Polymer-Binding Peptides for the Noncovalent Modification of Polymer Surfaces: Effects of Peptide Density on the Subsequent Immobilization of Functional Proteins

Peptides that specifically bind to polyetherimide (PEI) were selected, characterized, and used for the noncovalent modification of the PEI surface. The peptides were successfully identified from a phage-displayed peptide library. A chemically-synthesized peptide composed of the Thr-Gly-Ala-Asp-Leu-Asn-Thr sequence showed an extremely high binding constant for the PEI films (5.6 × 108 M−1), which was more than three orders of magnitude greater than that for the reference polystyrene films. The peptide was biotinylated and immobilized onto the PEI films to further immobilize streptavidin (SAv). The amount of SAv bound depended on the density of immobilized peptide. It gradually increased with an increasing density of immobilized peptide and achieved a maximum (2.1 pmol cm−2) at a peptide density of 19.8 pmol cm−2. The ratio of peptide used for immobilizing SAv at the maximum value was only 11%, and was partially due to the low accessibility of SAv to the biotin moieties on the PEI films. Moreover, the amoun...