Template‐assisted Flexible‐to‐rigid Transition of Peptides in Head‐to‐tail Self‐polymerization Enables Sequence‐controllable and Post‐modifiable Peptide Nanofibers

Peptide‐based nanofibers are promising materials for many essential applications and can be generalized into two categories, self‐assembling peptide nanofibers (SAPNs) and poly(amino acid) nanofibers (PAANs). Non‐covalent SAPNs are sequence‐controllable, but poorly stable and not suitable for post‐modification. While covalent PAANs are post‐modifiable, however, their sequences are either monotonic or undefined. The nanofibers obtained by head‐to‐tail covalent coupling polymerization of sequence‐known peptides, which we call series‐connected peptide nanofibers (SCPNs), promise to have the advantages of both SAPNs and PAANs, but they are barely reported. The undesired backbiting effect during the head‐to‐tail polymerization is one of the possible challenges. Here, we present a template‐assisted strategy to trigger the flexible‐to‐rigid transition of peptide units, which can avoid the backbiting effect and enable consecutive intermolecular polymerization of peptides to produce desired sequence‐controlled covalent SCPNs. SCPNs are highly stable and can function as excellent parent materials for various post‐processing to create diverse hierarchical materials independent of the peptide sequence. Moreover, SCPNs allow for the display of predetermined functional groups at regular intervals along the nanofibers by pre‐modification of the initial peptide sequence. SCPNs represent a new category of peptide‐based nanofibers with outstanding performances and vast potential.