Novel fabrication of a laccase biosensor to detect phenolic compounds using a carboxylated multiwalled carbon nanotube on the electropolymerized support

Biosensors research is one of the fastest growing fields in which tens of thousands of papers have been published over the years; even more, numerous biosensors have been developed for the detection of phenolic compounds, such as catechol which reacts with an appropriate enzymatic bioreceptor like laccase. A biosensing electrode for catechol detection was investigated by covalent immobilization of laccase on a glassy carbon electrode modified by conducting polymers built of poly(3,4-ethylenedioxythiophene), gold nanoparticles and carboxylated multiwalled carbon nanotubes. The fabrication process of the sensing surface was investigated by Fourier transform infrared spectroscopy, scanning electron microscopy and electrochemical procedures. The electrochemical results demonstrate that the enzyme was immobilized covalently onto the modified glassy carbon electrode by the interaction between carboxyl groups of the carboxylated multiwalled carbon nanotubes and laccase. The biosensor demonstrates a direct electron transfer between the electrode and immobilized laccase. Under optimum conditions, it presented two linear responses in the range of 0.1-0.5 and 11.99-94.11M. The limits of detection were found to be 0.11 and 12.26 mu M.