Cerium oxide bentonite nanocomposite-based colorimetric paper sensor for aflatoxins detection in cereal nuts, oilseed and legumes

Cerium oxide nanoparticles (NanoCeO2) and bentonite (Bent) based nanocomposite (CeO2-Bent) aqueous sensor drop casted on paper substrate has been used to detect food borne Aflatoxins (AFs) by Curcumin (Cur) functionalized redox reaction mediated colorimetric detection. Optical studies reveal that when chromophore-like Cur is first added to Nano CeO2/Bent, it creates a chelate complex that serves as a mediator for enhanced binding with AFs. Cur fictionalized CeO2-Bent in the presence of AFB1 result in a rapid electronic π - π * transition and showed change in color of the dye from red (pH 9.54) to yellow (pH 7). The Hypochromic shift from ∼510 nm to ∼433 nm was plotted linearly at 433 nm for increased AFB1 level in foods. The calculated LOD indicated values as 0.5 µg/Kg in corn, 2.4 µg/Kg in rice, 0.2 µg/Kg in peanut, 0.7 µg/Kg in almond, 7.8 µg/Kg in arhar and 9.2 µg/Kg in chana respectively. The results were validated with HPLC-FLD obtaining high accuracy and recovery. The sensor reagent further drop casted on paper showed a quick determination for presence of AFs.