Plasmonic graphene oxide aptasensor empowered for ultra‑sensitive and rapid detection of aflatoxin M1 in dairy product

Aflatoxins are toxic metabolites and potent carcinogens that pose a threat to both humans and animals even at trace levels. In this study, we developed a robust plasmonic graphene oxide-based aptasensor for rapid and specific detection of Aflatoxin M1(AFM1) in dairy products. The Graphene Oxide-Chitosan (GOCS) nanocomposite was applied onto an Au thin layer (gold chip) and functionalized with aptamers. The Finite-Difference Time-Domain (FDTD) technique was employed to simulate the evanescent field and surface plasmon resonance (SPR) behavior of the sensor, enabling optimization of its performance. Additionally, X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FE-SEM) analyses were conducted to examine the structure of GOCS/Au and the properties of the SPR sensor. The aptasensor successfully detected AFM1 in milk with a detection limit of 0.005 ng/mL and a linear range from 0.005 to 50 ng/mL. Given both the sensor's linear range and its low detection limit, it readily meets and surpasses the regulatory requirements of the European Union and the United States for permissible AFM1 levels in milk. The performance of the sensor was validated under various pH conditions and further compared to the High-Performance Liquid Chromatography (HPLC) method in the presence of other mycotoxins. The results demonstrated the high sensitivity and selectivity of the sensor, highlighting its strong potential for reliable AFM1 detection in diverse food samples.