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

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 mu g L-1 ENR for CD/AgNP-based FLFIA (C-FLFIA) and 0.25 mu g L-1 ENR for QD/AuNP-based FLFIA (Q-FLFIA). Meanwhile, the cut-off values were 5 mu g L-1 ENR for a traditional AgNP-based lateral flow immunochromatographic assay (Ag-LFIA) and 10 mu g 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 mu g kg(-1)(mu g L-1) ENR for C-FLFIA and 1.25-2.5 mu g kg(-1)(mu g 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.