Redox Hydrogel-Based Bienzyme Microelectrodes for Amperometric Monitoring of L-Glutamate

✍ Scribed by Ekaterina Mikeladze; Albert Schulte; Marcus Mosbach; Andrea Blöchl; Elisabeth Csöregi; Revaz Solomonia; Wolfgang Schuhmann

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 169 KB
• Volume: 14
• Category: Article
• ISSN: 1040-0397
• DOI: 10.1002/1521-4109(200203)14:6<393::aid-elan393>3.0.co;2-p

✦ Synopsis

Fabrication and characterization of amperometric bienzyme l-glutamate sensitive microelectrodes are the prerequisite for monitoring changes of l-glutamate concentration at glutamate-secreting cell cultures. The design of the glutamate microelectrodes is based on incorporating l-glutamate oxidase and horseradish peroxidase into a redox-hydrogel containing PVI 19 -dmeOs as the redox mediator and immobilizing this system onto the surface of platinum microdisk electrodes using a dip-coating procedure. For amperometric measurements of l-glutamate, these redox hydrogel-based bienzyme microelectrodes can be operated at low working potentials (À 50 mV vs. Ag/AgCl) decreasing the influence of electroactive interferants possibly present in biological samples. The l-glutamate microsensors are characterized by a good operation stability and sensitivity (0.038 AE 0.005 mA M À1 ), a low detection limit (0.5 mM in a conventional amperometric set-up and 0.03 mM in a Faraday cage, defined as three times the signalto-noise ratio), a linear range up to 50 mM and a response time of about 35 s. The glutamate biosensors have been applied for the direct measurement of l-glutamate release (upon chemical stimulation) from a population of immortalized hippocampal neurons (HN10 cells) demonstrating the possibility to amperometrically monitor in-situ lglutamate secretion from these cells.