GlyHisGlyHis immobilization on silicon surface for copper detection

Hybrid nanomaterials based on organic layer covalently grafted on semi-conductor surfaces appear as promising systems for innovative applications, especially in sensor field. In this work, we focused on the functionalization of silicon surface by the peptide GlyHisGlyHis, which forms stable complexes with metal ions. This property is exploited to achieve heavy metals recognition in solution. The immobilization was achieved using multi-step reactions: GlyHisGlyHis was anchored on a previously prepared carboxyl-terminated silicon surface using N-ethyl-N′-(3-dimethylaminopropyl)-carbodiimide (EDC)/N-hydroxysuccinimide (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 infrared spectroscopy Fourier transform (FTIR) in ATR (attenuated total reflexions) geometry and by atomic force microscopy (AFM). Electrochemical behaviour of such prepared electrodes was carried out in the presence of copper ions by means of cyclic voltammetry. The recorded cyclic voltammograms showed a surface reversible process corresponding to the Cu ²⁺ /Cu ⁺ couple in the complex Cu-GlyHisGlyHis immobilized on the silicon surface. Copper ions concentrations down than μM where detected. These results demonstrate the potential role of peptide-modified silicon electrodes in developing strategies for simple and fast detection of toxic metals in solution.