Thick-film biosensors for pesticides produced by screen-printing of graphite–epoxy composite and biocomposite pastes

The aim of the present work is to compare various thick-film configurations as well as the different enzyme immobilisation techniques used in the design of a pesticide biosensor. Three different strategies are employed for enzyme immobilisation. According to the first strategy the enzyme layer is applied manually onto the transducer (graphite–epoxy composite screen-printed onto copper tracks produced by photolithography technique) and then the immobilisation of enzyme via cross-linking with glutaraldehyde was performed. In the second strategy the biosensor fabrication is based on the screen-printing of an enzyme–hydroxyethyl cellulose (HEC) paste onto the same transducer. The third strategy consists in the biological material incorporation into the graphite–epoxy paste forming a biocomposite. The enzyme remains immobilised in the bulk of the paste which is screen-printed over copper tracks producing the biosensor in a single-step procedure. Analytical performances of biosensors designed by these three different configurations are compared.