Construction of Thermophilic Lipase-Embedded Metal-Organic Frameworks via Biomimetic Mineralization: A Biocatalyst for Ester Hydrolysis and Kinetic Resolution

Research Progress of Metal-Organic Frameworks as Drug Delivery Systems

Metal-organic frameworks (MOFs) are composite crystalline materials created through the coordination of metal ions and organic ligands. MOFs have attracted extensive attention in the biomedical field based on the advantages of internal porosity, customizable porosity, and facile surface modification. This review examines the utilization of MOFs in drug delivery systems, focusing on the research progress from the aspects of coloading drug systems, intelligent responsive carriers, biological macromolecule stabilizers, self-driving micro/nanomotors, and multifunctional living carriers. In addition, the current challenges the research faces are also discussed. The review aims to provide a reference for the further application of MOFs as advanced drug delivery systems.

Magnetic nanoflowers: a hybrid platform for enzyme immobilization

The use of organic-inorganic hybrid nanoflowers as a support material for enzyme immobilization has gained significant attention in recent years due to their high stability, ease of preparation, and enhanced catalytic activity. However, a major challenge in utilizing these hybrid nanoflowers for enzyme immobilization is the difficulty in handling and separating them due to their low density and high dispersion. To address this issue, magnetic nanoflowers have emerged as a promising alternative enzyme immobilization platform due to their easy separation, structural stability, and ability to enhance catalytic efficiency. This review focuses on different methods for designing magnetic nanoflowers, as well as future research directions. Additionally, it provides examples of enzymes immobilized in the form of magnetic nanoflowers and their applications in environmental remediation, biosensors, and food industries. Finally, the review discusses possible ways to improve the material for enhanced catalytic activity, structural stability, and scalability.

Bioinspired mp20 mimicking uricase in ZIF-8: Metal ion dependent for controllable activity

Mini protein mimicking uricase (mp20) has shown significant potential as a replacement for natural enzymes in the development of uric acid biosensors. However, the design of mp20 has resulted to an inactive form of peptide, causing of loss their catalytic activity. Herein, this paper delineates the impact of various metal cofactors on the catalytic activity of mp20. The metal ion-binding site prediction and docking (MIB) web server was employed to identify the metal ion binding sites and their affinities towards mp20 residues. Among the tested metal ions, Cu2+ displayed the highest docking score, indicating its preference for interaction with Thr16 and Asp17 residues of mp20. To assess the catalytic activity of mp20 in the presence of metal ions, uric acid assays was monitored using a colorimetric method. The presence of Cu2+ in the assays promotes the activation of mp20, resulting in a color change based on quinoid production. Furthermore, the encapsulation of the mp20 within zeolitic imidazolate framework-8 (ZIF-8) notably improved the stability of the biomolecule. In comparison to the naked mp20, the encapsulated ZIFs biocomposite (mp20@ZIF-8) demonstrates superior stability, selectivity and sensitivity. ZIF's porous shells provides excellent protection, broad detection (3-100 μM) with a low limit (4.4 μM), and optimal function across pH (3.4-11.4) and temperature (20-100°C) ranges. Cost-effective and stable mp20@ZIF-8 surpasses native uricase, marking a significant biosensor technology breakthrough. This integration of metal cofactor optimization and robust encapsulation sets new standards for biosensing applications.

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%.

Enzyme-Immobilized Porous Crystals for Environmental Applications

Developing efficient technologies to eliminate or degrade contaminants is paramount for environmental protection. Biocatalytic decontamination offers distinct advantages in terms of selectivity and efficiency; however, it still remains challenging when applied in complex environmental matrices. The main challenge originates from the instability and difficult-to-separate attributes of fragile enzymes, which also results in issues of compromised activity, poor reusability, low cost-effectiveness, etc. One viable solution to harness biocatalysis in complex environments is known as enzyme immobilization, where a flexible enzyme is tightly fixed in a solid carrier. In the case where a reticular crystal is utilized as the support, it is feasible to engineer next-generation biohybrid catalysts functional in complicated environmental media. This can be interpreted by three aspects: (1) the highly crystalline skeleton can shield the immobilized enzyme against external stressors. (2) The porous network ensures the high accessibility of the interior enzyme for catalytic decontamination. And (3) the adjustable and unambiguous structure of the reticular framework favors in-depth understanding of the interfacial interaction between the framework and enzyme, which can in turn guide us in designing highly active biocomposites. This Review aims to introduce this emerging biocatalysis technology for environmental decontamination involving pollutant degradation and greenhouse gas (carbon dioxide) conversion, with emphasis on the enzyme immobilization protocols and diverse catalysis principles including single enzyme catalysis, catalysis involving enzyme cascades, and photoenzyme-coupled catalysis. Additionally, the remaining challenges and forward-looking directions in this field are discussed. We believe that this Review may offer a useful biocatalytic technology to contribute to environmental decontamination in a green and sustainable manner and will inspire more researchers at the intersection of the environment science, biochemistry, and materials science communities to co-solve environmental problems.

Enhanced Enzymatic Performance of Immobilized Pseudomonas fluorescens Lipase on ZIF-8@ZIF-67 and Its Application to the Synthesis of Neryl Acetate with Transesterification Reaction

In this study, hybrid skeleton material ZIF-8@ZIF-67 was synthesized by the epitaxial growth method and then was utilized as a carrier for encapsulating Pseudomonas fluorescens lipase (PFL) through the co-precipitation method, resulting in the preparation of immobilized lipase (PFL@ZIF-8@ZIF-67). Subsequently, it was further treated with glutaraldehyde to improve protein immobilization yield. Under optimal immobilization conditions, the specific hydrolytic activity of PFL@ZIF-8@ZIF-67 was 20.4 times higher than that of the free PFL. The prepared biocatalyst was characterized and analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR). Additionally, the thermal stability of PFL@ZIF-8@ZIF-67 at 50 °C was significantly improved compared to the free PFL. After 7 weeks at room temperature, PFL@ZIF-8@ZIF-67 retained 78% of the transesterification activity, while the free enzyme was only 29%. Finally, PFL@ZIF-8@ZIF-67 was applied to the neryl acetate preparation in a solvent-free system, and the yield of neryl acetate reached 99% after 3 h of reaction. After 10 repetitions, the yields of neryl acetate catalyzed by PFL@ZIF-8@ZIF-67 and the free PFL were 80% and 43%, respectively.

Co-Immobilization of ADH and GDH on Metal-Organic-Framework: An Effective Biocatalyst for Asymmetric Reduction of Ketones

Chiral alcohols are not only important building blocks of various bioactive natural compounds and pharmaceuticals, but can serve as synthetic precursors for other valuable organic chemicals, thus the synthesis of these products is of great importance. Bio-catalysis represents one effective way to obtain these molecules, however, the weak stability and high cost of enzymes often hinder its broad application. In this work, we designed a biological nanoreactor by embedding alcohol dehydrogenase (ADH) and glucose dehydrogenase (GDH) in metal-organic-framework ZIF-8. The biocatalyst ADH&GDH@ZIF-8 could be applied to the asymmetric reduction of a series of ketones to give chiral alcohols in high yields (up to 99 %) and with excellent enantioselectivities (>99 %). In addition, the heterogeneous biocatalyst could be recycled and reused at least four times with slight activity decline. Moreover, E. coli containing ADH and GDH was immobilized by ZIF-8 to form biocatalyst E. coli@ZIF-8, which also exhibits good catalytic behaviours. Finally, the chiral alcohols are further converted to marketed drugs (R)-Fendiline, (S)-Rivastigmine and NPS R-568 respectively.

Ultrahigh Enzyme Loading Metal-Organic Frameworks for Deep Tissue Pancreatic Cancer Photoimmunotherapy

Protein drugs hold promise in treating multiple complex diseases, including cancer. The priority of protein drug application is precise delivery of substantial bioactive protein into tumor site. Metal-organic-framework (MOF) is widely considered as a promising carrier to encapsulate protein drug owing to the noncovalent interaction between carrier and protein. However, limited loading efficiency and potential toxicity of metal ion in MOF restrict its application in clinical research. Herein, a tumor targeted collagenase-encapsulating MOF via protein-metal ion-organic ligand coordination (PMOCol ) for refining deep tissue pancreatic cancer photoimmunotherapy is developed. By an expedient method in which the ratio of metal ion, histidine residues of protein and ligand is precisely controlled, PMOCol is constructed with ultrahigh encapsulation efficiency (80.3 wt%) and can release collagenase with high enzymatic activity for tumor extracellular matrix (ECM) regulation after reaching tumor microenvironment (TME). Moreover, PMOcol exhibits intensively poorer toxicity than the zeolitic imidazolate framework-8 biomineralized protein. After treatment, the pancreatic tumor with abundant ECM shows enhanced immunocyte infiltration owing to extracellular matrix degradation that improves suppressive TME. By integrating hyperthermia agent with strong near-infrared absorption (1064 nm), PMOCol can induce acute immunogenicity to host immunity activation and systemic immune memory production to prevent tumor development and recurrence.

Enzymes in "Green" Synthetic Chemistry: Laccase and Lipase

Enzymes play an important role in numerous natural processes and are increasingly being utilized as environmentally friendly substitutes and alternatives to many common catalysts. Their essential advantages are high catalytic efficiency, substrate specificity, minimal formation of byproducts, and low energy demand. All of these benefits make enzymes highly desirable targets of academic research and industrial development. This review has the modest aim of briefly overviewing the classification, mechanism of action, basic kinetics and reaction condition effects that are common across all six enzyme classes. Special attention is devoted to immobilization strategies as the main tools to improve the resistance to environmental stress factors (temperature, pH and solvents) and prolong the catalytic lifecycle of these biocatalysts. The advantages and drawbacks of methods such as macromolecular crosslinking, solid scaffold carriers, entrapment, and surface modification (covalent and physical) are discussed and illustrated using numerous examples. Among the hundreds and possibly thousands of known and recently discovered enzymes, hydrolases and oxidoreductases are distinguished by their relative availability, stability, and wide use in synthetic applications, which include pharmaceutics, food and beverage treatments, environmental clean-up, and polymerizations. Two representatives of those groups-laccase (an oxidoreductase) and lipase (a hydrolase)-are discussed at length, including their structure, catalytic mechanism, and diverse usage. Objective representation of the current status and emerging trends are provided in the main conclusions.

The effects of the chemical modification on immobilized lipase features are affected by the enzyme crowding in the support

In this article, we have analyzed the interactions between enzyme crowding on a given support and its chemical modification (ethylenediamine modification via the carbodiimide route and picryl sulfonic (TNBS) modification of the primary amino groups) on the enzyme activity and stability. Lipase from Thermomyces lanuginosus (TLL) and lipase B from Candida antarctica (CALB) were immobilized on octyl-agarose beads at two very different enzyme loadings, one of them exceeding the capacity of the support, one well under this capacity. Chemical modifications of the highly loaded and lowly loaded biocatalysts gave very different results in terms of activity and stability, which could increase or decrease enzyme activity depending on the enzyme support loading. For example, both lowly loaded biocatalysts increased their activity after modification while the effect was the opposite for the highly loaded biocatalysts. Additionally, the modification with TNBS of highly loaded CALB biocatalyst increased its stability while decrease the activity.

Metal-organic frameworks for enzyme immobilization and nanozymes: A laccase-focused review

Laccases are natural catalysts with remarkable catalytic activity. However, their application is limited by their lack of stability. Metal-organic frameworks (MOFs) have emerged as a promising alternative for enzyme immobilization. Enzymes can be immobilized in MOFs via two approaches: postsynthetic immobilization and in situ immobilization. In postsynthetic immobilization, an enzyme is embedded after MOF formation by covalent interactions or adsorption. In contrast, in in situ immobilization, a MOF is formed in the presence of an enzyme. Additionally, MOFs have exhibited intrinsic enzyme-like activity. These materials, known as nanozymes when they have the ability to replace enzymes in certain catalytic processes, have multiple key advantages, such as low cost, easy preparation, and large surface areas. This review presents a general overview of the most recent advances in both enzyme@MOF biocatalysts and MOF-based nanozymes in different applications, with a focus on laccase, which is one of the most widely investigated enzymes with excellent industrial potential.

Construction of molecular enrichment accelerators via assembly of enzyme surface grafted polymer and cyclodextrin achieving rapid and stable ester catalysis for biodiesel synthesis

Efficient and stable catalysis has always been the core concept of enzyme catalysis in industrial processes for manufacturing. Here, we constructed molecular enrichment accelerators to synergistically enhance enzyme activity and stability by assembling enzyme surface grafted polymer and cyclodextrin. At 40 °C, the enzyme activity of CalB-PNIPAM212/β-CD was 2.9 times that of CalB-PNIPAM212. The enzyme activity of CalB-PNIPAM428/γ-CD had reached 1.61 times that of CalB. At the same time, the stability of CalB-PNIPAM212/β-CD and CalB-PNIPAM428/γ-CD are slightly better than that of CalB under high temperature, organic solution and extreme pH conditions. The synergistic increase in activity and stability of the lipase-polymer assembly was achieved due to the structure of assembly, in which the role of cyclodextrin could enrich substrate affecting molecular diffusion. In addition, the lipase-polymer assembly proved to be an efficient catalyst for biodiesel synthesis, with a biodiesel conversion 1.4 times that of CalB at 60 °C. Therefore, this simple and low-cost lipase-polymer assembly provides new possibilities for the construction of high-efficiency industrial biocatalytic catalysts.

Fabrication of immobilized lipases for efficient preparation of 1,3-dioleoyl-2-palmitoylglycerol

This study aims to fabricate immobilized lipases for efficient preparation of 1,3-dioleoyl-2-palmitoyl-glycerol (OPO) through acidolysis of glycerol tripalmitate (PPP). Twelve (three types) supports and five lipases were studied carefully. Among them, the immobilized Thermomyces lanuginosa lipase (TLL) samples exhibited overall better performance than that of other immobilized lipases. Particularly, organic groups functionalized SBA-15 (R-SBA-15) supported TLL (TLL@R-SBA-15) samples gave PPP conversion from 97.70 to 99.00 % and OPO content from 59.52 to 64.73 %. After optimization, PPP conversion up to 99.07 %, OPO content 73.15 % and sn-2 palmitic acid content 90.09 % were obtained with TLL@C₁₈H₃₇-SBA-15 as catalyst. Moreover, TLL@C₁₈H₃₇-SBA-15 exhibited better acidolysis performance from 50 °C than that from 60 to 80 °C, which helped inhibit acyl migration. In addition, after 5 cycles of reuse, TLL@C₁₈H₃₇-SBA-15 retained 81.04 % (based on OPO content) and 98.88 % (based on sn-2 palmitic acid content) of its initial activity, indicating it had an attractive prospect in future applications.

Recent Advances in the Biocatalytic Mitigation of Emerging Pollutants: A Comprehensive Review

The issue of environmental pollution has been worsened by the emergence of new contaminants whose morphology is yet to be fully understood. Several techniques have been adopted to mitigate the pollution effects of these emerging contaminants, and bioremediation involving plants, microbes, or enzymes has stood out as a cost-effective and eco-friendly approach. Enzyme-mediated bioremediation is a very promising technology as it exhibits better pollutant degradation activity and generates less waste. However, this technology is subject to challenges like temperature, pH, and storage stability, in addition to recycling difficulty as it is arduous to isolate them from the reaction media. To address these challenges, the immobilization of enzymes has been successfully applied to ameliorate the activity, stability, and reusability of enzymes. Although this has significantly increased the uses of enzymes over a wide range of environmental conditions and facilitated the use of smaller bioreactors thereby saving cost, it still comes with additional costs for carriers and immobilization. Additionally, the existing immobilization methods have their individual limitations. This review provides state-of-the-art information to readers focusing on bioremediation using enzymes. Different parameters such as: the sustainability of biocatalysts, the ecotoxicological evaluation of transformation contaminants, and enzyme groups used were reviewed. The efficacy of free and immobilized enzymes, materials and methods for immobilization, bioreactors used, challenges to large-scale implementation, and future research needs were thoroughly discussed.

Enhanced lysosomal escape of cell penetrating peptide-functionalized metal-organic frameworks for co-delivery of survivin siRNA and oridonin

In recent years, small interfering RNA (siRNA) has been widely used in the treatment of human diseases, especially tumors, and has shown great appeal. However, the clinical application of siRNA faces several challenges. Insufficient efficacy, poor bioavailability, poor stability, and lack of responsiveness to a single therapy are the main problems affecting tumor therapy. Here, we designed a cell-penetrating peptide (CPP)-modified metal organic framework nanoplatform (named PEG-CPP33@ORI@survivin siRNA@ZIF-90, PEG-CPP33@NPs) for targeted co-delivery of oridonin (ORI), a natural anti-tumor active ingredient) and survivin siRNA in vivo. This can improve the stability and bioavailability of siRNA and the efficacy of siRNA monotherapy. The high drug-loading capacity and pH-sensitive properties of zeolite imidazolides endowed the PEG-CPP33@NPs with lysosomal escape abilities. The Polyethylene glycol (PEG)-conjugated CPP (PEG-CPP33) coating significantly improved the uptake in the PEG-CPP33@NPs in vitro and in vivo. The results showed that the co-delivery of ORI and survivin siRNA greatly enhanced the anti-tumor effect of PEG-CPP33@NPs, demonstrating the synergistic effect between ORI and survivin siRNA. In summary, the novel targeted nanobiological platform loaded with ORI and survivin siRNA presented herein showed great advantages in cancer therapy, and provides an attractive strategy for the synergistic application of chemotherapy and gene therapy.

Multivariate Porous Aromatic Frameworks with High Porosity and Hierarchical Structures for Enzyme Immobilization

As materials with permanently porous structures and readily modifying availability, porous aromatic frameworks (PAFs) are considered as promising porous materials with versatile functionality. Currently the designable synthesis of PAFs with the desired surface area and pore size is still a challenge, and instead kinetically irreversible coupling reactions for PAFs synthesis has resulted in the unpredictable connection of building units. Herein, a series of PAFs with highly porous and hierarchical structures were successfully synthesized through a multivariate inspired strategy, where multiple building units with various topologies and sizes were selected for PAFs synthesis. All the PAFs synthesized through this strategy possessed hierarchical structures and high specific surface areas at the same time. Encouraged by their high surface area and hierarchical structures, we loaded lipase onto one of the multivariate PAFs. The enzyme loading content of the obtained lipase@PAF-147 was as high as 1456 mg g^-1, which surpassed any other currently reported enzyme loading materials. The lipase@PAF-147 also exhibited favorable catalytic activity and stability to a model reaction of p-nitrophenyl caprylate (p-NPC) hydrolysis. This multivariate strategy inspired synthetic method broadens the selection of building units for PAFs design and opens a new avenue for the design of functional porous materials.

Lipase-based MIL-100(Fe) biocomposites as chiral stationary phase for high-efficiency capillary electrochromatographic enantioseparation

A novel chiral porous column was fabricated by lipase immobilized MIL-100(Fe) biocomposites as chiral stationary phase through covalent coupling and applied to capillary electrochromatographic enantioseparation. MOF-based lipase biocomposites not only enhance stereoselective activities but also improve the stability and applicability of the enzyme. The functionalized porous columns were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and powder X-ray diffraction. The performance of the porous column was evaluated by enantioseparating amino acid enantiomers, affording high resolution over 2.0. Besides, the enantio-resolutions of phenylephrine, phenylsuccinic acid, chloroquine, and zopiclone were also greater than 2.0. The relative standard deviations of run-to-run, intra-, and inter-day repeatability were within 4.0% in terms of resolution and retention time, exhibiting excellent stability of the column. Conceivably, the results show that MOF-based lipase composites as chiral stationary phase offer a highly efficient means for enantioseparation in capillary electrochromatography, attributing to the enhanced enantioselective activities of lipase by highly ordered frameworks.

Enhanced Activity of Enzyme Immobilized on Hydrophobic ZIF-8 Modified by Ni2+ Ions

The development of efficient enzyme immobilization to promote their recyclability and activity is highly desirable. Zeolitic imidazolate framework-8 (ZIF-8) has been proved to be an effective platform for enzyme immobilization due to its easy preparation and biocompatibility. However, the intrinsic hydrophobic characteristic hinders its further development in this filed. Herein, a facile synthesis approach was developed to immobilize pepsin (PEP) on the ZIF-8 carrier by using Ni²⁺ ions as anchor (ZIF-8@PEP-Ni). By contrast, the direct coating of PEP on the surface of ZIF-8 (ZIF-8@PEP) generated significant conformational changes. Electrochemical oxygen evolution reaction (OER) was employed to study the catalytic activity of immobilized PEP. The ZIF-8@PEP-Ni composite attains remarkable OER performance with an ultralow overpotential of only 127 mV at 10 mA cm^-2 , which is much lower than the 690 and 919 mV overpotential values of ZIF-8@PEP and PEP, respectively.

A comprehensive review on bio-mimicked multimolecular frameworks and supramolecules as scaffolds for enzyme immobilization

Immobilization depicts a propitious route to optimize the catalytic performances, efficient recovery, minimizing autocatalysis, and also augment the stabilities of enzymes, particularly in unnatural environments. In this opinion, supramolecules and multimolecular frameworks have captivated immense attention to achieve profound controllable interactions between enzyme molecules and well-defined natural or synthetic architectures to yield protein bioconjugates with high accessibility for substrate binding and enhanced enantioselectivities. This scholastic review emphasizes the possibilities of associating multimolecular complexes with biological entities via several types of interactions, namely covalent interactions, host-guest complexation, π - π ${\rm{\pi }}-{\rm{\pi }}$ interactions, intra/inter hydrogen bondings, electrostatic interactions, and so forth offers remarkable applications for the modulations of enzymes. The potential synergies between artificial supramolecular structures and biological systems are the primary concern of this pedagogical review. The majority of the research primarily focused on the dynamic biomolecule-responsive supramolecular assemblages and multimolecular architectures as ideal platforms for the recognition and modulation of proteins and cells. Embracing sustainable green demeanors of enzyme immobilizations in a quest to reinforce site-selectivity, catalytic efficiency, and structural integrality of enzymes are the contemporary requirements of the biotechnological sectors that instigate the development of novel biocatalytic systems.

Facile synthesis of dual-hydrolase encapsulated magnetic ZIF-8 composite for efficient removal of multi-pesticides induced pollution in water

Multi-pesticides pollution induced by organophosphorus insecticides (OPs) and aryloxyphenoxypropionate herbicides (AOPPs) has become a significant challenge in bioremediation of water pollution due to their prolonged and over application. Though a number of physical, chemical, and biological approaches have been developed for different pesticides, the explorations usually focus on eliminating single pesticide pollution. Herein, a heterostructure nanocomposite OPH/QpeH@mZIF-8, encapsulating OPs hydrolase OPH and AOPPs hydrolase QpeH in the magnetic zeolitic imidazolate frameworks-8 (mZIF-8), was synthesized through a facile one-pot method in aqueous solution. The immobilized OPH and QpeH in mZIF-8 showed high activities towards the two most common OPs and AOPPs, i.e., chlorpyrifos and quizalofop-P-ethyl, which were hydrolyzed to 3,5,6-Trichloro-2-pyridino (TCP) and quizalofop acid, respectively. Moreover, the magnetic nanocatalyst possessed great tolerance towards broad pH range, high temperatures, and different chemical solvents and excellent recyclability. More importantly, compared to free OPH and QpeH, OPH/QpeH@mZIF-8, with significantly enhanced degradation capability, exhibited enormous potential for simultaneous removal of chlorpyrifos and quizalofop-p-ethyl from the surface and industrial wastewater. Overall, the study demonstrates the applicability of this strategy for utilizing magnetic nanocatalysts encapsulating multiple enzymes due to its simplicity, high efficiency, and economic benefits to removing pesticide compound pollution from various water resources.

Biodiesel Production from Transesterification with Lipase from Pseudomonas cepacia Immobilized on Modified Structured Metal Organic Materials

This research presents the modification of MOF-199 and ZIF-8 using furfuryl alcohol (FA) as a carbon source to subsequently fix lipase from Pseudomonas cepacia and use these biocatalysts in the transesterification of African palm oil (APO). The need to overcome the disadvantages of free lipases in the biodiesel production process led to the use of metal organic framework (MOF)-type supports because they provide greater thermal stability and separation of the catalytic phase, thus improving the activity and efficiency in relation to the use of free lipase, disadvantages that could not be overcome with the use of other types of catalysts used in transesterification/esterification reactions for the production of biodiesel. The modification of MOFs ZIF-8 and MOF-199 with FA increases the pore volume which allows better immobilization of Pseudomonas cepacia lipase (PCL). The results show that these biocatalysts undergo transesterification with biodiesel yields above 90%. Additionally, studies were carried out on the effect of (1) enzyme loading, 2) enzyme immobilization time, (3) enzyme immobilization temperature, and (4) pH on the % immobilization of the enzyme and the specific activity. The results show that the highest immobilization efficiency for the FA@ZIF-8 support has a value of 91.2% when the load of this support was 3.5 mg/mg and has a specific activity of 142.5 U/g protein. The FA@MOF-199 support presented 80.3% enzyme immobilization and 125% U/g specific activity protein. We established that the specific activity increases in the period from 0.5 to 5.0 h for the systems under investigation. After this time, both the specific activity and the % efficiency of enzyme immobilization decrease. Therefore, 5.0 h (immobilization efficiency of 95 and 85% for FA@MOF-199, respectively) was chosen as the most appropriate time for PCL immobilization. Methods of adding methanol, with three and four steps, were tested, where biodiesel yields greater than 90% were obtained for the biocatalysts synthesized in this work (FA@ZIF-8-PCL and FA@MOF-199-PCL) and above 70% for free PCL, and the maximum yield was reached at a molar ratio between methanol and APO of 4:1 when using the one-step method under the same reaction conditions (as mentioned above). Only the results of FA@ZIF-8-PCL are presented here; however, it should be noted that the results for biocatalyst FA@MOF-199-PCL and lipase-free PCL presented the same behavior. The order of biocatalyst performance was FA@ZIF-8-PCL > FA@MOF-199-PCL > PCL-Free, which demonstrates that the use of FA as a modifier is a novel aspect in the conversion of palm oil into biodiesel components.

Towards Solving the PFAS Problem: The Potential Role of Metal-Organic Frameworks

Per- and polyfluoroalkyl substances (PFAS) are a group of recalcitrant molecules that have been used since the 1940s in a variety of applications. They are now linked to a host of negative health outcomes and are extremely resistant to degradation under environmental conditions. Currently, membrane technologies or adsorbents are used to remediate contaminated water. These techniques are either inefficient at capturing smaller PFAS molecules, have high energy demands, or result in concentrated waste that must be incinerated at high temperatures. This Review focuses on what role metal-organic frameworks (MOFs) may play in addressing the PFAS problem. Specifically, how the unique properties of MOFs such as their well-defined pore sizes, ultra-high internal surface area, and tunable surface chemistry may be a sustainable solution for PFAS contamination.

Hybrid biomimetic assembly enzymes based on ZIF-8 as “intracellular scavenger” mitigating neuronal damage caused by oxidative stress

Superoxide dismutase (SOD) was immobilized in zeolite imidazolate framework-8 (ZIF-8) through biomimetic mineralization method, namely SOD@ZIF-8, which was then used in the treatment of nerve damage by eliminating reactive oxygen species (ROS). A series of chemical characterization and enzymatic activity researches revealed that SOD was successfully embedded into ZIF-8 without apparent influence on the antioxidant activity of SOD. Cell level experiments showed that SOD@ZIF-8 could be effectively endocytosed by cells. The activity of SOD@ZIF-8 in scavenging ROS played a critical role in protecting SHSY-5Y cells from MPP+-induced cell model and relieving cell apoptosis, indicating that SOD@ZIF-8 could effectively rescue ROS-mediated neurological disorders though removing excessive ROS produced in vitro.

Construction Method of Industrial College in Vocational Colleges Based on Cluster Analysis Algorithm

In the context of the combination of industry and education, the construction of industrial colleges in vocational colleges can drive the scientific development of specialty settings in colleges and universities, and promote the way for colleges to expand students' practical teaching under the teaching of theoretical knowledge, and it is also an effective way for students to stimulate their learning enthusiasm and innovation enthusiasm. Colleges and universities can increase the direction and characteristics of specialist settings in colleges while enhancing instructors' professional level through school-business collaboration, and growing measures of talent training in colleges and universities plays a significant guiding role. The way to set up industrial colleges in vocational colleges reflects the development characteristics of talent training mode in the new era, and it is also an effective way to meet the practical training of students and the actual needs of society. It is a new school running mode of transforming productivity, cooperation, and mutual benefit, which is very worthy of promotion and development. This paper analyzes the problems existing in the construction of industrial colleges in vocational colleges in China and finds out the corresponding solutions. A path method of industrial college construction in vocational colleges based on the cluster analysis algorithm is proposed. The validity of this model is verified by experiments, which lays a foundation for the construction of industrial colleges in vocational colleges.

Biomimetic metal-organic frameworks as protective scaffolds for live-virus encapsulation and vaccine stabilization

The invaluable health, economic and social impacts of vaccination are hard to exaggerate. The ability to stabilize vaccines is urgently required for their equitable distribution without the dependence on the 'cold-chain' logistics. Herein, for the first time we report biomimetic-mineralization of live-viral vaccines using metal-organic frameworks (MOFs) to enhance their storage stability from days to months. Applying ZIF-8 and aluminium fumarate (Alfum), the Newcastle Disease Virus (NDV) V4 strain and Influenza A WSN strain were encapsulated with remarkable retention of their viral titre. The ZIF-8@NDV, ZIF-8@WSN and Alfum@WSN composites were validated for live-virus recovery using a tissue culture infectious dose (TCID₅₀) assay. With the objective of long-term stabilization, we developed a novel, trehalose (T) and skim milk (SM) stabilized, freeze-dried MOF@Vaccine composite, ZIF-8@NDV+T/SM. The thermal stability of this composite was investigated and compared with the control NDV and non-encapsulated, freeze-dried NDV+T/SM composite at 4 °C, RT, and 37 °C over a period of 12 weeks. We demonstrate the fragility of the control NDV vaccine which lost all viability at RT and 37°C by 12 and 4 weeks, respectively. Comparing the freeze-dried counterparts, the MOF encapsulated ZIF-8@NDV+T/SM demonstrated significant enhancement in stability of the NDV+T/SM composite especially at RT and 37 °C upto 12 weeks. STATEMENT OF SIGNIFICANCE: Vaccination is undoubtedly one of the most effective medical interventions, saving millions of lives each year. However, the requirement of 'cold-chain' logistics is a major impediment to widespread immunization. Live viral vaccines (LVVs) are widely used vaccine types with proven efficacy and low cost. Nonetheless, their complex composition increases their susceptability to thermal stress. Several LVV thermostabilization approaches have been investigated, including their complex engineering and the facile addition of stabilizers. Still, the lack of a universal approach urgently requires finding a stabilization technique especially when additives alone may not be sufficient. Herein, we demonstrate MOF biomimetic-mineralization technology to encapsulate LVVs developing an optimised composite which significantly preserves vaccines without refrigeration for extended periods of time.

Encapsulation of CALB by nucleotide/metal ions coordination nanoparticles: highly selective catalysis of esterification while poor performance in glycerolysis reaction

BACKGROUND

Enzymatic esterification is attracting for particular high-acid oil deacidification. In this study, Candida antarctica lipase B (CALB) was encapsulated into a series of nucleotide-hybrid metal coordination polymers (CPs), which were constructed by guanosine 5'-monophosphate (GMP) and various metals.

RESULTS

We here found that, most of the present CPs encapsulated CALB (CALB@CPs) samples were highly selective for esterification while poor in glycerolysis reaction. They exhibited quite poor performance in glycerolysis, with triacylglycerols (TAGs) conversion lower than 5%, despite this considerable enzymatic hydrolysis activities were observed. However, they (most of them) showed good performance in esterification of fatty acids and glycerol for TAG synthesis. In addition, the GMP/Tb (CPs constructed by GMP and Tb³⁺ ) encapsulated CALB (CALB@GMP/Tb) transformed over 98% of oleic acid into glycerides in the high-acid oil deacidification process, and TAG content from 87 to 89% was obtained. Moreover, the CALB@GMP/Tb showed good reusability in the esterification system.

CONCLUSION

The present CALB@CPs samples are selective for esterification and suitable for high-acid oils deacidification. This work provides a new system for enzymatic selectivity improvement study. © 2021 Society of Chemical Industry.

Glutamate Oxidase-Integrated Biomimetic Metal-Organic Framework Hybrids as Cascade Nanozymes for Ultrasensitive Glutamate Detection

The hybrid coupling of biocatalysts and chemical catalysts plays a vital role in the fields of catalysis, sensing, and medical treatment due to the integrated advantages in the high activity of natural enzymes and the excellent stability of nanozymes. Herein, a new nanozyme/natural enzyme hybrid biosensor was established for ultrasensitive glutamate detection. The MIL-88B(Fe)-NH₂ material with remarkable peroxidase mimic activity and stability was used as a nanozyme and carrier for immobilizing glutamate oxidase (GLOX) through Schiff base reaction to construct a chem-enzyme cascade detector (MIL-88B(Fe)-NH₂@GLOX). The resultant MIL-88B(Fe)-NH₂@GLOX exhibited a wide linear range (1-100 μM), with a low detection limit of 2.5 μM for glutamate detection. Furthermore, the MIL-88B(Fe)-NH₂@GLOX displayed excellent reusability and storage stability. After repeated seven cycles, MIL-88B(Fe)-NH₂-GLOX (GLOX was adsorbed on MIL-88B(Fe)-NH₂) lost most of its activity, whereas MIL-88B(Fe)-NH₂@GLOX still retained 69% of its initial activity. Meanwhile, MIL-88B(Fe)-NH₂@GLOX maintained 60% of its initial activity after storage for 90 days, while free GLOX only retained 30% of its initial activity. This strategy of integrating MOF mimics and natural enzymes for cascade catalysis makes it possible to design an efficient and stable chemo-enzyme composite catalysts, which are promising for applications in biosensing and biomimetic catalysis.

Fabricated Metal-Organic Frameworks (MOFs) as luminescent and electrochemical biosensors for cancer biomarkers detection

In the health domain, a major challenge is the detection of diseases using rapid and cost-effective techniques. Most of the existing cancer detection methods show poor sensitivity and selectivity and are time consuming with high cost. To overcome this challenge, we analyzed porous fabricated metal-organic frameworks (MOFs) that have better structures and porosities for enhanced biomarker sensing. Here, we summarize the use of fabricated MOF luminescence and electrochemical sensors in devices for cancer biomarker detection. Various strategies of fabrication and the role of fabricated materials in sensing cancer biomarkers have been studied and described. The structural properties, sensing mechanisms, roles of noncovalent interactions, limits of detection, modeling, advantages, and limitations of MOF sensors have been well-discussed. The study presents an innovative technique to detect the cancer biomarkers by the use of luminescence and electrochemical MOF sensors. In addition, the potential association studies have been opening the way for personalized patient treatments and the development of new cancer-detecting devices.

Superoxide dismutase-embedded metal–organic frameworks via biomimetic mineralization for the treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) is characterized by chronic and spontaneous inflammation in the gastrointestinal tract, and has been associated with an improved level of reactive oxygen species (ROS).

Recent Advances in Emerging Metal- and Covalent-Organic Frameworks for Enzyme Encapsulation

Enzyme catalysis enables complex biotransformation to be imitated. This biomimetic approach allows for the application of enzymes in a variety of catalytic processes. Nevertheless, enzymes need to be shielded by a support material under challenging catalytic conditions due to their intricate and delicate structures. Specifically, metal-organic frameworks and covalent-organic frameworks (MOFs and COFs) are increasingly popular for use as enzyme-carrier platforms because of their excellent tunability in structural design as well as remarkable surface modification. These porous organic framework capsules that host enzymes not only protect the enzymes against harsh catalytic conditions but also facilitate the selective diffusion of guest molecules through the carrier. This review summarizes recent progress in MOF-enzyme and COF-enzyme composites and highlights the pore structures tuned for enzyme encapsulation. Furthermore, the critical issues associated with interactions between enzymes and pore apertures on MOF- and COF-enzyme composites are emphasized, and perspectives regarding the development of high-quality MOF and COF capsules are presented.

Mechanistically Scoping Cell-Free and Cell-Dependent Artificial Scaffolds in Rebuilding Skeletal and Dental Hard Tissues

Rebuilding mineralized tissues in skeletal and dental systems remains costly and challenging. Despite numerous demands and heavy clinical burden over the world, sources of autografts, allografts, and xenografts are far limited, along with massive risks including viral infections, ethic crisis, and so on. Per such dilemma, artificial scaffolds have emerged to provide efficient alternatives. To date, cell-free biomimetic mineralization (BM) and cell-dependent scaffolds have both demonstrated promising capabilities of regenerating mineralized tissues. However, BM and cell-dependent scaffolds have distinctive mechanisms for mineral genesis, which makes them methodically, synthetically, and functionally disparate. Herein, these two strategies in regenerative dentistry and orthopedics are systematically summarized at the level of mechanisms. For BM, methodological and theoretical advances are focused upon; and meanwhile, for cell-dependent scaffolds, it is demonstrated how scaffolds orchestrate osteogenic cell fate. The summary of the experimental advances and clinical progress will endow researchers with mechanistic understandings of artificial scaffolds in rebuilding hard tissues, by which better clinical choices and research directions may be approached.

De Novo Approach to Encapsulating Biocatalysts into Synthetic Matrixes: From Enzymes to Microbial Electrocatalysts

Biocatalysts hold great promise in chemical and electrochemical reactions. However, biocatalysts are prone to inhospitable physiochemical conditions. Encapsulating biocatalysts into a synthetic host matrix can improve their stability and activity, and broaden their operational conditions. In this Review, we summarize the emerging de novo approaches to encapsulating biocatalysts into synthetic matrixes. Here, de novo means that embedding of biocatalysts and construction of matrixes take place simultaneously. We discuss the advantages and limitations of the de novo approach. On the basis of the nature of the biocatalysts and the synthetic frameworks, we specifically focus on two aspects: (1) encapsulation of enzymes (in vitro) in metal-organic frameworks and (2) encapsulation of microbial electrocatalysts (in vivo) on the electrode. For both cases, we discuss how the encapsulation improves biocatalysts' performance (stability, viability, activity, and etc.). We also highlight the benefit of encapsulation in facilitating the transport of charge carriers in microbial electrocatalysis.

Biomimetic self-assembly of lipase-zeolitic imidazolate frameworks with enhanced biosensing of protox inhibiting herbicides

Protox inhibiting herbicides such as nitrofen have detrimental effects on the environment and human health. The current work aims to fabricate a Candida rugosa lipase (CRL)-based electrochemical sensor for rapid and sensitive detection of protox inhibiting herbicides (nitrofen). We proposed the use of poly(vinylpyrrolidone) (PVP) and amino-acids to promote accumulation of Zn²⁺ ions at the surfaces of Candida rugosa lipase (CRL) and subsequently induce self-assembly of a CRL-zeolitic imidazolate framework (ZIF) structure. This process can be easily and rapidly achieved via a one-pot facile self-assembly method. Steady-state fluorescence spectroscopy indicated that CRL has undergone a conformational change following encapsulation within the ZIF structure. This conformational change is beneficial as the prepared PVP/Glu/CRL@ZIF-8 exhibited enhanced catalytic activity (207% of native CRL), and higher substrate affinity (lower K_m than native CRL) and showed high stability under harsh denaturing conditions. PVP/Glu/CRL@ZIF-8 was finally used for electrochemical biosensing of nitrofen. The fabricated biosensor has a wide linear detection range (0-100 μM), a lower limit of detection and a good recovery rate.

Efficient enzymatic synthesis of L-ascorbyl palmitate using Candida antarctica lipase B-embedded metal-organic framework

The Candida antarctica lipase B (CALB) was embedded in the metal-organic framework, zeolitic imidazolate framework-8 (ZIF-8), and applied in the enzymatic synthesis of L-ascorbic acid palmitate (ASP) for the first time. The obtained CALB@ZIF-8 achieved the enzyme loading of 80 mg g^-1 with 11.3 U g^-1 (dry weight) unit activity, 59.8% activity recovery, and 92.7% immobilization yield. Under the optimal condition, ASP was synthesized with over 75.9% conversion of L-ascorbic acid in a 10-batch reaction. Continuous synthesis of ASP was subsequently performed in a packed bed bioreactor with an outstanding average space-time yield of 58.1 g L^-1  h^-1 , which was higher than ever reported continuous ASP biosynthesis reactions.

Magnetic ZIF-8-Based Mimic Multi-enzyme System as a Colorimetric Biosensor for Detection of Aryloxyphenoxypropionate Herbicides

In the present study, a magnetic mimic multi-enzyme system was developed by encapsulating the aryloxyphenoxypropionate (AOPP) herbicide hydrolase QpeH and alcohol oxidase (AOx) in zeolitic imidazolate framework (ZIF-8) nanocrystals with magnetic Fe₃O₄ nanoparticles (MNPs) to detect AOPP herbicides. The structural, protein loading capacity and loading ratio, porosity, and magnetic properties of QpeH/AOx@mZIF-8 were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, nitrogen sorption, and vibrating sample magnetometry. An AOPP herbicide colorimetric biosensor made with QpeH/AOx@mZIF-8 had the highest sensitivity toward quizalofop-P-ethyl (QpE) with a limit of detection of 8.2 μM. This system was suitable to detect two other AOPP herbicides, including fenoxaprop-P-ethyl (FpE) and haloxyfop-P-methyl (HpE). The practical application of the biosensor was verified through quantitative analysis of QpE residues in industrial wastewater and field soils. Furthermore, QpeH/AOx@mZIF-8 exhibited excellent long-term storage stability (at least 50 days), easy separation by magnet, and reusability (at least 10 cycles), supporting its promising role in simple and low-cost detection of AOPP herbicides in real environmental samples.

Preparation of ZIF@ADH/NAD-MSN/LDH Core Shell Nanocomposites for the Enhancement of Coenzyme Catalyzed Double Enzyme Cascade

The field of enzyme cascades in limited microscale or nanoscale environments has undergone a quick growth and attracted increasing interests in the field of rapid development of systems chemistry. In this study, alcohol dehydrogenase (ADH), lactate dehydrogenase (LDH), and mesoporous silica nanoparticles (MSN) immobilized nicotinamide adenine dinucleotide (NAD⁺) were successfully immobilized on the zeolitic imidazolate frameworks (ZIFs). This immobilized product was named ZIF@ADH/NAD-MSN/LDH, and the effect of the multi-enzyme cascade was studied by measuring the catalytic synthesis of lactic acid. The loading efficiency of the enzyme in the in-situ co-immobilization method reached 92.65%. The synthesis rate of lactic acid was increased to 70.10%, which was about 2.82 times that of the free enzyme under the optimal conditions (40 °C, pH = 8). Additionally, ZIF@ADH/NAD-MSN/LDH had experimental stability (71.67% relative activity after four experiments) and storage stability (93.45% relative activity after three weeks of storage at 4 °C; 76.89% relative activity after incubation in acetonitrile-aqueous solution for 1 h; 27.42% relative activity after incubation in 15% N, N-Dimethylformamide (DMF) solution for 1 h). In summary, in this paper, the cyclic regeneration of coenzymes was achieved, and the reaction efficiency of the multi-enzyme biocatalytic cascade was improved due to the reduction of substrate diffusion.

Urate oxidase loaded in PCN-222(Fe) with peroxidase-like activity for colorimetric detection of uric acid

In the past two decades, the number of reports on the construction of uric acid (UA) sensors has increased dramatically, as it is a vital factor in the diagnosis of physiological functions and diseases. Among these sensors, cascade colorimetric detection based on peroxidase mimics has received great attention owing to the advantages of easier operation and more intuitive results. Herein, we report a simple UA detection method via the integration of urate oxidase (UOx) and PCN-222(Fe) with peroxidase-like activity, in which UOx is immobilized in PCN-222(Fe) by physical adsorption. UOx could catalyze the UA oxidation to produce H₂O₂, and then PCN-222(Fe) catalyzed the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H₂O₂ to generate a blue product with a maximum absorbance at 652 nm. Under optimal conditions, the increasing absorbance at 652 nm was proportional to the UA concentration. The linear range for UA detection was 10-800 μM with a limit of detection of 3.5 μM, and the cascade system has been successfully utilised for the detection of UA in human serum samples to demonstrate the accuracy of the proposed method. In conclusion, the cascade catalytic system based on the immobilization of UOx in PCN-222(Fe) has the potential to be used as a rapid and sensitive sensor for UA detection.

Metal-Organic Frameworks as a Versatile Materials Platform for Unlocking New Potentials in Biocatalysis

Biocatalysts immobilization with nanomaterials has promoted the development of biocatalysis significantly and made it an indispensable part of catalysis industries nowadays. Metal-organic frameworks (MOFs), constructed from organic linkers and metal ions or clusters, have raised significant interests for biocatalysts immobilization in recent years. The diversity of building units, molecular-scale tunability, and modular synthetic routes of MOFs greatly expand its ability as the host to integrate with biocatalysts. In this review, the general synthetic strategies of MOFs with biocatalysts are first summarized. Then, the recent progress of MOFs as a versatile host for a series of biocatalysts, including natural enzymes, nanozymes, and organism-based biocatalysts, followed by the introduction of MOFs themselves as biocatalysts, is discussed. Furthermore, the stimuli-responsive properties of MOFs themselves or the additional functionalization of protein, polymer, and peptide within/on MOF that enable the biocatalysts with the controllable and tunable behavior are also summarized, which could unlock new potentials in biocatalysis. Finally, a perspective of the upcoming challenges, potential impacts, and future directions of biocatalytic MOFs is provided.

Metal-organic frameworks for advanced drug delivery

Metal-organic frameworks (MOFs), comprised of organic ligands and metal ions/metal clusters via coordinative bonds are highly porous, crystalline materials. Their tunable porosity, chemical composition, size and shape, and easy surface functionalization make this large family more and more popular for drug delivery. There is a growing interest over the last decades in the design of engineered MOFs with controlled sizes for a variety of biomedical applications. This article presents an overall review and perspectives of MOFs-based drug delivery systems (DDSs), starting with the MOFs classification adapted for DDSs based on the types of constituting metals and ligands. Then, the synthesis and characterization of MOFs for DDSs are developed, followed by the drug loading strategies, applications, biopharmaceutics and quality control. Importantly, a variety of representative applications of MOFs are detailed from a point of view of applications in pharmaceutics, diseases therapy and advanced DDSs. In particular, the biopharmaceutics and quality control of MOFs-based DDSs are summarized with critical issues to be addressed. Finally, challenges in MOFs development for DDSs are discussed, such as biostability, biosafety, biopharmaceutics and nomenclature.