Magnetic metal-organic frameworks immobilized enzyme-based nano-biocatalytic systems for sustainable biotechnology

Immobilization of snailase and β-glucosidase on L-aspartic acid-modified magnetic amorphous ZIF for efficiently and sustainably producing ginsenoside compound K

Improving the catalytic efficiency and recyclability of immobilized enzyme remained a serious challenge in industrial applications. Enzyme immobilization in the amorphous zeolite imidazolate framework (aZIF) preserved high enzyme activity, but still faced separation difficulties and a low catalytic efficiency in practice. In this study, a one-pot co-precipitation method was used to form the enzyme-aZIF/magnetic nanoparticle (MNP) biocomposite by rapidly precipitating snailase (Sna) and β-glucosidase (β-G) with metal/ligand on MNP and modifying with L-aspartic acid (Asp). Thanks to Asp modification protecting the natural conformation of internal protein molecules and MNP stabilizing the conformation of active enzymes after immobilizing, Sna&β-G in the carrier had more stable conformations and higher catalytic efficiency than those in conventional ZIF-8, increasing the catalytic efficiency for converting ginsenoside Rb1 to rare ginsenoside compound K (CK) to 79.16 %. Moreover, while improving the stability of Sna&β-G, owing to the magnetism imparted by MNP, the immobilized enzyme maintained high enzyme activity and recovery after 7 cycles by rapid magnetic separation. The results provided guidance for developing immobilized Sna&β-G biocomposites with ideal catalytic efficiency and easy recovery to catalyze ginsenoside Rb1 to rare ginsenoside CK.

Icaritin production from Epimedium folium extract by a one-pot enzymatic cascade of a multifunctional glycosidase and rhamnosidase

Icaritin (ICT), a compound with diverse biological activities derived from Epimedium folium, is typically present in low concentrations in EFs. However, the abundant glycosyl-modified ICT compounds facilitate its transformation into ICT. Current biocatalytic production faces challenges, including low conversion rates and limited enzyme activity. This study developed a one-pot enzymatic cascade strategy for directly biotransform crude extracts of Epimedium folium (EEF) to produce ICT. The feasibility of catalyzing different ICT-related compounds in EEF was validated through molecular docking and substrate reactions. The selected glycosidase exhibited simultaneous activities as a glucosidase, xylosidase, and α-1,6-rhamnosidase, with the rhamnosidase showing outer-rhamnosidic activity and weak glucosidase activity. By using EFs as the substrate and employing whole-cells (Escherichia coli) containing LacS and BtRha proteins for synergistic catalysis, icariin can be efficiently synthesized within 6 h, achieving a conversion rate of 100 %. The enzymatic cascade for ICT production from crude extracts was elucidated by analyzing catalytic intermediates via HPLC. Compared to strategies using single or traditional multi-enzyme applications, this method shows advantages of ease to operation, high efficiency, and large production yield performance. This method has the potential to become an eco-friendly catalytic strategy for the large-scale production of icaritin.

Immobilization of snailase on glutamate modified MIL-88B(Fe) to efficiently convert the rare ginsenoside CK with high enzyme recyclability and stability

The carboxyl groups on MIL-88B(Fe) are crucial for the covalent immobilization of snailase, and the enzyme can convert common ginsenoside Rb1 into the rare ginsenoside compound K (CK) with higher bioavailability. The present study proposed glutamate-modified MIL-88B(Fe) for the immobilization of snailase to improve enzymatic activity and loading capacity. The surface topography characterized by SEM and CLSM indicated snailase was successfully encapsulated and uniformly distributed in the Sna@MIL-88B(Fe). The maximum immobilized capacities of snailase by MIL-88B(Fe)-Glu and MIL-88B(Fe) were 185 mg/g and 140 mg/g, respectively. Moreover, covalently immobilized snailase on MIL-88B(Fe)-Glu showed better pH, thermal, solvent, and storage stabilities than those immobilized on MIL-88B(Fe) and resolvase. Meanwhile, the reaction kinetics exhibited that the Km value of Sna@MIL-88B(Fe)-Glu (1.6 mM) was significantly lower than that of free snailase (2.1 mM), indicating a higher substrate affinity. Besides, more ginsenoside CK with higher conversion (60.71 %) was generated by Sna@MIL-88B(Fe)-Glu, even after five cycles. The glutamate modified covalent grafting method provides a highly efficient strategy for biocatalysis and a reference for the immobilized snailase-catalyzed transformation of rare ginsenosides CK.

Bioremediation of organic pollutants by laccase-metal-organic framework composites: A review of current knowledge and future perspective

Immobilized laccases are widely used as green biocatalysts for bioremediation of phenolic pollutants and wastewater treatment. Metal-organic frameworks (MOFs) show potential application for immobilization of laccase. Their unique adsorption properties provide a synergic effect of adsorption and biodegradation. This review focuses on bioremediation of wastewater pollutants using laccase-MOF composites, and summarizes the current knowledge and future perspective of their biodegradation and the enhancement strategies of enzyme immobilization. Mechanistic strategies of preparation of laccase-MOF composites were mainly investigated via physical adsorption, chemical binding, and de novo/co-precipitation approaches. The influence of architecture of MOFs on the efficiency of immobilization and bioremediation were discussed. Moreover, as sustainable technology, the integration of laccases and MOFs into wastewater treatment processes represents a promising approach to address the challenges posed by industrial pollution. The MOF-laccase composites can be promising and reliable alternative to conventional techniques for the treatment of wastewaters containing pharmaceuticals, dyes, and phenolic compounds. The detailed exploration of various immobilization techniques and the influence of MOF architecture on performance provides valuable insights for optimizing these composites, paving the way for future advancements in environmental biotechnology. The findings of this research have the potential to influence industrial wastewater treatment and promoting cleaner treatment processes and contributing to sustainability efforts.

Separable Metal-Organic Framework-Based Materials for the Adsorption of Emerging Contaminants

Thousands of chemicals have been released into the environment in recent decades. The presence of emerging contaminants (ECs) in water has emerged as a pressing concern. Adsorption is a viable solution for the removal of ECs. Metal-organic frameworks (MOFs) have shown great potential as efficient adsorbents, but their dispersed powder form limits their practical applications. Recently, researchers have developed various separable MOF-based adsorbents to improve their recyclability. The purpose of this review is to summarize the latest developments in the construction of separable MOF-based adsorbents and their applications in adsorbing ECs. The construction strategies for separable MOFs are classified into four categories: magnetic MOFs, MOF-fiber composites, MOF gels, and binder-assisted shaping. Typical emerging contaminants include pesticides, pharmaceuticals and personal care products, and endocrine-disrupting compounds. The adsorption performance of different materials is evaluated based on the results of static and dynamic adsorption experiments. Additionally, the regeneration methods of MOF-based adsorbents are discussed in detail to facilitate effective recycling and reuse. Finally, challenges and potential future research opportunities are proposed, including reducing performance losses during the shaping process, developing assessment systems based on dynamic purification and real polluted water, optimizing regeneration methods, designing multifunctional MOFs, and low-cost, large-scale synthesis of MOFs.

Surface Engineering of Superparamagnetic Graphene Oxide Nanosheet as a Chemically Tunable Platform for Facial Biofuel Production by Lipase

In this research, we utilized an efficient approach to synthesize superparamagnetic graphene oxide (SPGO) rapidly in a one-pot method using microwave irradiation of graphene oxide (GO), urea, and Fe(III) ion. Tannic acid (TA) was introduced to the surface of SPGO through a straightforward and eco-friendly process. Methods were devised to furnish GO nanosheets and modify their surfaces with TA in an environmentally friendly manner. Two series of nanosheets, namely, SPGO/TA-COOH and SPGO/TA-IM, were engineered on the surface and used for immobilizing lipase enzyme. Through various analytical tools, the unique biocatalysts SPGO/TA-COOH/L and SPGO/TA-IM/L were confirmed. These biocatalysts exhibited enhanced stability at high temperatures and pH levels compared with free lipase. They also demonstrated prolonged storage stability and reusability over four months and seven cycles, respectively. Furthermore, the catalytic activity of immobilized lipase showed minimal impairment based on kinetic behavior analysis. The kinetic constants of SPGO/TA-IM/L were determined as Vmax = 0.24 mM min-1, Km = 0.224 mM, and kcat = 0.8 s-1. Additionally, the efficiency of biocatalysts for biodiesel production from palmitic acid was studied, focusing on various reaction parameters, such as temperature, alcohol to palmitic acid molar ratio, water content, and lipase quantity. The esterification reaction of palmitic acid with methanol, ethanol, and isopropanol was tested in the presence of SPGO/TA-COOH/L and SPGO/TA-IM/L, and the corresponding esters were obtained with a yield of 30.6-91.6%.

Integration of multienzyme co-immobilization and biomimetic catalysis in magnetic metal-organic framework nanoflowers for α-amylase detection in fermentation samples

Multiple enzymes induce biological cascade catalysis is essential in nature and industrial production. However, the shortcomings of enzymes, including unsatisfactory stability, reusability, and sensitivity in harsh microenvironment, have restricted their broader use. Here, we report a facile method for fabricating a cascade system by combining the benefits of immobilized enzymes and biomimetic catalysis based on magnetic metal-organic framework nanoflowers (mMOFNFs). mMOFNFs prepared through the layered double hydroxide-derived strategy exhibited remarkable peroxidase-like activity and accessible amino interface, enabling it to serve not only as a reliable carrier for α-glucosidase and glucose oxidase fixation, but also as a nanozyme participating in cascade. On this basis, a colorimetric biosensor of excellent sensitivity and selectivity for α-amylase detection was constructed with a wide range (2-225 U L-1), low detection limit (2.48 U L-1), and rapid operation (30 min). This work provides a versatile strategy for establishing multi-enzyme cascade systems and rapid analysis of α-amylase.

Fast screening of α-glucosidase inhibitors from Ginkgo biloba leaf by using α-glucosidase immobilized on magnetic metal-organic framework

In this study, a ligand fishing method for the screening of α-glucosidase inhibitors from Ginkgo biloba leaf was established for the first time using α-glucosidase immobilized on the magnetic metal-organic framework. The immobilized α-glucosidase exhibited enhanced resistance to temperature and pH, as well as good thermal stability and reusability. Two ligands, namely quercitrin and quercetin, were screened from Ginkgo biloba leaf and identified by ultra-high performance liquid chromatography-tandem mass spectrometry. The half-maximal inhibitory concentration values for quercitrin and quercetin were determined to be 105.69 ± 0.39 and 83.49 ± 0.79 µM, respectively. Molecular docking further confirmed the strong inhibitory effect of these two ligands. The proposed approach in this study demonstrates exceptional efficiency in the screening of α-glucosidase inhibitors from complex natural medicinal plants, thus exhibiting significant potential for the discovery of antidiabetic compounds.

Advancements in enzyme immobilization on magnetic nanomaterials: toward sustainable industrial applications

Enzymes are widely used in biofuels, food, and pharmaceuticals. The immobilization of enzymes on solid supports, particularly magnetic nanomaterials, enhances their stability and catalytic activity. Magnetic nanomaterials are chosen for their versatility, large surface area, and superparamagnetic properties, which allow for easy separation and reuse in industrial processes. Researchers focus on the synthesis of appropriate nanomaterials tailored for specific purposes. Immobilization protocols are predefined and adapted to both enzymes and support requirements for optimal efficiency. This review provides a detailed exploration of the application of magnetic nanomaterials in enzyme immobilization protocols. It covers methods, challenges, advantages, and future perspectives, starting with general aspects of magnetic nanomaterials, their synthesis, and applications as matrices for solid enzyme stabilization. The discussion then delves into existing enzymatic immobilization methods on magnetic nanomaterials, highlighting advantages, challenges, and potential applications. Further sections explore the industrial use of various enzymes immobilized on these materials, the development of enzyme-based bioreactors, and prospects for these biocatalysts. In summary, this review provides a concise comparison of the use of magnetic nanomaterials for enzyme stabilization, highlighting potential industrial applications and contributing to manufacturing optimization.

Calcium-based MOFs as scaffolds for shielding immobilized lipase and enhancing its stability

The enzyme immobilization technology has become a key tool in the field of enzyme applications; however, improving the activity recovery and stability of the immobilized enzymes is still challenging. Herein, we employed a magnetic carboxymethyl cellulose (MCMC) nanocomposite modified with ionic liquids (ILs) for covalent immobilization of lipase, and used Ca-based metal-organic frameworks (MOFs) as the support skeleton and protective layer for immobilized enzymes. The ILs contained long side chains (eight CH2 units), which not only enhanced the hydrophobicity of the carrier and its hydrophobic interaction with the enzymes, but also provided a certain buffering effect when the enzyme molecules were subjected to compression. Compared to free lipase, the obtained CaBPDC@PPL-IL-MCMC exhibited higher specific activity and enhanced stability. In addition, the biocatalyst could be easily separated using a magnetic field, which is beneficial for its reusability. After 10 cycles, the residual activity of CaBPDC@PPL-IL-MCMC could reach up to 86.9%. These features highlight the good application prospects of the present immobilization method.

A comprehensive review on enzyme-based biosensors: Advanced analysis and emerging applications in nanomaterial-enzyme linkage

Biosensors with nanomaterials and enzymes detect and quantify specific targets in samples, converting recognition into measurable signals. The study explores the intrinsic synergy between these elements for detecting and quantifying particular targets in biological and environmental samples, with results demonstrated through bibliometric analysis and a comprehensive review of enzyme-based biosensors. Using WoS, 57,331 articles were analyzed and refined to 880. Key journals, countries, institutions, and relevant authors were identified. The main areas highlighted the multidisciplinary nature of the field, and critical keywords identified five thematic clusters, revealing the primary nanoparticles used (CNTs, graphene, AuNPs), major application fields, basic application themes, and niche topics such as sensitive detection, peroxidase activity, and quantum dot utilization. The biosensor overview covered nanomaterials and their primary applications, addressing recent advances and inherent challenges. Patent analysis emphasized the U.S. leadership in the industrial sector, contrasting with China's academic prominence. Future studies should focus on enhancing biosensor portability and analysis speed, with challenges encompassing efficient integration with recent technologies and improving stability and reproducibility in the nanomaterial-enzyme interaction.

Enhancing biocatalyst performance through immobilization of lipase (Eversa® Transform 2.0) on hybrid amine-epoxy core-shell magnetic nanoparticles

Magnetic nanoparticles were functionalized with polyethylenimine (PEI) and activated with epoxy. This support was used to immobilize Lipase (Eversa® Transform 2.0) (EVS), optimization using the Taguchi method. XRF, SEM, TEM, XRD, FTIR, TGA, and VSM performed the characterizations. The optimal conditions were immobilization yield (I.Y.) of 95.04 ± 0.79 %, time of 15 h, ionic load of 95 mM, protein load of 5 mg/g, and temperature of 25 °C. The maximum loading capacity was 25 mg/g, and its stability in 60 days of storage showed a negligible loss of only 9.53 % of its activity. The biocatalyst demonstrated better stability at varying temperatures than free EVS, maintaining 28 % of its activity at 70 °C. It was feasible to esterify free fatty acids (FFA) from babassu oil with the best reaction of 97.91 % and ten cycles having an efficiency above 50 %. The esterification of produced biolubricant was confirmed by NMR, and it displayed kinematic viscosity and density of 6.052 mm2/s and 0.832 g/cm3, respectively, at 40 °C. The in-silico study showed a binding affinity of -5.8 kcal/mol between EVS and oleic acid, suggesting a stable substrate-lipase combination suitable for esterification.

Immobilization of laccase on magnetic mesoporous silica as a recoverable biocatalyst for the efficient degradation of benzo[a]pyrene

Laccase is an efficient green biocatalyst, widely used for the degradation of various organic pollutants. However, free laccase is unstable and difficult to recover, which limits its practical application. In this study, a multilayer core-shell magnetic mesoporous silica (Fe3O4@d-SiO2@p-SiO2) microsphere with high specific surface area (275 m2 g-1) was fabricated for immobilization of laccase. The unique structure of Fe3O4@d-SiO2@p-SiO2 enabled the successful immobilization of laccase. Under the optimal immobilization conditions of laccase concentration of 1.5 mg mL-1, immobilization time of 6 h, immobilization pH of 6, the loading capacity of laccase was up to 567 mg g-1. Compared with free laccase, immobilized laccase exhibited remarkable pH stability, thermal stability and storage stability. Moreover, the immobilized laccase was easy to achieve magnetic recovery and possessed excellent reusability, with its activity remaining 58.2% after 10 consecutive reuses. More importantly, immobilized laccase had good degradation performance for benzo[a]pyrene (BaP), which can achieve rapid and efficient degradation of low concentration BaP over a wide range of pH and temperature. The removal efficiency of BaP was up to 99.0% within 1 h, and still exceeded 35.0% after 5 cycles. The removal of BaP by immobilized laccase was achieved through both adsorption and degradation. The degradation products and possible degradation pathways were determined by GC-MS analysis. This study indicated that Fe3O4@d-SiO2@p-SiO2 could effectively enhance the stability and biocatalytic activity of laccase, which is expected to provide a new clean biotechnology for the remediation of BaP contaminated sites.

Recent applications and future prospects of magnetic biocatalysts

Magnetic biocatalysts combine magnetic properties with the catalytic activity of enzymes, achieving easy recovery and reuse in biotechnological processes. Lipases immobilized by magnetic nanoparticles dominate. This review covers an advanced bibliometric analysis and an overview of the area, elucidating research advances. Using WoS, 34,949 publications were analyzed and refined to 450. The prominent journals, countries, institutions, and authors that published the most were identified. The most cited articles showed research hotspots. The analysis of the themes and keywords identified five clusters and showed that the main field of research is associated with obtaining biofuels derived from different types of sustainable vegetable oils. The overview of magnetic biocatalysts showed that these materials are also employed in biosensors, photothermal therapy, environmental remediation, and medical applications. The industry shows a significant interest, with the number of patents increasing. Future studies should focus on immobilizing new lipases in unique materials with magnetic profiles, aiming to improve the efficiency for various biotechnological applications.

Novel biocatalysts based on enzymes in complexes with nano- and micromaterials

In today's world, there is a wide array of materials engineered at the nano- and microscale, with numerous applications attributed to these innovations. This review aims to provide a concise overview of how nano- and micromaterials are utilized for enzyme immobilization. Enzymes act as eco-friendly biocatalysts extensively used in various industries and medicine. However, their widespread adoption faces challenges due to factors such as enzyme instability under different conditions, resulting in reduced effectiveness, high costs, and limited reusability. To address these issues, researchers have explored immobilization techniques using nano- and microscale materials as a potential solution. Such techniques offer the promise of enhancing enzyme stability against varying temperatures, solvents, pH levels, pollutants, and impurities. Consequently, enzyme immobilization remains a subject of great interest within both the scientific community and the industrial sector. As of now, the primary goal of enzyme immobilization is not solely limited to enabling reusability and stability. It has been demonstrated as a powerful tool to enhance various enzyme properties and improve biocatalyst performance and characteristics. The integration of nano- and microscale materials into biomedical devices is seamless, given the similarity in size to most biological systems. Common materials employed in developing these nanotechnology products include synthetic polymers, carbon-based nanomaterials, magnetic micro- and nanoparticles, metal and metal oxide nanoparticles, metal-organic frameworks, nano-sized mesoporous hydrogen-bonded organic frameworks, protein-based nano-delivery systems, lipid-based nano- and micromaterials, and polysaccharide-based nanoparticles.

Immobilization of Lipases Using Poly(vinyl) Alcohol

Lipases are very versatile enzymes because they catalyze various hydrolysis and synthesis reactions in a chemo-, regio-, and stereoselective manner. From a practical point of view, immobilization allows the recovery and stabilization of the biocatalyst for its application in different types of bioreactors. Among the various support options for immobilizing lipases is polyvinyl alcohol (PVA), which, when functionalized or combined with other materials, provides different characteristics and properties to the biocatalyst. This review analyzes the multiple possibilities that PVA offers as a material to immobilize lipases when combined with alginate, chitosan, and hydroxypropylmethylcellulose (HPMC), incorporating magnetic properties together with the formation of fibers and microspheres. The articles analyzed in this review were selected using the Scopus database in a range of years from 1999 to 2023, finding a total of 42 articles. The need to expand knowledge in this area is due to the great versatility and scaling possibilities that PVA has as a support for lipase immobilization and its application in different bioreactor configurations.