Multi-compartmental MOF microreactors derived from Pickering double emulsions for chemo-enzymatic cascade catalysis

Engineering- nanochannels with pH-responsive gates for direct detection of glucose in human blood serum

BACKGROUND

An abnormal blood glucose (Glu) level is a key signal of diabetes. The gluconic acid produced by Glu catalytic oxidation can cause changes in pH value.

RESULTS

Inspired by nature, in which organisms use pH as a chemical gate to regulate ion transport through cell membranes, we report a pH-gated electrochemical luminescence (ECL) sensing system for Glu detection based on the relationship between Glu metabolism and pH. The pH gate was designed on a TiO2 nanochannel membrane (NM) by modifying the channel entrance with polystyrene-b-poly(4-vinylpyridine) (P4VP) chains that convert from a hydrophobic into a hydrophilic state via a pH-responsive conformational switching at pKa 5.2. Due to the nanoconfinement effect of zeolite imidazolate (ZIF-8) frameworks and TiO2 nanochannels, the glucose oxidase (GOD) embedded in ZIF-8 exhibits enhanced catalytic efficiency for Glu oxidation, enabling the acidic product to regulate the hydrophilicity of the P4VP-based pH-responsive gate. The ECL luminophore Ru(dcbpy)32+ subsequently passes through the hydrophilic gate to reach the detection cell. This pH-gated Glu-responsive NM can effectively separate biological matrices from the detection cell, allowing direct sensing of Glu in complex biomatrices.

SIGNIFICANCE

The ECL technology, combined with the pH-triggered gate design enables straightforward Glu determination in undiluted serum, demonstrating an alternative ECL device for pretreatment-free clinical analysis.

Cobalt MOF-hybridized nanozyme catalysts breaking pH limitations for boosted chlorpyrifos sensing performance

Given the potential dangers of organophosphorus pesticides to food safety and human health, the development of a reliable and precise detection platform for pesticides is essential. In this study, we present a novel 'armor-plating' laccase-mimetic catalyst (DNA-Cu@MOFs)-based colorimetric platform, which enables stable and selective pesticide detection. The DNA-Cu@MOFs enhance catalytic stability and overcome pH limitations, enabling effective catalysis under neutral and alkaline physiological conditions, making them well-suited for practical applications in biosensor development. By combining the catalytic properties of DNA-Cu@MOFs with a high-affinity biorecognition element (acetylcholinesterase), the platform achieves a linear detection range of 3.0-90 ng mL-1 for chlorpyrifos, with a detection limit of 0.75 ng mL-1. Notably, this platform demonstrates significant stability in chlorpyrifos detection even in the presence of environmental interferents. This robust colorimetric platform offers new possibilities for pesticide detection and provides a solid foundation for the development of comprehensive and accurate pesticide monitoring systems.

Hierarchical encapsulation of enzymes with multishell metal-organic frameworks for sensitive detection of α-amylase activity in complex fermentation samples

In natural world, sophisticated cascade reactions occur in compartmentalized organelles. However, simulating cascade processes in living systems remains problematic, and the drawbacks of enzymes, including dissatisfactory stability, reusability, and sensitivity in extreme microenvironments, have hampered further applications. Here, we report a confined multi-enzyme system in which MnFe metal-organic framework (MFM) is applied to encapsulate enzymes through shell-by-shell epitaxial-overgrowth in diverse compartments. MFM possessed excellent peroxidase-mimicking activity and biocompatibility, enabling it to serve not only as a reliable carrier for multiple enzymes, but also as a high-performance nanozyme in cascades. Compared with free enzymes, this system exhibited significantly improved bioactivity and environmental tolerance. On this basis, the confined multi-enzyme system was applied for selective α-amylase analysis in complicated fermentation specimens with a broad linear range (5-500 U·L-1) and low detection limit (2.14 U·L-1). This work sheds new light on the construction of efficient biocatalytic cascades to accelerate applications in food manufacturing.

Host-Guest Synergy of Metal-Organic Frameworks for Enhanced Near-Infrared Ultrafast Laser Responsiveness

Host-guest metal-organic frameworks (MOFs) offer significant potential and value in regulating and optimizing novel material properties and functionalities, owing to the synergistic effects between the host framework and the guest units. This study reported two silver-based host-guest MOFs, [Ag(ATRZ)(BrO3)]n (CMOF-1) and [Ag(ATRZ)1.5(ClO4)]n (CMOF-2), as promising candidates for laser-responsive materials. These materials feature 1D and 3D structures, respectively, comprising Ag-ATRZ cationic MOF frameworks integrated with two distinct oxidizing anionic guests, BrO3 - and ClO4 -. CMOF-1 and CMOF-2 are synthesized through straightforward, environmentally benign methods, enabling rapid fabrication. The exceptional near-infrared (NIR) laser responsiveness of CMOF-1 and CMOF-2 was achieved through the modulation of the cationic MOFs (CMOFs) architectures and synergistic interactions between the host and guest components. Moreover, both exhibit ultrafast deflagration-to-detonation transition (DDT) capabilities, alongside excellent thermal stability. This work expands the application scope of host-guest MOFs, and provides an effective strategy for developing high-performance laser-responsive materials.

Enhancing Multi-Enzyme Cascade Activity in Metal-Organic Frameworks via Controlled Enzyme Encapsulation

To position multi-enzymes in a core-shell structure, the conventional layer-by-layer approach is often used. However, this method is time-consuming and complex, requiring multiple steps and the isolation of intermediates at each stage. To address this challenge, a sequential strategy is introduced for the controlled encapsulation of multi-enzymes within metal-organic frameworks (MOFs), achieving a core-shell structure without the need for intermediate isolation. Synchrotron Terahertz-Far-Infrared (THz-Far-IR) spectroscopy is employed to monitor this encapsulation process. The results revealed that the first enzyme is co-precipitated within the MOFs, followed by biomineralization upon the addition of a second enzyme, achieving distinct enzyme positioning. This approach is applicable to both two-enzyme and three-enzyme cascade systems. The results demonstrate that multi-enzyme cascade activity is significantly enhanced compared to conventional one-pot and layer-by-layer approaches, owing to optimal spatial arrangement, increased surface area, and improved enzyme conformation. Furthermore, the encapsulated enzymes exhibit strong resistance to high temperatures, proteolysis, and organic solvents, along with excellent reusability, making this method highly promising for industrial biocatalytic applications.

Nanozyme Cascade Self-Powered H2O2 Strategy for Chemiluminescence Array Sensor to Monitor and Deactivate Multiple Bacteria

Early warning and deactivation of multiple bacteria are highly desirable to prevent pathogen-responsible bacterial infectious illnesses. Here, we developed a nanozyme cascade self-powered H2O2 strategy for a chemiluminescence (CL) array immunosensor to enable high-throughput and simultaneous monitoring of multiple bacteria as well as their deactivation. Specifically, a novel ZIF-67@CoFePBA yolk-shell nanozyme was synthesized through a dissociation and re-coordination mechanism, exhibiting significantly enhanced peroxidase (POD)-like activity due to the confinement and synergistic effects. ZIF-67@CoFePBA nanozyme was utilized to immobilize glucose oxidase (GOx) for constructing the nanozyme cascade self-powered H2O2 system. ZIF-67@CoFePBA nanozyme can catalyze in-situ H2O2 to produce hydroxyl radicals (·OH), resulting in stable glow-type CL to construct array immunosensors without exogenous H2O2. The self-powered CL array sensor was exploited to simultaneously detect numerous bacteria with wide linear ranges of 1.5×10-1.5×107 CFU/mL for Staphylococcus aureus and 1.5×102-1.5×107 CFU/mL for Escherichia coli. Furthermore, the generated ·OH can destroy the internal structure of the bacteria and effectively eliminate them. This study provides a promising insight into the design of self-powered H2O2 sensors for high-throughput and simultaneous detection of multiple bacteria and their subsequent deactivation.

Fabrication of Porous Proteinaceous Microspheres via One-Step Pickering Double Emulsions: Controllable Structure and Interfacial Cascade Biocatalysis

Methods based on double emulsions for producing porous microspheres have gained popularity as an effective and adaptable strategy. However, these microspheres are frequently composed of organic polymers that lack sufficient mechanical strength. Additionally, the conventional two-step process and the use of surfactants present notable challenges. A promising solution is to replace traditional surfactants with inorganic particles, utilizing a Pickering emulsion approach. Herein, we introduced a one-step approach for creating Pickering double emulsions, followed by a straightforward solvent evaporation process to produce porous proteinaceous microspheres. By harnessing the enhanced stability of Pickering emulsions, we can manipulate the morphology and pore structure of the microspheres by varying the oil-(ethanol/water) volume ratio, the size and type of emulsifier, ripening time, rotary evaporation temperature, and the addition of enzymes. Furthermore, we innovatively proposed the coencapsulation of glucose oxide (GOx) and horseradish peroxidase (HRP) for interfacial cascade catalysis, showing excellent catalytic activity, recovery, and reusability. This study presents a new, scalable approach for producing porous microspheres using a one-step Pickering double emulsion. It demonstrates significant potential for interfacial biocatalysis, and is expected to be applied in fields such as medicine, drug delivery, and biotechnology due to their suitability for encapsulating bioactive materials.

MOF-Based Dual-Layer Pickering Emulsion: Molecular-Level Gating of Water Delivery at Water-Oil Interface for Efficient Photocatalytic Hydrogenation Using H2O as a Hydrogen Source

Biphasic system not only presents a promising opportunity for complex catalytic processes, but also is a grand challenge in efficient tandem reactions. As an emerging solar-to-chemical conversion, the visible-light-driven and water-donating hydrogenation combines the sustainability of photocatalysis and economic-value of hydrogenation. However, the key and challenging point is to couple water-soluble photocatalytic hydrogen evolution reaction (HER) with oil-soluble hydrogenation. Herein, we employed metal-organic frameworks (MOFs) and CdS nanorods to construct a MOF-CdS dual-layer Pickering emulsion (water in oil, W/O), which compartmented aqueous phase for photocatalytic HER and oil phase for hydrogenation. The hydrophobic MOF and hydrophilic CdS were isolated at the inner and outer layers of W/O emulsion, respectively. The molecularly regulated hydrophobicity of MOF controlled the water delivery onto CdS photocatalysts, which realized the synergistic regulation of HER and hydrogenation. In the photocatalytic hydrogenation of cinnamaldehyde, the highest yield of MOF-CdS Pickering emulsion reached 187.37 mmol ⋅ g-1 ⋅ h-1, 30 times that of the counterpart without emulsion (6.44 mmol ⋅ g-1 ⋅ h-1). Its apparent quantum yield reached 43.24 % without co-catalysts. To our knowledge, this performance is at a top-level so far. Our work realized the precise regulation of water-oil interface to effectively couple two reactions in different phases, providing new perspective for challenging tandem catalysis.

A Bio-Redox Dynamic Pickering Emulsion from Nature to Nature

The biosafety issue of Pickering emulsions has gradually become public. It is shown that the particles that make up Pickering emulsions, previously thought to be non-physiologically toxic, may also pose a potential threat to human life and health, as well as to ecosystems, due to their inherent emulsifying capacity. Hence, the principle of "from nature to nature" is proposed, which refers to emulsifiers that are of natural origin and can be metabolized by natural biological processes to eliminate their emulsifying ability. A feasible pathway by which the natural small molecule, thioctic acid, is exploited for the preparation of Pickering emulsions is also presented. The strategy of calcium ion-induced aggregation and ring-opening polymerization of sodium thioctate is utilized for the preparation of particulate emulsifiers, thus forming stable O/W-type Pickering emulsions. Benefiting from the antioxidant property of the thioctic acid moiety and the transdermal capacity of the emulsion itself, it combines protection of the bioactive substance with transdermal delivery. Furthermore, the particulate emulsifiers that are prepared, abundantly enriched with dynamic disulfide bonds, can be integrated into the natural metabolic pathway, specifically by being reduced through the involved glutathione, thereby facilitating their natural degradation and effectively mitigating any potential biological hazards.

Immobilized Multi-Enzyme/Nanozyme Biomimetic Cascade Catalysis for Biosensing Applications

Multiple enzyme-induced cascade catalysis has an indispensable role in the process of complex life activities, and is widely used to construct robust biosensors for analyzing various targets. The immobilized multi-enzyme cascade catalysis system is a novel biomimetic catalysis strategy that immobilizes various enzymes with different functions in stable carriers to simulate the synergistic catalysis of multiple enzymes in biological systems, which enables high stability of enzymes and efficiency enzymatic cascade catalysis. Nanozymes, a type of nanomaterial with intrinsic enzyme-like characteristics and excellent stabilities, are also widely applied instead of enzymes to construct immobilized cascade systems, achieving better catalytic performance and reaction stability. Due to good stability, reusability, and remarkably high efficiency, the immobilized multi-enzyme/nanozyme biomimetic cascade catalysis systems show distinct advantages in promoting signal transduction and amplification, thereby attracting vast research interest in biosensing applications. This review focuses on the research progress of the immobilized multi-enzyme/nanozyme biomimetic cascade catalysis systems in recent years. The construction approaches, factors affecting the efficiency, and applications for sensitive biosensing are discussed in detail. Further, their challenges and outlooks for future study are also provided.

Uniform and size-tunable dasatinib nanoemulsions synthesized by a high-throughput microreactor for enhanced temperature stability

This study introduces a high-throughput microreactor for preparing dasatinib nanoemulsions with precise control over particle size and uniformity. Leveraging the microreactor's advantages in mass transfer and mixing, we established an empirical correlation to predict and adjust nanoemulsion properties. Optimized operational parameters enabled the synthesis of stable dasatinib nanoemulsions with narrow size distributions and mean diameters below 20 nm, maintaining their stability and transparency under various storage conditions.

Open-Metal and Carboxamide-Tethered Redox-Active Undulated Framework for Mild-Condition Synthesis of Therapeutic Drugs and Tandem Catalysis with Size-Selectivity

A mixed-ligand-based thermo-chemically robust and undulated metal-organic framework (MOF) is developed that embraces carboxamide moiety-grafted porous channels and activation-induced generation of open-metal site (OMS). The guest-free MOF acts as an outstanding heterogeneous catalyst in Hantzsch condensation for electronically assorted substrates with low catalyst loading and short duration under greener conditions than the reported materials. Besides Lewis acidic OMS, the carboxamide group activates the substrate via two-point hydrogen bonding, highlighting the effectiveness of custom-made functionalities in this multi-component reaction. Importantly, the framework demonstrates first ever one-pot synthesis of 1,4-dihydropyridine-based antihypertensive drug foridon, along with four therapeutic molecules ethidine, nifedipine, nemadipine B and Nitrendipine, which are characterized via X-ray crystallography besides conventional spectroscopic analyses. The integration of redox-active Co(II) center and acid-base dual sites benefit the activated MOF catalyzing mild-condition alcohol oxidation-Knoevenagel condensation to produce benzylidene malononitriles with wide substrate tolerance and multicyclic performance. For both the multi-component and atom-economic reactions, astutely designed control experiments and density functional theory-based reaction energy profile rationalize synergistic catalysis via pore-decked antagonistic sites that predominantly transpires inside the MOF channel. This study marks a paradigm shift in sustainable catalysis through task-specific functionality fuelling, and provides valuable insights on structure-property synergism at the cutting-edge MOF design.

Fabrication of Compartmentalized Multienzyme Reactor for Colorimetric Biosensing of Glucose and Phenol with High Sensitivity

Enzymatic cascade reactions are widely utilized in food security, environmental monitoring, and disease diagnostics, whereas their practical application was hindered due to their limited catalytic efficiency and intrinsic fragility to environmental influences. Herein, a compartmentalized dual-enzyme cascade nanoreactor was constructed in metal-organic frameworks (ZIF-8) by a shell-by-shell growth method. ZIF-8 provided a good microenvironment to maintain the activity of enzymes and protected them against harsh conditions. Importantly, experimental results revealed that the encapsulation order and enzyme ratio affected the cascade catalytic activity. When the cascade enzyme ratio was 1:1 and horseradish peroxidase (HRP) was encapsulated in the inner layer with glucose oxidase (GOx) in the outer layer (H@ZIF-8@G@ZIF-8), the nanoreactor facilitated the mass transfer process of substrates and showed the highest cascade catalytic efficiency. The maximum reaction rate (Vmax) of H@ZIF-8@G@ZIF-8 was 294.96 nM s-1, which was 1.6 times greater than G@ZIF-8@H@ZIF-8 (182.84 nM s-1). Therefore, H@ZIF-8@G@ZIF-8 was effectively applied in glucose monitoring and phenol sensing. The glucose biosensor showed a low detection limit of 0.76 μM and a broad linear range of 5-300 μM. The phenol biosensor demonstrated a wide linear range (20-300 μM) with a detection limit of 0.60 μM. In addition, the spiked recovery experiments for glucose and phenol were carried out in serum (recovery: 95.26-100.04%) and tap water (recovery: 97.05-106.50%), respectively. The high accuracy demonstrated potential applications of the cascade system in biosensing and environmental detection.

An Efficient Bifunctional Core-Shell ZIF-90@ZIF-67 Composite as a Stable Pickering Interfacial Catalyst for the Deacetalization-Knoevenagel Tandem Reaction

Exploiting advanced solid particles is crucial to the construction of Pickering emulsions catalysis. Recently, metal-organic frameworks (MOFs) have been used as ideal emulsifiers stabilizing Pickering emulsions for interfacial catalysis. Although Pickering emulsions stabilized by core-shell MOFs have significant importance in practical studies, to date there have been very limited reports on this topic. Herein, ZIF-90@ZIF-67, a core-shell material with simultaneous acid-base bifunctionality, was synthesized by seeded epitaxial growth. It was firstly applied as an emulsifier in Pickering emulsions to catalyze the deacetalization-Knoevenagel tandem reaction, which exhibited excellent catalytic properties and achieved extremely high yields. Additionally, ZIF-90@ZIF-67 showed high stability and remained well repeatable after five cycles. This work provides a platform for the design of structurally and functionally diverse MOF-based Pickering emulsions interfacial catalysis.

Natural shellac-based microcapsules as lipase carriers for recyclable efficient Pickering interfacial biocatalysis

Enzyme is an important class of catalyst. However, the efficiency of enzyme-catalyzed reactions is constrained by the limited contact between the enzyme and its substrate. In this study, to overcome this challenge, lipase-loaded microcapsules were prepared from natural shellac and nanoparticles using the emulsion template method. These microcapsules can perform dual roles as stabilizers and enzyme carriers to construct a water-in-oil Pickering interfacial biocatalytic system. The results showed that the hydrolytic conversion of the microcapsules could reach 90% within 20 min, which was significantly higher than that of the traditional biphasic system. The catalytic activity was influenced by the oil-to-water volume ratio and the microcapsule content. The microcapsules remained highly catalytic efficiency even after storage for three months or seven cycles of reuse. These microcapsules were prepared without the use of any cross-linkers or harsh solvents. This green and efficient catalytic system has great application prospects in the food industry.

Reticular Chemistry for Enhancing Bioentity Stability and Functional Performance

Addressing the fragility of bioentities that results in instability and compromised performance during storage and applications, reticular chemistry, specifically through metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), offers versatile platforms for stabilization and enhancement of bioentities. These highly porous frameworks facilitate efficient loading and mass transfer, offer confined environments and selective permeability for stabilization and protection, and enable finely tunable biointerfacial interactions and microenvironments for function optimization, significantly broadening the applications of various bioentities, including enzymes, nucleic acids, cells, etc. This Perspective outlines strategies for integrating bioentities with reticular frameworks, highlighting new design ideas for existing issues within these strategies. It emphasizes the crucial roles of these frameworks for bioentities in enhancing stability, boosting activity, imparting non-native functions, and synergizing bioentity systems. Concluding with a discussion of the challenges and prospects in the design, characterization, and practical applications of these biocomposites, this Perspective aims to inspire further development of high-performance biocomposites in this promising field.

Stimuli-responsive Zn(ii) complexes showing the structural conversion and on/off switching of catalytic properties

In this work, we report a series of dinuclear Zn(ii) complexes and their corresponding catalytic properties for a transesterification reaction. We show that the structures and catalytic activity of the complexes are strongly dependent on their molecular structures surrounding the metal centres. The use of halides yields a series of [Zn2X4L] (X = Cl, Br, and I) complexes with low catalytic activity because of the fully saturated coordination environment, whereas Zn(ClO4)2 results in two isomeric [ZnL] n 1D coordination polymers with efficient catalytic properties, despite being susceptible to structural rearrangement and consequent changes in catalytic activity over time. The response to chemical stimuli to trigger anion exchange allows for switching on/off the systems' catalytic activity, simultaneously recovering the catalytic effect upon degradation and thus reconstructing the coordination environment of the 1D polymer.

CO2/N2 Triggered Aqueous Recyclable Surfactants for Biphasic Catalytic Reactions in the Pickering Emulsions

The utilization of Pickering emulsions in interfacial catalysis offers a promising environmental platform for biphasic reactions. However, complicated surface coating or chemical grafting methods are always required to prepare the surface-active catalysts for the Pickering emulsions, since most of them are commercially unavailable. Here, we report CO2-switchable Pickering emulsions for biphasic reactions, in which Pd@Al2O3 nanoparticles are in situ modified by a CO2/N2 responsive surfactant. Compared with the chemical grafted methods, the in situ formed Pickering interfacial catalysts avoid complex chemical modification. Furthermore, efficient demulsification and separation of the oil phase and the products without surfactant contaminations can be achieved by CO2 trigger. The Pickering interfacial catalysis system can also be reformed after the aqueous phase containing the catalyst nanoparticles, and the surfactant is recycled and reused. The strategy is universal for nitrobenzene reductions and alcohol oxidations, providing a convenient and green method for the preparation of Pickering catalysts with commercially available nanoparticles, efficient emulsion separation, and recovery of the catalyst nanoparticles and emulsifiers in various two-phase organic reactions.

Nucleation-Inhibited Emulsion Interfacial Assembled Polydopamine Microvesicles as Artificial Antigen-Presenting Cells

Albeit microemulsion systems have emerged as efficient platforms for fabricating tunable nano/microstructures, lack of understanding on the emulsion-interfacial assembly hindered the control of fabrication. Herein, a nucleation-inhibited microemulsion interfacial assembly method is proposed, which deviates from conventional interfacial nucleation approaches, for the synthesis of polydopamine microvesicles (PDA MVs). These PDA MVs exhibit an approximate diameter of 1 µm, showcasing a pliable structure reminiscent of cellular morphology. Through modifications of antibodies on the surface of PDA MVs, their capacity as artificial antigen presentation cells is evaluated. In comparison to solid nanoparticles, PDA MVs with cell-like structures show enhanced T-cell activation, resulting in a 1.5-fold increase in CD25 expression after 1 day and a threefold surge in PD-1 positivity after 7 days. In summary, the research elucidates the influence of nucleation and interfacial assembly in microemulsion polymerization systems, providing a direct synthesis method for MVs and substantiating their effectiveness as artificial antigen-presenting cells.

Precision Engineering of the Co-immobilization of Enzymes for Cascade Biocatalysis

The design and orderly layered co-immobilization of multiple enzymes on resin particles remain challenging. In this study, the SpyTag/SpyCatcher binding pair was fused to the N-terminus of an alcohol dehydrogenase (ADH) and an aldo-keto reductase (AKR), respectively. A non-canonical amino acid (ncAA), p-azido-L-phenylalanine (p-AzF), as the anchor for covalent bonding enzymes, was genetically inserted into preselected sites in the AKR and ADH. Employing the two bioorthogonal counterparts of SpyTag/SpyCatcher and azide-alkyne cycloaddition for the immobilization of AKR and ADH enabled sequential dual-enzyme coating on porous microspheres. The ordered dual-enzyme reactor was subsequently used to synthesize (S)-1-(2-chlorophenyl)ethanol asymmetrically from the corresponding prochiral ketone, enabling the in situ regeneration of NADPH. The reactor exhibited a high catalytic conversion of 74 % and good reproducibility, retaining 80 % of its initial activity after six cycles. The product had 99.9 % ee, which that was maintained in each cycle. Additionally, the double-layer immobilization method significantly increased the enzyme loading capacity, which was approximately 1.7 times greater than that of traditional single-layer immobilization. More importantly, it simultaneously enabled both the purification and immobilization of multiple enzymes on carriers, thus providing a convenient approach to facilitate cascade biocatalysis.

Photo-modulated activation of organic bases enabling microencapsulation and on-demand reactivity

A method is developed for facile encapsulation of reactive organic bases with potential application for autonomous damage detection and self-healing polymers. Highly reactive chemicals such as bases and acids are challenging to encapsulate by traditional oil-water emulsion techniques due to unfavorable physical and chemical interactions. In this work, reactivity of the bases is temporarily masked with photo-removable protecting groups, and the resulting inactive payloads are encapsulated via an in situ emulsion-templated interfacial polymerization method. The encapsulated payloads are then activated to restore the organic bases via photo irradiation, either before or after being released from the core-shell carriers. The efficacy of the photo-activated capsules is demonstrated by a damage-triggered, pH-induced color change in polymeric coatings and by recovery of adhesive strength of a damaged interface. Given the wide range of potential photo-deprotection chemistries, this encapsulation scheme provides a simple but powerful method for storage and targeted delivery of a broad variety of reactive chemicals, promoting design of diverse autonomous functionalities in polymeric materials.

Boosting Enzyme Activity in Enzyme Metal-Organic Framework Composites

Enzymes, as highly efficient biocatalysts, excel in catalyzing diverse reactions with exceptional activity and selective properties under mild conditions. Nonetheless, their broad applications are hindered by their inherent fragility, including low thermal stability, limited pH tolerance, and sensitivity to organic solvents and denaturants. Encapsulating enzymes within metal-organic frameworks (MOFs) can protect them from denaturation in these harsh environments. However, this often leads to a compromised enzyme activity. In recent years, extensive research efforts have been dedicated to enhancing enzymatic activity within MOFs, leading to the development of new enzyme-MOF composites that not only preserve their catalytic potential but also outperform their free counterparts. This Review provides a comprehensive review on recent developments in enzyme-MOF composites with a specific emphasis on their enhanced enzymatic activity compared to free enzymes.

Tuning Chemoenzymatic Pd/Laccase Conformation Toward Optimized Heterogeneous Aerobic Oxidation

Heterogeneous chemoenzymatic catalysts differing in their spatial organization and relative orientation of their enzymatic laccase and Pd units confined into macrocellular silica foams were tested on veratryl alcohol oxidation. When operating under continuous flow, we show that the catalytic efficiency of hybrids is significantly enhanced when the Pd(II) complex is combined with a laccase exhibiting a surface located lysine next to the T1 oxidation site of the enzyme.

Opportunities and Challenges of Metal-Organic Framework Micro/Nano Reactors for Cascade Reactions

Building bridges among different types of catalysts to construct cascades is a highly worthwhile pursuit, such as chemo-, bio-, and chemo-bio cascade reactions. Cascade reactions can improve the reaction efficiency and selectivity while reducing steps of separation and purification, thereby promoting the development of "green chemistry". However, compatibility issues in cascade reactions pose significant constraints on the development of this field, particularly concerning the compatibility of diverse catalyst types, reaction conditions, and reaction rates. Metal-organic framework micro/nano reactors (MOF-MNRs) are porous crystalline materials formed by the self-assembly coordination of metal sites and organic ligands, possessing a periodic network structure. Due to the uniform pore size with the capability of controlling selective transfer of substances as well as protecting active substances and the organic-inorganic parts providing reactive microenvironment, MOF-MNRs have attracted significant attention in cascade reactions in recent years. In this Perspective, we first discuss how to address compatibility issues in cascade reactions using MOF-MNRs, including structural design and synthetic strategies. Then we summarize the research progress on MOF-MNRs in various cascade reactions. Finally, we analyze the challenges facing MOF-MNRs and potential breakthrough directions and opportunities for the future.

Application and Development Prospect of Nanoscale Iron Based Metal-Organic Frameworks in Biomedicine

Metal-organic frameworks (MOFs) are coordination polymers that comprise metal ions/clusters and organic ligands. MOFs have been extensively employed in different fields (eg, gas adsorption, energy storage, chemical separation, catalysis, and sensing) for their versatility, high porosity, and adjustable geometry. To be specific, Fe2+/Fe3+ exhibits unique redox chemistry, photochemical and electrical properties, as well as catalytic activity. Fe-based MOFs have been widely investigated in numerous biomedical fields over the past few years. In this study, the key index requirements of Fe-MOF materials in the biomedical field are summarized, and a conclusion is drawn in terms of the latest application progress, development prospects, and future challenges of Fe-based MOFs as drug delivery systems, antibacterial therapeutics, biocatalysts, imaging agents, and biosensors in the biomedical field.