A hydroquinone biosensor using modified core–shell magnetic nanoparticles supported on carbon paste electrode

A hydroquinone biosensor was developed and used to determine hydroquinone concentration in compost extracts based on the immobilization of laccase on the surface of modified magnetic core–shell (Fe3O4–SiO2) nanoparticles. Laccase was covalently immobilized on the magnetic nanoparticles by glutaraldehyde, which was modified with amino groups on its surface. The obtained magnetic bio-nanoparticles were attached to the surface of carbon paste electrode with the aid of a permanent magnet to determine hydroquinone. A good microenvironment for retaining the bioactivity of laccase was provided by the immobilization matrix. The linear range for hydroquinone determination was 1 × 10−7 to 1.375 × 10−4 M, with a detection limit of 1.5 × 10−8 M. The current reached 95% of the steady-state current within about 60 s. Hydroquinone concentration in compost extracts was determined by laccase biosensor and HPLC, the results of the two methods were approximately the same.