Laccase-based biosensors for monitoring lignin

Four different ways to detect Kraft and soluble pine lignin using either soluble or immobilised Trametes hirsuta laccase have been investigated. In the first, the concentration of lignin was measured using laccase in homogeneous medium with a Clark electrode. In the second, laccase immobilised onto aminated porous glass beads was used in a reactor submerged into the lignin containing solution and the reaction was followed with a Clark electrode. The third and fourth techniques involved lignin detection using laccase modified spectrographic graphite electrodes, either used in flow injection mode or in batch mode, where lignin solutions were injected into an electrochemical cell. It was shown that the use of laccase modified graphite electrodes in conjunction with flow injection for amperometric lignin detection is an attractive perspective and our data form the basis for designing laccase-based biosensors to be applied for measuring lignin and its model compounds in waste water, e.g. from the pulp and paper industry.