ABSTRACT
Cation exchange (CX) reaction for the non-fluorescent ZnS nanocrystal clusters (NCCs) can be used to detect trace biomolecules . Nano clusters synthetized by hydrothermal synthesis are porous. So they can quickly release large amounts of Zn2+ from through cation exchange ( CX) reaction and nano cluster, generate fluorescent signal under the action of zinc reagent to detect fluorescence. The relationship between the release efficiency, target binding force of Zn2+ and its average diamete was investigated when the average diameter was 44 nm, 86 nm and 144 nm in this experiment. Results showed that the smallest nano cluster exhibited the highest cation exchange efficiency, and 71 percent of Zn2+ closed could be released by microwave radiation within 2 min. When the sandwich method of NCCs of 44-nm was used to detect immunoglobulin E (IgE) in a sandwich assay, the limit of detection (LOD) was 5 ng / L, which was 1000 times lower than that of ELISA. It turns out that CX for the ZnS NCCs is superior to the conventional signaling strategies in its high amplification efficiency, robustness, and biocompatibility.