Peptide-polymer conjugate material: Understanding its conformational preferences as a function of the degree of solvation

Abstract

The cyclic peptide cyc[(l-Gln-d-Ala-l-Lys-d-Ala)2] coupled with two poly(n-butyl acrylate) blocks forms a self-assembled material by the association of the cyclic peptide units with the acrylate chains protruding from the peptide scaffold. Structural details of this conjugated material in several environments were previously studied in Silico. However, the structure of the acrylate segments when adsorbed on mica did not match the experimental observations. In this work, we report a re-examination of the deposition process and we demonstrated that the presence of solvent traces during deposition is responsible of the unexpected behavior. Under experimental conditions, the solvent molecules compete with other species for forming interactions with the acrylate segments before and during its adsorption on mica. This competition interferes with the affinity of the acrylate segments towards mica and conditions their structural preferences. Only a total desolvation of the material prior to adsorption would allow an extended structure for the acrylate segments.