Inhibition-based biosensor for atrazine detection

This work presents an inhibition-based biosensor for the fast, simple and inexpensive determination of atrazine. The method is based on the inhibition of the enzyme tyrosinase from mushrooms (Tyr), immobilized on screen printed electrodes (SPEs). To optimize the biosensor performances several carbon based SPEs: graphite (G), graphene (GP), and multiwalled carbon nanotubes (MWCNTs) and immobilization techniques (physical and chemical) have been tested. Tyrosinase was immobilized on the electrode surface by either polyvinyl alcohol with styrylpyridinium groups (PVA-SbQ) as cross-linking agent or Nafion membranes as physical entrapment or bovine serum albumin with glutaraldehyde as chemical immobilization. In the presence of catechol as substrate, atrazine can be determined thanks to its inhibition activity towards the enzyme which catalyzes the oxidation of catechol to o-quinone. Under optimum experimental conditions, the best performance in terms of catalytic efficiency has been demonstrated by MWCNTs screen printed electrode with PVA-SbQ as immobilization method. The developed inhibition biosensor displays a linearity range towards atrazine within 0.5-20 ppm, a LOD of 0.3 ppm and acceptable repeatability and stability. This analysis method was applied to spiked drinking water samples with recoveries close to 95% respect to measurements carried out in PBS buffer. The low cost of this device and its good analytical performances suggest its application for the screening and monitoring of atrazine in real matrices.