Single Molecule Electrochemical Detection in Aqueous Solutions and Ionic Liquids

Area of Science:

• Electroanalytical Chemistry
• Nanotechnology
• Single Molecule Detection

Background:

• Single molecule electrochemical detection (SMED) presents significant challenges in electroanalytical chemistry.
• Requires specialized electrochemical cells and measurement techniques for high sensitivity.
• Existing methods often struggle with background noise and precise gap control.

Purpose of the Study:

• To develop and demonstrate a novel approach for SMED using a unique pipet cell design.
• To enable sensitive detection and analysis of individual molecules at the nanoscale.
• To overcome limitations of current SMED techniques, particularly background noise and gap size control.

Main Methods:

• Fabrication of a quad-probe pipet cell by pyrolytic carbon deposition into a quartz capillary.
• Creation of a nanogap cell by contacting the probe's meniscus with a substrate working electrode.
• Utilizing two carbon electrodes within the pipet to promote redox cycling of single molecules.

Main Results:

• Successful single molecule electrochemical detection achieved using the quad-probe pipet cell.
• Anticorrelated currents observed between tip and substrate electrodes, confirming single molecule events.
• Demonstrated low background noise in a droplet format, enabling detection in various solutions.

Conclusions:

• The quad-probe pipet cell offers a promising new platform for SMED.
• Precise nanogap control facilitates quantitative analysis of redox cycling dynamics.
• Opens opportunities for SMED in diverse media, including ionic liquids and aqueous solutions.