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BIOMIMETIC SENSOR IS ULTRASENSITIVE
Metal-binding peptide sensor lowers limits for copper ion detection

An electrochemical metal ion sensor developed in Australia has a detection limit for copper ions of less than 0.2 ppt.


SELECTIVE Peptide ligand attached to electrode binds copper

AUTHOR fabricated the sensor by covalently attaching the tripeptide glycine-glycine-histidine via a peptide bond to a gold electrode modified with a carboxylic acid-terminated self-assembled monolayer.

"We are attempting to exploit nature s ability to make highly selective ligands for binding a given metal ion using oligopeptides," AUTHOR tells. "Our approach provides a generic strategy for immobilizing oligopeptides in solid-state metal ion sensors. The strategy enables the selectivity of oligopeptide ligands for given metal ions to be tuned by varying the amino acids that make up the ligand."

He continues, "The detection limit is well below others reported in the literature for copper.

"The use of sensors with biomimetic recognition components should have a large impact on environmental chemistry, especially if this approach can be adapted for more toxic heavy-metal species," he says. "With these types of sub-ppt detection limits, applications in the analysis of unpolluted environments are a real possibility for out-of-laboratory measurements."

The Australian team now plans to use a combinatorial synthesis approach to modify electrodes using microcapillaries to deliver each amino acid. "This will allow us to rapidly screen the selectivities of different ligands," AUTHOR says.

The team s long-term goal is to prepare an electrode array of metal ion sensors on one sensing chip so that a whole suite of metal ions can be detected in environmental samples such as waste water



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