Voltammetric behavior of peptide-modified porous silicon after metal complexation

Hybrid nanomaterials based on organic layer covalently grafted on porous silicon (PSi) nanostructure appear as promising systems for innovative applications such as detecting of traces amounts and/or removing metal cations in water effluents. In this work, we focused on the functionalization of the PSi nanostructure by the peptide GlyCysGlyCys, which forms stable complexes with metal ions. This property is exploited to achieve toxic metal recognition in water using electrochemical methods. Peptide immobilization was achieved using multi-step reactions; GlyCysGlyCys was anchored on a previously prepared carboxyl-terminated PSi surface, using EDC/NHS coupling agents. This scheme is compatible with the mild conditions required for preserving the probe activity of the peptide. At each step of the functionalization, the surface was monitored by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Electrochemical behavior of such modified electrode was carried out after Nickel accumulation on the surface, by means of cyclic voltammetry. The recorded cyclic voltammograms showed a quasi-irreversible process corresponding to the Ni²⁺/Ni⁰ couple.