Hybrid Materials for the Enzymatic Reduction of Carbon-Dioxide

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Enzymes are the catalysts of choice for sustainable and organic solvent free chemical transformations, but there remain issues with the lack of stability and loss of activity of enzymes if their environment is not carefully controlled. In this project new bio-catalytic materials will be synthesised and characterised. The aim is to create robust enzyme-containing materials that have high activity for the reduction of carbon dioxide. Thin hydrogel layers (nm to mm thick) will be grown on solid supports for applications in supported enzyme catalysis. The hydrogel films will be created by the surface initiated ordering of di-peptide amphiphiles into hydrogel matrices both on flat surfaces and inside porous materials. Enzyme stability and activity will be improved in three ways. (1) The activity and stability of enzymes from both mesophiles (organisms that live in moderate environments) and extremophiles (organisms that thrive under extreme conditions) will be compared. (2) The enzyme will be immobilised in a peptide hydrogel matrix that mimics the extracellular matrix in biological organisms. The peptide gel will be a surface bound gel that has an open (99% water by volume) structure ideal for immobilising enzymes while still allowing the diffusion of small molecules in and out. In addition the gel will provide a locally controlled pH environment and prevent unfolding of the protein. (3) To improve stability still further and create a robust material, the hydrogel will be self-assembled on the internal surface area of a highly porous inorganic oxide film. The final product will be an integrated catalytic material that reduces carbon dioxide to formic acid and other useful organic feedstock molecules.