UC Irvine

Proteins and peptides may be a promising route to develop conductive materials capable of interfacing biological components with electronics for bioelectronic applications. Amino acid sequences can drive the self-assembly of supramolecular nanostructures, whose high surfaces area, soft material surfaces may be suitable for interfacing with biology. These sequences can be coupled with conjugated small molecules or metals to drive the aqueous self-assembly of water soluble, electronically-conductive nanomaterials, or these sequences, by themselves, can form electronically-conductive supramolecular structures. In this work, we demonstrate long-range, non-redox, and non-thermally activated electron transport in biological protein nanofibers purified from Geobacter sulfurreducens, and we replicate these unique conduction properties in non--stacked, self-assembled nanofibers constructed from a de novo peptide sequence. We demonstrate that natural amino acids can be used to form supramolecular nanofibers with high conductivities, comparable to conjugated materials, in the absence of delocalization. This micrometer-scale transport does not fit within the framework of long-range conduction mechanisms in organic materials, and thus suggests a rethinking of current electron transport models. We also characterize electronic and electrostatic properties in two other amino acid based supramolecular systems, demonstrating how amino acids can be used to tune the self- assembly and electronic properties of conductive materials. These findings suggest that amino acid based materials may be a viable platform for designing functional bioelectronic materials.