| Objective The experiment aimed to build a double honeycomb Ti O2 nanotube matrix column on titanium surface by a two-step anodization, then the aging Ti O2 nanotube matrix column were irradiated with ultraviolet light(UV) of a selected wavelength, followed by field emission scanning electron microscope(FESEM), X-ray photoelectron spectroscopy(XPS) and contact angle measuring instrument for surface characterization before and after UV irradiation. Meanwhile non-differentiation of murine bone marrow mesenchymal stem cells(MSCs) were cultured in vitro to explore the effects of UV irradiation on surface physicochemical properties and biological activity of aging Ti O2 nanotubes.Methods Metallurgical silicon carbide sandpaper of 800#-7000# were used to polish titanium surface step by step to the mirror effect. Then the titanium plates were cleaned ultrasonically in acetone, ethanol, deionized water for successively 15 min. Ammonium fluoride 1.5g, ethylene glycol 450 ml and deionized water 50 ml were applied to allocate electrolyte., Graphite was used as cathode, together with anode titanium plate as anode and the voltage was adjusted to 60 V, anodizing for 2.5h in self-made electrolyzer. These treated titanium plates were ultrasonicated for 15 min in deionized water to remove titanium oxidation film. The 12 V voltage was used to anodize the above washed titanium plates for 40 min again, which were then taken out and washed with deionizedwater as well as dried for later use. Titanium plates after two-step anodization were stored in dark for eight weeks to fully aging, then UV irradiation for 48 h. FESEM, XPS, contact angle measurements were applied to analyze surface nanostructure, chemical elements and the contact angle of titanium surface in fresh, aging and UV radiation group, respectively. Undifferentiated mouse bone marrow mesenchymal stem cells(MSCs) lines were cultured in vitro to detect the effect of titanium surface on MSCs cell adhesion, proliferation and differentiation, and the biological differences between groups were evaluated.Results FESEM indicated that Ti O2 nanotube matrix columns were formed on titanium surface after two-step anodization, honeycomb arrangement with the inner and outer tubes in order and the diameter of the outer tubes was 160 nm, inner tubes 20 nm. Meanwhile, FESEM displayed that UV irradiation did not change the morphology of titanium surface Ti O2 nanotubes. XPS results showed that the C element content in the aging titanium surface group was significantly higher than that in other groups, however, after UV irradiation the C element content restored to level of fresh group. The contact angle tests showed that the aging surface of group was hydrophobic, and the surface of UV irradiation group was super-hydrophilic. Cytology experiments in vitro showed that after MSCs were cultured for 24 h, there were cells adhering on the surface of titanium plates in three groups under FESEM. Cells in fresh group spread relatively open, high density, most fusiform shape, and extending pseudopodia. Cells density in aging group was significantly lower than that in fresh group and the majority of cells were cylindrical shape. The cells density in UV was significantly higher than that in aging group, spreading well and contact between cells was more than that in fresh group. The cells on surface of specimen on 1, 3, 5, 7 day after inoculation showed growth trend, and proliferative activity in UV group was more pronounced than that in other groups. Overall comparison showed that there was no significant difference on 1 day. However, three groups after inoculation on 3, 5, 7 day profiled overall statistically significantdifference(P<0.01). SNK method showed that at the same time point, differences were statistically significant(P<0.01) among three groups except that difference was not statistical significance on 1 day between groups.At different time points, AKP activity were increasing in three groups, meanwhile the overall statistical difference was significant(P<0.01). SNK method showed that the differences between groups were statistically significant(P<0.01).Conclusion UV irradiation can remove hydrocarbon contamination on the titanium surface, improve the surface hydrophilicity and delay time factors induced bioactive reduction of titanium-based Ti O2 nanotube surface. |
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