Controlled Self-Assembly of Peptide Nanotubes via Sequence Modification and Kinetic Control*

Synthetic peptides with the high sequence- and shape-specificity can serve as the assembly building blocks for the construction of controllable and complex nanoarchitectures. Computational design was employed to design peptides that can form antiparallel, alpha-helical tetrameric coiled-coil bundles in solution that then further assemble into higher order structures with targeted organization. The bundles self-assemble into homogenous nanotubes at pH 4.5. As analyzed by cryo-TEM, SAXS and STEM, a mono-layer tilted-bundle model is proposed to explain the nanotube structure. The charged state and distribution of the peptide bundles associated with the acidic solution condition are believed to be the reason triggering the formation of nanotubes. Rational sequence modifications were applied to control the dimensions of the nanotubes or to disrupt the tube nanostructure or to add metal-binding functionality. Moreover, kinetic control was applied in the assembly process to produce a branched nanotube morphology. Further crosslinking treatment can be applied to the branched nanotube system for the development of stable hyper-branched materials with potential applications.