Polypyrrole-Supported Membrane Proteins for Bio-Inspired Ion Channels

Abstract

Biomedical platforms constructed by immobilizing membrane proteins in matrices made of synthetic organic polymers is a challenge since the structure and function of these proteins are affected by environmental conditions. In this work an operative composite that regulates the diffusion of alkali ions has been prepared by functionalizing a supporting matrix made of poly(N-methylpyrrole) (PNMPy) with a β-barrel membrane protein (Omp2a) that forms channels and pores. The protein has been unequivocally identified in the composite and its structure has been shown to remain unaltered. The PNMPy-Omp2a platform fulfills properties typically associated to functional biointerfaces with biomedical applications (e.g. biocompatibility, biodegrabadility and hydrophilicity). The functionality of the immobilized protein has been examined by studying the passive ion transport response in presence of electrolytic solutions with Na + and K + concentrations close to those found in blood. Although the behavior of PNMPy and PNMPy-Omp2a is very similar for solutions with very low concentration, the resistance of the latter decreases drastically when the concentration of ions increases to ∼100 mM. This reduction reflects an enhanced ion exchange between the biocomposite and the electrolytic medium, which is not observed in PNMPy, evidencing that PNMPy-Omp2a is particularly well suited to prepare bio-inspired channels and smart biosensors.

Poly(3,4‐ethylenedioxythiophene):GlycosAminoGlycan Aqueous Dispersions: Toward Electrically Conductive Bioactive Materials for Neural Interfaces

“…[14] A widely used strategy to improve the side effects of organic electrochemical transistors and to enhance the biocompatibility and reduce the cytotoxicity of conducting polymers such as polypyrrole, polyaniline, or PEDOT is the use of biomolecules as dopants. [15][16][17] A variety of negatively charged biomolecules have been studied as dopants, such as alginate, dextran sulfate, chondroitin sulfate, [18][19][20] heparin, and hyaluronic acid. [11,21,22] In most of these reports, the conducting polymer/biomolecule complexes were prepared electrochemically limiting their scalability due to the low area of the electrode where the polymer is usually deposited.…”

Confinement of a β-barrel protein in nanoperforated free-standing nanomembranes for ion transport

“…24 Electrical impedance spectroscopy (EIS) studies evidenced that Omp2a promotes the passive transport of K + and Na + in solutions with relatively high ionic concentrations, preferentially favouring the diffusion of hydrated Na + with respect to that of hydrated K + . 24 Unfortunately, some drawbacks were also identified for such system. For instance, PNMPy membranes electrochemically synthesized were not self-standing, a stainless steel support being used to electropolymerize PNMPy.…”

Fibrin Association at Hybrid Biointerfaces Made of Clot‐Binding Peptides and Polythiophene

“…In the last few years, particular attention has been paid to biocomposites involving electroactive conducting polymers (ECPs), which due to their excellent properties are used to fabricate electrochemically active biointerfaces. Thus, devices based on the combination of ECPs and biomolecules have been successfully used as applications, for example bioinspired channels for ion‐exchange, electromechanical actuators, components of bioelectronics devices, aerogels for nerve regeneration, and bioactive platforms for tissue regeneration that mimic the growth of biological tissues …”