Designing Bioelectronic Interfaces with Peptidic Assemblies

Integration of synthetic electronic biomaterials with living systems has emerged as an approach for modulating or probing cellular behavior and tissue function that minimize the need for contact with traditional, bulky, and non-flexible inorganic electrodes. Bioelectronic materials have been demonstrated to effectively integrate with cells, in vitro tissue models, organoids, and even with small model organisms, but the long-term effects of these materials on living systems are rarely considered when designing a material. In this presentation, we present peptide-based structures functionalized with π-conjugated units as designer biomolecules that can be interfaced with excitable cells. We present herein structure-function relationships that demonstrate the dependence of assembly behavior on monomeric structure and assembly trigger used while in completely aqueous environments. First, we show that small molecule coupling agents that allow for anhydride formation generate peptidic π-conjugated conduits that are amenable to disassembly once the fuel is diminished and anhydride hydrolysis predominates. The compliance of a peptide-bearing quaterthiophene monomer to this process is highly dependent on the electrostatic nature of the peptide sequence used. On the other hand, peptide-polydiacetylene conjugates will also be discussed as π-conjugated assemblies that exhibit sequence-dependent photophysical and electrical properties. Our results show the differential impacts of amino acid size and polarity, and the degree that these molecular parameters can influence bulk properties based on the location of the residue substitution. Interestingly, we also show that the interaction of fibroblasts (as a model cell line) with the monomeric and polymeric equivalents of these peptide-polymer also sequence-dependence. Collectively, these findings shed light to the tunability of properties and assembly behavior of π-conjugated peptides under physiologically relevant environments. In the future, we will leverage these design principles for engineering biotic-abiotic interfaces that rely on the properties of these peptides functionalized with π-conjugated units.