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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. Source


Roman I.,Science METAV Research and Development S.A | Trusca R.D.,Science METAV Research and Development S.A | Soare M.-L.,Science METAV Research and Development S.A | Fratila C.,Research and Development National Institute for Nonferrous and Rare Metals | And 3 more authors.
Materials Science and Engineering C | Year: 2014

Titania nanotubes (TNTs) were prepared by anodization on different substrates (titanium, Ti6Al4V and Ti6Al7Nb alloys) in ethylene glycol and glycerol. The influence of the applied potential and processing time on the nanotube diameter and length is analyzed. The as-formed nanotube layers are amorphous but they become crystalline when subjected to subsequent thermal treatment in air at 550 C; TNT layers grown on titanium and Ti6Al4V alloy substrates consist of anatase and rutile, while those grown on Ti6Al7Nb alloy consist only of anatase. The nanotube layers grown on Ti6Al7Nb alloy are less homogeneous, with supplementary islands of smaller diameter nanotubes, spread across the surface. Better adhesion and proliferation of osteoblasts was found for the nanotubes grown on all three substrates by comparison to an unprocessed titanium plate. The sensitivity towards bovine alkaline phosphatase was investigated mainly by electrochemical impedance spectroscopy in relation to the crystallinity, the diameter and the nature of the anodization electrolyte of the TNT/Ti samples. The measuring capacity of the annealed nanotubes of 50 nm diameter grown in glycerol was demonstrated and the corresponding calibration curve was built for the concentration range of 0.005-0.1 mg/mL. © 2014 Elsevier B.V. Source


Roman I.,METAV Research and Development | Fratila C.,METAV Research and Development | Fratila C.,Research and Development National Institute for Nonferrous and Rare Metals | Vasile E.,METAV Research and Development | And 2 more authors.
Journal of Optoelectronics and Advanced Materials | Year: 2010

The paper presents the results of the stability evaluation by electrochemical polarization of experimental samples in a synthetic biological electrolyte, the Ringer solution. The cyclic voltammetry and the transmission electronic microscopy investigations show that the anodically oxidized and thermally untreated samples posses a thin, nanostructured, stable oxidic layer, with an ohmic behavior in the case of TA6V4 alloy. Titanium shows a typical behavior of electrochemically passivating metal, by polarization being evidenced a critical passivation potential with a corresponding critical current and a passivity domain characterized by a reduced passivity current. The electrochemical reactivity of the samples is unfavorably raised by thermal processing at 350 and 600oC in air, when the presence of detrimental anatase in the layers is evidenced by X-ray diffraction analysis. The same analysis shows that the favorable rutille appears in the the oxidic layer at 600oC, but it predominates or even becomes exclusive after the thermal treatment in air at 770oC. The thermochemical treatment at this temperature and the resulted crystalline nanostructures ensure an increase of the interface stability and an improvement of the ohmic behavior and biocompatibility characteristics for the oxidic layers achieved by following an anodic oxidation formula, both on titanium and its alloy. Source


Roman I.,Science METAV Research and Development S.A | Soare M.-L.,Science METAV Research and Development S.A | Trusca R.D.,Science METAV Research and Development S.A | Fratila C.,Research and Development National Institute for Nonferrous and Rare Metals | And 3 more authors.
Journal of the Electrochemical Society | Year: 2014

The paper proposes a new method for direct measurement of human alkaline phosphatase (ALP) and interleukin-6 and -8 (IL-6, IL-8) content using titania nanotubes (TNT) film as sensitive electrode. Under polarization, the interface characteristics are modified by the specific adhesion of proteins to the electrode surface, as shown by confocal fluorescence microscopy, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) investigations for all 3 biomarkers. These changes can be measured by electrochemical impedance spectroscopy (EIS). A thin and uniform gold plating is beneficial for electrochemical sensitivity toward the investigated biomarkers. This electrode reflects the low levels of human ALP in water and in dilute solutions of human serum (HS) and total protein extract (TPE) by EIS. Good calibrations were obtained for the enzyme activities of 50, 100 and 125 U/L, which go below the detection limit obtained by classical methods. Calibration of IL-6 was performed in the concentration range of 0.165 ÷ 1.645 nM. The paper demonstrates that the annealed and in vacuum gold plated TNT/Ti electrode with 50 nm diameter is a new and credible candidate for a highly stable sensor to be used in the human ALP and IL-6 direct determination. © 2014 The Electrochemical Society. Source

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