Diclofenac Monitoring in Food Using Amperometric Biosensors

In a significant breakthrough for food safety and water quality monitoring, a research group specializing in advanced nanomaterials and biosensor technology has developed a new tyrosinase biosensor with enhanced analytical capabilities. The research, published in the Journal of Analytical Chemistry with the DOI 10.1134/S1061934821050075, focuses on the determination of diclofenac content in various food products, including dairy, meat, and processed items.

Diclofenac, a widely used medication in the non-steroidal anti-inflammatory drug (NSAID) class, should be strictly controlled in food due to its potential presence in dairy products. It is one of the common medications used for analgesics and anti-inflammatory treatment in diseases of the musculoskeletal system. The presence of diclofenac in baby food is unacceptable, and its content in food products is strictly regulated, with European Union regulations setting an MPC for diclofenac in milk at 0.1 μg/l.

The developed biosensor uses a tyrosinase enzyme and is modified with composites of carbon nanotubes (CNT) and gold nanoparticles (Au NPs), as well as fullerene C60 and Au NPs. This modification improves the analytical characteristics of the biosensors, expanding the range of determined concentrations and reducing CH compared to the unmodified analogue.

The biosensors were developed as four types of amperometric biosensors: CNTs in chitosan, fullerene C60 in Boltorn H20, gold nanoparticles (Au NPs) in chitosan, and an immobilized tyrosinase enzyme. To assess the accuracy of the results obtained for the determination of diclofenac using the developed biosensors, the method of fluorescence polarization was used.

The biosensor showed noncompetitive inhibition in the presence of diclofenac during kinetic studies of the reaction of enzymatic conversion of phenol. This finding is crucial as it allows for the determination of diclofenac using the developed biosensors in the concentration range from 10 pM to 1 μM.

The research team also conducted studies on four milk samples with 1.5% fat content, and diclofenac was not detected in any of them. However, the determination of diclofenac content in dairy, meat, and processed products is still very important, as information about its content in seawater and wastewater has become increasingly common. This makes monitoring the drug's content in these environments an important task.

The development of these amperometric biosensors is beneficial for solving specific problems and developing the theory of biosensorics in general. Further improvement of biosensor devices with modern ideas about the role of the surface in the mechanism of analytical response is expected to contribute significantly to this field. The developed tyrosinase biosensor modified with CNT/Au NPs can also be used for milk quality control.