Development of an impedimetric immunosensor for the determination of 3-amino-2-oxazolidone residue in food samples

Faradaic impendence spectra that the immunosensor incubated with different concentrations of AOZ in 0.1 M phosphate buffer solution (pH 7.5) and 0.1 M KNO 3 containing 1.0 mM K 3[Fe(CN) 6]/K 4[Fe(CN) 6] (1:1 mixture). [Display omitted] ► A new method for AOZ detection was firstly reported based on immobilizing the self-made AOZ-McAb on the Au-SAMs by the impedimetric immunosensors. ► The proposed immunosensor exhibited high sensitivity, wide linear range, acceptable reproducibility and selectivity. It provided a simple method for direct detection of AOZ residue in food samples. ► The results were in good agreement with what was obtained by HPLC–MS/MS. Compared to HPLC–MS/MS, the proposed method can shorten the whole analysis time and simplify the sample's treatment. The use of furazolidone in food animals has been banned in European Union (EU) because of its carcinogenicity and mutagenicity on human health, but its continued misuse is widespread. Therefore, there is an urgent need for a simple, reliable, and rapid method for the detection of its marker residue, 3-amino-2-oxazolidinone (AOZ), in food products. In this regard, a sensitive and reliable electrochemical method was presented to detect AOZ based on a novel label-free electrochemical impedimetric immunosensor to address this need. The immobilization of monoclonal antibody against AOZ (denoted as AOZ-McAb) on the gold electrode was carried out through a stable acyl amino ester intermediate generated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydrosuccinimide (NHS), which could condense antibodies on the self-assembled monolayer (SAM). The detection of AOZ was performed by measuring the relative change in charge transfer resistance before and after AOZ and AOZ-McAb immunoreaction by electrochemical impedance spectroscopy (EIS). Under the optimized conditions, the relative change in charge transfer resistance was proportional to the logarithmic value of AOZ concentrations in the range of 20.0 to 1.0 × 10 4 ng mL −1 ( r = 0.9987). Moreover, the proposed immunosensor has a high selectivity to AOZ alone with no significant response to the metabolites of other nitrofuran antibiotics, such as 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ), semicarbazide (SEM), and 1-aminohydantoin hydrochloride (AHD). This protocol has been applied to detect AOZ in food samples with satisfactory results.