Fluorescence immunoassay based on the inner-filter effect of carbon dots for highly sensitive amantadine detection in foodstuffs.

Immunoassays with ultra-high sensitivity for the rapid detection of chemical contaminants in food are urgently required. However, conventional enzyme-linked immunosorbent assay (ELISA) usually suffer from the moderate sensitivity. Herein, we aim to improve the sensitivity of conventional ELISA by employing the fluorescent carbon dots (CDs) as the signal probes based on the principle of inner filter effect (IFE). In this strategy, the enzymatically formed products of horseradish peroxidase/alkaline phosphatase efficiently quenched the CDs via the IFE. The absorption signal of the conventional ELISA was converted into the fluorescence signal. The fluorescent immunoassay was successfully developed and used to detect amantadine residues in chicken, achieving a limit of detection of 0.02 ng mL-1. The fluorescent immunoassay is a straightforward, extendable and general strategy and exhibits potential in detecting trace amounts of chemical contaminants in foodstuff.