Entity

Time filter

Source Type


Duta L.,Romanian National Institute for Lasers, Plasma and Radiation Physics | Popa A.C.,Army Center for Medical Research | Popa A.C.,Carol Davila University of Medicine and Pharmacy | Popa A.C.,National Institute of Materials Physics Bucharest | And 2 more authors.
Romanian Reports in Physics | Year: 2014

We report on the synthesis by PLD of bioactive glass (BG) films onto ultra high molecular weight polyethylene acetabular cups, and their preliminarily characterization after immersion in simulated body fluid. Fourier Transform Infrared spectra evidenced the strong depolymerization of the BG coatings. Scanning Electron Microscopy evidenced that the typical PLD film surface was converted after soaking in SBF to a rough one consisting of acicular crystals. Energy Dispersive Spectroscopy analysis demonstrated a remarkable conservation of the targets stoichiometry. The functionalization of acetabular cups with BG films by PLD should allow for the fabrication of implant coatings with improved osteoinductive characteristics. © 2014 Romanian Reports in Physics. All rights reserved.


Stan G.E.,National Institute of Materials Physics Bucharest | Popa A.C.,Army Center for Medical Research | Popa A.C.,Carol Davila University of Medicine and Pharmacy | Bojin D.,Polytechnic University of Bucharest
Digest Journal of Nanomaterials and Biostructures | Year: 2010

In this study, Fourier Transform Infrared Spectroscopy (FTIR) in Attenuated Total Reflectance mode was employed as main characterization technique to investigate the reaction mechanisms in vitro (SBF) of bioglass and glass-ceramic sputtered coatings. Two bioglass compositional systems are compared in order to gain more information regarding their in vitro bioreactivity. Important correlations between the concentration of non-bridging silicon-oxygen (Si-O-NBO) groups and the content of network modifiers were found. FTIR revealed that the high concentrations of Si-O-NBO groups are promoting the enhancing of coatings' reactivity. This information could be very useful for the development and tailoring of new bioactive glasses with an optimum biological behaviour. By varying the compositional features and the structural state, the sputtered glassy coatings exhibited different in vitro behaviour: inertness, resorbability and bioactivity.


Popa A.C.,National Institute of Materials Physics Bucharest | Popa A.C.,Army Center for Medical Research | Stan G.E.,National Institute of Materials Physics Bucharest | Besleaga C.,National Institute of Materials Physics Bucharest | And 4 more authors.
ACS Applied Materials and Interfaces | Year: 2016

This work reports on the unprecedented magnetron sputtering deposition of submicrometric hollow cones of bioactive glass at low temperature in the absence of any template or catalyst. The influence of sputtering conditions on the formation and development of bioglass cones was studied. It was shown that larger populations of well-developed cones could be achieved by increasing the argon sputtering pressure. A mechanism describing the growth of bioglass hollow cones is presented, offering the links for process control and reproducibility of the cone features. The composition, structure, and morphology of the as-synthesized hollow cones were investigated by energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), grazing incidence geometry X-ray diffraction (GIXRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM)-selected area electron diffraction (SAED). The in vitro biological performance, assessed by degradation tests (ISO 10993-14) and cytocompatibility assays (ISO 10993-5) in endothelial cell cultures, was excellent. This allied with resorbability and the unique morphological features make the submicrometer hollow cones interesting candidate material devices for focal transitory permeabilization of the blood-brain barrier in the treatment of carcinoma and neurodegenerative disorders. © 2016 American Chemical Society.


Stan G.E.,National Institute of Materials Physics Bucharest | Popa A.C.,National Institute of Materials Physics Bucharest | Popa A.C.,Army Center for Medical Research | Popa A.C.,Carol Davila University of Medicine and Pharmacy | And 3 more authors.
Applied Surface Science | Year: 2013

Bioglasses (BG) are the inorganic materials exhibiting the highest indices of bioactivity. Their appliance as films for bio-functionalization of metallic implant surfaces has been regarded as an optimal solution for surpassing their limited bulk mechanical properties. This study reports on magnetron sputtering of alkali-free BG thin films by varying the target-to-substrate working distance, which proved to play an important role in determining the films' properties. Post deposition heat-treatments at temperatures slightly above the glass transformation temperature were then applied to induce inter-diffusion processes at the BG/titanium substrate interface and strengthening the bonding as determined by pull-out adherence measurements. The morphological and structural features assessed by SEM-EDS, XRD, and FTIR revealed a good correlation between the formations of inter-metallic titanium silicide phases and the films' bonding strength. The highest mean value of pull-out adherence (60.3 ± 4.6 MPa), which is adequate even for load-bearing biomedical applications, was recorded for films deposited at a working distance of 35 mm followed by a heat-treatment at 750°C for 2 h in air. The experimental findings are explained on the basis of structural, compositional and thermodynamic considerations. ©2013 Elsevier B.V. All rights reserved.


Popa A.C.,Army Center for Medical Research | Popa A.C.,Carol Davila University of Medicine and Pharmacy | Popa A.C.,National Institute of Materials Physics Bucharest | Stan G.E.,National Institute of Materials Physics Bucharest | And 5 more authors.
Journal of Materials Science: Materials in Medicine | Year: 2013

Radio-frequency Plasma Enhanced Chemical Vapour Deposition (in different methane dilutions) was used to synthesize adherent and haemocompatible diamond-like carbon (DLC) films on medical grade titanium substrates. The improvement of the adherence has been achieved by interposing a functional buffer layer with graded composition TixTiC1-x (x = 0-1) synthesized by magnetron co-sputtering. Bonding strength values of up to ~67 MPa have been measured by pull-out tests. Films with different sp 3/sp2 ratio have been obtained by changing the methane concentration in the deposition chamber. Raman spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction were employed for the physical-chemical characterization of the samples. The highest concentration of sp3-C (~87 %), corresponding to a lower DLC surface energy (28.7 mJ/m2), was deposited in a pure methane atmosphere. The biological response of the DLC films was assayed by a state-of-the-art biological analysis method (surface enhanced laser desorption/ionization-time of flight mass spectroscopy), in conjunction with other dedicated testing techniques: Western blot and partial thromboplastin time. The data support a cause-effect relationship between sp3-C content, surface energy and coagulation time, as well as between platelet-surface adherence properties and protein adsorption profiles. © 2013 Springer Science+Business Media New York.

Discover hidden collaborations