Protein-based conductive materials

Biological charge transfer processes are based on the controlled transport of charges (electrons, protons, ions) across specific pathways within proteins from the nm-scale up to the μm scale. With this biological inspiration, we report here on a new family of conductive and free-standing biological materials. We have used the serum albumin protein to form various types of materials, which were later functionalized in a bioinspired fashion to exhibit efficient electron transport on the centimeter length scales. Furthermore, we show that the same protein-based materials can be functionalized in different ways for the formation of efficient ionomers with measured ionic conduction of >10 mS/cm at room temperature. Due to the protein-based nature of our materials, it enables us to explore the governing factors and mechanisms of long-range biological charge transport. Nonetheless, our new materials have several attractive properties for their possible integration in various applications. Our materials are environmentally friendly, they possess inherent biodegradability and their formation obeys to most principals of green chemistry. In terms of their mechanical properties, they have high elastic modulus of ~160 MPa, but at the same time they are highly stretchable, capable of stretching more than 4 times their length. They have high resistance to harsh organic solvents and acids, they are very easy to form, and have a very low price tag with materials cost of around $1/cm². Currently, we explore the use of the materials for biomedical application (tissue engineering), for organic ionic electrodes and for energy applications such as membranes for fuel cells.