Urea Impedimetric Biosensor Based on Modified Gold Microelectrode with 2-Amino-6-Purinethiol

In this report, an electrochemical microbiosensor for urea monitoring was developed using the self-assembled monolayers (SAM) strategy. Modified gold microelectrode with a monomolecular layer of 2-amino-6-purinethiol (APT) was used for the immobilization of urease biomolecules through glutaraldehyde (GA) as an intermediate monolayer. The building of the bridge system was evaluated by electrochemical impedance spectroscopy measurements (EIS). To separate the real response of the developed microbiosensor from other parasitic effects, we have registered the response of the modified gold microelectrode to urea addition before and after each modification step. During the control procedures we have noticed the ability of interaction of 2-amino-6-purinethiol with urea by forming hydrogen bonded. Electrochemical impedance spectroscopy measurements are suitable to detect interactions between the urea molecules in solution and the aminopurinethiolate monolayer on gold surface electrode. In addition, contact angle measurements were carried out to determine the hydrophobic/hydrophilic character and the thermodynamic characteristics of the modified gold surface electrode. As a result, we conclude that modified gold microelectrode by 2-amino-6-purinethiol/Glutaraldehyde/urease multi-layer can work as good promoters for urea determination.