Quantum dot labeled immunoassay using zinc oxide nanowires

In this paper, we proposed a novel and efficient quantum dot (QD)-based immunoassay method on the zinc oxide (ZnO) nanowire substrate. The ZnO nanowire substrate increases the immobilization sites for biomolecules, which results in the enhancement of fluorescence signal in QD-labeled immunoassay. However, energy transfer happens between the ZnO nanowire and QDs when QD is introduced as a labeling material. To prevent this energy transfer, we applied biotin-streptavidin complex to prolong the distance between two nanomaterials. Triple layers of biotin-streptavidin complexes reduced the energy transfer successfully. This immunoassay system was applied to quantify the concentration of carcinoembryonic antigen (CEA).