A Novel Laccase Immobilization Approach Using Simultaneously Electrodeposition of 3, 4-Ethylenedioxythiophene, Gold Nanoparticles and Functionalized Multi-Walled Carbon Nanotube to Detect Catechol

Laccases are phenoloxidases, that can oxide phenolics. Catechol (1,2-dihydroxybenze) is one of the phenolics that is broadly utilized in various industries. Nanomaterials and conductive polymers can be utilized as a support medium for the laccase immobilization and phenolic biosensors. This paper describes a new enzymatic biosensor being developed to determine phenols such as catechol and showed the laccase catalytic reaction in the presence of phenolic substrates. It is based on the glassy carbon electrode fabricated with electrodepositing of poly (3,4-ethylenedioxythiophene) (PEDOT), carboxyl group functionalized multiwalled carbon nanotube (MWCNTCOOH), and gold nanoparticles in combination, thereafter immobilizing of the laccase on the electropolymerized material on the electrode surface using the covalent binding of laccase to MWCNTCOOH. The simply fabricated laccase biosensor response was characterized via voltammetry techniques and Fourier transform infrared (FTIR) spectroscopy. Using differential pulse voltammetry (DPV), the biosensor results indicated that the detection limit, sensitivity, and linear range are 0.35 µM, 3.52 µA mM^-1, 1 – 4 µM, respectively, as well as the correlation coefficient of 0.95 under optimal conditions. By investigation of scan rate effect on cyclic voltammograms of laccase biosensor, transfer coefficient (α) and standard heterogeneous rate constant (ks) were estimated to be 0.68 and 0.083 s^-1. The proposed biosensor incorporates the pleasant electrocatalytic properties of nanomaterials with the PEDOT properties to decrease the oxidation potential and improve the electron transfer rate, detection limit and sensitivity.