Enzymatic Sensor Using Mediator‐Screen‐Printed Carbon Electrodes

Abstract

Abstract A new glucose sensor was developed using screen‐printed ferrocyanide/carbon electrodes. The ferrocyanide is included in the carbon ink of the commercial screen‐ printed electrode. The immobilization of enzymes glucose oxidase (Gox) and horseradish peroxidase (HRP) were carried out in a very easy way. An aliquot of 10 µL of a Gox/HRP mixture was deposited on the electrode surface and left there until dried (approximately 1 h) at room temperature. The ferricyanide generated enzymatically was detected amperometrically applying a potential of −0.1 V (vs. Ag pseudo reference electrode). The sensor, so constructed, shows a good sensitivity to glucose (−2.12 µA/mM) with a slope deviation of ±0.06 µA/mM and a linear range comprised between 0.05 and 1 mM of glucose, with a limit of detection of 0.025 mM. These sensors show good intersensor reproducibility and a high stability. When they are stored at 4 °C, no significant changes in the slope value of the glucose calibration plot were found after 3 months. Glucose was determined in real samples as honey, blood, drink for babies and glucosed drink with a great accuracy.