Quantitative Detection of Glyphosate by Simultaneous Analysis of UV Spectroscopy and Fluorescence Using DNA-Labeled Gold Nanoparticles

A sandwich-type immunosensor composed of antigen−double target/probe DNA-coated gold nanoparticles (NPs) was developed for the measurement of fluorescence intensity and quantitative analysis of single-stranded DNA based on the concentration of free glyphosate. The reaction between the antigen−double DNA−gold NPs and immobilized antibody on the substrate was carried out for 2 h. The results of the antigen−antibody reaction were measured on the basis of the fluorescence intensity obtained from comparison with the free antigens at concentrations of 0.01−100 μg mL−1 for the detection of immobilized antigen−double DNA−gold NPs. For the quantitative analysis based on the concentration of glyphosate(0.01−100 μg mL−1), the immunosensor response also revealed the same detection range of glyphosate using DNA detection.