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.

A Membrane‐Intercalating Conjugated Oligoelectrolyte with High‐Efficiency Photodynamic Antimicrobial Activity

“…[1] Certain MICOEs lead to increases in the current generation of bioelectrochemical systems, [2] serve as cell staining methods, [3] and provide the molecular basis for membrane permeation and antimicrobial function. [1] Certain MICOEs lead to increases in the current generation of bioelectrochemical systems, [2] serve as cell staining methods, [3] and provide the molecular basis for membrane permeation and antimicrobial function.…”

“…It is also worth considering that the light penetration increases and light toxicity decreases with longer wavelengths. Key structural elements include a) electronrich (thieno[3,2-b]thiophene) and electron-poor ( [1,2,5]thiadiazolo [3,4-c]pyridine) subunits that give rise to red shifted charge transfer excited states, [5d, 11] b) at opology and molecular length that are commensurate for insertion into lipid membranes, [4d, 11a] and c) six cationic pendant groups for solubility in aqueous media. [1a, 4b,d] We thus designed PTTP, see Scheme 1.…”

Salt-induced thermochromism of a conjugated polyelectrolyte

“…Indeed, beyond their use in electronic devices, 23,25 the water-solubility and biocompatibility of CPEs has been exploited in biological applications, for bioelectrochemistry, 26 biosensing, [27][28][29] cell imaging, highly emissive neutral conjugated polymers 36 or in hybrid devices with perovskites, 37 therefore investigation of charge transfer states and their lifetimes is central to the operation of such devices. The detection of the triplet excited state of CPEs is crucial for the generation of singlet oxygen and subsequent light-activated antibacterial activity, 38 while polaron formation and extension of their lifetime is an important target for cationic CPEs employed in artificial photosynthesis.…”

Membrane permeabilization by conjugated oligoelectrolytes accelerates whole-cell catalysis

“…10,15,21,22 Despite its utility, the origin of DSSN+ improvement in bioelectrochemical devices remains under debate. 9,10,17,21,[23][24][25][26][27][28][29][30] Model membrane studies have shown that COEs increase ion conductance across the membrane. 13 To add to mechanistic complexity, recent results suggest that COEs may interact with other components in the cell envelope, such as lipopolysaccharides and cholic acid.…”