Direct voltammetry of catalase immobilized on silica sol–gel and cysteine modified gold electrode and its application

The direct voltammetry of catalase (CAT) immobilized in silica sol–gel film in the presence of cysteine on gold electrode was investigated. The CAT electrode showed a pair of well-defined and quasi-reversible cyclic voltammetry peaks. It can be used as an electrochemical biosensor for the determination of hydrogen peroxide. The calibration range of H2O2 was from 1 to 30 μmol L−1 and the detection limit was 0.4 μmol L−1 at a signal-to-noise ratio of 3. The interaction of CAT and aluminum ion was also investigated based on the CAT-modified electrode. The electrochemical activity of the CAT-modified electrode was increased with the addition of Al3+. The experimental results of voltammetry and fluorescence spectroscopy indicated that the conformation of CAT molecule was altered by the formation of Al–CAT complex with Al3+, which may influence the activity of CAT.