Quantum dots / TiO2 hybrid photonic crystal: Fabrication and application for highly sensitive and visible region-responsive biosensor

Abstract

In this work, by combining a photonic crystal (PhC) and highly luminescent material, we developed an extremely sensitive PhC sensor that allows detection by single wavelength fluorescence intensity change in the visible wavelength region. We fabricated a titanium dioxide (TiO2) PhC containing quantum dots (QDs) inside the PhC structure and confirmed that the fluorescence intensity of the QDs was enhanced. Fluorescence enhancement occurs because of the total reflection and light confinement of the QD fluorescence inside the TiO2 PhC structure. The response to changes in the surrounding refractive index and protein adsorption was confirmed. Furthermore, for biosensing applications, troponin T (TnT), an acute myocardial marker, was determined using an antigen-antibody reaction. It was found that a TnT level of 100 fg/mL, which is considerably less than the cutoff value of 100 pg/mL, was successfully detected. The lower limit of detection (LOD) was found to be 58.2 fg/mL, which is 1/40 of that of the conventional enzyme-linked immunosorbent assay (ELISA) method (LOD: 2 pg/mL). It was demonstrated that the present TiO2 PhC-containing QDs can be used as a sensor device for the highly sensitive detection and determination of disease biomarkers.