Poly(dimethylsiloxane) cross-linked carbon paste electrodes for microfluidic electrochemical sensing.

Area of Science:

• Electrochemistry
• Microfluidics
• Biosensors
• Materials Science

Background:

• Electrochemical biosensors integrated into microfluidic devices offer small size and portability.
• A significant challenge in this field is the fabrication of reliable electrodes.
• Existing methods often face limitations in cost, robustness, or patternability.

Purpose of the Study:

• To present an alternative method for creating integrated, low-cost, robust, and patternable carbon paste electrodes (CPEs) for microfluidic applications.
• To demonstrate the electrochemical performance and ease of chemical modification of these novel CPEs.
• To validate the utility of modified CPEs for detecting specific analytes in biological samples.

Main Methods:

• Fabrication of CPEs using graphite powder and a poly(dimethylsiloxane) (PDMS)-mineral oil binder within microfluidic channels.
• Optimization of binder composition for physical robustness and electrochemical performance.
• Chemical modification of CPEs with multi-walled carbon nanotubes (MWCNT) for catecholamine detection and cobalt phthalocyanine (CoPC) for thiol detection.

Main Results:

• Developed robust and patternable CPEs suitable for microfluidic integration.
• CoPC-modified CPEs showed a nearly 2-fold signal improvement for detecting dithiothreitol (DTT).
• MWCNT-modified CPEs demonstrated an order of magnitude improvement in the limit of detection for dopamine.
• Successfully detected thiols in red blood cell lysate using CoPC-CPEs and monitored catecholamine release from PC12 cells using MWCNT-CPEs.

Conclusions:

• The novel PDMS-oil based CPEs offer a cost-effective and robust solution for microfluidic electrochemical biosensors.
• Electrode modification with MWCNT and CoPC significantly enhances sensitivity for target analytes.
• These modified electrodes are suitable for practical applications in biological sample analysis and cellular monitoring.