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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.

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A comparative assessment is presented, by cyclic voltammetry, of the electrochemical performances of experimental samples of nickel base superalloy layer samples L1, with a maximum thickness of 0 . 5 mm, and L2 and L3 successively thinned, produced by laser cladding on a support of carbon steel OLC45 as compared with the reference materials, commercial nickel base superalloys with a similar chemical composition, as well as an analysis of the variation of these properties in the bulk of the layer. The electrolyte used was 1N sulphuric acid; the polarisation rate, between 2400 and 1200 mV(SCE), was 200 mV s 21 at 18uC. The superalloy samples present complete electrochemical passivation in two stages during the first polarisation cycle, with passivation currents (i p ) of order only 20-60 mA cm 22 . The spontaneous passivation tendency shown by all the analysed superalloy samples is not seen on the L1, L2 and L3 samples; they suffer net electrochemical passivation processes during all 10 polarisation cycles, and the passivation current does not fall below 800 mA cm 22 ; the passivation critical potentials (i cp ) are also situated in another, more noble field. The existence of two passivation critical potentials is specific for nickel and hardening c9 and c0 phases. The nickel behaves characteristically only for the L1 sample, the two current maxima (i cp1 and i cp2 ) being attributed to it. The other L samples, with the successively thinned layers, are electrochemically passivated in a single stage, marked by high current consumption. Nevertheless, the laser clad layers have typical passivation properties in reducing acids, such as the sulphuric acid in the present study. The electrochemical performance of these layers decreases as the investigation depth increases, approaching the steel base which has an active behaviour, lacking passivation properties. It can be supposed that iron diffusion from the steel base took place, as higher as the section is approaching the steel/layer interface.

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.