The main focus of this work is the modification of membranes via incorporation of phenylenevinylene oligoelectrolytes with the goal of tailoring their optical and electronic properties and their applications. Initial inception was based upon the idea that molecular architectures sharing kindred dimensions and distribution of hydrophilic and hydrophobic regions with that of phospholipid bilayers could be exploited for insertion of target compounds into membranes, subsequently modifying their optoelectronic properties. The general architecture of our conjugated oligoelectrolytes (COEs) consists of linear and hydrophobic donor-pi-donor chromophores flanked at both ends with hydrophilic ionic pendant groups. These COEs are water-soluble, optically active and exhibit photophysical features sensitive to the polarity of the surrounding medium. Synthetic membranes were first employed for characterization of COE/membrane interactions.

A combination of UV/visible absorbance and photoluminescence spectroscopies, and confocal microscopy were employed to confirm membrane incorporation. Examination of COE emission intensity profiles when in stationary multi-lamellar vesicles obtained with a polarized excitation source indicates that the orientations of these molecules are highly ordered, such that the hydrophobic electronically-delocalized region positions within the inner membrane with the long molecular axis perpendicular to the bilayer plane. Electrochemistry experiments provide evidence that COEs of this type facilitate transmembrane electron transport across lipid bilayers supported on glassy carbon electrodes. Fluorescence imaging of biological samples, including yeast and bacteria, stained with our oligoelectrolytes indicates preferential COE accumulation within cell membranes.

The optical and electronic behavior of our COEs in membrane systems inspired their application for mediating charge transport across cell membranes between sites within microorganisms and electrodes of bioelectronic devices. The COEs were shown to facilitate more intimate bioelectronic interactions in microbial fuel cells and bioelectrochemical cells. Analysis of bioelectronic device performance as a function of COE structure and operating conditions yielded critical insight into the function of the COEs and has motivated current studies aimed at elucidating the specific mechanism by which COEs facilitate bioelectronic interactions. Development of key structure-function-property relationships within the various facets of our study necessitates modulation of COE structural features, thus a versatile synthetic strategy was developed to access the many COE analogs employed in this work.