A simple approach for protein covalent grafting on conducting polymer films.

Covalent immobilization of biomolecules, such as proteins, on conducting polymer films is critical to organic bioelectronics to create tailored interfaces with biological systems. In this study, we propose a simple approach to graft proteins on films of the conducting polymer poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS). PEDOT:PSS is a biocompatible and easy to process conducting polymer, widely used in bioelectronics. However, it does not possess any chemical reactive groups available for protein grafting. By mixing a commercial PEDOT:PSS suspension with the modified biopolymer carboxymethylated dextran (CMD), we obtained films displaying carboxyl (-COOH) groups allowing for covalent grafting of proteins via amide bonds, without any further functionalization step. By fine-tuning the concentration of CMD as well as those of a conductivity enhancer (glycerol) and a crosslinking agent (glycidoxypropyltrimethoxysilane, GOPS) in the film processing mixture, we were able to produce COOH-functionalized PEDOT:PSS films displaying excellent electrical conductivity and high stability in an aqueous environment.