Ultra-confined controllable cyclic peptides as supramolecular biomaterials

The capacity to design molecules capable of orchestrated movements in response to specific stimuli could yield functional biomaterials suitable for diverse innovative materials and devices. However, the rational design of molecules capable of precisely orchestrated movements remains exceedingly difficult. As a stepping-stone toward this goal, we have developed a method for manufacturing precisely designed cyclic peptide molecules with a single degree of freedom. We demonstrate that the structural configuration of these molecules can be precisely determined under different external stimuli and explore the mechanism by which these molecules form supramolecular self-assemblies. Our experimental analysis of these assemblies reveals that our constrained cyclic peptides form nanotube structures through sheet-like hydrogen bonding. Unexpectedly, these higher-order structures can achieve remarkably rigid (∼10 GPa) and stable architectures at high temperatures—comparable to the most rigid proteinaceous materials in nature. The design strategy described here could facilitate the development of molecular machines, smart materials, and other applications that require fine-tuned regulation of biomolecular behavior.