  In this work, we design a TiO2 nanomembrane (TiNM) that can be used as a
nanofilter platform for a selective enrichment of specific proteins. After use
the photocatalytic properties of TiO2 allow to decompose unwanted remnant on
the substrate and thus make the platform reusable. To construct this platform
we fabricate a free-standing TiO2 nanotube array and remove the bottom oxide to
form a both-end open TiNM. By pyrolysis of the natural tube wall contamination
(C/TiNM), the walls become decorated with graphitic carbon patches. Owing to
the large surface area, the amphiphilic nature and the charge adjustable
character, this C/TiNM can be used to extract and enrich hydrophobic and
charged biomolecules from solutions. Using human serum albumin (HSA) as a model
protein as well as protein mixtures, we show that the composite membrane
exhibits a highly enhanced loading capacity and protein selectivity and is
reusable after a short UV treatment.
