesis, structure evolution and in vitro b... more 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 HPO4 2- 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 prepa...
The 70SiO2-30CaO (wt.%) sol-gel glasses doped with 1, 3 and 5 NbF5 (wt.%) were prepared via polys... more The 70SiO2-30CaO (wt.%) sol-gel glasses doped with 1, 3 and 5 NbF5 (wt.%) were prepared via polystep sol-gel route. The synthesized glasses were characterized by XRD, FTIR and SEM. Changes in 1.5 SBF solutions were measured by ICP-AES. XRD of the glasses stabilized at 700°C for 6 hours proved the presence of niocalite. FTIR was consistent with XRD data. The in vitro bioactivity study of all glasses prepared were carried out by soaking in 1.5 simulated body fluid (1.5 SBF) at 37°C for 6 and 12 days in static conditions. The FTIR reveals the formation of A-type and B-type carbonate containing hydroxyapatite (CO3HA) layer. Changes in 1.5 SBF solutions, after 6 days of soaking, show that the Ca concentration increased significantly, compared to the initial Ca content in the 1.5 SBF solution before in vitro test. After 12 days of immersion, the Ca concentration decreased, i.e., the formation of HA phase consumed Ca from 1.5 SBF solution. For all soaking times, the concentration of P is m...
In this work we present experimental results about synthesis, structure evolution and in vitro bi... more In this work we present experimental results about synthesis, structure evolution and in vitro bioactivity of new calcium phosphate silicate/wollastonite (CPS/W) glass-ceramics. The samples obtained were synthesized via polystep sol-gel process with different Ca/P+Si molar ratio (R). The structure of the materials obtained was studied by XRD, FTIR spectroscopy and SEM. XRD showed the presence of Ca15(PO4)2(SiO4)6, β-CaSiO3 and α-CaSiO3 for the sample with R=1.89 after thermal treatment at 1200°C/2h. The XRD results are in good agreement with FTIR analysis. SEM denotes that apatite formation can be observed after soaking in simulated body fluid (SBF).
In the present work Polyurethane (PU)/Bioglass (BG) composite materials were synthesized with dif... more In the present work Polyurethane (PU)/Bioglass (BG) composite materials were synthesized with different content of BG (10 and 20 mol.%) as filler. The 85S Bioglass was synthesized via polystep sol-gel method. The chemical composition of BG is 85SiO2-10CaO-5P2O5 (wt.%). The synthesis of PU was carried out by a two-step polyaddition reaction. The 85S BG was added in situ during the polymerization reaction. In vitro bioactivity of the prepared composites was examined in the presence of 1.5 SBF for 7 days in static conditions. The structure of synthesized PU/BG composites before and after in vitro test was determined by XRD, FTIR and SEM. XRD of the samples before in vitro test proved that the phase of γCa2P2O7 in the PU/20BG is visible. FTIR revealed the presence of urethane bond between OH-(from BG) and NCO groups (from PU). Based on FTIR results after in vitro test in 1.5 SBF solutions, A/B-carbonate containing hydroxyapatite (CO3HA) was formed. XRD proved that HA was formed on the s...
The silicocarnotite, as an inorganic part of the coatings, has been synthesized using a polystep ... more The silicocarnotite, as an inorganic part of the coatings, has been synthesized using a polystep sol-gel method. The chemical composition of the prepared silicocarnotite sol is described as 58.12 CaO, 29.42 P2O5, 12.45 SiO2 (wt%), where Ca/P+Si = 1,67. The acid soluble type I collagen, as an organic part of the obtained coatings, was mixed with silicocarnotite powder in a weight ratio of 25:75 and 75:25 weight ratio without cross-linkage. The acidity of the obtained mixture was readjust with 25% NH4OH to pH = 9.0. The mixture was then dried at 37°C for 12 h. The growth of B-type carbonate containing hydroxyapatite (B-type CO3HA) in which CO3 2+→PO4 3− on the surface of collagen/silicocarnotite coatings soaked in 1.5 simulated body fluid (1.5 SBF) was observed. The nucleation of B-type CO3HA was estimated on the obtained coatings after 3 days immersion in 1.5 SBF. The negatively charged carboxylate groups from the collagen surface may be responsible for the HA deposition. This was co...
In the present study, novel hybrid materials of Collagen (C) and Calcium Phosphate Silicate/Wolla... more In the present study, novel hybrid materials of Collagen (C) and Calcium Phosphate Silicate/Wollastonite (CPS/W) were synthesized. The CPS/W ceramic was prepared via polystep sol-gel method. The dissolution test of CPS/W ceramic was filled with TRIS-HCl buffer. FTIR depicts that hydroxyl carbonate apatite (OHCO3HA) was observed after 3 days of immersion in TRIS-HCl buffer. Biohybrids of C-CPS/W were produced from diluted hydrochloric acid collagen type I and ceramic powder with different ratios of C and CPS/W equal to 25:75 and 75:25 wt.%. The synthesized hybrids were characterized by FTIR, XRD and SEM. FTIR depicts a “red shift” if amide I could be attributed to the fact that the collagen prefers to chelate Ca2+ from partial dissolution of CPS/W ceramic. The growth of B-type carbonate containing hydroxyapatite (B-CO3HA) on the C-CPS/W hybrids soaked in 1.5SBF was observed. The negatively charged carboxylate groups from the collagen may be responsible for hydroxyapatite (HA) deposit...
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Papers by Lachezar Radev