A phenol biosensor based on immobilizing tyrosinase to modified core-shell magnetic nanoparticles supported at a carbon paste electrode [An article from: Analytica Chimica Acta]

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Description:
A phenol biosensor was developed based on the immobilization of tyrosinase on the surface of modified magnetic MgFe"2O"4 nanoparticles. The tyrosinase was first covalently immobilized to core-shell (MgFe"2O"4-SiO"2) magnetic nanoparticles, which were modified with amino group on its surface. The resulting magnetic bio-nanoparticles were attached to the surface of carbon paste electrode (CPE) with the help of a permanent magnet. The immobilization matrix provided a good microenvironment for the retaining of the bioactivity of tyrosinase. Phenol was determined by the direct reduction of biocatalytically generated quinone species at -150mV versus SCE. The resulting phenol biosensor could reach 95% of steady-state current within 20s and exhibited a high sensitivity of 54.2@mA/mM, which resulted from the high tyrosinase loading of the immobilization matrix. The linear range for phenol determination was from 1x10^-^6 to 2.5x10^-^4M with a detection limit of 6.0x10^-^7M obtained at a signal-to-noise ratio of 3. The stability and the application of the biosensor were also evaluated.