Atomistic molecular dynamics study on the influence of high temperatures on the structure of peptide nanomembranes candidates for organic supercapacitor electrode

Abstract

Recently, a series of organic structures formed by peptide self-assembly have been reported, among which stand out the peptide nanomembranes with promising applications in the energy storage field. In these applications, the nanomembranes can be subjected to high temperatures. Although the effects of temperature are well known in lipid membranes, in peptide ones they lack further investigation. In this sense, we present a study based on fully atomistic molecular dynamics simulation, which demonstrates the behavior of peptide membranes formed by Alanine (A) and Arginine (R) electrically charged and uncharged, A6R1+ and A6R, at temperatures of 300 K, 320 K, 340 K, 360 K, 380 K, 400 K, 420 K, 440 K, 460 K, 480 K, and 500 K. We report a detailed analysis based on the total average number of Hydrogen Bonds (HBs) between the residues and between the residues with the water molecules, as well as the average lifetime of each of these interactions. Our results demonstrate that a hydrogen-bond network is maintained in the range of temperature evaluated contributing to the stability of the peptide nanomembranes. The increase in temperature causes only a small variation in the total number of HBs, however, the HBs lifetime of these interactions is drastically affected by temperature, providing greater dynamics in the peptide-peptide interaction, favoring greater mobility of these molecules as the temperature rises, as confirmed by the Einstein's diffusion coefficient, also obtained in this study. The HBs results together with the Coulomb and vdW interactions, show that the membrane structures are quite stable in withstanding high temperatures, which may indicate a potential application in coatings, liquid separation, and especially in supercapacitors since the nanomembranes formed by A6R1+ and A6R peptide present pores in all 2D-material favoring a slight infiltration of ionic liquid in the material surface, which directly impacts energy storage efficiency.