Experimental and theoretical studies on electropolymerization of polar amino acids on platinum electrode Taleb Alhedabi a, b ,H  el  ene Cattey c , Christophe Roussel d , Virginie Blondeau-Patissier e , Tijani Gharbi a , Guillaume Herlem a, * a Nanomedicine Lab EA4662, Bat. E, Universit e de Bourgogne Franche-Comt e, UFR Sciences & Techniques, 16 route de Gray, 25030 Besançon Cedex, France b Department of Chemistry, College of Science, University of Thi-qar, Thi-qar, Iraq c Institut ICMUB - CNRS 6302, Universit e de Bourgogne Franche-Comt e, UFR Sciences et Techniques Mirande, 9 Avenue Alain Savary, 21000 Dijon, France d Ecole Polytechnique F ed erale de Lausanne, Section of Chemistry and Chemical Engineering, Station 6, CH-1015 Lausanne, Switzerland e Institut FEMTO-ST, UMR CNRS 6174, Department Time-Frequency, 26, Chemin de l' epitaphe, 25030 Besançon Cedex, France highlights graphical abstract  Anodic oxidation of polar amino acids with uncharged R group on platinum electrode.  Polypeptide bonds revealed by ATR- IR and XPS spectroscopies.  The film growth depends on the chemistry of the polar amino acid. article info Article history: Received 28 July 2016 Received in revised form 9 October 2016 Accepted 15 October 2016 Available online 17 October 2016 Keywords: Polar amino acid Electropolymerization DFT Thin polymer film Spectroscopy pH sensing abstract The anodic oxidation of polar amino acids (L-serine, L-threonine, L-asparagine, and L-glutamine) in aqueous electrolyte on smooth platinum electrode was carried out by cyclic voltammetry coupled to electrochemical quartz crystal microbalance (EQCM). pH (zwitterion, acidic and alkaline) effects on their electrochemical behavior were examined. The maximum current values are measured for zwitterion species. In addition, the current increases with increasing of concentration and scan rate, and decreases with increasing pH. The resulting passivation was studied by spectroscopic analysis such as attenuated total reflection FT infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and mass spectroscopy (MALDI-TOF). From thin film coatings observed on the electrode surface, peptide bonds are found, and are in favor of electropolymerization of these polar amino acids into poly-L-amino acids in an irreversible way. Scanning electronic microscopy was also used to study the morphology of these elec- trodeposited L-amino acids. The electrodeposited poly-L-amino acids on Pt electrode were tested as bioinspired transducer for pH sensing purposes. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Electropolymerization process can lead to conducting or insu- lating polymers which are used in many applications including pH sensor and biosensors [1e4]. In this context, amino acids are good * Corresponding author. E-mail address: guillaume.herlem@univ-fcomte.fr (G. Herlem). Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys http://dx.doi.org/10.1016/j.matchemphys.2016.10.021 0254-0584/© 2016 Elsevier B.V. All rights reserved. Materials Chemistry and Physics 185 (2017) 183e194