Fluorescence quenching biomimetic ELISA based on quantum dots for enrofloxacin detection in animal-derived foods

In this study, two novel fluorescence quenching biomimetic enzyme-linked immunosorbent assays were constructed for the sensitive detection of enrofloxacin (ENRO) in animal-derived foods. In this strategy, the fluorescence of quantum dots (QDs) was efficiently quenched by the enzymatic formation of horseradish peroxidase (HRP) and prussian blue nanoparticles (PBNPs) in biomimetic enzyme-linked immunosorbent (BELISA). Under the optimal conditions, the detection limit (IC15) of the method using HRP was 1.67 ng/L, and the sensitivity (IC50) was 0.57 μg L−1, while IC15 of the method using PBNPs reached to 1.02 ng/L, and IC50 was 0.04 μg L−1. The recoveries of these proposed methods ranged from 83.37-118.08 %, with the CV values of 0.32–17.01 %. The results from the proposed methods showed high agreement with results yielded by using HPLC. In a conclusion, this conversion of the absorption signal into fluorescent signals led to an increase in the sensitivity of ENRO detection in animal-derived foods. And it is worth noting that compared to the proposed fluorescence quenching BELISA using HRP as catalyst, the method using PBNPs as catalyst showed a higher sensitivity with a 14-fold lower IC50, demonstrating the good application prospect of nano-enzyme in biomimetic immunoassay.