Experimental investigation of peptide self-assembly structures and applications

The chemistry and applications of peptides are some of the major fields of biotechnology in today's world. This brings sufficient amount of interest to develop new bioengineering tools. Especially, introduction of nanotechnology to our lifes allows researches to characterise the details at 'nano-scale' which opens up to more questions and as a result looking for more answers. Over the years, self-assembly developed to understand the dynamic behavior of the molecules with intermolecular interactions. Peptides are molecules which are small fragments of proteins that naturally exist and tend to self-assemble to form macrostructures. In the current study, small oligopeptide molecules are considered. Peptide sequences with the combination of non-polar Alanine aminoacids with positively charged Lysine residues are investigated. Thus, Ala-Ala-Ala-Ala-Ala-Ala-Lys (A6K) and Ala-Ala-Ala-Ala-Ala-Ala-Ala-Ala-Ala-Ala-Lys (A10K) are the model peptides which were studied. A6K were dissolved and its self-assembly behaviour was investigated in both water (H2O) and deuterium oxide (D2O). Also the effect of altering pH to self-assembly of the A6K was studied by addition of NaOH. Self-assembling properties of A6K in the solution form were analysed by using imaging and scattering techniques. An extended phase diagram was obtained for the peptide A6K to classify the formed macrostructures. Since the molecule of the peptide is pulverized with a counter-ion, the electrostatic effect was also investigated for different counter-ions such as tri-flouro acetate (tfa-) and chloride (Cl-). For application, the model peptide A10K was chosen and the cytotoxicty of peptide were studied. The self-assembly behaviour of A10K was previously studied. Varying cell lines were used during the experimental studies such as fibroblast (TM3, HDF), ephitelial cells (Vero), endothel cells (HUVEC) and keratinocytes (HaCaT). Then, in vitro scratch assay were utilized for A10K, to explore this peptide as a potential tool for wound healing.