A stable, label-free optical interferometric biosensor based on TiO2 nanotube arrays.

Area of Science:

• Nanotechnology
• Biomedical Engineering
• Materials Science

Background:

• Label-free biosensing is crucial for real-time biomolecule detection.
• Titanium dioxide (TiO2) nanotubes offer unique properties for biosensor development.
• Protein A is a common capture probe for immunoglobulin G (IgG).

Purpose of the Study:

• To develop and evaluate a TiO2 nanotube array biosensor for label-free rabbit IgG detection.
• To assess the specificity and stability of the TiO2 nanotube biosensor.
• To compare the performance of TiO2 nanotube biosensors with traditional silica (SiO2) biosensors.

Main Methods:

• Fabrication of a thin film array of TiO2 nanotubes.
• Immobilization of protein A capture probes onto nanotube inner pore walls via electrostatic adsorption.
• Label-free optical interferometry for IgG detection.
• Aqueous stability testing across a range of pH values.
• Specificity confirmation using non-binding chicken IgG.

Main Results:

• The TiO2 nanotube array successfully enabled label-free sensing of rabbit IgG.
• Specificity was confirmed through control experiments with chicken IgG.
• The TiO2 nanotube array demonstrated excellent aqueous stability in the pH range of 2 to 12.
• Porous SiO2 sensors showed significant degradation at pH values above 8.

Conclusions:

• TiO2 nanotube arrays are a promising platform for stable, label-free optical biosensing.
• The protein A-functionalized TiO2 nanotube sensor offers high specificity for rabbit IgG detection.
• TiO2 nanotube biosensors present a significant advantage in terms of aqueous stability over SiO2-based sensors.