Green upconversion nanoparticles for 2, 4- dichlorophenoxyacetic acid and fenitrothion detection

Abstract

Upconversion fluorescence analysis is an increasingly popular novel technique with biological and biomedical applications owing to its high detection sensitivity, non-invasive mode and superior photo-stability. Herein, water-soluble green β-NaYF4:Yb, Er UCNPs were prepared via a facile wet-chemical technique, then conjugated with rabbit anti-2, 4-dichlorophenoxyacetic acid immunoglobulin G (2, 4-D-IgG) and rabbit anti-fenitrothion IgG (fenitrothion-IgG), respectively. The content of 2, 4-D-IgG and fenitrothion-IgG in labeled-samples were quantitatively analyzed by the Coomassie-Brilliant-Blue method. The 2, 4-D-IgG (or fenitrothion-IgG) labeled with β-NaYF4:Yb, Er UCNPs conjugates can be used as fluorescent bio-labels for the detection of 2, 4-D and fenitrothion under 980 nm near-infrared excitation. An immunochromatographic strip was then successfully constructed based on the antibody-UCNPs conjugates. The detection limits of 2, 4-D and fenitrothion pesticide residues were 5 ng/mL and 11 ng/mL, respectively. The experimental results indicate that the biocompatible green UCNPs have great advantages as bio-labeling materials for low-molecular-weight pesticide residue analysis.