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.