Monitoring of glucose and glutamate using enzyme microstructures and scanning electrochemical microscopy

Glucose oxidase and glutamate oxidase lines, with typical width of 100 µm, were patterned on gold surfaces using a micro-dispensing system, by shooting 100 pl droplets of the corresponding enzyme solutions. The probe of a scanning electrochemical microscope (SECM) was then carefully positioned in the close proximity of the enzyme microstructure and poised to + 600 mV vs. Ag/AgCl, KCl 0.1 M. The H2O2, generated by the enzyme lines at different concentrations of glucose and glutamate in the surrounding solution, was sequentially monitored. Reproducible calibration curves for glucose and glutamate were obtained in one single experiment, proving that the combination of enzyme microstructures with SECM can provide a new way of achieving multianalyte detection.