Carboxylic Acid-Functionalized Conductive Polypyrrole as a Bioactive Platform for Cell Adhesion

TLDR

Electroactive polymers such as polypyrrole are attractive for biomedical uses like electrode coatings and tissue scaffolds, and modifying them with biological moieties is sought to improve the biomaterial–tissue interface. The study aims to synthesize and characterize a carboxyl‑functionalized polypyrrole (PPyCOOH) that can be readily modified with biological moieties. The authors used FTIR, XPS, fluorescence microscopy, and four‑point probe measurements to confirm carboxyl incorporation and semiconductor‑range conductivity of PPyCOOH. HUVECs showed enhanced attachment and spreading on RGD‑modified PPyCOOH films, indicating that PPyCOOH can serve as a bioactive conducting platform for diverse biomedical applications.

Abstract

Electroactive polymers such as polypyrrole (PPy) are highly attractive for a number of biomedical applications, including their use as coatings for electrodes or neural probes and as scaffolds to induce tissue regeneration. Surface modification of these materials with biological moieties is desired to enhance the biomaterial−tissue interface and to promote desired tissue responses. Here, we present the synthesis and physicochemical characterization of poly(1-(2-carboxyethyl)pyrrole) (PPyCOOH), a PPy derivative that contains a chemical group that can be easily modified with biological moieties at the N-position of the polymer backbone. FTIR, XPS, and fluorescence microscopy were used to demonstrate the successful incorporation of carboxylic acid (−COOH) functionality into PPy materials, and a four-point probe analysis was used to demonstrate electrical conductivity in the semiconductor range. Human umbilical vascular endothelial cells (HUVECs) cultured on PPyCOOH films surface-modified with the cell-adhesive Arg-Gly-Asp (RGD) motif demonstrated improved attachment and spreading. Thus, PPyCOOH could be useful in developing PPy composites that contain a variety of biological molecules as bioactive conducting platforms for specific biomedical purposes.