METAV Research and Development

Bucharest, Romania

METAV Research and Development

Bucharest, Romania
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Savva I.,University of Cyprus | Odysseos A.D.,EPOS Iasis | Evaggelou L.,University of Cyprus | Marinica O.,Polytechnic University of Timişoara | And 4 more authors.
Biomacromolecules | Year: 2013

The fabrication of electrospun magnetoactive fibrous nanocomposite membranes based on the water-soluble and biocompatible poly(ethylene oxide) (PEO), the biocompatible and biodegradable poly(l-lactide) (PLLA) and preformed oleic acid-coated magnetite nanoparticles (OA.Fe3O4) is reported. Visualization of the membranes by electron microscopy techniques reveals the presence of continuous fibers of approximately 2 μm in diameter, with the magnetic nanoparticles being evenly distributed within the fibers, retaining at the same time their nanosized diameters (∼5 nm). Thermal gravimetric analysis measurements suggest that the magnetic nanoparticles embedded within the polymer fibers affect favorably the thermal stability of the membranes. Moreover, assessment of their magnetic characteristics by vibrating sample magnetometry discloses tunable superparamagnetic behavior at ambient temperature. For the first time, the biocompatibility and biodegradability of PEO/PLLA and the tunable magnetic activity of the OA.Fe3O4 are combined in the same drug delivery system, with N-acetyl-p-aminophenol (acetaminophen) as a proof-of-concept pharmaceutical. Furthermore, their heating ability under alternating current (AC) magnetic field conditions is evaluated using frequency of 110 kHz and corresponding magnetic field strength of 25 mT (19.9 kA/m). Consequently, these magnetoactive fibrous nanocomposites exhibit promising characteristics for future exploitation in magnetothermally triggered drug delivery. © 2013 American Chemical Society.

Savva I.,University of Cyprus | Constantinou D.,University of Cyprus | Marinica O.,Polytechnic University of Timişoara | Vasile E.,METAV Research and Development | And 2 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2014

The fabrication of magnetoactive fibrous nanocomposite membranes based on poly(vinyl pyrrolidone) (PVP), poly(L-lactide) (PLLA) and pre-formed oleic acid coated magnetite nanoparticles (OA Fe3O4) is presented. The aforementioned materials have been prepared by means of the electrospinning technique following a single-step fabrication process. The PVP/PLLA/OA Fe 3O4 nanocomposite membranes were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that provided information on the fiber diameters as well as on the morphological and dimensional characteristics of the OA Fe3O4 nanoparticles embedded within the fibers. The thermal stability of these materials was evaluated by means of thermal gravimetric analysis (TGA) measurements. Finally, vibrational sample magnetometry (VSM) analysis disclosed superparamagnetic behavior at room temperature. The combination of the hydrophilic, biocompatible and photo-crosslinkable PVP with the biodegradable PLLA and the superparamagnetic OA Fe3O4 nanoparticles within these materials allows for the future development of crosslinked fibrous magnetoactive nanocomposites exhibiting high stability in aqueous solutions, with potential use in biomedical and environmental applications. © 2013 Elsevier B.V. All rights reserved.

Marinescu C.,Institute of Physical Chemistry Ilie Murgulescu | Sofronia A.,Institute of Physical Chemistry Ilie Murgulescu | Rusti C.,National Institute of Research and Development for Non Ferrous and Rare Metals | Piticescu R.,National Institute of Research and Development for Non Ferrous and Rare Metals | And 4 more authors.
Journal of Thermal Analysis and Calorimetry | Year: 2011

The aim of the article is to investigate the influence of particle size on titanium dioxide phase transformations. Nanocrystalline titanium dioxide powder was obtained through a hydrothermal procedure in an aqueous media at high pressure (in the range 25-100 atm) and low temperature (≤200 °C). The as-prepared samples were characterized with respect to their composition by ICP (inductive coupled plasma), structure and morphology by XRD (X-ray diffraction), and TEM (transmission electron microscopy), thermal behavior by TG (thermogravimetry) coupled with DSC (differential scanning calorimetry). Thermal behavior of nanostructured TiO2 was compared with three commercial TiO2 samples. The sequence of brookite-anatase-rutile phase transformation in TiO2 samples was investigated. The heat capacity of anatase and rutile in a large temperature range are reported. © 2010 Akadémiai Kiadó, Budapest, Hungary.

Stan M.-S.,University of Bucharest | Memet I.,University of Bucharest | Fratila C.,Research and Development National Institute for Nonferrous and Rare Metals | Krasicka-Cydzik E.,University of Zielona Gora | And 2 more authors.
Journal of Biomedical Materials Research - Part A | Year: 2015

One of the major research interests of nanomedicine is the designing of harmless and biocompatible medical devices. To improve the features of Ti surface, TiO2 based nanotube (TNT) films (50 nm diameter) achieved by anodic oxidation and thermal treatment were grown on titanium and on Ti6Al4V and Ti6Al7Nb alloys. Their in vitro toxicity and biocompatibility were investigated using G292 osteoblast cell line. The LDH release after 24 and 48 h of exposure demonstrated that TNT layers were not cytotoxic. The cell growth on TNT films deposited on titanium and Ti6Al4V was significantly increased compared with Ti6Al7Nb. F-actin staining showed a better organized actin cytoskeleton in osteoblasts grown on these two samples, which provide the best conditions for osteoblast attachment and spreading. Analysis of GSH distribution revealed a higher nuclear level in the samples with TNTs compared with Ti plate without nanotubes, indicating an active proliferation. Thus, nuclear glutathione levels can be used as a useful biomarker for biocompatibility assessment. Our results suggest that the substrate for TNTs can have a significant impact on cell morphology and fate. In conclusion, the TNT/Ti and TNT/Ti6Al4V were toxicity-free and can provide a proper nanostructure for a positive cell response. © 2014 Wiley Periodicals, Inc.

Vasile E.,METAV Research and Development | Dumitru F.,Polytechnic University of Bucharest | Razvan A.,Polytechnic University of Bucharest | Oprea O.,Polytechnic University of Bucharest | Andronescu C.,Polytechnic University of Bucharest
Digest Journal of Nanomaterials and Biostructures | Year: 2013

We have prepared ordered mesoporous silicas incorporating the ureido benzo-crown ether: 3- (triethoxysilyl) propyl isocyanate modified 4'-aminobenzo-15-crown-5 ether, TESPIC-CE, either by direct synthesis (co-condensation method, route A) or by post-synthesis grafting strategy (route B). Elemental analysis and XPS measurements, FT-IR spectra, TG/DSC analyses, X-ray powder diffraction, TEM/HRTEM, and N2 sorption isotherms were used to characterise the novel functionalized mesoporous silicas. Grafting of ureido benzo-crown ether onto silica inner surface resulted in the reduction of surface area from ~1000 m2/g of the pure MCM-41 used as reference to 707 m2/g for MCM-41B(TESPIC-CE) and to 903 m2/g for MCM-41B(TESPIC)+CE, suggesting that for comparable TESPIC-CE content into silica framework, the heterogeneous method lead to better sorption properties: higher surface area and more efficiently grafting of crown ether inside pores. Interestingly, the MCM-41A(TESPIC-CE) silica obtained by template-directed co-condensation reaction exhibits a relatively high surface area (618 m2/g) while containing about twice as much organic content into mesoporous framework than MCM-41B(TESPIC-CE) or MCM-41B(TESPIC)+CE.

Vasile E.,METAV Research and Development | Rusen E.,Polytechnic University of Bucharest | Mocanu A.,Polytechnic University of Bucharest | Patrascu M.,Polytechnic University of Bucharest | Calinescu I.,Polytechnic University of Bucharest
Colloid and Polymer Science | Year: 2012

The present study presents two different methods to obtain hybrid material formed by the poly [styrene (ST)-poly(ethylene glycol) methyl ether methacrylate (PEGMA) 1100] and silver (Ag 0). The aim has been to cover the polymeric particles with Ag 0 shell. The first method consisted of mixing Ag 0 nanoparticles dispersion with poly (ST-PEGMA 1100) dispersion, while in the second method, the Ag 0 nanoparticles have been generated in situ. The hybrid materials have been characterized by MO, dynamic light scattering, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray energy dispersive spectrometry, and ultraviolet-visible spectrophotometry. The results confirm the obtaining of two types of morphologies. In the first case, the nanoparticles have been arranged in the interspatial zones of the polymer particles, while in the second method, the Ag 0 nanoparticles have covered the polymer particles. Thus, the film obtained using the second method is more suitable for the practical application, as a separation membrane, using the antiseptic properties of Ag 0. © 2011 Springer-Verlag.

Stancu I.-C.,Polytechnic University of Bucharest | Dragusin D.M.,Polytechnic University of Bucharest | Vasile E.,METAV Research and Development | Trusca R.,METAV Research and Development | And 2 more authors.
Journal of Materials Science: Materials in Medicine | Year: 2011

Artificial bone composites exhibit distinctive features by comparison to natural tissues, due to a lack of self-organization and intimate interaction apatite-matrix. This explains the need of "bio-inspired materials", in which hydroxyapatite grows in contact with self-assembling natural polymers. The present work investigates the function of a rational design in the hydroxyapatite-forming potential of a common biopolymer. Gelatin modified through intrinsic interactions with calcium alginate led through freeze-drying to porous hydrogels, whose architecture, constitutive features and chemistry were investigated with respect to their role on biomineralization. The apatite-forming ability was enhanced by the porosity of the materials, while the presence of alginate-reinforced Gel elastic chains, definitely favored this phenomenon. Depending on the concentration, polysaccharide chains act as "ionic pumps" enhancing the biomineralization. The mineralization-promoting effect of the peptide-polysaccharide network strictly depends on the hydrogels structural, compositional and morphological features derived from the interaction between the above mentioned two components. © Springer Science+Business Media, LLC 2011.

Vasile E.,METAV Research and Development | Serafim A.,Polytechnic University of Bucharest | Dragusin D.-M.,Polytechnic University of Bucharest | Petrea C.,Polytechnic University of Bucharest | And 2 more authors.
Journal of Nanoparticle Research | Year: 2012

In this work, we developed a simple method of surface functionalization of polymer substrates to provide them with the ability to form biomimetic hydroxyapatite (HA) when incubated in synthetic body fluids (SBF). In a first step, gold nanoparticles (AuNPs) were used as surface nanostructuring units for a biocompatible polymer, poly(2-hydroxyethyl methacrylate), known to not promote biomineralization in SBF, and under physiological conditions. The treatment of AuNPs-modified substrate with mercaptosuccinic acid leads to brushes of carboxyl-ended chains self-assembled onto the gold-polymer hybrid nanosurface. The main aim of this work was to demonstrate that these multianionic nanosurfaces would induce HA formation when incubated in solutions mimicking physiologic conditions. The formation of apatite and its morphology and composition were successfully investigated by means of high resolution scanning and transmission electron microscopy with energy dispersive X-ray microanalysis, infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Emphasis was put on the nucleation of HA in areas with agglomerated carboxyl-ended functionalized nanoparticles. The results obtained in this study may unlock new applications for smart active coatings based on functionalized AuNPs, such as the induction of biomineralization. © 2012 Springer Science+Business Media B.V.

Mihaly M.,Polytechnic University of Bucharest | Comanescu A.F.,Polytechnic University of Bucharest | Rogozea A.E.,Ilie Murgulescu Institute of Physical Chemistry | Vasile E.,METAV Research and Development | Meghea A.,Polytechnic University of Bucharest
Materials Research Bulletin | Year: 2011

NiO-silica based materials have been synthesized by microemulsion assisted sol-gel procedure. The versatility of these soft nanotechnology techniques has been exploited in order to obtain different types of nanostructures, such as NiO nanoparticles, NiO silica coated nanoparticles and NiO embedded in silica matrix. These materials have been characterized by adequate structural and morphology techniques: DLS, HR-TEM/SAED, BET, AFM. Optical and semiconducting properties (band-gap values) of the synthesized materials have been quantified by means of VIS-NIR diffuse reflectance spectra, thus demonstrating their applicative potential in various electron transfer phenomena such as photocatalysis, electrochromic thin films, solid oxide fuel cells. © 2011 Elsevier Ltd. All rights reserved.

Vasile O.-R.,Polytechnic University of Bucharest | Andronescu E.,Polytechnic University of Bucharest | Ghitulica C.,Polytechnic University of Bucharest | Vasile B.S.,Polytechnic University of Bucharest | And 3 more authors.
Journal of Nanoparticle Research | Year: 2012

Nanostructured ZnO particles with different crystallite dimensions, in the range between 5.7 and 21.8 nm, with poly-crystalline structure, have been obtained, in a facile manner, using the pyrosol method. The microstructure and properties of the obtained powders were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) with selected area electron diffraction and fluorescence spectroscopy. From the XRD spectra it was observed that, starting from 600 °C, zinc oxide with wurtzite structure is obtained. The particles have spherical morphology, as it can be seen from SEM images, with an average particle size ranging from 0.2 to 2 μm. The TEM analysis reveals that the particles are in fact agglomerates, nanostructured, with an average nanoparticles size as low as 13.9 nm. The composition, morphology and size of obtained particles are influenced by the synthesis temperatures, as well as by the concentration of precursor solutions. © Springer Science+Business Media Dordrecht 2012.

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