Protein-Engineered Photoresponsive Conductive Nanofibers

Photoconductive nanomaterials are critical in the development of advanced optoelectronics, which span photovoltaics to biomedicine. These materials are often derived from inorganic, molecular, and polymeric crystalline semiconductors that facilitate charge transfer upon absorption of ultraviolet and near infrared light. These types of materials are broadened to include single-domain protein-based nanofibers. Coiled-coil protein domains found in nature transport electrons when possessing pi-stacked aromatic rings and undergo supramolecular assembly into fibers. Whereas conductive protein nanofibers have previously been leveraged for high-resistance organic materials, a conductive helical assembled fiber (CHAF) is reported, composed of phenylalanines in the core capable of photoresponsivity. It is demonstrated that CHAF and a leucine-replaced CHAF control (L-CHAF) exhibit distinct photoconductive responses to near infrared (NIR) light. The sequence-controlled system reported here illustrates photoconductive protein fibers as a promising platform for the next generation of new biocompatible nanomaterials.