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In this study, the surfactant activated lipase from Aspergillus oryzae was used to prepare magnetic hybrid nanoflowers by embedding Fe3O4 magnetic nanoparticles (MNPs) into hybrid nanoflowers (MhNF). Meanwhile, MNPs were integrated into the activated lipase hybrid nanoflowers through covalent cross-linking (cross-linked-MhNF). Activity recovery of the MhNF and cross-linked-MhNF was 190% and 174%, respectively. However, activity recovery of lipase hybrid nanoflowers (hNF) only retained 77%. Furthermore, the MhNF displayed higher Kcat/Km value than free lipase, indicating high catalytic efficiency of MhNF. Compared with free lipase, the MhNF exhibited high tolerance against methanol and storage stability. Furthermore, the MhNF could be easily recycled by magnet without obvious activity loss. After reusing for 10 cycles, the activated hNF only retained 26% activity of its original activity, while the MhNF still maintained 84% activity of its initial activity, indicating excellent reusability. In the reaction of producing biodiesel from soybean oil, the MhNF-catalyzed biodiesel yield reached 88%, while the free enzyme was only 69%. The yield of biodiesel catalyzed by MhNF was maintained at 76% even after 6 consecutive cycles.

Enzyme catalysis has been attracting increasing interest in the past twenty years. Nevertheless, most reports concerning enzyme catalysis have been carried out using single enzymes. Recent years, multiple enzyme cascade reactions have a significant role for the production of many compounds at an industrial level because they permit to perform very complex reactions. Especially, the development of coimmobilized multienzymatic systems is increasingly driven by economic and environmental constraints that provide an impetus to develop alternatives to conventional multistep synthetic methods. Up to now, process optimization and novel strategies of coimmobilized multienzymatic systems hardly have been reviewed. In this review, we focus on some recent novel techniques in preparing co-immobilized multienzymatic systems and the up-to-date advances in the application of multienzymatic systems. Moreover, we also discuss the improvements that co-immobilization multienzymatic systems offer enzymes such as reusability, catalytic activity, and stability.

In this study, carbonic anhydrase (CA, EC 4.2.1.1) molecules were embedded into metal-organic frameworks (MOFs) via co-precipitation (CA@ZIF-8), and then these CA@ZIF-8 nanocomposites were encapsulated in the poly(vinyl alcohol) (PVA)-chitosan (CS) hydrogel networks to prepare CA@ZIF-8-PVA-CS composite hydrogels (PVA/CS/CA@ZIF-8) with high activity, stability, and reusability. The immobilization efficiency of CA was greater than 70%, suggesting the high immobilization efficiency. The prepared PVA/CS/CA@ZIF-8 composite membranes displayed excellent higher stability against a high temperature, denaturants, and acid than free CA and CA@ZIF-8. Furthermore, these membranes exhibited an excellent performance for CO2 capture. The amount of calcium carbonate obtained by PVA/CS/CA@ZIF-8 hydrogel membranes was 20- and 1.63-fold than free CA and CA@ZIF-8 composites, respectively. Furthermore, the hydrogel membranes exhibited superior reusability and mechanical strength. The hydrogel membrane maitained 50% of its original activity after 11 cycles. However, CA@ZIF-8 completely lost activity. These results indicated that the PVA/CS/CA@ZIF-8 membranes can be efficiently applied to capture CO2 sequestration.

Lipase-inorganic hybrid nanoflowers were prepared using Ca3(PO4)2 as the inorganic component and lipase from Aspergillus oryzae (A. oryzae) as the organic component. The influences of metal ions with different valence, various additives (surfactant), and synthesis conditions on the activity of the lipase hybrid nanoflowers were systematically investigated. Results revealed that the valence state of metal ions played an important role on the shape and activity of lipase hybrid nanoflowers. The synthesized lipase hybrid nanoflowers using bivalence metal ions (Ca2+, Mn2+, and Zn2+) as the inorganic components exhibited relative high activity. However, very low activities were observed in the lipase hybrid nanoflowers using univalent metal ions (Ag+) or trivalent metal ions (Al3+, Fe3+). More importantly, Ca2+ not only induced self-assemble of lipase hybrid nanoflowers, but also activated the enzyme activity by inducing conformational changes in lipase from A. oryzae. As a result, lipase/Ca3(PO4)2 hybrid nanoflowers (hNF-lipase) exhibited the high activity. The hNF-lipase displayed 9, 12, and 61 folds higher activity than lipase/Ag3PO4 hybrid nanoflowers, lipase/AlPO4 hybrid nanoflowers, and lipase/FePO4 nanoflowers, respectively. Compared with free lipase, the hNF-lipase displayed 172 % increase in activities by using 0.15 mM Tween-80 as an activity inducer (activated hNF-lipase). Furthermore, the hNF-lipase and activated hNF-lipase exhibited increased stability against high temperature and denaturant, and had good storage stability and reusability.

CO2 capture by immobilized carbonic anhydrase (CA) has become an alternative and environmental friendly approach in CO2 sequestration technology. However, the immobilized CA usually exhibits low CO2 sequestration efficiency due to no gas adsorption function for the conventional CA supports. Metal organic frameworks (MOFs) are an excellent material for gas adsorption and enzyme immobilization. Herein, a combined immobilization system of CA and ZIF-8 with cruciate flower-like morphology for CO2 adsorption was prepared for the first time by adsorbing CA onto ZIF-8. The immobilization efficiency was greater than 95%, and the maximum activity recovery reached 75%, indicating the highly efficient immobilization process. The resultant CA@ZIF-8 composites exhibited outstanding thermostability, the tolerance against denaturants, and reusability compared with free CA. Furthermore, we demonstrated for the first time that the shape of ZIF-8 could be controlled by adjusting concentrations of Zn2+ ions at the high concentration of 2-methylimidazole (1 M). More importantly, we also demonstrated the applicability of the CA@ZIF-8 composites to the sequestration of CO2 in carbonate minerals. The yields of the CaCO3 obtained by using CA@ZIF-8 composites were 22-folds compared to free CA. Thus, this CA@ZIF-8 composite can be successfully used as a robust biocatalyst for sequestration of CO2.

In this study, carbonic anhydrase (CA, EC 4.2.1.1) molecules were embedded into metal-organic frameworks (MOFs) via co-precipitation (CA@ZIF-8), and then these CA@ZIF-8 nanocomposites were encapsulated in the poly(vinyl alcohol) (PVA)-chitosan (CS) hydrogel networks to prepare CA@ZIF-8-PVA-CS composite hydrogels (PVA/CS/CA@ZIF-8) with high activity, stability, and reusability. The immobilization efficiency of CA was greater than 70%, suggesting the high immobilization efficiency. The prepared PVA/CS/CA@ZIF-8 composite membranes displayed excellent higher stability against a high temperature, denaturants, and acid than free CA and CA@ZIF-8. Furthermore, these membranes exhibited an excellent performance for CO

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