RESUMEN
BACKGROUND: Previous studies have shown that titanium nanotubes with different diameters affect the adhesion and growth of cells on the implant surface. OBJECTIVE: To investigate the effects of annealing treatment on the biological behaviors of fibroblasts on the surface of TiO2 nanotubes with different diameters. METHODS: TiO2 nanotubes were prepared by polishing pure titanium samples through anodizing at 5 V and 20 V respectively, and then annealed. The pure titanium samples were divided into six groups: P (polishing titanium), NT5 (TiO2 nanotubes prepared at 5 V), NT20 (TiO2 nanotubes prepared at 20 V), A-P (annealing treatment and polishing titanium), A-NT5 (TiO2 nanotubes prepared at 5V and annealed) and A-NT20 (TiO2 nanotubes formed at 20 V and annealed). Field emission scanning electron microscopy was used to obsesrve the surface topography. Fibroblasts were inoculated on the surface of each group of samples. After 60 and 120 minutes of culture, the number of cells adhering to titanium sample surface was counted using cell nucleus staining method. On day 1 of culture, cell morphology was observed using scanning electron microscopy. On days 1, 3 and 5 of culture, cell proliferation was detected by MTT method. On day 3 of culture, the secretion of collagen fiber was detected by picro-sirius red staining method. RESULTS AND CONCLUSION: (1) The annealing treatment had no significant effect on the morphology and diameter of the nanotubes. (2) The number of adherent cells in the NT5 and NT20 groups was significantly lower than that in the P group. The annealing treatment increased the number of fibroblasts on the surface of polished pure titanium and decreased the number of fibroblasts in the NT5 and NT20 groups. (3) Annealing enhanced the viability of fibroblasts on the surface of polished pure titanium and decreased the viability of cells on the surface of nanotubes prepared at 5 and 20 V. (4) Cell viability in the NT5 and NT20 groups was lower than that in the P group. Annealing treatment increased the viability of cells on the surface of polished pure titanium and decreased the viability of cells on the surface of nanotubes prepared at 5 and 20 V. (5) The level of collagen on the surface of nanotubes in the NT5 and NT20 groups was higher than that in the P group. Annealing treatment increased the level of collagen on the surface of polished pure titanium and decreased the level of collagen in the NT5 and NT20 groups. These findings suggest that TiO2 nanotubes inhibit the adhesion, spreading and proliferation of fibroblasts to different degrees; annealing treatment can enhance this inhibitory effect; TiO2 nanotubes enhance collagen secretion by fibroblasts to different degrees, and annealing treatment inhibits the enhancement.
RESUMEN
<p><b>OBJECTIVE</b>To study the effect of Ti-TiO2 nanotubes with different diameters on the adhesion of fibroblast and osteoblast, and to find which diameter was more favorable for cells' respective adhesion.</p><p><b>METHODS</b>Pure titanium sheets were polished and then anodized at different potentials for 1 h with Ti as anode and Pt as cathode. TiO2 nanotubes formed at 1, 5, 10 and 20 V potentials served as experimental groups and polished pure titanium served as control group. Field emission scanning electron microscopy (Fe-SEM) was used to analyze the surface topography. Stained nucleus with Hoechst33342 were used to measure the cell adhesion. The cell shape on the sample surface were analyzed with Fe-SEM.</p><p><b>RESULTS</b>TiO2 nanotube array of different inner diameters from 15 nm to 100 nm were grown on titanium sheets by anodization at potentials from 1 to 20 V. At 30, 60 and 120 min, fibroblast adhesion at nanotubes anodized at 5 V was (141 ± 9), (388 ± 14) and (489 ± 15) respectively, significantly less than any other nanotube surface at the same time (P < 0.01). Nanotubes anodized at 20 V had the least inhibitory effect for fibroblast adhesion with a number of (579 ± 14) at 120 min, and the cell shape was also inhibited. At 30, 60 and 120 min, osteoblast had a significant better adhesion on nanotubes formed at 5 V than it did on any other surface at the same time (P < 0.01), except the control group at 30 min, with the adhesion number of (198 ± 10), (431 ± 10) and (501 ± 10) respectively, and osteoblast had a abundant spread on nanotubes formed at 5 V; while osteoblast adhesion on nanotubes anodized at 20 V was (152 ± 11), (403 ± 9) and (465 ± 12) respectively, less than on any other nanotube surface within the same time (P < 0.05), and the cell shape on the surface changed to be more elongate.</p><p><b>CONCLUSIONS</b>Fibroblast adhesion is inhabited more or less on Ti-TiO2 nanotubes of different diameters. Nanotubes formed at 5 V have the most osteoblast adhesion, and inhibit fibroblast adhesion.</p>