Direct Assembly and Metal-Ions Binding Properties of Oxytocin Monolayer on Gold Surfaces.

Peptides are very common recognition entities which are usually attached to surfaces using multistep processes. These processes require modification of the native peptides and of the substrates. 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 a simple single-step formation of native oxytocin monolayer on gold surface. These surfaces were characterizations by atomic force spectroscopy, spectroscopic ellipsometry and x-ray photoelectron spectroscopy. We took advantage of the native disulfide bridge of the oxytocin for anchoring the peptide to the Au surface, while preserving the metal ion binding properties. Self-assembled oxytocin monolayer was used by electrochemical impedance spectroscopy for metal ion sensing leading to sub-nanomolar sensitivities for zinc or copper ions.