Enzyme immobilization is essential to the commercial viability of various critical large‐scale biocatalytic processes. However, challenges remain for the immobilization systems, such as difficulties ...in loading large enzymes, enzyme leaching, and limitations for large‐scale fabrication. Herein, we describe a green and scalable strategy to prepare high‐performance biocatalysts through in situ assembly of enzymes with covalent organic frameworks (COFs) under ambient conditions (aqueous solution and room temperature). The obtained biocatalysts have exceptional reusability and stability and serve as efficient biocatalysts for important industrial reactions that cannot be efficiently catalyzed by free enzymes or traditional enzyme immobilization systems. Notably, this versatile enzyme immobilization platform is applicable to various COFs and enzymes. The reactions in an aqueous solution occurred within a short timeframe (ca. 10–30 min) and could be scaled up readily (ca. 2.3 g per reaction).
In situ assembly of enzymes and covalent organic frameworks (COFs) enables the environmentally benign large‐scale fabrication of a new generation of high‐performance biocatalysts. This approach shows how limitations in enzyme immobilization can be overcome and it opens up a new avenue for the scalable fabrication of high‐performance biocatalysts to accelerate enzyme industrialization.
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•Novel poly(methyl methacrylate)/Fe3O4 electrospun material was obtained.•The laccase immobilization by covalent binding and encapsulation was carried out.•The biocatalysts are ...characterized by improvement stability and reusability.•Removal of tetracycline by immobilized enzyme at wide range of pH and temperature.•Oxidation, dehydrogenation and demethylation governed conversion of tetracycline.
In the presented study poly(methyl methacrylate) (PMMA) and magnetite nanoparticles were used to prepare novel PMMA/Fe3O4 electrospun nanofibers. The obtained materials were characterized, and then modified and used as supports for covalent binding and encapsulation of laccase from Trametes versicolor. High enzyme loading (63.2 mg of laccase per 1 cm2 of support) was recorded for the system after covalent binding, and the formation of stable interactions was confirmed, as leaching of the enzyme from the support did not exceed 12%. Furthermore, the obtained biocatalytic systems exhibited excellent pH, thermal and storage stability as well as reusability: after 40 days of storage and 5 successive biocatalytic cycles they retained 80% of their initial properties. Experiments on the removal of antibiotic showed that both immobilized laccases possess high ability to convert tetracycline. Under optimal process conditions (pH 5, temperature 25 °C, tetracycline solution concentration 1.0 mg L−1) the removal efficiency reached 100% and 94% for covalently bonded and encapsulated laccase. Finally, the degradation products were examined to investigate the degradation mechanism. The data showed that oxidation, dehydrogenation and demethylation are major reactions in the degradation of tetracycline using immobilized laccase. The findings demonstrate clearly that laccase immobilized by covalent binding and encapsulation using electrospun materials has the potential for application in environmental protection processes for the removal of antibiotics.
Biocatalytic nanofiltration (NF) membranes incorporated with enzymes show high capacity for micropollutants (MPs) removal. However, there remains significant challenges such as the lack of ...molecular-level tailoring for skin layer design and effective strategy for enzyme immobilization. In this work, layer-by-layer (LBL) assembly based biocatalytic NF membranes were fabricated for bisphenol (BPA) removal by immobilizing laccase into the skin layer during the LBL polyelectrolytes assembly with controlled crosslinking and immobilization. This strategy enables simultaneous enzyme immobilization and NF skin layer formation. Three laccase immobilization strategies (i.e., post immobilization, post crosslinking, and post crosslinking and immobilization) on skin layer were explored to prepare NF membrane for evaluating BPA removal efficiency. The post immobilization was identified as the optimal strategy, which endowed the biocatalytic NF membrane with a pure water permeability of 10.9 ± 0.4 LMH/bar and MgCl2 rejection of 97.2 ± 0.3% under 2 bar pressure, alongside competitive laccase loading (238.8 ± 3.5 μg/cm2) and laccase activity (0.6 U/cm2). The optimal biocatalytic NF membrane exhibited an improvement in BPA removal of 79.5% under an incubation mode and 92.5% under a full recycling mode. The removal efficiencies were ~240% higher than that of the unmodified LBL membrane and clearly comparable to other reported biocatalytic membranes. This performance was attributed to the synergistic effect of membrane rejection, adsorption and laccase catalysis. The optimal biocatalytic NF membrane was found to be robust after six cycles within 14 days, while maintaining a relatively high BPA removal efficiency and salt rejection. Overall, our results open up a new avenue for enzyme immobilization into the skin layer of membranes for designing high-efficient biocatalytic NF membranes for MPs removal.
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•Laccase-decorated LBL skin layer is prepared on lumen side of hollow fiber membrane.•Effects of different laccase immobilization strategies on BPA removal are explored.•Post immobilization strategy endows the membrane with a competitive NF performance.•Desired BPA removal efficiency is achieved with optimal biocatalytic membrane.•The long-term reusability and stability for BPA removal are confirmed.
Enzymes have been incorporated into a wide variety of fields and industries as they catalyze many biochemical and chemical reactions. The immobilization of enzymes on carbon nanotubes (CNTs) for ...generating nano biocatalysts with high stability and reusability is gaining great attention among researchers. Functionalized CNTs act as excellent support for effective enzyme immobilization. Depending on the application, the enzymes can be tailored using the various surface functionalization techniques on the CNTs to extricate the desirable characteristics. Aiming at the preparation of efficient, stable, and recyclable nanobiocatalysts, this review provides an overview of the methods developed to immobilize the various enzymes. Various applications of carbon nanotube-based biocatalysts in water purification, bioremediation, biosensors, and biofuel cells have been comprehensively reviewed.
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•CNTs act as stable support material for enzyme immobilization.•Enhancement of chemical properties of CNTs through surface functionalization.•Achievement of target specificity via enzyme immobilization.•Enzyme immobilized CNTs for biomedical and environmental applications.
•Nano-sized meso-HOF (nmHOF) was designed for in situ enzyme immobilization.•–COOH/–NH2 residues on enzyme triggered the formation of enzyme@nmHOF.•Enzyme@nmHOF had pore size of 2.4 nm and particle ...size from 19.9 ± 6.4 to 56.4 ± 20.1 nm.•Catalytic activity of enzyme@nmHOF was close to free enzyme.•Enzyme@nmHOF exhibited excellent chemical stabilities against external stimuli.
Hydrogen-bonded organic frameworks (HOFs) are promising carriers for enzyme immobilization. HOFs suitable for enzyme reactions containing nicotinamide cofactors and/or larger molecule substrates are to be explored. Herein, we report the first example of nano-sized mesoporous HOFs (nmHOFs) for in situ enzyme immobilization. Taking tetrakis(4-amidiniumphenyl) methane (TAM) and 1,3,6,8-tetrakis(p-benzoic acid) pyrene (H4TBAPy) as building blocks, enzymes induce the assembly of TAM and H4TBAPy into enzyme-nmHOF (named enzyme@TaTb) in aqueous solution. The larger π-conjugated H4TBAPy building block and the electrostatic/hydrogen-bonding interactions between TAM in nmHOF and –COOH/–NH2 residues in enzymes trigger the formation of TaTb with pore aperture of 2.4 nm and particle size from 19.9 ± 6.4 to 56.4 ± 20.1 nm. As a demonstration, lactate dehydrogenase (LDH) that can convert pyruvate into lactate in the presence of NADH is immobilized in TaTb nmHOF. Compared with LDH@ZIF-8 and LDH@Bio-HOF-1, LDH@TaTb affords faster diffusion of NADH and pyruvate, thus exhibiting ultrahigh activity close to the free LDH. Meanwhile, the exoskeleton of TaTb nmHOF is capable of stabilizing enzymes through spatial confinement, rendering superior stability against external negative stimuli. The TaTb nmHOF is also used for immobilizing α-amylase and horseradish peroxidase. Our study may facilitate the development of HOFs into platform carriers for enzyme immobilization.
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•Biocatalytic membrane processes produce environmentally friendly and energy-efficient processes.•Enzyme immobilization is the simplest solution to long-term operational stability, ...activity and reuse.•Modified immobilization methods improve the performance of enzymes over common immobilization methods.•Biocatalytic membranes compared with electrocatalytic and photocatalytic membrane processes.•Biocatalytic membranes have the potential to be used in antifouling and emerging pollutant degradation applications.
Biocatalytic membranes, which are fabricated by taking advantage of the synergetic effect of membranes and enzymes, have been one of the attractive treatment methods as sustainable and environmentally friendly. In biocatalytic membrane systems, enzymes can be free or immobilized, but the number of immobilized applications increases due to the advantages of immobilization. Immobilization is one of the critical points to improve the storage and operational stability of enzymes. Additionally, immobilized enzymes have a significant benefit over free enzymes in terms of reusability. This review summarizes recent advances in the preparation of biocatalytic membranes with the different immobilization methods of enzymes in/on membranes, paying particular attention to recent approaches for anti-fouling and emerging pollutant degradation applications. Also, some future outlooks were briefly presented.
In recent years, enzyme immobilization has been presented as a powerful tool for the improvement of enzyme properties such as stability and reusability. However, the type of support material used ...plays a crucial role in the immobilization process due to the strong effect of these materials on the properties of the produced catalytic system. A large variety of inorganic and organic as well as hybrid and composite materials may be used as stable and efficient supports for biocatalysts. This review provides a general overview of the characteristics and properties of the materials applied for enzyme immobilization. For the purposes of this literature study, support materials are divided into two main groups, called Classic and New materials. The review will be useful in selection of appropriate support materials with tailored properties for the production of highly effective biocatalytic systems for use in various processes.
The primary means of immobilizing enzymes are to boost the enzyme productivity and operational stability, alongside facilitating the reuse of enzymes. Notwithstanding the aforementioned benefits, ...enzyme immobilization promotes high catalytic activity and stability, convenient handling of enzymes, in addition to their facile separation from reaction mixtures without contaminating the products. This review describes the choices of support materials and cross-linkers together with several mechanisms that influence the performance, stabilization and hyperactivation of immobilized enzymes. Altering enzyme properties often changes the enzyme structure due to random modifications in the behavior, which in some cases can be positive or negative. Future strategy to develop new generations of immobilized enzymes should capitalize on the rapid advances of genetic manipulation, organic chemistry, computational chemistry and bioinformatics, reactor and reaction design. Upcoming efforts to improve enzymes as industrial biocatalysts must consider their development for increased selective promiscuity suitable for multiple biotransformations, either independently or as catalytic cascade processes thereby enhance the cost-effectiveness of the processes.
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•Highlights on different choices of support materials.•Usage of crosslinkers for enzyme immobilization.•Future strategy to develop new generations of immobilized enzymes.
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•Magnetic nanoparticles synthesis and amino-functionalization.•Preparation of magnetic cross-linked laccase aggregates from Trametes hirsuta.•Easy recycling of magnetic cross-linked ...laccase aggregates.•Disability of laccase immobilization by cross-linked enzyme aggregates method.•Successful bisphenol A removal using magnetic cross-linked laccase aggregates.
Enzymatic removal of Bisphenol A (BPA), acknowledged as an environmentally friendly approach, is a promising method to deal with hard degradable contaminants. However, the application of “enzymatic treatment” has been limited due to lower operational stability and practical difficulties associated with recovery and recycling. Enzyme immobilization is an innovative approach which circumvents these drawbacks. In this study, laccase from Trametes hirsuta was used for BPA removal. Amino-functionalized magnetic Fe3O4 nanoparticles were synthesized via the co-precipitation method followed by surface modification with (3-aminopropyl)trimethoxysilane (APTMS). The as-prepared nanoparticles were utilized for the immobilization of laccase with the magnetic cross-linked enzyme aggregates method (MCLEAs). Activity recovery of 27% was achieved, while no immobilized laccase was observed in the cross-linked enzyme aggregates method. The performance of immobilized laccase was measured by analyzing the degradation of BPA pollutant. The maximum removal efficiency of 87.3% was attained with an initial concentration of 60 ppm throughout 11 h.
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•Synthesis S-decorated dendrimer immobilized on the magnetic nanoparticles.•Tuning enzyme through the four-component Ugi reaction.•Immobilizing of lipase on the support through the ...covalent bonds.•The excellent catalytic activity of synthesized structure in biodiesel production.
Two new biocatalysts have been synthesized by immobilizing lipase on the magnetic nanoparticles S-decorated dendrimer, through physisorption (TDMNP@CRL) and SS covalent bonds (TDMNP@tuned CRL) (CRL: Candida rugosa lipase). The Ugi four-component reaction as a promising strategy was used for tuning lipase and decoration of enzyme with SH to form SS bonds in TDMNP@tuned CRL. The synthesized biocatalysts illustrated better performance in various ranges of temperature and pH compared to free enzyme and storage stability for 60 days. The excellent stability of the synthesized biocatalyst in different conditions and the presence of magnetic nanoparticles in the structure which provides a very convenient strategy for separation have made it a very distinguished candidate for biodiesel production. The effective factors on biodiesel production including temperature, time, the mole ratio of alcohol to oil, w/w of water to oil, and amount of catalyst were explored and under the optimized conditions, the yield of biodiesel production was 78 % in the presence of TDMNP@tuned CRL which confirmed by 1H NMR spectroscopy. Furthermore, the biocatalyst was easily separated by an external magnet and successfully reused four times without loss of its activity.
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