Development of a Highly Sensitive Direct Competitive Fluorescence Enzyme Immunoassay Based on a Nanobody-Alkaline Phosphatase Fusion Protein for Detection of 3-Phenoxybenzoic Acid in Urine.

ABSTRACT: 3-Phenoxybenzoic acid (3-PBA) is a human urinary metabolite of many pyrethroid insecticides and can be used as a biomarker to monitor human exposure to these pesticides. A rapid and sensitive direct competitive fluorescence enzyme immunoassay (dc-FEIA) for detecting 3-PBA on the basis of a nanobody (Nb)-alkaline phosphatase (AP) fusion protein was developed. The anti-3-PBA Nb-AP fusion protein was expressed and purified. The 50% inhibitory concentration (IC₅₀) and linear range of dc-FEIA were 0.082 and 0.015-0.447 ng/mL, respectively, with a detection limit of 0.011 ng/mL. The IC₅₀ of dc-FEIA was improved by nearly ten times compared with those of one-step and three-step direct competitive enzyme-linked immunosorbent assay (dc-ELISA). Spiked urine samples were detecte

SUBMITTER: Huo J 

PROVIDER: S-EPMC6442738 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature