Size-Selective Separation of Macromolecules by Nanochannel Titania Membrane with Self-Cleaning (Declogging) Ability

We report on a simple and self-organizing process for the fabrication of TiO2 nanochannel membranes with a channel width of 8-10 nm that can be used for size selective separation of macromolecules (proteins). The membrane, consisting of self-aligned oxide channels, is formed by complete anodization of a thin Ti foil under specific electrochemical conditions in a glycerolphosphate electrolyte. Due to self-cleaning properties of TiO2, clogged membranes (for example due to extended use) can easily be fully reopened and thus are reusable. As the TiO2 after anodic formation directly contains anatase crystallites (the most photoactive TiO2 crystal form) no thermal treatment of the membrane is required (avoiding the danger of thermally induced cracking).