Toward Artificial Enzyme Analogues for Cellulose Hydrolysis Using High-throughput Screening

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1033017LeeIntellectual MeritsA sustainable and environmentally friendly source of ethanol for transportation fuel is cellulose, which is the major component of lignocellulosic plant biomass. Hydrolysis of cellulose generates glucose, which can be fermented to ethanol. However, in general, the hydrolysis of cellulose is a difficult process, and is currently the rate-limiting step in the cellulose-to-ethanol conversion. Cellulase enzymes with very specific catalytic structures are capable of efficient cellulose hydrolysis without byproduct formation. However, enzymes are relatively slow, thermally unstable, and expensive, as they must be biologically produced are not readily reusable. The proposed research will develop and understand the function of artificial enzyme analogues that can hydrolyze cellulose and its subunits. Artificial enzyme structures will be created by molecular imprinting of cellulose oligomers onto organic-inorganic hybrid solid catalyst supports based on sol-gel methods. This strategy has the potential to combine the efficiency and specificity of protein-based enzymes with the robustness and cost effectiveness of heterogeneous solid catalysts.In the proposed research, artificial enzyme analogues for hydrolysis of cello-oligomers and cellulose will be generated based on a molecular-imprinting sol-gel technique combined with a high-throughput synthesis and screening method. Molecular cavities generated by the imprinting process will provide specific binding domains for sub-units of cellulose as well as solid acid sites required for hydrolysis of glycosidic bonds. To potentially enhance substrate hydrolysis and promote induced fit between the molecularly imprinted catalyst and substrate, the flexibility of the sol-gel catalysts will be tuned by adding organo-silanes to the sol-gel matrix. It is hypothesized that the specificity of the molecularly-imprinted catalysts would hinder side reactions that lead to degradation of glucose, which is a major problem with conventional solid-acid catalysts. The high throughput method will be able to screen a large number (~10,000) of synthesis parameters to optimize the composition and structure of the molecularly-imprinted catalysts.Broader ImpactsThe proposed education and outreach activities are designed to stimulate student interest in biomass energy and fundamental ideas in science and engineering. Undergraduate students from underrepresented groups recruited through the Louise Stokes Alliance for Minority Participation (AMP) Summer Undergraduate Research Program will be given opportunities to participate in the research. As part of the outreach plan, the PI will work with a local cable access TV station to develop programming on the current state of energy landscape and the importance of developing renewable energy technologies. This scientific program will be aired throughout the Philadelphia metro area.