A label-free silver wire based impedimetric immunosensor for detection of aflatoxin M1 in milk

A highly sensitive and selective label-free impedimetric immunosensor based on silver (Ag) wire electrode for the detection aflatoxin M1 (AFM1) in milk is presented. The sensor was constructed by functionalizing Ag wire coupled with selective monoclonal antibodies of AFM1 through self assembled monolayers. The antigen–antibody interaction was quantified by measuring impedance in the frequency range (1–100 Hz) at 10 mV applied ac potential. A linear working range (6.25–100 pg mL−1) for AFM1 was obtained with 20 min analysis time. The sensor sensitivity was found to be about 2.1% impedance change per decade with limit of quantitation 6.25 pg mL−1 and limit of detection 1 pg mL−1. Good recoveries were obtained with SD = 1.13 and R2 = 0.982 in spiked milk samples. The proposed method is useful for sensitive analysis of AFM1 in milk.