A phenol biosensor based on immobilizing tyrosinase to modified core-shell magnetic nanoparticles supported at a carbon paste electrode

摘要

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 -150 mV versus SCE.The resulting phenol biosensor could reach 95% of steady-state current within 20 s and exhibited a high sensitivity of 54.2 muA/mM,which resulted from the high tyrosinase loading of the immobilization matrix.The linear range for phenol determination was from 1 x 10~(-6)to 2.5 x 10~(-4)M with a detection limit of 6.0 x 10~(-7)M obtained at a signal-to-noise ratio of 3.The stability and the application of the biosensor were also evaluated.