The Self-assembly Behavior Of An Amphiphilic Peptide And Its Basic Research Of Applications

Due to their unique features, such as the rich self-assembly driving forces, novelself-assembly nanostructures, the multiple special capabilities and good biocompatibility, etc,among the emerging self-assembling molecules, short peptide based self-assemblednanomaterials are extremely attractive as building blocks for nano-biomaterials, drug delivery,tissue engineering scaffolds and many other applications. This paper describes a new kind of9-residue half-sequence ionic-complementary peptide P-X8,to study its self-assembly processin aqueous solution and reveal the essence and discipline of assembly.The secondary structures of peptides are usually determined by their sequences, However,experimental evidence indicates that some particular sequences of peptides have alternativesecondary structures under different experimental conditions, the changes of environmentalfactors make the interaction of the non-covalent changes to control the morphology ofassembling, In this paper, we investigated the self-assembly behaviors of P-X8in differentenvironmental factors(concentration, temperature, denaturant, salt ions). The peptide wasable to self-assemble into nanofibers, but the nanofiber morphologies were various when thepeptide at different concentrations. When the temperature cooling back from the elevatedtemperature to the original25℃, the damage could be recovered in a short time. Thedenaturing agent SDS degraded the branched nanofibers, from the analogical AFMobservation also provides a good explanation for the similar effect of SDS to the assemblypeptide, when the peptide was incubated in SDS, the nanofibers were turned into smallernanospheres, and the globular beads were homogeneous distribution. it was interesting to findthat when the peptide was conserved in the9.77mМ NaCl solution, it had a very similarsecondary structure with the same concentration of fresh peptide aqueous solution.Amphipathic peptides composed of alternating hydrophobic and hydrophilic amino acids,which pointing to one face and the other face of the amino bond, respectively. The second partof this dissertation introduces the new-designed peptide P-X8, which applying in the drugdelivery. The ability of the peptide to stabilize the hydrophobic model drug pyrene and thehydrophobic anticancer agent psoralen was tested in this research. The results showed that the hydrophobic substances were stabled as colloidal suspension by the peptide P-X8. Moreover,the maximum suspension concentration of pyrene in the suspension was dependent on theconcentration of peptide. The third part of this paper was to test whether the peptide P-X8canbe used as a potential haemostat, when the1%(w/v) P-X8solution was simply applied to awound in the SD rat liver section in vitro, the surface of wound will instantly forms ajelly-like blood-hydrogel that aggregates blood cells acting as an effective hemostatictreatment. The morphology of blood cells was changed from concaved disc into a newaspect,which was almost covered by3D nanofibers matrix of peptide P-X8. So, P-X8maybecome a nano-hemostatic agent for minor bleeding or oozing wounds.