Since the annealed nanotubes have been dehydrated and transformed selleck into a pure anatase phase, the reaction between ScCO2 and TiO2·xH2O or Ti(OH)4 to generate the C-H functional groups does not occur during the process.
Figure 4 XPS surface analysis results, in terms of spectra for C 1 s . Of the as-grown, ScCO2-treated, and ScCO2-treated TiO2 nanotubes of 100 nm in diameter with UV light irradiation. Figure 5 Raman spectra of as-grown 100-nm-diameter TiO 2 nanotubes treated with ScCO 2 fluid and subsequent UV light irradiation. The human fibroblast cell behavior in response to the as-grown and ScCO2-treated TiO2 nanotubes is studied. To evaluate the fibroblast cell attachment on the TiO2 nanotubes, cytoskeleton actin was stained with rhodamine phalloidin that expressed red fluorescence and nuclei were stained with DAPI that
expressed blue fluorescence. The actin immunostaining shows very selleck chemicals llc different cell-material contact morphology for the TiO2 nanotubes of different diameters (see Figure 6). For both as-grown and ScCO2-treated samples, there are much longer and well-defined actin fibers noted on fibroblasts cultured on 25-nm- and smaller diameter nanotubes with respect to the larger ones. It is well known that cells have to adhere on a material surface first and then spread for further cell division. Better cell adhesion can cause more activation of intracellular signaling cascades through integrin coupled to actin cytoskeleton [38, 39]. Therefore, the smaller Selonsertib diameter nanotubes
give more focal points for fibroblasts to get attached, thus help in the cell adhesion. FE-SEM was used for the detailed Erastin price observation of cell adhesion (see Figure 7). The fibroblasts on the smaller diameter TiO2 nanotubes reveal good cell adhesion with an elongated flatten morphology, while those on the 50-nm- and larger diameter nanotubes show rounded morphology and lack of cell spreading. It is known that cells recognize surface features when a suitable site for adhesion has been detected. Cells then stabilize the contact by forming focal adhesions and mature actin fibers, followed by recruiting tubulin microtubules [38]. The actin cytoskeleton is linked to integrins which are located within the adhesions. Our findings suggest that the cytoskeleton on the smaller diameter nanotubes should be formed better than that on the larger diameter ones for both as-grown and ScCO2-treated nanotubes. These observations also indicate that with UV light irradiation to recover the surface wettability, ScCO2-treated TiO2 nanotube surface is suitable for the cell adhesion. Figure 6 Fluorescent images of the fibroblast cell attachment. On the as-grown (upper column) and ScCO2-treated (lower column) TiO2 nanotubes of different diameters. The red fluorescence indicates cytoskeletal protein actin filament, and the blue fluorescence indicates nuclei.