română ELENA DINU, MIHAELA BÎRSAN, CRISTINA GHIŢULICĂ, GEORGETA VOICU, ECATERINA ANDRONESCU
Abstract
Calcium nitrate tetrahydrate (Ca(NO3)2·4H2O) and triethyl phosphate (C6H15O4P) were used as raw materials in order to prepare at room temperature by the sol-gel method a phospahate-based nanopowder, as precursor for hydroxyapatite (HAp).
The thermal behavior of the precursors was investigated by thermal analysis methods (DTA/TG).The precursor powder was uniaxially pressed as cylindrical specimens, which were thermally treated at temperatures range between 850 and 1300°C for 2 hours. The as-prepared ceramics were investigated from phase composition, chemical and morphological point of view by X-ray diffraction, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM).
Besides, the HAp-based ceramics were characterized from the point of view of the mechanical behavior by determining the compressive mechanical proprieties.
Keywords
sol-gel method, thermal analysis, X-ray methods, SEM, TEM
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Year
2013
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Issue
43 (1)
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Pages
55-60
ELENA DINU, CRISTINA GHIŢULICĂ, GEORGETA VOICU, MIHAELA BÎRSAN, ECATERINA ANDRONESCU
Abstract
In order to obtain phosphate biomaterials, non-conventional wet-chemical methods are generally used. Therefore in this work the spray-pyrolysis method was chosen. For this purpose, calcium nitrate tetrahydrate (Ca (NO3)2·4H2O) and triethyl phosphate (C6H15O4P) were used as raw materials. By optimizing the spray-pyrolysis synthesis parameters, hydroxyapatite (HAp) nanopowders were prepared at different pyrolysis temperatures ranged between 600 and 1000°C.
The thermal behavior of the precursors was investigated by thermal analysis methods (TG- DTG). The HAp nanopowders were characterized from phase composition, chemical and morphological point of view by X-ray diffraction, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM).
Due to these techniques, information regarding the effect of the synthesis temperature on the main characteristics of the HAp powders were provided.
Keywords
spray-pirolysis, thermal analysis, X-ray methods, SEM, TEM
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Year
2013
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Issue
43 (1)
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Pages
61-67
ALEXANDRU MIHAI GRUMEZESCU, ECATERINA ANDRONESCU, ANTON FICAI, GEORGETA VOICU, OCTAVIAN COCOŞ, MARIANA CARMEN CHIFIRIUC
Abstract
The aim of this paper was to obtain a hybrid biostructure, combining the Eugenia caryophyllata essential oil and a silica network and to demonstrate by in vitro studies its potential chemotherapeutic value to improve the efficacy of different classes of antibiotics currently used against Gram-positive and Gram-negative bacterial strains. The obtained hybrid structure significantly improved the activity of topic antibiotics, such as bacitracin and neomycin sulfate, by significantly decreasing their minimal inhibitory concentration. This antibiotics potentiating activity, together with no measurable in vitro cytotoxicity, make this hybrid structure potentially relevant for biomedicine applications, especially in the antimicrobial therapy.
Keywords
hybrid material, silica, drug delivery, biocompatibility, antimicrobial therapy
ALINA MARIA HOLBAN, ALEXANDRU MIHAI GRUMEZESCU, ANTON FICAI, CARMEN MARIANA CHIFIRIUC, VERONICA LAZĂR, RADU RĂDULESCU
Abstract
During recent years there is an increased interest in magnetite nanoparticles for their wide use in biomedical applications, as prevention of microbial colonization and targeted drug delivery systems. They could stabilize the volatile active components of the essential oils improving their antimicrobial activity. Here we report a newly prepared nano-bio-active coated surface for improved antimicrobial activity of classical wound dressings. Our results demonstrate that the reported nano-modified wound care textiles exhibit a great anti-fungal biofilm activity. These properties recommend the recently fabricated nano-bio-active coatings for the design of new antimicrobial medical surfaces.
Keywords
hydroxyapatite, XRD, FTIR, pyromorphite
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Year
2013
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Issue
43 (3)
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Pages
300-305
SORIN ION JINGA, GEORGETA VOICU, IONELA VASILE, ALINA IOANA BĂDĂNOIU
Abstract
Synthesis of vitreous material which was the basis for the obtaining the glass-ceramic type masses was performed by sol-gel method at normal temperature; its composition corresponds to the system CaO-SiO2-P2O5-CaF2-MgO. Tetraethyl orthosilicate (C6H~16O3Si - TEOS), calcium nitrate tetra hydrate (Ca(NO3)2·4H2O), triethyl phosphate (C6H15O4P - TEP), magnesium acetate ((CH3-COO)2Mg) and calcium fluoride (CaF2) were used as raw materials. The glass-ceramic masses were obtained by the thermal treatment at 700°C of dry gel resulted in sol-gel synthesis, followed by calcination at different temperatures- 700°C, 800°C and 1000°C. The obtained glass-ceramic materials were characterized by thermal analysis (DTA-TG), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The glass-ceramics were also characterized from the point of view of bioactivity by an in-vitro test, which consists in soaking the samples in simulated body fluid (SBF) for a period of 14 days at a temperature of 37°C; the resulted materials were characterized from the point of view of their mineralogical composition (by XRD) and morphology (by SEM). At the surface of the specimens was observed the formation of a brittle layer containing mainly fluoroapatite with a spherical morphology i.e. agglomerations of spherical shaped crystals and rods, as well as the presence of fluoroapatite with "raspberry" type morphology.
Keywords
sol-gel method, glass-ceramic, apatite phases, fluoroapatite, in-vitro test
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Year
2013
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Issue
43 (4)
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Pages
396-401
ANA MARIA HOLBAN, ALEXANDRU MIHAI GRUMEZESCU, ECATERINA ANDRONESCU, VALENTINA GRUMEZESCU, CARMEN MARIANA CHIFIRIUC, RADU RĂDULESCU
Abstract
With the continuous increasing rate of antibiotic resistance, novel therapeutic approaches aiming to reduce resistance and bacterial tolerance to antibiotics are currently developing. Nanotechnology seems an efficient approach in dealing with resistant infections. One of the most challenging idea is to produce materials and surfaces exhibiting high antimicrobial effects but also a good biocompatibility with human cells. In this paper, we report a newly fabricated biocompatible, resorbable bioactive wound dressing based on polyvinyl alcohol and usnic acid functionalized magnetite nanoparticles (Fe3O4@UA). This material revealed a good anti-staphylococcal activity, mainly due to the bio-active natural usnic acid (UA) compound entrapped into Fe3O4@UA. This wound dressing produces an efficient and prolonged release of the bio-active compound. Furthermore, its absorbent structure recommends this material as a good candidate for treating infected wounds.
Keywords
magnetite nanostructure, usnic acid, antimicrobial activity, functionalized nanoparticles