Page 74 - Magnesium-based supports for stem cell therapy of vascular disease - Mónica Echeverry Rendón

CHAPTER 4
parameter. For single anodized samples this calculation was about 73.2, 64.6 and 39.5 μm2 for NAF, HMT and MAN respectively. For samples with two-step anodization, this area was around 34.7 and 21.7 μm2 for NAF-HMT and NAF- MAN, correspondingly. For bare c.p Mg this value was about 182.9 μm2. The penetration of the corrosion products layer as seen in the SEM cross-section images (Fig. 8) and the respective area values calculated, closely agreed with the results obtained in the hydrogen evolution test (Fig. 7) for the average corrosion rates. The NAF-MAN anodized sample exhibited the higher corrosion resistance of the systems studied here, followed by the NAF-HMT and MAN samples and the lower corrosion resistances showed by NAF and HMT samples.
Fig.8. Surface and cross-section of samples of anodized Mg. after 1 month of immersion in NaCl. NAF (A-B), HMT (C-D), MAN (E-F), NAF-HMT (G-H) and NAF-MAN (I-J) and untreated sample (K-L).
3. 4 Biological assessments
In general, proliferation of sentinel cells on all surfaces was reduced compared to tissue culture plastic (Fig. 9). Result of cytotoxicity test showed in Fig.9 that cells in the coatings with a single anodizing had less mitochondrial activity which can be related with the phenomena described in the corrosion rate curves where during the first days, when a fast peak of degradation was registered. However this was not observed for samples with double coatings. It should be noted that error bars on HTM and MAN, NAF-HMT samples make these statistically equal, however analyzing the trend of the data it is observed that a high mortality was observed in untreated c.p Mg where the cell biological activity decreased in high proportion.
The percentage of change between both point times was specified in each set of bars. Cells grown on NAF and c.p Mg showed a reduction in mitochondrial activity after 72 h; HMT, MAN and NAF-HMT did not show changes in the cell population and NAF-MAN had a similar response to the control (cells grown on plastic).
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