A flow-through amperometric sensor based on dialysis tubing and free enzyme reactors

Area of Science:

• Electrochemistry
• Biosensors
• Analytical Chemistry

Background:

• Enzyme immobilization is a common but complex step in biosensor development.
• Free enzyme solutions can offer advantages in sensor performance and simplicity.
• Flow-through systems are valuable for continuous or high-throughput analysis.

Purpose of the Study:

• To develop a generic flow-through amperometric microenzyme sensor without enzyme immobilization.
• To demonstrate the sensor's capability for detecting physiologically relevant analytes.
• To assess the sensor's performance characteristics, including linear range and detection limits.

Main Methods:

• Utilized semi-permeable dialysis tubing to transport samples to a microcavity containing working and reference electrodes.
• Filled the microcavity with free enzyme solutions (lactate oxidase, glucose oxidase, glutamate oxidase) to create specific amperometric sensors.
• Tested sensor performance for glucose, lactate, and glutamate detection.

Main Results:

• Developed amperometric sensors for glucose, lactate, and glutamate using a simple, non-immobilization method.
• Achieved wide linear ranges: 0-35 mM for glucose, 0-3 mM for lactate, and 0-5 mM for glutamate.
• Established low detection limits in the range of 15-50 microM for the analytes.

Conclusions:

• The described flow-through microenzyme sensor offers a simplified approach to biosensor fabrication by avoiding enzyme immobilization.
• The sensor demonstrates effective detection of key metabolites within their physiological concentration ranges.
• The system shows promise for application in flow injection analysis (FIA) systems.