Electrosynthesis of pyrrole 3-carboxylic acid copolymer films and nanotubes with tunable degree of functionalization for biomedical applications

Tailoring polypyrrole (PPy), an electroactive polymer, with functional groups to which a variety of bioactive molecules can be tethered is highly attractive for building biological structures on conducting surfaces for a range of biomedical applications. In this respect, we investigate the effects of three independent electrosynthesis parameters, namely the applied potential, the composition of the comonomer solution and the film thickness on the incorporation of carboxylic acid-functionalized pyrrole units (Py-COOH) into polypyrrole/Py-COOH copolymer films. FT-IR, XPS and fluorescence microscopy results show that a larger Py-COOH content is inserted in films electrosynthesized at low potential, that the surface functionality of the copolymer films increases with the molar percentage of Py-COOH in the comonomer solution, and that Py-COOH units are preferentially incorporated in the earlier stage of the electrosynthesis process. The method is further adapted for preparing functionalized PPy copolymer nanotubes with potential application in drug delivery. Specifically, functionalized copolymer nanotubes are electrosynthesized through the template method in polycarbonate membrane. Carboxylic acid groups available at the outer surface of these nanostructures are then derivatized to covalently immobilize poly(ethylene glycol) chains, a protein-repellent polymer, so as to enhance the antifouling properties of these promising delivery vehicles.