Biomedical platforms constructed
by immobilizing membrane proteins
in matrixes made of synthetic organic polymers is a challenge because
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(<i>N</i>-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 with functional
bio-interfaces 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 the presence of electrolytic solutions with Na<sup>+</sup> and
K<sup>+</sup> 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 bioinspired
channels and smart biosensors
