Electrochemical Sensing Platform Based on Tyrosinase Immobilized Magnetite Chitosan Nanobiocomposite Film and Its Application as Catechol Biosensor

The easy design of an enzyme electrode using tyrosinase immobilized magnetite chitosan nanobiocomposite film (TMCG) and its applicability for electrochemical sensing platform are reported in this work. The sensor components were characterized by scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Stable biomaterial was obtained by chemical immobilization of the enzyme to chitosan structure with glutaraldehyde. Magnetite nanoparticles were homogeneously distributed on the chitosan surface. Nyquist curves revealed that, chitosan and tyrosinase enzyme exhibit higher resistance to the electron transfer while magnetite nanoparticles promote the electron transfer as a result of their nanostructure behaviors. In addition to well defined oxidation peak, new reduction peak was observed from CV analysis after magnetite modification as a result of electrochemical reduction of enzymatically produced o-quinone to the catechol. The developed biosensor (TMCG * ) selectively detected the catechol at a sensitivity of 0.057A/M in a linear range from 1 μM to 30 μM with a detection limit of 260 nM and K m value of 22.5 μM. These findings strongly indicate that TMCG * is applicable as an electrochemical sensing platform for detection of the sample that inhibits the tyrosinase enzyme in tap water.