Electrocatalyzed synthesis of polypeptides on platinum surface in concentrated glycine electrolytes and ab initio calculations coupled to spectroscopic analysis

The anodic oxidation of glycine in aqueous electrolyte on smooth platinum electrode was carried out by electrochemical quartz crystal microbalance coupled to cyclic voltammetry technique. Here, we performed electrochemical experiments in concentrated glycine-based electrolyte. Contrary to studies made in diluted medium, the reaction we describe leads to a strongly grafted polymer on the surface at pH values superior to 6, and up to 13, in an irreversible way. The electrodeposited mass is even very significant at pH 13. Several methods such as AFM topography and spectroscopic techniques were performed to characterize the resulting coating. The polymer growth in alkaline conditions during the anodic oxidation of glycine in water probably involves an electrocatalytic step. We showed the presence of amide bonds and then polypeptide formation on the smooth platinum surface. Periodic ab initio calculations on polyglycine II were performed and compared to XPS and vibrational spectra.