Surface functionalization of electrically conductive polypyrrole film with hyaluronic acid

Abstract

A surface modification technique was employed to functionalize electrically conductive polypyrrole (PPY) films with hyaluronic acid (HA). The PPY film was first graft copolymerized with 2-hydroxyethyl acrylate (HEA) and subsequently silanized with (3-aminopropyl)triethoxysilane (ATS) via Si-O bonding with the hydroxyl groups of the grafted HEA polymer. Water-soluble carbodiimide-activated hyaluronic acid was then covalently immobilized through amide linkage formation with the primary amine groups introduced on the PPY film surface via the ATs silanization process. The amount of HA immobilized could be varied by changing the concentration of the primary amide groups on the PPY film surface. The immobilized HA was biologically active, as evaluated by using a protein binding assay, and it retained a significant degree of its activity after 4 days storage in air. The present mlethod of covalent immobilization of HA on PPY film surface offers the advantages of preserving the film's electrical conductivity and mechanical strength and at the same time improving the film's surface wettability.