(4ej) Bio-Inspired Energy Systems and Programmable Materials

With design through evolution and molecule-by-molecule construction Nature creates materials with complex functions and that are embedded with detailed molecular information. Here, we present two engineering examples of materials that mimic biological functions to produce multi-functional hydrogels for electrode and surface modifications and hydrogels with programmed biological signaling. 1) Using a general method of enzymatic and multi-functional hydrogel design we create biocatalytic electrodes and oxidative enzymatic hydrogels for the potential use in alternative energy systems. The hydrogels are created with a ?bottom-up' approach through the self-assembly of chimeric fusion proteins. Self-assembly functionality is achieved by appending leucine zipper domains to the termini of the desired functional proteins, and compatible crosslinks allow for the co-assembly of two or more different building blocks into multi-functional hydrogels. The physical properties and enzymatic activities of the hydrogels are tunable, and we demonstrate control of the intra-gel spacing between functional building blocks. 2) With a biomaterials screen we reveal extracellular matrix (ECM) compositions that can be used to program hydrogels to promote epithelial-to-mesenchyme transition in progenitor cells. A microarrays of nano-liter sized hyaluronic acid (HA)-based hydrogels containing ECM components identified from the proteomic analysis of the developing atrioventricular (AV) cushion were screened for endothelial progenitor cell (EPC) adhesion and the expression of EMT markers. Confirmation of the screening results in the macroscale reveals functional EMT of transformed EPCs on HA-fibronectin hydrogels. These two bio-inspired engineering examples are strong answers to the question: how does Nature create complex functional materials and how can we learn from these examples to inspire new energy systems and programmable materials?