Fig. 3

Loading efficiency and release profiles of minocycline loaded on the TiO₂ nanotubes fabricated under different voltage. a The loading efficiencies of minocycline was (60.36 ± 7.15)% for TiO₂ nanotubes developed at 20 V, (78.17 ± 3.02)% for TiO₂ nanotubes developed at 30 V, (83.4 ± 5.63)% for TiO₂ nanotubes developed at 40 V and (80.05 ± 4.28)% for TiO2 nanotubes developed at 50 V. Asterisk indicates significant difference value compared with other groups (p < 0.05), while horizontal line indicates values that are statistically similar (p > 0.1). b The initial release amount decreased obviously on the TiO₂ nanotubes developed at 20 V, the 96 h release amount of minocycline was (93.44 ± 3.05)% for TiO₂ nanotubes developed at 20 V, (92.19 ± 3.24)% for TiO₂ nanotubes developed at 30 V, (91.5 ± 4.58)% for TiO₂ nanotubes developed at 40 V and (92.53 ± 3.09)% for TiO₂ nanotubes developed at 50 V