Electro-enzyme coupling systems for selective reduction of CO_(2)

To address the energy crisis and alleviate the rising level of CO_(2)in the atmosphere,various CO_(2)capture and utilization(CCU)technologies have been developed.The use of electro-enzyme coupling systems is a promising strategy for the sustainable production of fuels,chemicals and materials using CO_(2)as the feedstock.In this review,the recent progresses in the development of electro-enzyme coupling systems for the selective reduction of CO_(2)are systematically summarized.We first provide a brief background about the significance and challenges in the direct conversion of CO_(2)into value-added chemicals.Next,we describe the materials and strategies in the design of electrodes,as well as the common enzymes used in the electro-enzyme coupling systems.Then,we focus on the state-of-the-art routes for the electro-enzyme coupling conversion of CO_(2)into a variety of compounds(formate,CO,methanol,C≥2chemicals)by a single enzyme or multienzyme systems.The emerging approaches and materials used for the construction of electro-enzyme coupling systems to enhance the electron transfer efficiency and the catalytic activity/stability are highlighted.The main challenges and perspectives in the integration of enzymatic and electrochemical strategies are also discussed.

An enzyme-loaded reactor using metal-organic framework-templated polydopamine microcapsule

Ultrathin polydopamine microcapsules with hierarchical structure and porosity were prepared for the immobilization of multienzymes using metal-organic framework(MOF) as the template.The multienzyme/MOF composite was first prepared using a "one-pot" co-precipitation approach via the coordination and self-assembly of zinc ions and 2-methylimidazole in the presence of enzymes.The obtained nanoparticles were then coated with polydopamine thin layer through the self-polymerization of dopamine under alkaline condition.The polydopamine microcapsules with an ultrathin shell thickness of ~48 nm were finally generated by removing the MOF template at acidic condition.Three enzymes were encapsulated in PDA microcapsules including carbonic anhydrase(CA),formate dehydrogenase(FateDH),and glutamate dehydrogenase(GDH).FateDH that catalyzed the main reaction of CO_(2) reduction to formic acid retained 94.7% activity of equivalent free FateDH.Compared with free multienzymes,the immobilized ones embedded in PDA microcapsules exhibited 4.5-times higher of formate production and high catalytic efficiency with a co-factor-based formate yield of 342%.

Boosted activity by engineering the enzyme microenvironment in cascade reaction: A molecular understanding

Engineering of enzyme microenvironment can surprisingly boost the apparent activity.However,the underlying regulation mechanism is not well-studied at a molecular level so far.Here,we present a modulation of two model enzymes of cytochrome c(Cty C)and D-amino acid oxidase(DAAO)with opposite pH-activity profiles using ionic polymers.The operational pH of poly(acrylic acid)modified Cyt C and polyallylamine modified DAAO was extended to 3-7 and 2-10 where the enzyme activity was larger than that at their optimum pH of 4.5 and 8.5 by 106%and 28%,respectively.The cascade reaction catalyzed by two modified enzymes reveals a 1.37-fold enhancement in catalytic efficiency compared with their native counterparts.The enzyme activity boosting is understood by performing the UV-vis/CD spectroscopy and molecular dynamics simulations in the atomistic level.The increased activity is ascribed to the favorable microenvironment in support of preserving enzyme native structures nearby cofactor under external perturbations.

Editorial for special issue on green biomanufacturing

Green biomanufacturing refers to the use of industrial biotechnology for the advanced production of biofuels,bio-based chemicals,and bioproducts.It involves the concepts of cleaner production and circular economy,and aims at sustainable developments with enhanced energy and environmental systems.Green biomanufacturing is of great significance to the transformation and upgrading of traditional chemical industry.The past decade has witnessed the surge of new green biomanufacturing technologies such as innovation of industrial enzymes,construction of industrial strains,intelligent biomanufacturing processes and equipments,utilization of sustainable biomass,etc.These innovated techniques have led to intriguing applications in a diverse range of fields including biopharmaceuticals,energy,environment,textile,and so on.