Synthesis and characterization of multi-functional histidine-containing peptide amphiphiles

Abstract

A self-assembly of supramolecular polymers in water is of particular interest in development of new functional materials, biomaterials and drug carriers. This kind of assembly involves weak noncovalent interactions such as electrostatic interactions, coordination binding, H-bonding, π-π interactions, solvophobic effects and van der Waals interactions. Amphiphilic molecules are known to form different types of aggregates being governed by these interactions. We are interested in developing peptide amphiphiles (PAs) as biologically relevant amphiphilic molecules with tunable structural and self-assembly properties. PAs are generally produced by N-terminus modification of a peptide sequence with a fatty acid that assists intermolecular interactions. In this study, we designed and synthesized a series of PAs consisting of Val-Val-Ala-Gly-His-His sequence and alkyl tail of varying length (C12–C17) using solid phase synthesis technique. The effect of the alkyl tail length on the self-assembly of PAs was studied. Hydrophobicity of PAs increased in proportion to the length of alkyl component. Pyrene probe based fluorescent spectroscopy, dynamic light scattering and electron microscopy techniques were used to evaluate critical micellar concentrations and morphology of PA aggregates. PAs formed nanofibers with His-His motif exposed on the surface. Moreover, the aggregation of PAs was pH sensitive. At basic pH, PAs formed hydrogels indicating sol-gel polymerization of PA aggregates due to formation of nanofiber network. In addition, cellular compatibility of PA aggregates and hydrogels were assessed on different mammalian cells. Our results can be used to develop potentially safe peptide-based stimuli-responsive materials for cell and drug delivery. Authors acknowledge RSF support (grant 20-73-10105).