Abstract
In this work, a mixed self-assembled monolayer (SAM) formed by 1.2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-(biotinyl) (biotinyl-PE) and 16-mercaptohexadecanoic acid was grafted on gold electrode. Horseradish peroxidase conjugated streptavidin was attached on the SAM through biotin-streptavidin interaction. Cyclic voltammetry and impedance spectroscopy were applied to characterize the electric properties of the self-assembled monolayer and to monitor biosensor building-up process. During impedance measurements, the charge transfer resistance decreased significantly after enzymatic reaction with hydrogen peroxide. The response was very sensitive in the range of 10-100 mM and the detection limit attained 10 mu M. The constructed biosensor was successfully tested in milk samples and was able to detect as low as 50 mu M of hydrogen peroxide. (C) 2008 Elsevier B.V. All rights reserved.