Horseradish peroxidase-based organic-phase enzyme electrode

Area of Science:

• Electrochemistry
• Biotechnology
• Analytical Chemistry

Background:

• Organic-phase enzyme electrodes (OPEEs) offer unique analytical capabilities.
• Horseradish peroxidase (HRP) exhibits catalase-like activity, decomposing hydroperoxides.
• Acetonitrile serves as a suitable organic solvent for certain enzymatic reactions.

Purpose of the Study:

• To investigate an OPEE based on HRP immobilized on Nafion-coated spectroscopic graphite.
• To evaluate the electrode's response to hydrogen peroxide (H2O2) and cumene hydroperoxide in acetonitrile.
• To determine the detection limits and response characteristics of the HRP-based electrode.

Main Methods:

• Immobilization of HRP within Nafion on a spectroscopic graphite electrode.
• Amperometric detection in an acetonitrile solution.
• Varying applied potentials to measure electrochemical response.
• Linear sweep voltammetry and open circuit potential measurements.

Main Results:

• The OPEE demonstrated amperometric response due to oxygen reduction from hydroperoxide decomposition by HRP's catalase-like activity.
• Linear response to H2O2 and cumene hydroperoxide observed up to 700 microM.
• Detection limits were approximately 45 microM for H2O2 and 100 microM for cumene hydroperoxide.
• Nernstian dependence observed between 0.2 and 2.0 mM H2O2.

Conclusions:

• The HRP-based OPEE is a viable sensor for hydroperoxide detection in organic media.
• The electrode's response mechanism involves the catalase-like activity of HRP.
• The observed Nernstian behavior suggests a two-electron disproportionation process.