Conjugated oligoelectrolytes (COEs) boost the electrical performance of a wide range of bioelectrochemical systems, yet their mechanism of action remains incompletely understood. One possible mode of action is that COEs permeabilize the cell envelope. We thus examined the effect of tetracationic COE, DSSN+, on the permeability of the inner and outer membrane of Escherichia coli by detecting extracellular activity of normally periplasmic and cytoplasmic enzymes. DSSN+ increases the release of the periplasmic enzyme alkaline phosphatase (ALP) up to 20-fold, but does not significantly change the release of the cytoplasmic enzyme β-galactosidase. Additionally, DSSN+ caused a 2-fold increase in the turnover of a cytoplasmic substrate. These studies present a more complete understanding of the mechanism of action in bioelectrochemical systems and pivot future applications of COEs towards a method for improving whole-cell catalysis.
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