Sweet Sensor for the Detection of Aflatoxin M1 in Whole Milk

Recently, there is an increase in interest to develop user-friendly monitoring devices in healthcare, environmental, and agrofood fields for a fast detection of contaminants. Aflatoxins (AFs) are a group of toxic substances produced by the fungi of species Aspergillus that contaminate cereals and dried fruits. When dairy cows ingest feed contaminated with aflatoxin B1 (AFB1), it is metabolized and transformed in the liver into a carcinogenic form aflatoxin M1 (AFM1), which is eliminated through the milk. In this work, we developed a sensor assay to detect low amounts of AFM1 directly in whole milk. For this purpose, we produced monospecific polyclonal antibody (IgGMS-M1) that was able to bind with high avidity to AFM1. Then, we conjugated the antibody to the invertase enzyme from Saccharomyces cerevisiae. This enzyme is able to convert sucrose into fructose and glucose. After incubation of invertase-conjugated anti-AFM1 antibody with milk containing AFM1, we measured the produced glucose by a glucometer. The produced glucose was then correlated to the amount of AFM1 present in the milk. The obtained results show that the assay is easily customizable as a portable instrument for on-site AFM1 measurements. In addition, the results point out that the assay is very sensitive since it can detect the presence of 27 parts per trillion (ppt) of AFM1 in whole milk, a value lower than the AFM1 quantities in milk and dairy products set by the European Commission (50 ppt).