Amperometric Tyrosinase Biosensors Based on Nanomaterial-Modified Electrodes for Aflatoxin M1

We propose amperometric biosensors for the determination of aflatoxin M1, based on screen-printed platinum electrodes modified by carbon nanotubes (CNT), graphene oxide (GO), gold nanoparticles (Au-NP) in chitosan, and immobilized tyrosinase. The conditions for obtaining gold nanoparticles are optimized. Aflatoxin M1 exhibits properties of a reversible tyrosinase inhibitor, which makes ensures its determination using biosensors modified by nanomaterials in the concentration range 1 x 10(-11)-1 x 10(-6) M with LOD = 5 x 10(-12) M. The kinetic studies of the enzymatic conversion of phenol in the presence of aflatoxin M1 and a tyrosinase biosensor show both two-parameter mismatch inhibition (modification with a CNT/Au-NP composite) and two-parameter coordinated inhibition (modification with GO/Au-NP). Using the proposed enzyme sensors based on tyrosinase, the procedures for determining aflatoxin M1 in dairy products are tested.