Enzyme-Modified Microelectrode for Simultaneous Local Measurements of O₂ and pH

Area of Science:

• Electrochemistry and Biosensors
• Analytical Chemistry
• Biochemical Process Monitoring

Background:

• Miniaturized probes offer local resolution for analyzing biochemical processes.
• Multiparametric measurements are crucial for a comprehensive understanding of processes.
• Existing electroanalytical methods often require separate probes for simultaneous measurements.

Purpose of the Study:

• To develop an enzymatic microbiosensor for simultaneous detection of dissolved oxygen (O2) and pH.
• To enable truly simultaneous local measurements at the micrometer scale using a single probe.
• To simplify analytical setups for multiparametric biochemical analysis.

Main Methods:

• Fabrication and characterization of a micrometer-sized microelectrode.
• Modification of a gold microelectrode with a multicopper oxidase for O2 reduction.
• Utilizing the pH-dependent bioelectrocatalytic process for simultaneous O2 and pH sensing.

Main Results:

• The microbiosensor demonstrated linear current response to O2 up to 17.2 mg L⁻¹, with a sensitivity of (5.56 ± 0.13) nA L mg⁻¹ and LOD of (0.5 ± 0.3) mg L⁻¹.
• A linear pH response was observed between pH 5.2 and 7.5 with a slope of -(47 ± 8) mV per pH unit.
• Proof-of-concept examples validated the system's capability for simultaneous local O2 and pH measurements.

Conclusions:

• The developed enzymatic microbiosensor successfully achieves simultaneous local detection of O2 and pH from a single measurement point.
• This strategy significantly simplifies analytical instrumentation compared to existing methods.
• The sensor provides a novel approach for high-resolution, multiparametric analysis of biochemical processes.