A dual-signal immunochromatographic assay using quantum dots and polydopamine coated gold nanoparticles for detection of sodium pentachlorophenate in animal-derived food

Sodium pentachlorophenate (PCP-Na) has been widely used as herbicide, pesticide, and fungicide, causing extensive and prolonged contamination. It can persistently remain in water, soil and plants, which might eventually accumulate in animal-derived food and jeopardize human health. In this study, a qualitative naked -eye observing immunochromatographic assay was developed for the detection of PCP-Na, which could reflect the result by a positive signal readout of fluorescence mode and negative signal readout of colorimetric mode within 10 min. The visual limit of detection (vLOD) in the fluorescence mode of QDs under ultraviolet light was 0.4 ng/ mL, and in the colorimetric mode of Au@PDA under natural light was 25 ng/mL. Except for the metabolite pentachlorophenol (PCP) of PCP-Na, the immunochromatographic test strip has no obvious cross-reaction to 2-chlorophenol, 2, 4, 5-trichlorophenol, 4-chlorophenol, phenol, 2, 4, 6-trichlorophenol, and 2, 4-dichlorophenol. The recovery test in practical samples showed that the results of test strip was comparable to that of HPLC-MS/ MS (recoveries ranging from 80.51 % to 99.74 %, with CV ranging from 0.07 % to 3.14 %), and the limit of detection (LOD) of PCP-Na in practical samples was 4 mu g/kg. To the best of our knowledge, this study firstly reported an immunochromatographic assay for PCP-Na through a dual signal readout mode, which has great potential for on-site sample screening.