Ultrasonic-Aided Fabrication of Nanostructured Au-Ring Microelectrodes for Monitoring Transmitters Released from Single Cells

We report a novel ultrasonic-aided fast and straightforward approach to fabricate Au microelectrodes by electroless deposition of nanostructured gold films on the rigid outer surface of pulled glass capillaries. Microelectrodes with tip diameters ranging from several hundred nanometers to several micrometers were fabricated within 20 min via three sequential ultrasonication steps. The ultrasonication technique has been validated to be a very effective route in engineering the morphology of Au film surfaces and improves the fabrication efficiency of Au microelectrodes. The nanostructured surfaces of the Au microelectrodes demonstrate excellent sensing activity and antifouling for dopamine oxidation. The microelectrodes were applied for measurement of catecholamines released from exocytosis events from single chromaffin cells and exhibited faster dynamic peak parameters, compared with carbon fiber microelectrodes. This report provides a generally accessible and complementary platform for analyzing catecholamines release events, which should be useful for new electrode designs and neurochemical sensing.