Fabrication of a Voltammetric Biosensor in Combination with Enzyme-linked Immunosorbent Assay to Detect Aflatoxin M1 in Milks

Background and Objectives: Aflatoxin M1 is one the most important mycotoxin contaminants of milks. Various methods have been described to detect aflatoxins in milks, including chromatography, enzyme-linked immunosorbent assay and colorimetry. Regarding high sensitivity of electrochemical sensor based methods, the aim of the present study was to fabricate an accurate sensitive voltametric biosensor for the rapid detection of aflatoxin M1.  Materials & Methods: In the present study, a biosensor based on magnetic and gold nanoparticles modified with pencil graphite electrodes was combined with high-performance liquid chromatography to identify aflatoxin M1. Electrochemical behaviors of the biosensor were investigated at various stages of fabrication, including immobilization of magnetic nanoparticles, gold nanoparticles, aptamers and analytics using cyclic voltammetry and electrochemical impedance spectroscopy techniques. Results: Results showed that the current peak and charge transfer resistance respectively increased and decreased as the nanoparticles were immobilized, while the current peak and charge transfer resistance increased, compared to the unmodified electrode with the aptamer and analytics immobilization. Assessment of the functional characteristics revealed that the biosensor desirable repeatability (4.6%), reproducibility (8.8%) and acceptable stability (14 days). The biosensor limit of detection was 40 ng/l and the recovery proportion range was reported 93.5–89.6 and 102–105 for biosensor and high-performance liquid chromatography, respectively. Conclusion: The suggested biosensor presented a limit of detection lower than that of Iranian national standard for milk (100 ng/l). Analysis of aflatoxin M1 contaminated milk samples using the biosensor showed a recovery proportion range close to that of high-performance liquid chromatography.