Long range surface plasmon-enhanced fluorescence spectroscopy for the detection of aflatoxin M1 in milk

A novel biosensor for the highly sensitive detection of aflatoxin M1 (AFM1) in milk was developed. This biosensor is based on surface plasmon-enhanced fluorescence spectroscopy (SPFS) which was advanced through the excitation of long range surface plasmons (LRSPs). In SPFS, the binding of fluorophore-labeled molecules to the sensor surface is probed with surface plasmons (SPs) and the emitted fluorescence light is detected. This approach takes advantages of the enhanced intensity of electromagnetic field occurring upon the resonant excitation of SPs which directly increases the fluorescence signal. For the detection of AFM1, LRSP-enhanced fluorescence spectroscopy was combined with an inhibition immunoassay in which a derivative of AFM1 was immobilized on the sensor surface and antibodies against AFM1 were used as recognition elements. The developed biosensor allowed for the detection of AFM1 in milk within 53 min at concentrations as low as 0.6 pg mL−1. The achieved limit of detection was about two orders of magnitude lower than the maximum AFM1 residue level in milk stipulated by the European Commission legislation.