Figure 3. Programming hierarchical structures with a peptide code.

(A) Molecular graphics representation of the complementary interactions between the DNA (top) and DNA-mimetic peptide amphiphiles (bottom), and the corresponding morphologies of bundled fibers observed in both systems by scanning electron microscopy. (B-D) Scanning electron micrographs of bundled and twisted fiber morphologies of varying diameters: (B) 140.5 ± 15 nm; (C) 332 ± 37 nm, and (D) 905 ± 190 nm, and the corresponding dimer molecular graphics and chemical sequences of the DNA-mimetic peptide amphiphiles that form the superstructures (EG refers to ethylene oxide and C16 is the number of carbons in the aliphatic terminus of the amphiphiles). Quantification of bundle diameters utilized a minimum of 15 randomly selected images (taken from three independent batches) for each system.