A stable, label-free optical interferometric biosensor based on TiO _2 Nanotube Arrays

摘要

Optical interferometry of a thin film array of titanium dioxide (TiO _2) nanotubes allows the label-free sensing of rabbit immunoglobulin G (IgG). A protein A capture probe is used, which is immobilized on the inner pore walls of the nanotubes by electrostatic adsorption. Control experiments using IgG from chicken (which does not bind to protein A) confirms the specificity of the protein A-modified TiO_2 nanotube array sensor. The aqueous stability of the TiO_2 nanotube array was examined and compared with porous silica (SiO_2), a more extensively studied thin film optical biosensor. The TiO_2 nanotube array is stable in the pH range 2 to 12, whereas the porous SiO_2 sensor displays significant degradation at pH > 8.