Development of optical biosensor based on photonic crystal made of TiO2 using liquid phase deposition.

We fabricated a titanium dioxide (TiO₂)-based photonic crystal (PhC) using liquid phase deposition (LPD) to develop highly sensitive optical biosensors. The optical characteristics of the PhCs in the visible region were sensitive to the change in the refractive index of the surrounding medium due to an antigen–antibody reaction; thus, applications using the optical biosensor are expected to be highly sensitive. However, a base material with a high refractive index is indispensable for the fabrication of the PhC. Here, TiO₂, which has optical transparency in the visible region, was selected as the high refractive index base material. The present LPD method allowed fabrication using low-cost apparatus. Furthermore, the mild conditions of the LPD method led to formation of TiO₂-based PhC with fewer crack structures. Finally, the anti-neuron-specific enolase antibody was immobilized onto the TiO₂-based PhC surface, and 1–1000 ng/mL of the neuron-specific enolase antigen was successfully detected. [ABSTRACT FROM AUTHOR]