**2.3 Peptide immobilization on gold**

Peptides (100µM) were grafted at least in triplicat on the gold surface of the biochip by electrochemical copolymerization of pyrrole-peptide conjugates using a solution containing 20 mmol/L pyrrole, 100 µmol/L of pyrrolated peptides and 10% glycerol in phosphate buffer (50 mmol/L). The polymerisation step was performed by a short 100 ms electrical pulse (2 V) between the counter electrode located in the needle of the microarrayer and the prism gold layer (Cherif et al., 2006, Villiers et al., 2009). Another grafting method based on electro-deposition of diazonium-peptide adducts (Corgier et al., 2009) was also used, as indicated in the text. The prism was rinsed with distilled water and saturated at room temperature for 2h using various mediums as indicated in the text. After washing with distilled water, the prism was positioned in the SPRi-Plex and used immediately.
