Competitive immunoassay using enzyme-regulated Fe3O4@COF/Fe3+ fluorescence probe for natural chloramphenicol detection

Accurate and sensitive detection of chloramphenicol (CAP) in natural samples is essential for ensuring human health. Herein, an enzyme-regulated fluorescence sensor using Fe3O4@COF/Fe3+ probe, is developed for CAP determination. Fe3O4@COF, synthesized via hydrothermal method, exhibits dual functions as a magnetic carrier and signal probe. Bovine serum albumin conjugated-chloramphenicol, adsorbed on the surface of Fe3O4@COF, competes with CAP for antibody binding. The antibody interacts with alkaline phosphatase via the biotinstreptavidin system. Meanwhile, ascorbic acid, produced from the enzyme-catalyzed reaction dominated by alkaline phosphatase, effectively restores the fluorescence of Fe3O4@COF that is quenched by Fe3+. After experimental verification and gradual optimization, a logarithmic linear relationship between CAP concentration and fluorescence intensity is established in the range of 2 x 10(-4) -10 mu g mL(-1), with a good limit of detection (9.2 x 10(-5) mu g mL(-1)). Proposed method exhibits excellent stability (15 days) and reusability (8 cycles), providing a sensitive and reliable method for accurate CAP detection. The readouts show good agreement with HPLC and recoveries during laboratory and natural CAP analysis.

Automated summary

Accurate and sensitive detection of chloramphenicol (CAP) in natural samples is achieved using an enzyme-regulated fluorescence sensor. A Fe3O4@COF/Fe3+ probe is developed, where Fe3O4@COF acts as a magnetic carrier and signal probe. The sensor demonstrates good stability, reusability, and a logarithmic linear relationship between CAP concentration and fluorescence intensity, providing a reliable method for CAP detection with a low limit of detection.