Amperometric tyrosinase biosensor based on Fe3O4 nanoparticles-chitosan nanocomposite

A novel tyrosinase biosensor based on Fe3O4 nanoparticles-chitosan nanocomposite has been developed for the detection of phenolic compounds. The large surface area of Fe3O4 nanoparticles and the porous morphology of chitosan led to a high loading of enzyme and the entrapped enzyme could retain its bioactivity. The tyrosinase-Fe3O4 nanoparticle-chitosan bionanocomposite film was characterized with atomic force microscopy and AC impedance spectra. The prepared biosensor was used to determine phenolic compounds by amperometric detection of the biocatalytically liberated quinone at -0.2 V vs. saturated calomel electrode (SCE). The different parameters, including working potential, pH of supporting electrolyte and temperature that governs the analytical performance of the biosensor have been studied in detail and optimized. The biosensor was applied to detect catechol with a linear range of 8.3 x 10(-8) to 7.0 x 10(-5) mol L-1, and the detection limit of 2.5 x 10(-8) mol L-1. The tyrosinase biosensor exhibits good repeatability and stability. Such new tyrosinase biosensor shows great promise for rapid, simple, and cost-effective analysis of phenolic contaminants in environmental samples. The proposed strategy can be extended for the development of other enzyme-based biosensors. (c) 2008 Elsevier B.V. All rights reserved.