Seamless integration between biological systems and electrical components is essential for enabling a twinned biochemical–electrical recording and therapy approach to understand and combat neurological disorders. Employing bioelectronic systems made up of conjugated polymers, which have an innate ability to transport both electronic and ionic charges, provides the possibility of such integration. In particular, translating enzymatically polymerized conductive wires, recently demonstrated in plants and simple organism systems, into mammalian models, is of particular interest for the development of next-generation devices that can monitor and modulate neural signals. As a first step toward achieving this goal, enzyme-mediated polymerization of two thiophene-based monomers is demonstrated on a synthetic lipid bilayer supported on a Au surface. Microgravimetric studies of conducting films polymerized in situ provide insights into their interactions with a lipid bilayer model that mimics the cell membrane. Moreover, the resulting electrical and viscoelastic properties of these self-organizing conducting polymers suggest their potential as materials to form the basis for novel approaches to in vivo neural therapeutics.

A novel approach is introduced to modulate the threshold voltage of organic electrochemical transistors (OECTs) that are fabricated by electropolymerizing the channel material between the source and drain electrodes. To achieve this, we adjust the ratio of two water-soluble tri-thiophene monomers, which share the same backbone, but present either anionic or zwitterionic sidechains, during channel formation. This approach allows for a continuous modulation of both the electropolymerization onset potential and the native doping state of the film. We attribute the effect of monomer blends displaying properties that are a weighted average of their components to the formation of nanoscale monomer aggregates that have a uniform internal charge density. Through an investigation of monomer aggregation behavior, polymer film growth, and device properties of OECTs fabricated by electropolymerization, we highlight the importance of monomer aggregation in the electropolymerization of conducting polymers. The ability to tune both electropolymerization onset and the OECT threshold voltage has significant implications for the development of more complex circuits for integrated neuromorphic computing, biosensing, and bioelectronic systems.

The dual capability of conductive polymers to conduct ions and electrons, in combination with their flexible mechanical properties, makes them ideal for bioelectronic applications. This study explores the in situ enzymatic polymerization of water-soluble pi-conjugated monomers on native lipid bilayers derived from the F11 cell line, mimicking mammalian neural membranes. Enzymatic polymerization was catalyzed using horseradish peroxidase (HRP) in the presence of oxidant hydrogen peroxide (H2O2) and monitored via electrochemical quartz crystal microbalance with dissipation (EQCM-D) and electrochemical impedance spectroscopy (EIS). Results showed polymerization with HRP. The structural properties of the formed polymer films were characterized ex situ using atomic force microscopy (AFM), while the quality of the F11 native lipid vesicles and bilayer was respectively assessed through dynamic light scattering (DLS) and fluorescence recovery after photobleaching (FRAP) techniques. This work demonstrates, for the first time, the feasibility of the in situ formation of conductive polymers on native lipid membranes, offering a promising approach for the development of minimally invasive neural electrodes to diagnose and treat neurological disorders.