Impedimetric Urea Biosensor Based on Modified Gold Electrode with Urease Immobilized on Glutathione Layer

In this work, a glutathione (GSH) modified gold microelectrode was used for the covalent immobilization of urease biomolecules via the glutaraldehyde-coupling agent. The self-assembled monolayers (SAMs) onto the gold surface was investigated by using the electrochemical impedance spectroscopy measurements (EIS). Before urease grafting, a significant interaction was noticed between urea and the glutathione layer by forming hydrogen bonds. The H-NMR analysis was carried out to highlight the possibility of having a covalent link between urea and the GSH deposited layer. In addition, contact angle measurements were carried out to determine the hydrophobic/hydrophilic feature of the modified gold surface electrode. After urease immobilization a stable and high sensitive impedimetric urea biosensors was obtained with a sensitivity of 8.73 10-8 Ω-1mM-1 for the low concentrations range and a sensitivity of 7.03 10-9 Ω-1mM-1 for the high concentrations range. Copyright © 2014 IFSA Publishing, S. L.