Open-Architecture Monolayered Metal–Organic Framework for Seamless Enzyme Integration in Photoenzymatic Catalysis

Metal-organic frameworks (MOFs) have been employed as versatile support platforms for enzyme immobilization and functional moiety integration. However, their intrinsic pore size limitation and synthetic conditions hinder the accommodation of large enzymes and restrict cooperative catalysis between enzymes and embedded functional components. Herein, we propose a general open-architecture strategy by designing monolayered MOFs (monoMOFs) to enable unrestricted enzyme immobilization and the seamless integration of diverse photoenzymatic systems. A porphyrin-based monoMOF, Hf-DBP, with a thickness of ∼1.8 nm was synthesized using photosensitizing H2DBP as the linker. Glutamate dehydrogenase (GDH) was covalently immobilized onto Hf-DBP via a bifunctional N-hydroxysuccinimide linker (NHS-Linker) without steric hindrance, fully retaining its native activity. In contrast to representative 3D MOFs such as ZIF-8, the open monolayered architecture of Hf-DBP eliminates pore-confinement effects, enabling a substantially higher enzyme loading and improved enzyme-substrate accessibility. A Cp*Rh-based electron mediator (H-MBP-Rh) was anchored onto the Hf-DBP to enable selective photocatalytic regeneration of bioactive 1,4-NADH, achieving ∼90.6% regeneration within 30 min and a turnover frequency (TOF) of up to 182 h-1. Coimmobilization of H-MBP-Rh and GDH within a single monoMOF scaffold enabled an efficient photoenzymatic cascade for light-driven α-ketoglutarate reduction, delivering ∼96.3% together with a production rate of 3.06 μmol mg-1 h-1. The generality of this platform was further demonstrated using alcohol dehydrogenase (ADH), achieving an ultrahigh propanol TOF of 86 282 h-1. This work overcomes the structural limitations of conventional MOFs and establishes monoMOFs as powerful and general platforms for constructing high-performance photoenzymatic systems.