Diameter-sensitive biocompatibility of anodic TiO2 nanotubes treated with supercritical CO2 fluid

Ming Ying Lan, Chia Pei Liu, Her Hsiung Huang, Jeng Kuei Chang, Sheng Wei Lee*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


This work reports on the diameter-sensitive biocompatibility of anodic TiO2 nanotubes with different nanotube diameters grown by a self-ordering process and subsequently treated with supercritical CO2 (ScCO2) fluid. We find that highly hydrophilic as-grown TiO2 nanotubes become hydrophobic after the ScCO2 treatment but can effectively recover their surface wettability under UV light irradiation as a result of photo-oxidation of C-H functional groups formed on the nanotube surface. It is demonstrated that human fibroblast cells show more obvious diameter-specific behavior on the ScCO2-treated TiO2 nanotubes than on the as-grown ones in the range of diameters of 15 to 100 nm. This result can be attributed to the removal of disordered Ti(OH)4 precipitates from the nanotube surface by the ScCO2 fluid, thus resulting in purer nanotube topography and stronger diameter dependence of cell activity. Furthermore, for the smallest diameter of 15 nm, ScCO2-treated TiO2 nanotubes reveal higher biocompatibility than the as-grown sample.

Original languageEnglish
Pages (from-to)1-8
Number of pages8
JournalNanoscale Research Letters
Issue number1
StatePublished - 6 May 2013


  • Anodic oxidation
  • Biocompatibility
  • Fluid
  • Human fibroblast cells
  • Nanotubes
  • Supercritical CO
  • TiO


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