Deposition of polypyrrole thin film through the molecular interaction with a designer peptide

A conductive chlorine-doped polypyrrole (PPyCl) thin film was prepared via chemical oxidation on a nonconductive silicon wafer where a designer peptide with specific affinity for PPyCl was immobilized. The physical and electrical properties of PPyCl films prepared in this way were characterized. The designer peptide greatly improved the adhesion of the PPyCl film to the substrate because of the specific interaction between the peptide residues and polypyrrole film. This improved adhesion force suggests the existence of additional molecular interaction as well as electrical attraction between the Asp side chain and the PPyCl backbone. In addition, the PPyCl film on the peptide-immobilized surface showed increased conductivity. Investigation on the molecular structure indicated that the PPyCl backbone structure was controlled during the polymerization by interaction with the designer peptide. This designer peptide could be useful for the preparation of biopolymer hybrid materials and at interfaces where a biocompatible linker is required.