A rapid competitive ELISA assay of Okadaic acid level based on epoxy-functionalized magnetic beads

Using newly designed epoxy group activated carbon shell magnetic beads as a goat against mouse antibody (G-Mab) carrier, a competitive immunoassay was conducted on the surface of G-Mab-coated magnetic beads (G-Mab-MBs). Mouse monoclonal antibody against Okadaic acid (MAb), Okadaic acid-horseradish peroxidase conjugate (OA-HRP) and OA were simultaneously added into a reaction system. The enzyme-linked immunosorbent assay (ELISA) was performed in a 96-well microplate incorporated with magnetic bars. Detection of the OA level by using the current approach provided an excellent linear relationship in the range of 0.35-25.0 mu g L-1 with a half-maximal inhibitory concentration IC50 of 3.27 mu g L-1 and LOD values of 0.35 mu g L-1. The shellfish matrix and other algal toxins presented in the sample extraction did not produce obvious interference. As a comparison, tests were conducted via commercial ELISA and liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the corresponding analytical results demonstrated the reliability of the current protocol.