Laccase based amperometric biosensor for industrial waste waters: A comparative study on covalent immobilization methods on gold electrode

Abstract

The behaviour of three different laccase-based amperometric biosensors was studied in view of their use in agricultural or industrial waters polluted by phenolic compounds. Catechol was used as model substrate. Laccase from Trametes versicolor was immobilized directly on gold electrode on one biosensor (type A) by crosslinking with glutaraldehyde while, on the second biosensor (type B), laccase was covalently bound to organothiol layers on gold electrode and finally on the third biosensor (type C) laccase was covalently bound to silanized gold electrode. For each biosensor type, gold electrode of Clark type DO sensor was used for immobilization. The linear range, sensitivity and time stability of each biosensor type were investigated. Among the electrodes tested, type C biosensor was superior to the other types in terms of sensitivity, limit of detection (LOD), response time and operating stability. Biosensor response reached steady state within 3min and exhibited maximum activity at pH7. Furthermore, sample application and accuracy of the three types of sensors were also detected.