Protein-Based Ionic Materials

Nature is relying on the capability of proteins to mediate ions in preferred directions, such as the ionic transport across the two sides of a membrane through a protein. Inspired by this natural capability of proteins to mediate ions, we design several protein-based free-standing materials that are capable of mediating ions, specifically protons. By various physical and chemical pre- or post-polymerization modifications, we explore the ionic transport mechanism across the protein-based material, highlighting the important factors associated with its transport efficiency. Post-polymerization modifications also allow us to chemically graft into the protein-based biopolymer light-sensitive molecule capable of generating opto-ionic materials. We also show the capability to introduce electronic conduction into the protein-based material either by blending or by chemical modifications, thus creating a mixed ionic-electronic conductor. From an application point of view, and due to our choice of using a sustainable source of proteins from waste sources, our protein-based ionic materials can be highly scalable at low cost. Our main application direction for our protein-based conductive biomaterials is for biological interfaces in the field of biosensing. Here, we can either utilize the ionic transport for making sensors for electrophysiological sensing or use the mixed conduction of the functionalized biopolymer for transistor-based sensing.