Matrices For Enzyme Immobilization Research Articles

Protein Immobilization on Bacterial Cellulose for Biomedical Application.

New carriers for protein immobilization are objects of interest in various fields of biomedicine. Immobilization is a technique used to stabilize and provide physical support for biological micro- and macromolecules and whole cells. Special efforts have been made to develop new materials for protein immobilization that are non-toxic to both the body and the environment, inexpensive, readily available, and easy to modify. Currently, biodegradable and non-toxic polymers, including cellulose, are widely used for protein immobilization. Bacterial cellulose (BC) is a natural polymer with excellent biocompatibility, purity, high porosity, high water uptake capacity, non-immunogenicity, and ease of production and modification. BC is composed of glucose units and does not contain lignin or hemicellulose, which is an advantage allowing the avoidance of the chemical purification step before use. Recently, BC-protein composites have been developed as wound dressings, tissue engineering scaffolds, three-dimensional (3D) cell culture systems, drug delivery systems, and enzyme immobilization matrices. Proteins or peptides are often added to polymeric scaffolds to improve their biocompatibility and biological, physical-chemical, and mechanical properties. To broaden BC applications, various ex situ and in situ modifications of native BC are used to improve its properties for a specific application. In vivo studies showed that several BC-protein composites exhibited excellent biocompatibility, demonstrated prolonged treatment time, and increased the survival of animals. Today, there are several patents and commercial BC-based composites for wounds and vascular grafts. Therefore, further research on BC-protein composites has great prospects. This review focuses on the major advances in protein immobilization on BC for biomedical applications.

Synthesis and comparison of the performance of two different water-soluble phthalocyanine based electrochemical biosensor

Herein, a comparative study between novel water-soluble phthalocyanine-based biosensors was performed for the application of glucose sensing. For this purpose, two different copper (II) and manganese (III) phthalocyanines and their water-soluble derivatives were synthesized, and then their role as a supporting material for enzyme immobilization was evaluated by comparing their sensor performances. Two different phthalocyanine (AP-OH2-MnQ (MnPc) and AP-OH2-CuQ (CuPc)) were tested using electrochemical biosensor with immobilized glucose oxidase (GOx). To the best of our knowledge, the related water-soluble phthalocyanine-based glucose biosensors were attempted for the first time, and the developed approach resulted in improved biosensor characteristics. The constructed biosensors GE/MnPc/GOx and GE/CuPc/GOx showed good linearity between 0.003–1.0 mM and 0.05–0.4 mM, respectively. The limit of detection was estimated at 0.0026 mM for the GE/MnPc/GOx and 0.019 mM for the GE/CuPc/GOx. KMapp and sensitivity values were also calculated as 0.026 mM and 175.043 µAmM−1 cm−2 for the GE/MnPc/GOx biosensor and 0.178 mM and 117.478 µAmM−1 cm−2 for the GE/CuPc/GOx biosensor. Moreover, the fabricated biosensors were successfully tested to detect glucose levels in beverages with high recovery results. The present study shows that the proposed water-soluble phthalocyanines could be a good alternative for quick and cheap glucose sensing with improved analytical characteristics.

Obtaining a biodegradable biocatalyst – study on lipase immobilization on spent coffee grounds as potential carriers

Coffee waste can be reused as matrices for enzyme immobilization, as it contains various organic compounds able to adsorb catalytic proteins. In this study, spent coffee grounds were used as a support in the immobilization process in their native form and after being pretreated with hexane, ethanol, and sulphuric acid solution, respectively. Microbial lipases from Aspergillus oryzae, Thermomyces lanuginosus, and Rhizomucor miehei were adsorbed on the carrier, and as a reference, the abovementioned lipases were also immobilized on a synthetic matrix - Lewatit VP OC 1600. The research investigated the impact of the purification step on the immobilization process and the full characteristics of the obtained biocatalysts. The hydrolytic and synthetic activities of the immobilized enzyme preparations were tested, as well as substrate specificity, recovery, and temperature and pH activity profiles. SEM and FTIR analyses were also performed. The results showed that the chemical composition of coffee waste influenced the activity of the obtained biocatalysts, and the lack of hemicellulose caused a reduction in lipolytic activity. The study reveals that spent coffee grounds can be a potential support for enzyme immobilization, and lipases adsorbed on them have improved properties such as hydrolytic or synthetic activity, and stability in pH.

Hydroxyapatite: An Eco-Friendly Material for Enzyme Immobilization.

Biocatalysis has emerged in the last decade as a valuable and eco-friendly tool in chemical synthesis, allowing in several instances to reduce or eliminate the use of hazardous reagents, environmentally dangerous solvents and harsh reaction conditions. Enzymes are indeed able to catalyse chemical transformations on non-natural substrates under mild reaction conditions, still maintaining their high chemo-, regio-, and stereoselectivity. Enzyme immobilization, i. e. the grafting of enzymes on solid supports, can be viewed as an enabling technology, as it allows a better control of the reaction and the recycling of the biocatalyst, thus rendering economically viable the use of expensive enzymes also on a large scale. To pursue a sustainable approach, the supports for enzyme immobilization should be eco-friendly and possibly renewable. This review highlights the use of hydroxyapatite (HAP), an inorganic biomaterial able to confer strength and stiffness to the bone tissue in animals, as carrier for enzyme immobilization. HAP is a cheap, non-toxic and biocompatible material, with high surface area and protein affinity. Different enzyme classes, immobilization strategies, and the use of diverse HAP-based supports will be discussed, underlining the immobilization conditions and the properties of the obtained biocatalysts.

Multivariate mesoporous MOFs with regulatable hydrophilic/hydrophobic surfaces as a versatile platform for enzyme immobilization

Zeolitic imidazole frameworks materials-8 (ZIF-8), a member of the metal-organic framework (MOFs) series, have been extensively used as a host matrix for enzyme immobilization. However, the microporous structure and hydrophobicity, as well as the protonation of the precursor 2-methylimidazole (2-MeIm) of ZIF-8, remain considerable challenges in maintaining the activity of immobilized enzymes. Here, novel multivariate mesoporous MOFs (mMOFs) with regulatable hydrophilic/hydrophobic surfaces were designed by the multivariate competitive strategy and pore modification engineering. 3-Methyl-1H-1,2,4-triazole (3-MTZ) and 5-methyltetrazole (5-MTA) were employed to partially replace 2-MeIm. These were then combined with zinc sulfate heptahydrate (soft templates) to yield mMOFs in a methanol solution. As a proof-of-concept application, we used mMOFs as carriers for enzyme immobilization and investigated the properties of the immobilized enzymes. Benefiting from their mesoporous structure, hydrophilic surface, and improved microenvironment, multivariate mMOFs exhibit a strong ability to stabilize enzyme conformation and increase enzyme activity compared with traditional ZIF-8. Our study offers an avenue for the controllable preparation of well-designed MOF structures, which will further broaden the application opportunities of MOF materials for enzyme immobilization.

Improved performance of Pseudomonas fluorescens lipase immobilized on a magnetic mesoporous solvothermal hybrid-nanocarrier and its application in ultrasonication assisted estolide synthesis

The exponential growth of the biotechnological market necessitates the exploring novel, economically viable materials for enzyme immobilization to enhance the biocatalyst performance. This study involves preparing a hybrid carrier with a magnetic mesoporous nature, using milled rice husk (MRH) and multi-walled carbon nanotubes (MWCNTs) via a one-pot solvothermal process at 200 °C for 6 h. The carrier, rich in-NH2 groups, was chemically bonded to Pseudomonas fluorescens lipase (PFL) using EDC/NHS cross-linkers. The synthesized support achieved a maximum PFL loading of 94.92 mg of protein per gram of support. Moreover, the maximum activity recovery was achieved at 1196 %, under the optimal conditions: immobilization temperature 25℃, pH 9.0, immobilization time 2 h and PFL mass concentration 4 mg/mL. Subsequently, the derived enzyme was used to catalyze ricinoleic acid esterification to synthesize estolide under ultrasound-assisted conditions. The optimized principal parameters for reaction temperature, reaction time, and immobilized lipase loading were respectively determined to be 48.99 °C, 1.60 h, and 3.09 % via response surface methodology. Ricinoleic acid conversion reached 65.23 % under the optimal conditions with the assistance of 40 % power and 40 kHz ultrasonic frequency. Furthermore, remarkable operational stability was also observed, with a retention rate of 49.28 %, even after 10 consecutive batches. This study demonstrates promising prospects for industrial-scale application using ultrasound as a fast and ecologically friendly procedure.

Supra-biological performance of immobilized enzymes enabled by chaperone-like specific non-covalent interactions

Designing complex synthetic materials for enzyme immobilization could unlock the utility of biocatalysis in extreme environments. Inspired by biology, we investigate the use of random copolymer brushes as dynamic immobilization supports that enable supra-biological catalytic performance of immobilized enzymes. This is demonstrated by immobilizing Bacillus subtilis Lipase A on brushes doped with aromatic moieties, which can interact with the lipase through multiple non-covalent interactions. Incorporation of aromatic groups leads to a 50 °C increase in the optimal temperature of lipase, as well as a 50-fold enhancement in enzyme activity. Single-molecule FRET studies reveal that these supports act as biomimetic chaperones by promoting enzyme refolding and stabilizing the enzyme’s folded and catalytically active state. This effect is diminished when aromatic residues are mutated out, suggesting the importance of π-stacking and π-cation interactions for stabilization. Our results underscore how unexplored enzyme-support interactions may enable uncharted opportunities for using enzymes in industrial biotransformations.

Stereoselective reduction of diarylmethanones via a ketoreductase@metal-organic framework.

Mainly owing to their well-defined pore structures and high surface areas, metal-organic frameworks (MOFs) have recently become a versatile class of materials for enzyme immobilization. Nevertheless, most previous studies were focused on model enzymes such as cytochrome c, catalase, and glucose oxidase, with the application of MOF-derived biocomposites for (asymmetric) organic synthesis being rare. In the present work, the immobilization of the ketoreductase KmCR2 onto the zeolitic imidazolate framework (ZIF), a prominent type of MOF, was pursued using the controlled co-precipitation strategy, with a low 2-methylimidazole (2-mIM)/Zn molar ratio of 8 : 1 being employed. Such fabricated biocomposites denoted as KmCR2@ZIF were found to exist mainly in an amorphous phase, as suggested by the scanning electron microscopy (SEM) and powder X-ray diffraction (PXRD) data. Improved thermal and storage stabilities were observed for KmCR2@ZIF compared with the free enzyme. Stereoselective reduction of nine diarylmethanones 1 catalyzed by KmCR2@ZIF was performed, and the corresponding enantioenriched diarylmethanols 2 were afforded in 40-92% conversions with good to excellent optical purities (up to >99% ee). Critically, the current work demonstrated that the unique characteristic of KmCR2, namely the substituent position-controlled stereospecificity (meta versus para or ortho), was not altered upon the enzyme immobilization onto the ZIF.

Enzyme stability in polymer hydrogel-enzyme hybrid nanocarrier containing phosphorylcholine group.

Enzymes are biological catalysts with good biocompatibility and high efficiency and have been widely used in many fields, such as wastewater treatment, biosensors, and the medical industry. However, their inherently low stability under conditions of practical use limits further applications. Zwitterionic polymers possessing a pair of oppositely charged groups in their repeating units can increase protein stability because of their good biocompatibility and high water content. In this study, zwitterionic copolymer nanogels comprising poly(2-methacryloyloxyethyl phosphorylcholine (MPC)-co-methacrylic acid-N-hydroxy succinimide ester (MNHS)) (PMS) were synthesized via reversible addition-fragmentation chain-transfer polymerization (RAFT). β-Galactosidase (β-gal) was post-modified within zwitterionic polymer nanogels with a covalently-bound spacer and the activity was compared with that of directly immobilized β-gal and free β-gal. Compared with direct immobilization, covalent immobilization with a spacer could reduce the structural change of β-gal, as confirmed by the circular dichroism spectra. Although the activity of β-gal decreased after immobilization, the hybrids of the β-gal immobilized nanogels, termed hybrid nanogel-enzymes, demonstrated superior stability compared to the free enzymes. The hybrid nanogel-enzymes maintained their function against inactivation by organic solvents and proteinases owing to their high water content, anti-biofouling properties, and limited mass transfer. They can also withstand protein aggregation at high temperatures and maintain their activity. Compared to direct immobilization, immobilization with a spacer resulted in a dramatic increase in the enzyme activity and a slight decrease in the stability. These results indicate that polymer nanogels containing phosphorylcholine units are promising materials for enzyme immobilization, expanding the scope of enzyme applications.

Polymer-Based Strategies for Enzyme Immobilization: A Comprehensive Review

Enzyme immobilization refers to the process of attaching or confining enzymes onto a solid support or within a matrix, often made of polymers or other materials. This immobilization creates a stable and controlled environment for the enzyme to interact with substrates and perform catalysis. The primary goal of enzyme immobilization is to enhance enzyme stability, reusability, and activity under specific conditions, making them more practical and efficient for various biotechnological, industrial, and medical applications.
 Immobilization methods can vary widely, including physical adsorption, covalent bonding, entrapment within matrices, encapsulation, crosslinking, and more. These methods provide a means to control the interactions between the enzyme and the surrounding environment, affecting factors such as substrate accessibility, enzyme orientation, and stability.
 Due to their ease of fabrication and superior structural adaptability, polymer compounds in a variety of physical forms, including beads, films, fibers,and coatings,have become popular as supportive materials for enzyme immobilization. For enzyme immobilization, a number of natural polymers, including agar, agarose, alginate, dextran, chitosan,and carrageenan, as well as synthetic polymers, such as polyamides, polystyrene, and polyacrylamide, are often employed as a carrier system. The immobilization offers a cost-effective system for various applications in biotechnology, industry, and research.

Film-shaped reusable smart polymer to produce lactose-free milk by simple immersion

In this study, we report the synthesis and characterization of a highly manageable polyacrylic film material for enzyme immobilization, using β-galactosidase (β-gal) as a model enzyme. The material is based on commercially available monomers and achieves efficient immobilization of β-gal through the formation of azo linkages between amino styrene groups in the polyacrylic material and the enzyme. The immobilized enzyme demonstrates superior performance compared to free enzyme in lactose hydrolysis of UHT milk, achieving lactose concentrations below 0.1% (<1 mg/mL), indicating its potential for lactose hydrolysis in dairy products. The film-shaped material is designed for easy submersion and removal, similar to a smart card, and offers reusability, with the ability to be reused at least 10 times without loss of enzymatic activity. Characterization of the immobilized enzyme on the polymeric material was performed using various techniques, including scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and Raman spectroscopy. Protein release studies confirmed the stability of the immobilized enzyme during prolonged incubation in aqueous solution without significant enzyme leakage. Overall, the polyacrylic film material demonstrates promise as a simple and efficient approach for enzyme immobilization, with potential applications in various industries, including the food industry.

Application of electrospun chitosan-based nanofibers as immobilization matrix for biomolecules

Nanofiber meshes from electrospun chitosan, highly modified with biotin and arylazides, are well-suited for application as enzyme immobilization matrices. To test this, catalytically active biomolecules were immobilized onto photocrosslinked nanofibrous nonwovens consisting mainly of biotinylated fungal chitosan and a small amount (10 w%) of poly ethylene oxide. In this study, we show that over 10 μg eugenol oxidase per milligram dry polymer matrix can be loaded on UV-crosslinked chitosan nanofibers. We further demonstrate that bound enzyme activity can be fully retained for over 7 days of storage at ambient conditions in aqueous buffer. Samples loaded at maximum enzyme carrying capacity were tested in a custom-made plug-flow reactor system with online UV-VIS spectroscopy for activity determination. High wettability and durability of the hydrophilic chitosan support matrix enabled continuous oxidation of model substrate vanillyl alcohol into vanillin with constant turnover at flow rates of up to 0.24 L/h for over 6 h. This proves the above hypothesis and enables further application of the fibers as stacked microfluidic membranes, biosensors, or structural starting points for affinity crosslinked enzyme gels.Key points•Biotinylated chitosan-based nanofibers retain enzymes via mild affinity interactions•Immobilized eugenol oxidase shows high activity and resists continuous washing•Nanofiber matrix material tolerated high flow rates in a continuous-flow setupGraphical

Preparation of isocyanate-containing hydrogel films as antibacterial enzyme immobilization matrices

Sulfobetaine-based isocyanate-containing hydrogel films were synthesized on glass surfaces and the immobilization of small molecules and proteins onto those films was demonstrated. Synthesis of hydrogel films and their functionalizations were confirmed using FTIR spectroscopy. Obtained polymer films were used as matrices for the immobilization of the antibacterial enzyme lysostaphin (Lys). Successful immobilization of Lys enzyme was demonstrated using FTIR and Bradford analyses. The antibacterial activity of enzyme-immobilized surfaces against different Staphylococcus aureus (S. aureus) bacterial strains was evaluated. Enzyme-conjugated surfaces showed 90% killing efficacy against S. aureus 35 bacteria, and the antibacterial activity of those surfaces was maintained for at least 30 days and multiple exposures to the bacteria. The enzyme-immobilized hydrogel coatings reported here provide a promising antibacterial surface against S. aureus.

Exploring the synergistic effects of enzyme@lactoferrin hybrid on biomimetic immobilization: Unveiling the impact on catalytic efficiency

Metal-organic frameworks (MOFs) have gained attention as a hopeful material for enzyme immobilization due to their advantageous characteristics, for instance, high surface area and easy construction conditions. Nonetheless, the confinement effect and competing coordination often lead to partial or complete inactivation of the immobilized enzymes. In this study, we present a novel strategy, the lactoferrin-boosted one-pot embedding approach, which efficiently connects enzymes with lactoferrin (LF) hybrid Graphene Oxide (GO)//Pt Nanoparticles/MOF-74 (referred to as enzyme@LF@rGO/PtNP@MOF-74). This approach demonstrates a high embedding efficiency. By employing a hybrid of LF and GO/Pt Nanoparticles as synchronous ligands for Zn-MOF-74, we provide a suitable environment for enzyme immobilization, resulting in enhanced enzymatic activity. The lipase@LF@rGO/PtNP@MOF-74 exhibits improved stability and resistance to organic solvents and significantly enhanced in thermal stability of the lipase@LF@rGO/PtNP@MOF-74 comparing to the free enzyme. The lipase@LF@rGO/PtNP@MOF-74 displayed excellent long-term storage stability, which could protect more than 80 % of the initial activity for 8 weeks. Besides, the lipase@LF@rGO/PtNP@MOF-74 had high reusability, which showed a high degree of activity (more than 75 %) after 20 cycles. As a bio-macromolecule, lactoferrin possesses bio-affinity, creating a favorable microenvironment for enzymes and minimizing the impact of external factors on their conformation and activity during bio-macromolecule utilization.

Polymer-Grafted 3D-Printed Material for Enzyme Immobilization—Designing a Smart Enzyme Carrier

One way to enhance the flow properties of packed bed reactors, including efficient mass transfer and high catalyst conversion rates, is the use of 3D printing. By creating optimized structures that prevent channeling and high pressure drops, it is possible to achieve the desired target. Nevertheless, additively manufactured structures most often possess a limited surface-area-to-volume-ratio, especially as porous printed structures are not standardized yet. One way to achieve surface-enhanced 3D-printed structures is surface modification to introduce surface-initiated polymers. In addition, when stimuli-sensitive polymers are chosen, autonomous process control is prospective. The current publication deals with the application of surface-induced polymerization on 3D-printed structures with the subsequent application as an enzyme carrier. Surface-induced polymerization can easily increase the number of enzymes by a factor of six compared to the non-modified 3D-printed structure. In addition, the swelling behavior of polyacrylic acid is proven, even with immobilized enzymes, enabling smart reaction control. The maximum activity of Esterase 2 (Est2) from Alicyclobacillus acidocaldarius per g carrier, determined after 2 h of polymer synthesis, is 0.61 U/gsupport. Furthermore, universal applicability is shown in aqueous and organic systems, applying an Est2 and Candida antarctica lipase B (CalB) catalyzed reaction and leaving space for improvement due to compatibility of the functionalization process and the here chosen organic solvent. Overall, no enzyme leaching is detectable, and process stability for at least five subsequent batches is ensured.

Construction of Immobilized Enzymes with Yeast and Metal-Organic Frameworks for Enhanced Biocatalytic Activities.

Metal-organic frameworks (MOFs) have become promising host materials for enzyme immobilization and protection. Herein, ZIF-8 nanocubes were successfully self-assembled onto yeast as a biological template to obtain hybrid Y@ZIF-8. The size, morphology, and loading efficiency of ZIF-8 nanoparticles assembled on yeast templates can be well-regulated by adjusting the various synthetic parameters. Particularly, the amount of water significantly affected the particle size of ZIF-8 assembled on yeast. Through using a cross-linking agent, the relative enzyme activity of Y@ZIF-8@t-CAT could be greatly enhanced and remained the highest even after seven consecutive cycles, with improved cycling stability, as compared to that of Y@ZIF-8@CAT. In addition to the effect of the physicochemical properties of Y@ZIF-8 on the loading efficiency, the temperature tolerance, pH tolerance, and storage stability of Y@ZIF-8@t-CAT were also systematically investigated. Importantly, the catalytic activity of free catalase was decreased to 72% by 45 days, while the activity of the immobilized catalase remained above 99%, suggesting good storage stability. The present work demonstrates that yeast-templated ZIF-8 nanoparticles have a high potential to be used as biocompatible immobilization materials and are promising candidates for the preparation of effective biocatalysts in biomedicine applications.

Surfactant-based metal-organic frameworks (MOFs) in the preparation of an active biocatalysis.

Metal-organic frameworks (MOFs) are used as ideal support materials thanks to their unique properties and have become the focus of interest in enzyme immobilization studies, especially in recent years. In order to increase the catalytic activity and stability of Candida rugosa lipase (CRL), a new fluorescence-based MOF (UiO-66-Nap) derived from UiO-66 was synthesized. The structures of the materials were confirmed by spectroscopic techniques such as FTIR, 1H NMR, SEM, and PXRD. CRL was immobilized on UiO-66-NH2 and UiO-66-Nap by adsorption technique and immobilization and stability parameters of UiO-66-Nap@CRL were examined. Immobilized lipases UiO-66-Nap@CRL exhibited higher catalytic activity (204U/g) than UiO-66-NH2 @CRL (168U/g), which indicates that the immobilized lipase (UiO-66-Nap@CRL) carries sulfonate groups, this is due to strong ionic interactions between the surfactant's polar groups and certain charged locations on the protein surface. The Free CRL lost its catalytic activity completely at 60°C after 100min, while UiO-66-NH2 @CRL and UiO-66-Nap@CRL retained 45 % and 56 % of their catalytic activity at the end of 120min, respectively. After 5 cycles, the activity of UiO-66-Nap@CRL remained 50 %, while the activity of UiO-66-NH2 @CRL was about 40 %. This difference is due to the surfactant groups (Nap) in UiO-66-Nap@CRL. These results show that the newly synthesized fluorescence-based MOF derivative (UiO-66-Nap) can be an ideal support material for enzyme immobilization and can be used successfully to protect and increase the activities of enzymes.

Research Progresses and Application of Biofuel Cells Based on Immobilized Enzymes

Enzymatic biofuel cells (EBFCs) are devices that use natural enzymes as catalysts to convert chemical energy from bio-sourced fuels into electrical energy. In this review, we summarize recent research progress and applications in the field of biofuel cells based on immobilized enzymes. Specifically, we discuss how to optimize and improve the electrochemical performance and operational stability of enzymatic biofuel cells through enzyme immobilization materials, enzyme immobilization methods, electron transfer improvement on enzyme electrodes, and cell construction methods. We also cover current and future practical applications of biofuel cells based on immobilized enzymes, including implantable enzymatic biofuel cells and wearable enzymatic biofuel cells. Additionally, we present some of the issues that still need to be addressed in the field of biofuel cells based on immobilized enzymes to ensure their technical and commercial viability and sustainability.

Insight into Bioactivity of In‐situ Trapped Enzyme‐Covalent‐Organic Frameworks

AbstractSelecting a suitable support material for enzyme immobilization with excellent biocatalytic activity and stability is a critical aspect in the development of functional biosystems. The highly stable and metal‐free properties of covalent‐organic frameworks (COFs) make them ideal supports for enzyme immobilization. Herein, we constructed three kinds of COFs via a biofriendly and one‐pot synthetic strategy at room temperature in aqueous solution. Among the three developed COFs (COF‐LZU1, RT‐COF‐1 and ACOF‐1), the horseradish peroxidase (HRP)‐incorporated COF‐LZU1 is found to retain the highest activity. Structural analysis reveals that a weakest interaction between the hydrated enzyme and COF‐LZU1, an easiest accessibility by the COF‐LZU1 to the substrate, as well as an optimal conformation of enzyme together promote the bioactivity of HRP‐COF‐LZU1. Furthermore, the COF‐LZU1 is revealed to be a versatile nanoplatform for encapsulating multiple enzymes. The COF‐LZU1 also offers superior protection for the immobilized enzymes under harsh conditions and during recycling. The comprehensive understanding of interfacial interactions of COF host and enzyme guest, the substrate diffusion, as well as the enzyme conformation alteration within COF matrices represents an opportunity to design the ideal biocatalysts and opens a broad range of applications of these nanosystems.

Carbonic Anhydrase Enhanced UV-Crosslinked PEG-DA/PEO Extruded Hydrogel Flexible Filaments and Durable Grids for CO2 Capture.

In this study, poly (ethylene glycol) diacrylate/poly (ethylene oxide) (PEG-DA/PEO) interpenetrating polymer network hydrogels (IPNH) were extruded into 1D filaments and 2D grids. The suitability of this system for enzyme immobilization and CO2 capture application was validated. IPNH chemical composition was verified spectroscopically using FTIR. The extruded filament had an average tensile strength of 6.5 MPa and elongation at break of 80%. IPNH filament can be twisted and bent and therefore is suitable for further processing using conventional textile fabrication methods. Initial activity recovery of the entrapped carbonic anhydrase (CA) calculated from esterase activity, showed a decrease with an increase in enzyme dose, while activity retention of high enzyme dose samples was over 87% after 150 days of repeated washing and testing. IPNH 2D grids that were assembled into spiral roll structured packings exhibited increased CO2 capture efficiency with increasing enzyme dose. Long-term CO2 capture performance of the CA immobilized IPNH structured packing was tested in a continuous solvent recirculation experiment for 1032 h, where 52% of the initial CO2 capture performance and 34% of the enzyme contribution were retained. These results demonstrate the feasibility of using rapid UV-crosslinking to form enzyme-immobilized hydrogels by a geometrically-controllable extrusion process that uses analogous linear polymers for both viscosity enhancement and chain entanglement purposes, and achieves high activity retention and performance stability of the immobilized CA. Potential uses for this system extend to 3D printing inks and enzyme immobilization matrices for such diverse applications as biocatalytic reactors and biosensor fabrication.