Carbon Decorated TiO2 Nanotube Membranes: A Renewable Nanofilter for Size- and Charge Selective Enrichment of Proteins

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.