The Ultrasensitive Detection of Aflatoxin M 1 Using Gold Nanoparticles Modified Electrode with Fe 3+ as a Probe.

The increasing incidence of diseases caused by highly carcinogenic aflatoxin M 1 (AFM 1 ) in food demands a simple, fast, and cost-effective detection technique capable of sensitively monitoring AFM 1 . Recent works predominantly focus on the electrochemical aptamer-based biosensor, which still faces challenges and high costs in experimentally identifying an efficient candidate aptamer. However, the direct electrochemical detection of AFM 1 has been scarcely reported thus far. In this study, we observed a significant influence on the electrochemical signals of ferric ions at a gold nanoparticle-modified glassy carbon electrode (AuNPs/GCE) by adding varying amounts of AFM 1 . Utilizing ferricyanide as a sensitive indicator of AFM 1 , we have introduced a novel approach for detecting AFM 1 , achieving an unprecedentedly low detection limit of 1.6 × 10 -21 g/L. Through monitoring the fluorescence quenching of AFM 1 with Fe 3+ addition, the interaction between them has been identified at a ratio of 1:936. Transient fluorescence analysis reveals that the fluorescence quenching process is predominantly static. It is interesting that the application of iron chelator diethylenetriaminepentaacetic acid (DTPA) cannot prevent the interaction between AFM 1 and Fe 3+ . With a particle size distribution analysis, it is suggested that a combination of AFM 1 and Fe 3+ occurs and forms a polymer-like aggregate. Nonetheless, the mutual reaction mechanism between AFM 1 and Fe 3+ remains unexplained and urgently necessitates unveiling. Finally, the developed sensor is successfully applied for the AFM 1 test in real samples, fully meeting the detection requirements for milk.