Effect of hexafluoroisopropyl alcohol on the self-assembly behavior of peptide and the underlying mechanism

Self-assembly of peptides provides an important way for constructing new materials and generating new functions. However, due to the complexity of non-covalent interactions, the directional control of the shape and size of peptide assembly still remains challenging. In this study, the organic solvent hexafluoroisopropanol (HFIP) was introduced into the system to regulate the self-assembly behavior of the peptide Fmoc-KI4K-CONH2. The results demonstrated that Fmoc-KI4K-CONH2 self-assembled to form fiber bundles in pure water. When a small amount of HFIP was introduced into the system, the morphology of the assembly changed from fiber bundles to thinner nanotubes. Increasing the HFIP content further reduced the hydrophobic effect, leading to the formation of very fine nanofibers. These results demonstrated that the hydrophobic interaction can be effectively regulated by the introduction and content control of the organic solvent HFIP, and then the width of the assembly can be regulated directionally. This study provided a simple and effective way for regulating the size and morphology of peptide assemblies, which can promote the application of peptide-based biomaterials in different fields.