Two fluorescence quenching immunochromatographic assays based on carbon dots and quantum dots as donor probes for the determination of enrofloxacin

Abstract

Two “turn-on” pattern fluorescence-quenching lateral flow immunochromatographic assays (FLFIAs) based on carbon dot (CD)/silver nanoparticle (AgNP) and quantum dot (QD)/gold nanoparticle (AuNP) fluorescence quenching systems were developed for the specific and rapid detection of enrofloxacin (ENR) in animal-derived food. The visual cut-off values were 0.1 μg L⁻¹ ENR for CD/AgNP-based FLFIA (C-FLFIA) and 0.25 μg L⁻¹ ENR for QD/AuNP-based FLFIA (Q-FLFIA). Meanwhile, the cut-off values were 5 μg L⁻¹ ENR for a traditional AgNP-based lateral flow immunochromatographic assay (Ag-LFIA) and 10 μg L⁻¹ ENR for AuNP-based LFIA (Au-LFIA). In spiked and procured animal-derived food samples (crucian, perch, pork, beef, chicken, and milk), the cut-off values were 0.5–1 μg kg ⁻¹ (μg L⁻¹) ENR for C-FLFIA and 1.25–2.5 μg kg⁻¹ (μg L⁻¹) for Q-FLFIA. The cut-off values of the two assays are much lower than the maximum limits of ENR set by standardization agencies around the world.