Enzymes such as oxidoreductases can catalyze the synthesis of a wide range of chemicals, especially chiral acids, alcohols and ketones. Nevertheless, the redox reactions catalyzed by these oxireductases enzymes require a cofactor such as pyridine nucleotides (NAD(P)H). Yet, cofactors are generally too expensive to be consumed stoichiometrically for the production of commodity chemicals as they can react only once. An alternative would be to regenerate and reuse the cofactors. This can be achieved applying a secondary substrate-driven enzymatic reaction along with the primary synthesis or, alternatively, by electrochemically reducing NAD+ to the enzymatically active species 1,4-NADPH on an electrode surface. Methods including chemical, electrochemical, photochemical, microbial and enzymatic reactions have all been investigated for cofactor regeneration. Electrochemical regeneration has been used as an alternative to the enzymatic route. Another strategy is to immobilize enzymes onto nanoparticles surface. In these systems the enzyme configuration, orientation and density can be controlled by changing the nanomaterial surface chemistry. The ability to control both the enzyme configuration/density on the nanoparticle and the mobility of the enzyme-nanoparticle system has shown increased target-specific avidity. Among the semiconductor oxides, cerium dioxide (CeO2) has attracted much attention for the development of electrochemical biosensors in recent years due to its excellent properties, including biocompatibility, higher surface/area ratio, high chemical stability and excellent electronic conductivity. The functionalization of CeO2 with gold nanoparticles (AuNPs) increases its stability, conductivity and biocompatibility, being more effective for the immobilization of biomolecules and a desirable interface for electrochemical reactions. In this project we intend to fabricate modified glassy carbon electrodes (GCE) to be applied in the electrochemical regeneration of cofactors. Nanorods of gold, CeO2 and Au/CeO2 will be used as catalysts for the direct regeneration of cofactors on GCE electrodes by using natural and artificial cofactors. An effective catalyst for the cofactor regeneration is not only a scientific challenge to be investigated and understood, as also a reaction of high interest for the chemical industry. By the interdisciplinary synergy of materials science with biochemistry it is intended to contribute with the highest level of scientific knowledge to an industrial challenge to be overcome, which is the cofactor regeneration by designed nanomaterials.
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