Dense surface functionalization using peptides that recognize differences in organized structures of self-assembling nanomaterials.

We obtained novel peptides that selectively bind to self-assembling peptide nanomaterials from a random peptide library displayed on phages. Affinity-dependent peptide screening gave phage clones displaying peptides with selective affinities against two kinds of highly networked nanofibers constructed of β-sheet peptides. Both peptide nanofibers have similar primary structures. Binding analyses of phage-displayed peptides by enzyme-linked immunosorbent assays demonstrated that the screened peptides specifically bind to the target nanofibers rather than to non-target nanofibers. Dot blot assays using chemically-synthesized peptides revealed that one screened peptide with the sequence Thr-Tyr-Leu-Pro-Trp-Pro-Ala has an affinity constant of 2.6 × 10(6) M(-1) against the target nanofibers. This affinity is 350 times greater than its affinity for non-target nanofibers and 90 times greater than its affinity for mixed nanofibers that contain 50% target nanofibers. These results suggest that this screened peptide can recognize organized fine-structures. Surface modification of the peptide nanofibers with the screened peptide demonstrated that the peptide specifically binds to discrete binding sites on the target nanofibers. Cell adhesion assays on the nanofibers by means of RGDS-conjugated screened peptides showed that the number of adhered cells is largely dependent on the amount of bound RGDS-peptide. These results suggest that screened peptides can recognize the organization of self-assembled peptide nanomaterials, and that the conjugation of functional groups to the peptides can be used to functionalize the target nanomaterials. Furthermore, simultaneous use of individual specific peptides that have specificities for nanomaterials can generate highly dense functionalized self-assembling peptide nanomaterials.