The Study On Self-assembly Of Surfactant-like Peptides

In recent years, peptide self-assembly has attracted considerable attention due to its application in the design and fabrication of functional nanostructures, which led to the development of advanced biomedical materials. Surfactant-like peptides are similar with the phospholipids both in structures and chemical properties. They can undergo self-assembly to form well-ordered nanostructures though the hydrophobic interaction in solution. The surfactant-like peptide self-assembly has become a hot spot in this field due to its potential applications in drug carrier materials.At present, there are few reports on the regularity and mechanism of surfactant-like peptide self-assembly, more theoretical still should be improved. To study the effect of weak interaction between the peptide molecules on the behavior of self-assembly, a series of peptides were designed with different length of hydrophobic and hydrophilic regions. We tried to control the morphology of the self-assembled peptides and investigated the mechanism of the self-assembly through adjusting the ratio of hydrophobic to hydrophilic region and the hydrophobicity of the amino acids. This work focused on the tunable self-assembly of surfactant-like peptides by designing the sequence and may establish the theorial foundation.The designed cationic peptides in this dissertation were synthesized by use of classic Fmoc strategy solid phase method. The peptides were analysed and purified by reverse-phase HPLC and the purifications of the peptides were all well over 95%. Their structures were confirmed by mass spectrometry (MS). The secondary structures of the peptides were characterized by circular dichroism (CD) and the morphology of self-assembles was characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Pyrene probe fluorescence analysis indicated that the peptides could form hydrophobic domains in which pyrene molecules were imbedded and underwent self-assembly in the form of micelles. Then, the critical micelle concentration (CMC) was calculated according to the result of fluorescence analysis.The results above indicated that hydrophobic force, charge interaction, secondary structure of the surfactant-like peptides influenced the behavior of peptide self-assembly. The regularity and mechanism of the surfactant-like peptides were proposed, which could provide available information for the development of self-assembling peptide materials.