KCS

Nature utilizes solar energy for the synthesis of various compounds, which remains as a target model for the development of artificial photosynthetic system. In biocatalysis systems, enzymes catalyze and build intricate products with high specificity in environmentally benign conditions. Many enzymes, particularly, the oxidoreductases depend on nicotinamide co-factors such as NAD (nicotinamide adenine dinucleotide) and NADP (nicotinamide adenine dinucleotide phosphate) for their biological/industrial functions. The high cost of these co-factors, however, remains as one of the major hurdles in industrialization of many promising enzymatic processes. Therefore, an efficient method of their in situ regeneration has long been expected to provide a means of making the process economically and industrially feasible. In the regeneration of co-factors, so far, a number of strategies such as enzymatic, electrochemical methods etc., had been devised and investigated, but these strategies are still associated with their own drawbacks. The use of light energy for the regeneration of co-factors is envisioned to provide the opportunity of harnessing the clean and abundant solar energy. Therefore, we developed the photocatalyst-redox enzyme coupled bioreactor system that exemplified solar synthesis in a simple heterogeneous system. Generating NADH in non-enzymatic light-driven process and coupling it to the enzymatic dark reaction catalysis for chemical synthesis via photobiocatalysis, the present work remains conceptually a novel model. Also it demonstrates successfully a new and potentially promising visible-light driven artificial photosynthesis system for the ultimate goal of utilization of solar energy in chemical synthesis.