Electrochemical Response of α/β‐peptides: Influence of the Peptide Length, Stereochemistry and Self‐Assembly on the Performance of Peptide‐Based Electrochemical Sensors

Abstract The electrochemical response of α/β‐peptides with (L‐Ala‐β‐Fpg)_n sequence, where β‐Fpg refers to syn 3‐amino‐2‐(2‐fluorophenyl)‐3‐phenylpropanoic acid, has been investigated examining the effects of the peptide length (n = 1–3), the stereochemistry of the β^2,3‐diaryl‐amino acid and their self‐assembly. α/β‐Peptides have been deposited by drop‐casting on a conducting polymer (CP) film, which is previously electropolymerized on a stainless steel conducting substrate. The current‐potential response of the CP coated by the different studied peptides suggests that, for α/β‐peptides, the role played by the electron transport through intermolecular stacking of aromatic side groups prevails over peptide length and stereochemistry. In order to prove such a hypothesis, the experimental conditions used to achieve an ordered self‐assembly are optimized for one of the α/β‐peptides. The achieved self‐assembled structures, which consist of well‐defined long microfibers, considerably improve the electrochemical response of the CP. Finally, the prepared α/β‐peptide‐based electrodes are used to electrochemically detect the oxidation of nicotinamide adenine dinucleotide (NADH). The analytical parameters are better for electrodes with well‐defined peptide microfibers than for uncoated CP, corroborating the importance of π‐π stacking interactions in the response of α/β‐peptides.