Electrochemical Detection of Copper Using a Gly-Gly-His Modified Carbon Nanotube Biosensor

Diazonium ion chemistry has been used to electrochemically graft aminophenyl layers onto p-type silicon (100) substrates. A condensation reaction was used to immobilise single-walled carbon nanotubes with high carboxylic acid functionality directly to this layer. The surface immobilised carbon nanotubes were then modified with the tripeptide Gly-Gly-His for the selective detection of copper ions in aqueous environments. The stepwise assembly and sensitivity of this biosensor to copper was characterised by X-ray photoelectron spectroscopy and differential pulse voltammetry, respectively. The ability to detect copper ion concentrations down to 1 mu M was demonstrated. As this biosensor combines the advantages of a silicon substrate for easy integration into sophisticated electrical and electronic devices, diazonium salt derived films for stability in aqueous environments and carbon nanotubes for desirable electrochemical properties, it is expected to have important future applications in environmental sensing.