The Need

NAD(P)H is used as a reducing co-factor for the synthesis of biochemicals (e.g., conversion of aldehydes to alcohols) using biocatalysts or even microbes. Butanol is an important feedstock used in the chemical industry and shows great potential as a biofuel. Butanol is produced from fossil fuels but can be generated renewably by bacterial fermentation of lignocellulosic biomass hydrolysates (LBH). A major obstacle to butanol production from LBH is the cost of fermentation-essential cofactors or co-enzymes, which are presently not renewable.

The Technology

This invention centers around the development of a novel and inexpensive in-house developed nano-heterostructured (Ni/Cu₂O/Cu) cathode to photoelectrochemically regenerate cofactors (NADH and NADPH). Butanol has tremendous promise as an additive to gasoline and diesel to render the combustion of these fuels efficient and clean. Economical means of ex vivo regeneration of NAD(P)H from the NAD(P)⁺, the product of NADPH oxidation, would enable biosynthesis of butanol from butyraldehyde to continue unabated even if cellular redox is no longer available. In brief, a p-type semiconductor, Cu₂O (cuprous oxide), is electrodeposited onto a copper mesh to a thickness of tens of microns. A protective and catalytic layer (thickness estimated to be in tens of nanometers) of Ni (nickel) is then deposited using dc sputtering. This Ni/Cu₂O/Cu nano-heterolayer is then photoelectrochemically treated in phosphate buffer using visible light from a 10-mW green (532 nm) laser for one hour to enable surface modification and use as a novel cathode for electrochemical conversion of NAD(P)⁺ to NAD(P)H. The overcoat of Ni renders the electrode reusable and effective in producing highly pure NAD(P)H, free of the inactive dimer form (as shown by MALDI FT-ICR mass spectrometry).

Competitive Advantages

• Far more cost-effective method of regenerating cofactors than current methods
• Simple, scalable two-step manufacturing process
• Low energy input
• Straightforward NADPH regeneration experimental setup that complements current bio-fermentation processes used for production of biofuels from biomass.

Commercial Applications

• Biofuel Production
• Green Energy
• Solar energy conversion, i.e., photogalvanic conversion of light to a current source.