Sensitive Time-Resolved Fluorescence Immunoassay for Quantitative Determination of Oxyfluorfen in Food and Environmental Samples

Abstract

The direct and indirect competition time-resolved fluorescence immunoassays (dc-TRFIA, ic-TRFIA) were established by combining the autofluorescence properties of lanthanide europium (Eu) with the monoclonal antibody of oxyfluorfen. The purified Eu antibody was optimized and the conditions such as the working concentration of the Eu antibody, monoclonal antibody, and working buffer were optimized. In the optimal condition, the IC50 of dc-TRFIA was 10.27 ng/mL, the lowest detection limit IC10 was 0.071 ng/mL, the detection range (IC10-IC90) was 0.071–1074.3 ng/mL, and the detection range (IC10-IC90) and IC50 of ic-TRFIA were 0.024–504.6 and 2.76 ng/mL, respectively. The comparison showed that the sensitivity and detection limit of ic-TRFIA were superior to dc-TRFIA. The cross reaction (CR) tests showed that the CR with other oxyfluorfen structure analogs was <0.02%, except that there was a certain CR with the benzofluorfen (CR = 11.58) and the bifenox (CR = 8.23%). The average recoveries of ic-TRFIA were 74.6–108.3%, and the RSDs were between 2.1 and 10.9%, in the addition recovery test with five substrates. The results of the correlation test with the real samples of GC-ECD showed that they were highly correlated (y = 0.975x – 0.4446, R2 = 0.9901), which proved that the TRFIA method established in this study had high reliability and accuracy and could be used in environment and agricultural products for rapid detection of oxyfluorfen residues.

Sensitive time-resolved fluoroimmunoassay for the quantitative detection of okadaic acid

“…In this study, we established an indirect competition TRFIA for OA in shellfish. Goat anti-mouse IgG, i.e., secondary antibody, was labeled with europium for low detection limit and high sensitivity (Esteve-Turrillas et al, 2010;Sesay et al, 2013;Li et al, 2014;Sheng et al, 2020). Compared with labeling the primary antibody, labeling the secondary antibody avoids the interference of the marker to the binding site of the antigen on the first antibody.…”

“…Rareearth metal ions, Eu 3+ and Sm 3+ , are used as labels because of their characteristics of high fluorescence intensity, ability to overcome high-background absorption, and long relaxation time (Wang et al, 2009;Huang et al, 2009;Zhang et al, 2011). TRFIA has been used for the detection of small molecules, such as salbutamol in the environment, aflatoxin b1 in feed, and oxyfluorfen in food, and has demonstrated excellent sensitivity and accuracy (Hu et al, 2018;Fang et al, 2019;Sheng et al, 2020). In this study, an OA detection method was developed using TRFIA on the basis of competitive immunization and applied this TRFIA method on shellfish.…”

Time-Resolved FRET-Based Immunosensor for the Ultrasensitive and Rapid Detection of Cd2+

“…Shen et al established time-resolved fluorescence microspheres (TRFMs) for the detection of hydrochlorothiazide, and the limit of detection (LOD) was 1/14 lower than the liquid chromatography-tandem mass spectrometry method. Besides, the TRF materials were also extensively used in medical diagnosis − and the detection of food contaminants, such as biotoxins, pathogenic microorganisms, pesticides, heavy metal ions, biomarkers, etc. − Recently, several researchers indicated that compared with ELISA, the sensitivity of the TRF immunosensor was greatly improved by 1–2 orders of magnitude and the measuring time was significantly reduced by more than 50%. , Moreover, TRF sensors can be effectively operated to increase the signal-to-background ratio with their special fluorescence properties. , …”

A Microfluidic Chip-Based MRS Immunosensor for Biomarker Detection via Enzyme-Mediated Nanoparticle Assembly

“…CLIA is a highly sensitive detection method, but it uses chemiluminescent substances as markers, which leads to defects such as high background values, poor stability, and low reproducibility (Zhang et al, 2018;Xiao and Xu, 2020). As a typical commercialized product, ELISA has the advantage of high stability and good repeatability, while elaborate preprocessing and washing steps lead to the strict requirement for professional operators (Zhao et al, 2019;Sheng et al, 2021). Therefore, there is an urgent need for a low background, high-throughput, and easy-to-operate system to achieve rapid, sensitive, and accurate analysis of targets.…”