Simultaneous detection of 2, 4-dichlorophenoxyacetic acid and fenitrothion through lanthanide doped β-NaYF4 upconversion nanoparticles with different emitting light colors

Abstract A real-time, on-site rapid and sensitive detection method of low-molecular chemical pollutants was developed by an immunochromatographic strip based on the competitive reaction between the pesticide antigens and polyclonal antibody labeled with upconversion nanoparticles (UCNPs) bio-probes. Two polyclonal antibodies of 2, 4-D and fenitrothion were labeled by β -NaYF 4 :Yb, Er (green phosphors) and β -NaY(Gd)F 4 :Yb, Er (red phosphors) UCNPs respectively and dropped to the conjugation pads on the immunochromatographic strip. The competitors of fenitrothion-OVA and 2, 4-D-OVA were immobilized onto a nitrocellulose membrane to form two test lines T 1 and T 2 , respectively. Meanwhile, the goat anti-rabbit IgG was built onto a nitrocellulose membrane to form control lines (C). The detection limits of 2, 4-D and fenitrothion are 5 ng/mL and 12 ng/mL respectively by using the UCNPs-based immunochromatographic strip. The demonstrated results indicated that two different emitting colors UCNPs have great superiority as luminescent bio-probes for simultaneous detection of low-molecular pesticide residues.