A coupled enzyme-photocatalytic system for efficient NADH regeneration and L-glutamate production

The coupling of photocatalytic assemblies with enzyme-catalyzed reactions offers a promising strategy for storing light energy in the form of chemical bonds, producing clean fuels and high-value chemicals. Such systems require high performance and robustness of all components, as well as effective coupling between inorganic and enzymatic modules to achieve efficient light harvesting and high product yields. In this work, a composite photocatalytic module, consisting of a heterostructure formed by silver nanoclusters (AgNCs) and graphitic carbon nitride (g-C 3 N 4 ), was coupled with an amino-containing Rh-based complex ([Cp*Rh(bpy(NH₂)₂)H₂O] 2+ ) for more efficient electron delivery and NADH recycling. The regenerated NADH was subsequently utilized by the enzymatic module, where the metal-organic framework (MOF) ZIF-90 was employed as a protective compartmentalization matrix for NADH-dependent L-glutamate dehydrogenase (GluDH). The resulting system achieved efficient conversion of NAD + to NADH, along with a notable L-glutamate production rate of 570 μmol g cat −1  h −1 , underscoring the potential of composite photosynthetic systems and paves the way for future improvements through enhanced integration and optimization of key photocatalytic modules.