A fluorescence immunoassay based on CdTe : Zn/ZnS quantum dots for the rapid detection of bacteria, taking Delftia tsuruhatensis CM’13 as an example

Abstract

A fluorescence immunoassay has been widely applied in different fields due to its high sensitivity, simple operations, and high accuracy. Quantum dots (QDs) are often selected as labels in a fluorescence immunoassay due to their high fluorescence, better stability, and biocompatibility. In this study, novel doped CdTe : Zn/ZnS QDs with stability and a high photoluminescence quantum yield (40.78%) were prepared by the water synthesis method and used as labels to conjugate with goat anti-rabbit IgG to establish a fluorescence immunoassay (FLISA) for bacteria compared to the traditional enzyme-linked immunosorbent assay (ELISA) based on the reaction between an antibody and an antigen. A good linear relationship between the fluorescence intensity and concentrations of D. tsuruhatensis CM13 was found when the concentrations were in the range of 10³ CFU mL⁻¹–10⁸ CFU mL⁻¹. The limit of detection (LOD) of D. tsuruhatensis CM13 was 1.25 × 10³ CFU mL⁻¹ by FLISA, which was about 80 times lower than the LOD obtained from ELISA (10⁵ CFU mL⁻¹). This indicated that our FLISA method has higher sensitivity than traditional ELISA, and the CdTe : Zn/ZnS QDs synthesized in this paper have good applications in the rapid sensitive detection of microorganisms.