Oxytocin-derived metal ion biosensors

Peptides are commonly used as recognition elements for biosensing. These peptides are usually attached to surfaces as label-free recognition ligands by multistep processes. The outcome of these tedious processes is a modified peptide that, in many cases, doesn’t preserve many of its features. Using functional groups in native peptides for their assembly on surfaces without affecting their biological activity can facilitate the preparation of biosensors. Herein we present several strategies to modify gold surfaces with peptide layers. Exposure of modified surfaces to metal ions induces conformational changes in the peptide layer and thus can affect the electronic and electrochemical properties of the device. We used this phenomenon for biosensor design. Our approach utilizes the neuropeptide Oxytocin which is a known native metal ion chelator. While one functional group is used to anchor the peptide to Au surface, the peptide still preserves the ion-binding properties. The chelation event was monitored using various electrochemical methods and surface chemistry analysis and supported by theoretical simulations.