“EDTA•2Na-Mn+” based-signal regulation strategy for the construction of vigorous and progressive detection platforms with various signals

The "ethylenediamine tetraacetic acid disodium salt-metal" ("EDTA•2Na-Mn+") based-signal regulation strategy has been successfully developed for the construction of vigorous and progressive immunoassays with various signals, including 1) EDTA•2Na-Fe3+@aptamer/gold nanorods (Ea-Fe3+/AuNRs) with photothermal signal; 2) silica nanoparticles (SiO2 NPs) @EDTA•2Na-Au3+@aptamer/gold nanoparticles (Sea-Au3+/AuNPs) with colorimetric signal; 3) SiO2 NPs@EDTA•2Na-Cd2+@aptamer-cDNA/gold nanoclusters (Seac-Cd2+/AuNCs) with fluorescence signal. Concretely, EDTA•2Na chelates Fe3+, Au3+, and Cd2+ fiercely to selectively regulate the metallization of AuNRs, growth of AuNPs, and synthesis of AuNCs. Using Aflatoxin B1 as a model target, these assays could achieve limits of detection at 0.15 pg/mL, 0.19 pg/mL, and 0.2 fg/mL, respectively. The relative standard deviation of 2.17 % indicates good consistency for food samples detection. Compared with conventional ELISA, these high-performance enzyme-free "EDTA•2Na-Mn+" platforms exhibit the superiors of low cost and enhanced sensitivity, thereby expanding the building of biosensors that eliminate the use of enzymes. Importantly, these platforms endow multiple signals that can realize the mutually corroborate with noninterference for one target detection. The diversity of signals endows the flexible selection of those platforms for food samples detection with different colors and matrices.