Composite Enzyme/CaCO3@Hydrogel Particles for Continuous Cascade Multienzymatic Catalysis

Abstract

Immobilization of multiple enzymes in particles creates opportunities to organize a complex network of biochemical reactions for continuous cascade catalysis. In this work, hydrogel particles integrated with enzyme/CaCO₃ nanoparticles are created via droplet-template synthesis for the continuous cascade catalysis of CO₂ into methanol. Three enzymes, including formate dehydrogenase (FateDH), formaldehyde dehydrogenase (FaldDH), and alcohol dehydrogenase (ADH), are separately immobilized in these CaCO₃ nanoparticles inside the hydrogel particles. The obtained FateDH/CaCO₃@PEGDA, FaldDH/CaCO₃@PEGDA, and ADH/CaCO₃@PEGDA hydrogel particles enable good performance for cascade enzymatic catalysis in batch, showing a higher conversion rate than the free enzymes and the hydrogel particles coencapsulated with the three enzymes. Meanwhile, these enzyme/CaCO₃@PEGDA hydrogel particles exhibit good repeatability for the cascade enzymatic catalysis, typically showing a ∼12% decrease in conversion rate after 7 cycles. Moreover, these enzyme/CaCO₃@PEGDA hydrogel particles are filled in a U-shaped reactor for continuous cascade enzymatic catalysis. When three units of such reactors are sequentially used, these enzyme/CaCO₃@PEGDA hydrogel particles allow efficient conversion of CO₂ dissolved in solution into methanol, exhibiting a maximum methanol yield at 6.00 mM. This work provides a simple, environmentally friendly, and low-cost strategy for creating multienzyme-immobilized particles for cascade enzymatic catalysis.