Membrane-intercalating conjugated oligoelectrolytes: impact on bioelectrochemical systems.

ABSTRACT

Conjugated oligoelectrolytes (COEs), molecules that are defined by a π-delocalized backbone and terminal ionic pendant groups, have been previously demonstrated to effectively reduce charge-injection/extraction barriers at metal/organic interfaces in thin-film organic-electronic devices. Recent studies demonstrate a spontaneous affinity of certain COEs to intercalate into, and align within, lipid bilayers in an ordered orientation, thereby allowing modification of membrane properties and the functions of microbes in bioelectrochemical and photosynthetic systems. Several reports have provided evidence of enhanced current generation and bioproduction. Mechanistic approaches suggest that COEs influence microbial extracellular electron transport to abiotic electrode surfaces via more than one proposed pathway, including direct electron transfer and meditated electron transfer. Molecular dynamics simulations as a function of molecular structure suggest that insertion of cationic COEs results in membrane thinning as the lipid phosphate head groups are drawn toward the center of the bilayer. Since variations in molecular structures, especially the length of the conjugated backbone, distribution of ionic groups, and hydrophobic substitutions, show an effect on their antimicrobial properties, preferential cell localization, and microbial selection, it is promising to further design novel membrane-intercalating molecules based on COEs for practical applications, including energy generation, environmental remediation, and antimicrobial treatment.