Biomimetic Self-Assembly of Triskelion Peptide Analogues Into Supramolecular Polyhedra

We designed a triskelion molecule using the self-assembling peptide analogue, Fmoc- Phenylalanine-Tyrosine (FPT). The triskelion peptide analogue was obtained by conjugating FPT to Tris(2-aminoethyl)amine (TAEA). The resulting molecule, (FPT₃-TAEA), resembles the three-fold symmetry of the cage-forming protein clathrin. Interestingly, FPT₃-TAEA molecules are found to self-assemble into nanocages not in the pure form, but when mixed with the linear FPT molecules. Dynamic light scattering shows that the diameter of nanocages is around 17 nm. High-resolution TEM image of the samples indicate similar dimension and a hollow structure. We propose that the structure of the nanocage follows the architecture of a Buckyball that has 60 vertices. One FPT₃-TAEA molecule is located at each vertex. Two FPT molecules form anti-parallel β-sheet, which results in two clingy ends linking two legs of different triskelion molecules to form each polygon edge. This model is supported by the measurement of dimension. To validate this hypothesis, we study the change in the formation of nanocages when altering the ratio of FPT₃-TAEA to FPT. The study provides some criteria to construct polyhedra structures from peptide self-assembly and insights to control the pore size and cage dimension.