"Armor-Plating" Enzymes with Metal-Organic Frameworks (MOFs)

Achievements and challenges in glucose oxidase-instructed multimodal synergistic antibacterial applications

Glucose oxidase (GOx) with unique catalytic properties and inherent biocompatibility can effectively oxidize both endogenous and exogenous glucose with oxygen (O2) into gluconic acid and hydrogen peroxide (H2O2). Accordingly, the GOx-based catalytic chemistry offers new possibilities for designing and constructing multimodal synergistic antibacterial systems. The consumption of glucose permanently downregulates bacterial cell metabolism by blocking essential energy supplies, inhibiting their growth and survival. Additionally, the production of gluconic acid could downregulates the pH within the bacterial infection microenvironment, enhancing the production of hydroxyl radicals (∙OH) from H2O2 via enhanced Fenton or Fendon-like reactions and triggering the pH-responsive release of drugs. Furthermore, the generated H2O2 in situ avoids the addition of exogenous hydrogen peroxide. Therefore, it is possible to design GOx-based multimodal antibacterial synergistic therapies by combining GOx-instructed cascade reactions with other therapeutic approaches such as chemodynamic therapies (CDT), hypoxia-activated prodrugs, photosensitizers, and stimuli-responsive drug release. Such multimodal strategies are expected to exhibit better therapeutic effects than single therapeutic modes. This tutorial review highlights recent advancements in GOx-instructed multimodal synergistic antibacterial systems, focusing on design philosophy and construction strategies. Current challenges and future prospects for advancing GOx-based multimodal antibacterial synergistic therapies are discussed.

Enhanced the Trans-Cleavage Activity of CRISPR-Cas12a Using Metal-Organic Frameworks as Stimulants for Efficient Electrochemical Sensing of Circulating Tumor DNA

Continued development of clustered regularly interspaced short palindromic repeats (CRISPR)-powered biosensing system on the electrochemical interface is vital for accurate and timely diagnosis in clinical practice. Herein, an electrochemical biosensor based on manganese metal-organic frameworks (MOFs)-enhanced CRISPR (MME-CRISPR) is proposed that enables the efficient detection of circulating tumor DNA (ctDNA). In this design, customized enzyme stimulants (Mn2+) are co-assembled with Cas12a/crRNA to form enzyme-MOF composites, which can be released quickly under mild conditions. The MOFs-induced proximity effect can continuously provide adequate Mn2+ to sufficiently interact with Cas12a/crRNA during the release process, enhancing the trans-cleavage activity of complex available for biosensor construction. The MOFs-based enzyme biocomposites also afford efficient protection against various external stimulus. It is demonstrated that the developed biosensor can achieve ultrasensitive detection of epidermal growth factor receptor L858R mutation in ctDNA with a low detection limit of 0.28 fm without pre-amplification. Furthermore, the engineered mismatch crRNA enables the biosensor based on MME-CRISPR to detect single nucleotide variant with a high signal-to-noise ratio. More importantly, it has been successfully used to detect the targets in clinical practice, requiring low-dose samples and a short time. This strategy is believed to shed new light on the applications of cancer diagnosis, treatment, and surveillance.

Inert-remodeling strategy to build bimetal-confined nitrogen-doped carbon nanozyme for colorimetric-chemiluminescent imaging dual-mode cascade enzyme sensing

The metal-organic frameworks (MOFs)-derived nanozymes in air atmosphere have gained great attention in biosensing fields. Nevertheless, this derivative pattern may result in the destabilization of the MOF framework and the aggregation of active sites, consequently diminishing its catalytic activity. Herein, we reported an inert-remodeling strategy to build bimetal-confined nitrogen-doped carbon nanozyme for dual-mode cascade enzyme biosensing. The strategy was easily achieved by pyrolysis of MOFs (CoNi-ZIF-67 as model) precursor in argon atmosphere, leading to the formation of CoNi bimetallic nanoparticles uniformly confined nitrogen-doped carbon (CoNi-CN) nanozyme. This derivative nanozyme exhibits significantly enhanced peroxidase (POD)-like activity, which is 4 times higher than that of NiCo2O4 nanozyme (CoNi-ZIF-67 derivative in air atmosphere) and 54 times higher than that of CoNi-ZIF-67 precursor. The excellent POD-like activity of CoNi-CN nanozyme is ascribed to the following facts: i) integrate structure with uniformly dispersed CoNi bimetal active sites; ii) confinement effect of CoNi bimetal encapsulated in CN architecture. Integrating with glucose oxidase (GOx) to prepare cascade enzyme of CoNi-CN@GOx, colorimetric-chemiluminescent imaging sensor based on CoNi-CN@GOx cascade system was developed for glucose detection. Glucose was assayed in wide linear ranges of 0.08-15 mM (colorimetric) and 0.1-30 mM (CL imaging). This research provides a promising inert-remodeling strategy to construct high-performance nanozyme for dual mode biosensing applications.

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.

Anti-biopassivated Reticular Micromotors for Bladder Cancer Therapy

The limited lifespan of enzyme-powered micro/nanomotors (MNMs) hinders their biomedical applications due to the easy deactivation in tumor microenvironments. In this study, by taking advantage of hydrogen bond-rich metal-organic frameworks (MOFs), we design anti-biopassivated urease-powered MOF motors (Ur-MOFtors) with sustained motility for bladder cancer therapy. Such reticular Ur-MOFtors exhibited an exceptionally long locomotion lifespan exceeding 90 min in highly concentrated urea, which was an 18-fold enhancement compared with urease-adsorbed MOFs, resulting in excellent anti-biopassivation of MOFtors. The underlying molecular mechanism of persistent motion involves hydrogen bonding interaction between the MOF skeleton and the catalytic product, as identified by in situ infrared spectroscopy and density functional theory. Based on the preserved enzymatic activity comparable to native urease, the self-propulsion pathway of Ur-MOFtors is driven by ionic self-diffusiophoresis with the positive chemotactic motion toward urea. Benefiting from the persistent motion of Ur-MOFtors in physiological urea, a rapid bladder cancer therapy was achieved with few instillation sessions and short treatment cycles during intravesical administration. This hydrogen bond-rich framework presents a promising anti-biopassivated approach to overcoming the short lifespan and easy deactivation of enzymatic motors for advanced therapeutic robotics.

Recent advances in metal-organic frameworks for catalysing organic transformation

Metal-organic frameworks (MOFs) have garnered considerable attention due to their tunable properties, well-defined porosity, and structural versatility, making them effective catalysts for organic transformations. This review explores recent advances in MOF-based catalysis, emphasizing the roles of metal centres and organic linkers, as well as the synergistic effects arising from their combination. Additionally, guest molecule encapsulation and morphology modulation as effective strategies for improving catalytic efficiency are also discussed. Finally, future challenges and opportunities for MOFs as heterogenous catalysts are highlighted.

In Situ Encapsulation of Organophosphorus Hydrolase into a Reduction-Catalytic Cu-MOF for Chemoenzymatic Cascade Conversion of Methyl Parathion to 4-Aminophenol

The highly toxic organophosphate pesticide methyl parathion (MP) is widely used in agriculture and thus poses significant risks to the environment. Organophosphorus hydrolase (OPH) can effectively catalyze the hydrolysis of MP, but generate a toxic product of 4-nitrophenol (4-NP), so the following reduction of 4-NP to 4-aminophenol (4-AP) with low toxicity but high economic value has been designed for sustainable development. Therefore, the cascade conversion of highly hazardous MP to economically valuable 4-AP is an attractive strategy for both environmental remediation and industrial applications. In this study, we synthesized a reduction-catalytic cupric metal-organic framework (CuBDC) in solvent-free aqueous phase and under mild conditions and in situ encapsulated OPH within CuBDC via a cation polyelectrolyte poly(allylamine hydrochloride) (PAH)-assisted biomineralization, creating a chemoenzymatic cascade catalyst (OPH-PAH@CuBDC) for MP conversion to 4-NP. The optimized OPH-PAH@CuBDC exhibited 154% hydrolysis activity of free OPH, 130% reduction activities of pure CuBDC, and an average cascade conversion rate of 6.2 μmol·min-1·gcatalyst-1, affording a complete conversion of 50 μM MP to 4-AP in only 6 min at low reductant concentration (20 mM NaBH4), due to the Cu2+-activation effect on the encapsulated OPH and the PAH-induced exposure of more reduction-catalytic sites, respectively. Furthermore, OPH-PAH@CuBDC retained 95% activity in 10 day storage and about 50% activity in 10 recycles. The results proved that OPH-PAH@CuBDC is a promising chemoenzymatic catalyst with great potential in practical applications for MP detoxification and resourcilization.

An aggregation-induced conformation locking strategy facilitates the activation of lipase biocatalyst

Lipase represents one of the most important industrial biocatalysts, with a global market value of $590.5 million by 2020. However, their catalytic efficiency is often hindered by a closed "lid" conformation. Here, we present an aggregation-induced conformation locking strategy that enables the facile synthesis of highly activated lipase hybrid biocatalysts. Lipase is self-activated into an open-lid conformation via solvent-mediated aggregation, followed by conformational locking within a two-dimensional metal-organic framework (MOF). The resulting MOF biocatalyst provides high accessibility to the locked lipase aggregates through its long-range ordered pore channels, achieving a hydrolytic efficiency 5.30 times greater than that of native lipase. To the best of our knowledge, this represents a record-high activation efficiency for ester hydrolysis among the reported lipase-based hybrid biocatalysts to date. We also demonstrate its feasibility to catalytically accelerate transesterification and esterification reactions, showing up to as 6.64 times higher yield than native lipase and impressive recyclability.

Hierarchical mesoporous ZIF-8-immobilized enzyme microreactor coupled with HPLC for screening of α-glucosidase inhibitors from green tea

Hierarchical mesoporous ZIF-8 (HZIF-8) was synthesized using a thermosensitive hydrogel as a soft template. Zinc ions (Zn2+) were uniformly dispersed on the hydrogel surface through metal-ion coordination with salicylic acid and melamine, followed by coordination with 2-methylimidazole at room temperature. After the thermal removal of salicylic acid and melamine, HZIF-8 was obtained which exhibited a bimodal pore structure comprising both micropores and mesopores. α-Glucosidase (α-Glu) was encapsulated into HZIF-8 via an in-situ diffusion method to construct an immobilized α-Glu microreactor. The morphological and structural characteristics of HZIF-8 before and after α-Glu immobilization were thoroughly characterized using Fourier transform infrared spectroscopy (FT-IR), electron microscopy, X-ray diffraction (XRD), and Brunauer-Emmet-Teller (BET) analysis. The immobilization optimization studies revealed that the optimal immobilization time was 3 h, and the ideal mass ratio of HZIF-8 to α-Glu was 5:2 (w/w). Under these conditions, the α-Glu loading capacity reached 82.09 μg/mg, and the immobilized α-Glu microreactor still retained 70% enzyme activity after seven cycles. The application of the HZIF-8-α-Glu microreactor was verified by coupling with high performance liquid chromatography (HPLC) for the offline screening of α-Glu inhibitors in green tea extract. The experimental results demonstrated the application of the immobilized α-Glu microreactor by screening out catechin and epicatechin gallate from the tea extract.

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.

Diversified nanocarrier design to optimize glucose oxidase-mediated anti-tumor therapy: Strategy and progress

Given the inherent complexity and heterogeneity of tumors, current therapeutic approaches often fall short in meeting prognostic requirements. Starvation therapy (ST) utilizing glucose oxidase (GOx) has emerged as a promising strategy, specifically targeting tumor glucose consumption to disrupt nutrient supply. However, the therapeutic potential of GOx is significantly hampered by its inherent limitations as a protein, particularly its poor stability and short in vivo half-life. In recent years, the development of nanocarriors has provided an effective platform for intravenous and local tumor delivery of GOx. This review systematically examines three key strategies in GOx delivery: stimulus-response, biofilm modification, and local delivery. The progress in various carrier systems for GOx-mediated tumor therapy is comprehensively summarized, providing valuable insights for nanocarrier design. Furthermore, the existing challenges and future directions to advance the development of GOx-based tumor therapies are critically analyzed.

Crystal Phase Transition-Driven Integration of Enzymes into 2D Metal-Organic Frameworks

In situ encapsulation of enzymes within a metal-organic framework (MOF) represents a promising technique for engineering robust biocatalysts. However, the success of enzyme encapsulation is often constrained by intricate interfacial interactions between enzyme surfaces and MOF precursors, limiting the versatility of this MOF method. Herein, we introduce a phase transition strategy for encapsulating enzymes within a Zn-HHTP framework, demonstrating its effectiveness across a wide range of enzymes irrespective of their surface chemistry. In this approach, enzyme molecules are preloaded in a zinc oxide (ZnO) template through a simple yet efficient coprecipitation process, followed by a ZnO-to-Zn-HHTP MOF crystal phase transition in the presence of ligand precursors, resulting in the formation of a quasi-mesoporous hybrid Zn-HHTP MOF inside, for which the original enzymes are preserved. The long-range ordered quasi-mesopore channels enhance substrate accessibility to the immobilized enzymes, endowing enzyme@Zn-HHTP with higher catalytic activity compared to enzymes immobilized within the well-known MOF, ZIF-8, which has narrow apertures. Additionally, the resultant enzyme@Zn-HHTP exhibits exceptional structural stability across a broad pH range (3-14), and Zn-HHTP can provide robust protection against enzyme denaturation by heat, organic solvents, and proteases. This work offers a facile and reliable phase transition strategy for synthesizing active and robust MOF biocatalysts, advancing biocatalysis across various fields.

Coordination Polymer Packaging Approach for Simplifying the Isolation and Recovery of Dissolved Organic Matter from Water

Dissolved organic matter (DOM) is the most abundant carbon substance in the hydrosphere, and its participation in the global carbon cycle makes it crucial for global warming issues. The isolation and recovery of DOM, however, remain formidable challenges. Herein, we report a simple yet efficient coordination polymer packaging (CPP) strategy for DOM isolation and recovery in water samples. This method relies on a DOM-triggered coordination polymer deposition principle, akin to natural biomineralization, transforming hard-to-separate DOM to undissolving precipitate within 1 min. The DOM-encased coordination polymer is acid-sensitive, facilitating the DOM recovery by simply acidifying the solution to pH 6. This CPP approach achieves ∼90% isolation and ∼80% recovery efficiency across a wide range of DOM concentrations and exhibits excellent stability under diverse environmental conditions, with an estimated cost of $4.1 per gram of DOM isolated per ton of water, which is 3 orders of magnitude cheaper than existing methods. The feasibility of the CPP approach was demonstrated with real water samples, including surface water, wastewater, and landfill leachate. We believe this straightforward, facile, time-saving, and cost-effective approach holds significant potential to refine the hydrospheric carbon recycle by simplifying DOM management and thereby contributing to mitigating the adverse global climate changes.

Unravelling the Potential of Crude Enzyme Extracts for Biocatalyst Entrapment in Metal-Organic Frameworks

To bolster the applicability of enzymes as catalysts, it is imperative not only to address their inherent fragility, particularly when used under harsh organic-synthetic reaction conditions, but also to mitigate deactivation during purification and enable applicability in a broad range of organic-synthetic transformations. Currently, the process of purification of crude enzyme extracts and subsequent heterogenization to obtain immobilized biocatalysts often leads to partial enzyme deactivation and represents, at least in part, a resource-intensive process that is driving up the overall production efforts. To tackle both the enzyme fragility and deactivation during purification and immobilization, we propose the direct use of crude enzyme extracts obtained from cell lysis instead of pure enzymes and their entrapment in metal-organic framework (MOF) structures. We focus on three enzyme types with varying sensitivities: aldoxime dehydratase, imine reductase, and lipase. We evaluate the effects of different metal sources (Al, Fe, Co, Ni, Cu, and Zn), their oxidation state and counterions, and MOF synthesis parameters on enzyme stability and activity during their entrapment in the MOF structures. Based on this, we optimize protocols for enzyme entrapment in Fe-MIL-88A, Fe-MIL-100, Zn-MOF-74, and Zn-ZIF-8 and develop a fast-aqueous room temperature synthesis of Al-MIL-53. Investigation of the biocatalytic performance of the enzyme@MOF biocomposites suggests that enzyme entrapment in MOFs using crude enzyme extracts can effectively maintain enzyme activity and stability in various catalytic reactions, offering a perspective for an efficient pathway for industrial applications.

In Situ Metal-Organic Framework Growth in Serum Encapsulates and Depletes Abundant Proteins for Integrated Plasma Proteomics

Protein biomarkers in human serum provide critical insights into various physiological conditions and diseases, enabling early diagnosis, prognosis, and personalized treatment. However, detecting low-abundance protein biomarkers is challenging due to the presence of highly abundant proteins that make up ∼99% of the plasma proteome. Here, we report the use of in situ metal-organic framework (MOF) growth in serum to effectively deplete highly abundant serum proteins for integrated proteomic analysis. Through biomolecule-mediated nucleation of a zeolitic imidazolate framework (ZIF-8), abundant plasma proteins are selectively encapsulated within ZIF-8 and removed from serum via centrifugation, leaving a depleted protein fraction in the supernatant. Bottom-up proteomics analysis confirmed significant depletion of the topmost abundant proteins, many at depletion levels exceeding 95%. Such depletion enabled the identification of 277 total proteins in the supernatant (uncaptured) fraction in a single-shot analysis, including 54 proteins that were only identified after depletion, 12 drug targets, and many potential disease biomarkers. Top-down proteomics characterization of the captured and uncaptured protein fractions at the proteoform-level confirmed this method is not biased toward any specific proteoform of individual proteins. These results demonstrate that in situ MOF growth can selectively and effectively deplete high-abundance proteins from serum in a simple, low cost, one-pot synthesis to enable integrated top-down and bottom-up proteomic analysis of serum protein biomarkers.

Synergistic optimization strategies for the development of multienzymatic cascade system-based electrochemical biosensors with enhanced performance

Multienzymatic cascade system (MCS) strategies have been a topic of growing interest in the electrochemical biosensor research field owing to their many advantages. By combining two or more enzymes in an appropriate manner, MCS approaches can extend the range of detection for particular analytes while improving the overall efficiency of biocatalytic cascade reactions. Compared with mono-enzyme biosensors, the integration of MCS and electrochemical biosensor platforms is inherently more challenging owing to the increased complexity of the resultant system. In recent years, substantial progress in the development of MCS-based electrochemical biosensors with enhanced analytical performance has been made. This review provides an overview of the types of MCS strategies and their biosensor applications, together with a summary of synergistic optimization approaches that can help improve key parameters including sensitivity, selectivity, and stability when designing MCS-based electrochemical biosensors. These discussions include examples of published biosensor platforms (2016-2024) while also surveying key advances in associated research areas including redox mediators/enzyme co-immobilization, enzyme engineering, multienzyme spatial regulation, enzyme-nanozyme integration and others. Lastly, a brief overview of current challenges and future perspectives pertaining to MCS-based electrochemical biosensor design is provided.

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.

SynBioNanoDesign: pioneering targeted drug delivery with engineered nanomaterials

Synthetic biology and nanotechnology fusion represent a transformative approach promoting fundamental and clinical biomedical science development. In SynBioNanoDesign, biological systems are reimagined as dynamic and programmable materials to yield engineered nanomaterials with emerging and specific functionalities. This review elucidates a comprehensive examination of synthetic biology's pivotal role in advancing engineered nanomaterials for targeted drug delivery systems. It begins with exploring the fundamental synergy between synthetic biology and nanotechnology, then highlights the current landscape of nanomaterials in targeted drug delivery applications. Subsequently, the review discusses the design of novel nanomaterials informed by biological principles, focusing on expounding the synthetic biology tools and the potential for developing advanced nanomaterials. Afterward, the research advances of innovative materials design through synthetic biology were systematically summarized, emphasizing the integration of genetic circuitry to program nanomaterial responses. Furthermore, the challenges, current weaknesses and opportunities, prospective directions, and ethical and societal implications of SynBioNanoDesign in drug delivery are elucidated. Finally, the review summarizes the transformative impact that synthetic biology may have on drug-delivery technologies in the future.

Mimicomes: Mimicking Multienzyme System by Artificial Design

Enzymes are widely distributed in organelles of cells, which are capable of carrying out specific catalytic reactions. In general, several enzymes collaborate to facilitate complex reactions and engage in vital biochemical processes within cells, which are also called cascade systems. The cascade systems are highly efficient, and their dysfunction is associated with a multitude of endogenous diseases. The advent of nanotechnology makes it possible to mimic these cascade systems in nature and realize partial functions of natural biological processes both in vitro and in vivo. To emphasize the significance of artificial cascade systems, mimicomes is first proposed, a new concept that refers to the artificial cascade catalytic systems. Typically, mimicomes are able to mimic specific natural biochemical catalytic processes or facilitate the overall catalytic efficiency of cascade systems. Subsequently, the evolution and development of different types of mimicomes in recent decades are elucidated exhaustedly, from the natural enzyme-based mimicomes (immobilized enzyme and vesicle mimicomes) to the nanozyme-based mimicomes and enzyme-nanozyme hybrid mimicomes. In conclusion, the remaining challenges in the design of multifunctional mimicomes and their potential applications are summarized, offering insights into their future prospects.

Urease-powered micro/nanomotors: Current progress and challenges

Enzyme-powered micro/nanomotors (MNMs) (EMNMs) use natural enzymes to facilitate the decomposition of fuels, including hydrogen peroxide (H2O2), glucose, triglycerides, and urea to provide power. EMNMs can achieve self-propulsion through the in situ utilization of biofuels without additional fuels, exhibiting excellent biocompatibility and significant potential for application in the biomedical field. Compared with H2O2, which may cause oxidative damage to the body, urea exhibits superior biosafety characteristics. Presently, urease-powered MNMs (UMNMs) have made notable progress in their applications in the biomedical field and have garnered considerable attention from researchers. In this review, we present the latest advancements in the biomedical field of UMNMs, primarily focusing on: 1) diverse materials used for constructing the fundamental framework of motors; 2) control of motor movement through the regulation of enzymatic reaction rates; and 3) research directions for the clinical application of motors, including in vivo imaging, biomarker detection, cancer treatment, optical therapy, overcoming biological barriers, antibacterial interventions, antithrombotic strategies, and gastric disease management. Despite showing immense potential in biomedical applications, there are still several challenges impeding its practical implementation, such as maintaining activity in the in vivo environment while accurately targeting specific sites to achieve the desired clinical therapeutic effects.

Research progress on the synthesis, performance regulation, and applications of Prussian blue nanozymes

Nanocatalytic medicine offers a novel solution to address the issues of low efficacy, potential side effects, and the development of drug resistance associated with traditional therapies. Therefore, developing highly efficient and durable nanozymes is of great significance for treating diseases related to oxidative stress. In recent years, prussian blue nanoparticles (PBNPs) have been demonstrated to possess multiple enzyme-like catalytic activities and are thus referred to as prussian blue nanozymes (PBNZs). Their excellent biocompatibility and biodegradability make PBNZs promising candidates as biomedical materials. Due to their remarkable catalytic activities, PBNZs have shown great potential in various biomedical applications, such as heavy metal detoxification, antioxidative damage, and anticancer therapies. This paper systematically summarizes the Synthetic strategies of PBNZs, analyzes the regulatory factors of their catalytic performance, and highlights the corresponding modulation methods. Furthermore, the biomedical applications of PBNZs are also reviewed. This study aims to provide researchers with insights and inspirations for the design and preparation of high-performance PBNZs.

Intra-Mesopore Immunoassay Based on Core-Shell Structured Magnetic Hierarchically Porous ZIFs

It is crucial yet challenging to sensitively quantify low-abundance biomarkers in blood for early screening and diagnosis of various diseases. Herein, an analytical model of intra-mesopore immunoassay (IMIA) was proposed, which was competent to examine various biomarkers at the femtomolar level. The success is rooted in the design of an innovative superparamagnetic core-shell structure with Fe3O4 nanoparticles (NPs) at the core and hierarchically porous zeolitic imidazolate frameworks as a shell (Fe3O4@HPZIF-8), achieved through a soft-template directed self-assembly coupled with confinement growth mechanism. Such a unique configuration conceptualized IMIA where the HPZIF-8 shell served as a solid carrier to cover capture antibodies while the Fe3O4 core assisted its rapid separation. The large pore channels not only provided a stable microenvironment to maintain the recognition ability of captured antibodies but also enhanced their coating density, thus promoting the probability of capturing and binding target antigens, significantly improving immunoassay (IA) sensitivity. The practical clinic IA for cTnI (Cardiac Troponin I, biomarker of acute myocardial infarction (AMI)) in human serums was exemplified. The developed IMIA could accurately quantify slight fluctuations in cTnI concentrations in the serums of AMI patients at different stages after symptom onset with more than 100-fold enhancement of limit of detection (LOD) in comparison to conventional plate-based enzyme-linked immunosorbent assay (ELISA). Such high sensitivity of IMIA makes it a powerful tool for the accurate diagnosis of different diseases by altering the type of primary capture antibody.

Integrating Enzymes with Reticular Frameworks To Govern Biocatalysis

Integrating enzymes with reticular frameworks offers promising avenues for access to functionally tailorable biocatalysis. This Minireview explores recent advances in enzyme-reticular framework hybrid biocomposites, focusing on the utilization of porous reticular frameworks, including metal-organic frameworks, covalent-organic frameworks, and hydrogen-bonded organic frameworks, to regulate the reactivity of an enzyme encapsulated inside mainly by pore infiltration and in situ encapsulation strategies. We highlight how pore engineering and host-guest interfacial interactions within reticular frameworks create tailored microenvironments that substantially impact the mass transfer and enzyme conformation, leading to biocatalytic rate enhancement, or imparting enzymes with non-native biocatalytic functions, including substrate selectivity and new activity. Additionally, the feasibility of leveraging the photothermal effect of a framework to optimize the local reaction temperature and photoelectric effect to elicit diverse photoenzyme-coupled reactions is also summarized in detail, which can expand the functional repertoire of biocatalytic transformations under light irradiation. This Minireview underscores the potential of reticular frameworks as tunable and reliable platforms to govern biocatalysis, offering pathways for engineering sustainable, efficient, and selective biocatalytic reactors in pharmaceutical, environmental, and energy-related applications.

Compartmentalized co-immobilization of cellulase and cellobiose phosphorylase within zeolitic imidazolate framework efficiently synthesizes 1-p-Glc: Glycosylation of 18FDG

Enzymatic glycosylation is an efficient and biocompatible approach to enhance natural product bioavailability. Cellobiose phosphorylase, a novel glycosyltransferase, utilizes 1-phospho-glucose (1-p-Glc) as a glycosyl donor for regioselective glycosylation of various natural substrates. However, the high cost of 1-p-Glc limits the economic feasibility of the process. Thus, a dual-enzyme cascade system involving cellulase AcCel9A and cellobiose phosphorylase CbCBP using a co-immobilization strategy was developed to overcome this challenge. The system utilizes low-cost carboxymethyl cellulose (CMC) for continuous 1-p-Glc production, which was then used in the fluorodeoxy glucose (FDG) glycosylation to generate fluorodeoxy cellobiose (FDC), which potentially traces fungal infections. The compartmentalized co-immobilization of the two enzymes within the internal and external regions of a porous zeolitic imidazolate framework-8 (ZIF-8) carrier enhanced the overall stability of the dual-enzyme system. The immobilized enzymes retained approximately 63.3 % activity after seven reuse cycles and 74 % catalytic efficiency after 12 days of storage at room temperature. Therefore, the developed co-immobilized multi-enzyme system holds significant potential for industrial biocatalysis applications.

Construction of electrochemical immunosensors based on Au@MXene and Au@CuS nanocomposites for sensitive detection of carcinoembryonic antigen

Cancer is currently one of the major causes of human mortality and has received widespread attention. In this paper, Au@CuS composite nanomaterial as a sandwich immunosensor tag for carcinoembryonic antigen (CEA) detection strategy was studied. Herein, Au@CuS composite nanomaterials were obtained by Au nanoparticles modified with CuS, which were combined with secondary antibody (Ab2) to construct an immunosensor that interacted with H2O2 to produce a current response. The anti-CEA primary antibody (Ab1) was fixed on the glassy carbon electrode (GCE) modified by Au@MXene. The completed electrochemical immunosensor was constructed with rapid detection and high sensitivity for CEA. Under optimal conditions, the linearity ranged from 0.01 pg/mL to 0.5 ng/mL, and the detection limit was 3.8 fg/mL. This tactic possesses good reproducibility, constancy and selectivity. At the same time, this strategy has latent practical value for the test of other tumor markers.

Nanoencapsulation of Living Microbial Cells in Porous Covalent Organic Framework Shells

Encapsulating living cells within nanoshells offers an important approach to enhance their stability against environmental stressors and broaden their application scope. However, this often leads to impaired mass transfer at the cell biointerface. Strengthening the protective shell with well-defined, ordered transport channels is crucial to regulating molecular transport and maintaining cell viability and biofunctionality. Herein, we report the construction of covalent organic framework (COF) mesoporous shells for single-cell nanoencapsulation, providing selective permeability and comprehensive protection for living microbial cells. The COF shells ensure nutrient uptake while blocking large harmful molecules and UV-C radiation, thereby preserving cell viability and metabolic activity. Integration of such crystalline porous shells with genetically modified cell factories for metabolic production is further investigated, revealing no adverse effects, as demonstrated by riboflavin production. Moreover, the COF shell effectively shields cells, ensuring efficient bioproduction even after being treated under harsh conditions. This versatile encapsulation approach is applicable for different cell types, providing a robust platform for cell surface engineering.

Recent Progress in Enzyme Immobilization to Metal-Organic Frameworks to Enhance the CO2 Conversion Efficiency

Climate change and the energy crisis, driven by excessive CO2 emissions, have emerged as pressing global challenges. The conversion of CO2 into high-value chemicals not only mitigates atmospheric CO2 levels but also optimizes carbon resource utilization. Enzyme-catalyzed carbon technology offers a green and efficient approach to CO2 conversion. However, free enzymes are prone to inactivation and denaturation under reaction conditions, which limit their practical applications. Metal-organic frameworks (MOFs) serve as effective carriers for enzyme immobilization, offering porous crystalline structures that enhance enzyme stability. Moreover, their high specific surface area facilitates strong gas adsorption, making enzyme@MOF composites particularly advantageous for CO2 catalytic conversion. In this paper, we review the synthesis technologies and the application of enzyme@MOFs in CO2 catalytic conversion. Furthermore, the strategies, including the enhancement of CO2 utilization, coenzyme regeneration efficiency, and substrate mass transfer efficiency, are also discussed to further improve the efficiency of enzyme@MOFs in CO2 conversion. The aim of this review is to present innovative ideas for future research and to highlight the potential applications of enzyme@MOFs in achieving efficient CO2 conversion.

Aldehyde Directed In Situ Loading of Ag Nanodots Around the Open Metal Sites of MOFs for the Tandem Catalysis of Nitrate to Ammonia

Both spatial arrangement and intrinsic activity of electrocatalysts with dual-active sites are widely designed to match the coupling reaction between nitrate and water, in which most of the reactive intermediates can be optimized to achieve a high yield rate of ammonia. Herein, by introducing the aldehyde group inside metal-organic frameworks (MOFs) in advance, an aldehyde-induced method is achieved to direct the in situ nucleation of Ag nanodots depending on the mesopores of MOFs via a simple silver mirror reaction. The key point here is that the spatial arrangement between the aldehyde group and open metal sites is fixed end to end, which makes the aldehyde group a built-in redox-active site to drive the in situ nucleation of Ag nanodots next to the open metal sites of MOFs. Accordingly, by varying the metal sites of MOFs, a group of M-MOFs@Ag (M = Fe, Co, Ni, Cu, etc.) hybrids with dual active sites are acquired. Taking Ni-MOFs@Ag as an example, the interaction between Ni2+ and Ag sites makes it available for the tandem catalysis of nitrate-to-ammonia, in which the H· and NO2 - generated on the open Ni2+ sites and Ag nanodots, respectively, can migrate to each other to evolve into ammonia.

Enhancing Biocatalysis: Metal-Organic Frameworks as Multifunctional Enzyme Hosts

Enzymes are highly efficient and selective catalysts that operate under mild conditions, making them invaluable for various chemical transformations. However, their limitations, such as instability and high cost, call for advancements in enzyme immobilization and the development of suitable host materials. Metal-organic frameworks (MOFs), characterized by high porosity, crystallinity, and tunability, are promising candidates for enzyme encapsulation. Among these, zirconium-based MOFs (Zr-MOFs) stand out due to their exceptional structural diversity and chemical stability. The physical and chemical properties of Zr-MOFs can be tuned and characterized with atomic precision, and their interactions with enzymes can be analyzed through a range of techniques spanning from chemistry and materials science to biochemistry. This tunable platform provides opportunities to systematically investigate the impact of encapsulation on the stability and activity of enzymes in order to develop design rules for enzyme hosts. In this Account, we discuss experimentally validated concepts for designing MOF hosts based on their structural properties and enzyme encapsulation mechanisms. We present methods to enhance enzyme catalytic performance through encapsulation and strategies for creating multifunctional enzyme@MOF systems via host modifications. We start by highlighting the importance of host structural design that maximizes substrate diffusion and enzyme availability, with particular focus on MOFs containing hierarchical mesoporous structures such as those in the csq topology. We then delve into the encapsulation process and host-guest interactions examined through techniques such as microscopy, calorimetry, and computational methods, which provide guidelines to fine-tune the local pore chemical environment to enhance enzyme stability and catalytic activity. Techniques found in biochemistry, such as isothermal titration calorimetry (ITC) and confocal laser scanning microscopy (CLSM), were developed to investigate enzyme encapsulation mechanisms, revealing high-entropy-driven host-guest affinity. Additionally, we discuss cases in which enzyme@MOF systems demonstrated enhanced catalytic activities and multifunctional capabilities. Encapsulated enzymes have demonstrated improved thermal and chemical stabilities compared to their free counterparts, maintaining activity under conditions that typically lead to denaturation. Additionally, the highly tunable nature of the MOF platforms allows them to support more complex systems such as tandem reactions, enabling applications in biophotocatalysis, bioelectrocatalysis, and targeted therapeutic protein delivery. The versatility of enzyme@MOFs promises extensive applications in both research and industrial processes across fields including biotechnology, pharmaceutical development, and environmental science. We provide an outlook for promising directions for enzyme@MOF research, with the aim of continuing innovation and exploration. We hope that this Account can benefit chemists, biologists, and material scientists toward designing efficient and adaptable next-generation biocatalytic composite materials.

Evaluation of the immobilized enzymes function in soil remediation following polycyclic aromatic hydrocarbon contamination

The bioremediation of polycyclic aromatic hydrocarbon (PAHs) from soil utilizing microorganisms, enzymes, microbial consortiums, strains, etc. has attracted a lot of interest due to the environmentally friendly, and cost-effective features. Enzymes can efficiently break down PAHs in soil by hydroxylating the benzene ring, breaking the C-C bond, and catalyze the hydroxylation of a variety of benzene ring compounds via single-electron transfer oxidation. However, the practical application is limited by its instability and ease to loss function under harsh environmental conditions such as pH, temperature, and edaphic stress etc. Therefore, this paper focused on the techniques used to immobilize enzymes and remediate PAHs in soil. Moreover, previous research has not adequately covered this topic, despite the employment of several immobilized enzymes in aqueous solution cultures to remediate other types of organic pollutants. Bibliometric analysis further highlighted the research trends from 2000 to 2023 on this field of growing interest and identified important challenges regarding enzyme stability and interaction with soil matrices. The findings indicated that immobilized enzymes may catalyzed PAHs via oxidation of OH groups in benzene rings, and generate benzyl radicals (i.e., •OH and •O2) that undergo further reaction and release water. As a result, the intermediate products of PAHs further catalyze by enzyme and enzyme induced microbes producing carbon dioxide and water. Meanwhile efficiency, activity, lifetime, resilience, and sustainability of immobilized enzyme need to be further improved for the large-scale and field-scale clean-up of PAHs polluted soils. This could be possible by integrating enzyme-based with microbial and plant-based remediation strategies. It can be coupled with another line of research focused on using a new set of support materials that can be derived from natural resources.

Engineering enzyme conformation within liquid-solid hybrid microreactors for enhanced continuous-flow biocatalysis

The artificial engineering of an enzyme's structural conformation and dynamic properties to promote its catalytic activity and stability outside cellular environments is highly pursued in industrial biotechnology. Here, we describe an elegant strategy of combining the rationally designed liquid-solid hybrid microreactor with a tailor-made polyethylene glycol functional ionic liquid (PEG-IL) microenvironment to exercise a high level of control over the configuration of enzymes for practical continuous-flow biocatalysis. As exemplified by a lipase driven kinetic resolution reaction, the obtained system exhibits a 2.70 to 30.35-fold activity enhancement compared to their batch or traditional IL-based counterparts. Also, our results demonstrate that the thermal stability of encapsulated lipase can be significantly strengthened in the presence of PEG groups, showcasing a long-term continuous-flow stability even up to 1000 h at evaluated temperature of 60 oC. Through systematic experiment and molecular dynamics simulation studies, the conformational changes of the active site cavity in the modified lipases are correlated with enzymatic properties alteration, and the pronounced effects of PEG-groups in stabilizing enzyme's secondary structures by delaying unfolding at elevated temperatures are identified. We believe that this study will guide the design of high-performance enzymatic systems, promoting their utilization in real-world biocatalysis applications.

A polymer deposition-mediated surface-charge reformation strategy: reversing the MOF biomineralization behavior

Biomineralization of a porous metal-organic framework (MOF) shell onto biomacromolecule templates is a burgeoning strategy to construct robust biocatalysts. However, it strongly relies on the interfacial interaction between MOF precursors and enzyme surface, significantly limiting the generalization of this nanotechnology. Herein, we identify polymers that are well-suited for deposition onto target biomacromolecules via supramolecular interactions and introduce a polymer deposition-mediated surface-charge reformation strategy to facilitate the biomineralization of porous MOFs, including ZIF-8, ZIF-90, and ZIF-zni onto enzymes. We investigate nine commercially available polymers to find that those with dense -SO3H and -COOH groups effectively regulate the surface-charge properties of the enzymes that are unfavorable for biomineralization. The polymer-enzyme complex thus formed retains its original bioactivity and offers significantly elevated sites to accumulate metal precursors, triggering the in-place MOF biomineralization. We demonstrate that this approach allows access to diverse MOF biocatalysts independent of the enzyme surface chemistry, which are difficult to be synthesized by previous biomineralization methods. Given the highly specific bioactivity and structural stability of the MOF biocatalysts, a chemiluminiscence sensor platform is developed for the sensitive detection of hydrogen sulfide (H2S) biomarkers, with a low limit of detection of 0.09 nM that is superior to most of the reported methods. This study provides an effective and universal strategy for MOF biomineralization using fragile enzymes as biotemplates and offers new insights into accessing multifunctional MOF hybrid biocatalysts.

Nanomaterial-based regulation of redox metabolism for enhancing cancer therapy

Altered redox metabolism is one of the hallmarks of tumor cells, which not only contributes to tumor proliferation, metastasis, and immune evasion, but also has great relevance to therapeutic resistance. Therefore, regulation of redox metabolism of tumor cells has been proposed as an attractive therapeutic strategy to inhibit tumor growth and reverse therapeutic resistance. In this respect, nanomedicines have exhibited significant therapeutic advantages as intensively reported in recent studies. In this review, we would like to summarize the latest advances in nanomaterial-assisted strategies for redox metabolic regulation therapy, with a focus on the regulation of redox metabolism-related metabolite levels, enzyme activity, and signaling pathways. In the end, future expectations and challenges of such emerging strategies have been discussed, hoping to enlighten and promote their further development for meeting the various demands of advanced cancer therapies. It is highly expected that these therapeutic strategies based on redox metabolism regulation will play a more important role in the field of nanomedicine.

Emerging near-infrared targeting diagnostic and therapeutic strategies for ischemic cardiovascular and cerebrovascular diseases

Ischemic cardiovascular and cerebrovascular diseases (ICCDs), including thrombosis, ischemic stroke and atherosclerosis, represent a significant threat to human health, and there is an urgent requirement for the implementation of emerging diagnostic and therapeutic approaches to improve symptoms and prognosis. As a promising noninvasive modality offering high spatial and temporal resolution with favorable biocompatible properties, near-infrared (NIR) light has demonstrated a vast and profound potential in the biomedical field in recent years. Meanwhile, nanomedicine carriers are undergoing rapid development due to their high specific surface area, elevated drug loading capacity, and unique physicochemical properties. The combination of NIR light with targeted nanoprobes modified with different functional components not only maintains the high penetration depth of NIR irradiation in biological tissues but also significantly enhances the targeting specificity at the lesion site. This strategy allows for the realization of on-demand drug release and photothermal effects, thus inspiring promising avenues for the diagnosis and treatment of ICCDs. However, the clinical translation of NIR imaging and therapy is still hindered by significant obstacles. The existing literature has provided a comprehensive overview of the advancements in NIR-based nanomedicine research. However, there is a notable absence of reviews that summarize the NIR-mediated targeting strategies against ICCDs in imaging and therapy. Therefore, this review concludes the application of the emerging targeting probes combined with NIR radiation for ICCDs classified by molecular targets, analyzes the current challenges, and provides improvement strategies and prospects for further clinical translation. STATEMENT OF SIGNIFICANCE: Ischemic cardiovascular and cerebrovascular diseases (ICCDs) represent a significant threat to human health. Recently, near-infrared (NIR) light combined with targeting probes have been employed for the diagnosis and treatment of ICCDs, offering exceptional advantages including rapid feedback, high penetration depth, on-demand drug release, and favorable biocompatibility. However, there is a notable absence of reviews that summarize the NIR light-mediated targeting strategies for the imaging and therapy of ICCDs. Therefore, this review summarizes the emerging targeting probes combined with NIR light classified by molecular targets, and the proposes potential improvement strategies for clinical translation. This review elucidates the potential and current status of NIR-based techniques in ICCDs, while also serving as a reference point for additional targeted therapeutic strategies for ICCDs.

Integrating Biocatalysts into Metal-Organic Frameworks: Disentangling the Roles of Affinity, Molecular Weight, and Size

The integration of biocatalysts within metal-organic frameworks (MOFs) is attracting growing interest due to its potential to both enhance biocatalyst stability and sustain biocatalyst activity in organic solvents. However, the factors that facilitate the post-synthetic infiltration of such large molecules into MOF pores remain unclear. This systematic study enabled the identification of the influence of biocatalyst molecular size, molecular weight and affinity on the uptake by an archetypal MOF, NU-1000. We analyzed a range of six biocatalysts with molecular weights from 1.9 kDa to 44.4 kDa, respectively. By employing a combination of fluorescence tagging and 3D-STED confocal laser scanning microscopy, we distinguished between biocatalysts that were internalized within the MOF pores and those sterically excluded. The catalytic functions of the biocatalysts hosted within the MOF were investigated and found to show strong variations relative to the solvated case, ranging from a two-fold increase to a strong decrease.

Enhanced Interfacial Electron Transfer in Photocatalyst-Natural Enzyme Coupled Artificial Photosynthesis System: Tuning Strategies and Molecular Simulations

Laccase is capable of catalyzing a vast array of reactions, but its low redox potential limits its potential applications. The use of photocatalytic materials offers a solution to this problem by converting absorbed visible light into electrons to facilitate enzyme catalysis. Herein, MIL-53(Fe) and NH2-MIL-53(Fe) serve as both light absorbers and enzyme immobilization carriers, and laccase is employed for solar-driven chemical conversion. Electron spin resonance spectroscopy results confirm that visible light irradiation causes rapid transfer of photogenerated electrons from MOF excitation to T1 Cu(II) of laccase, significantly increasing the degradation rate constant of tetracycline (TC) from 0.0062 to 0.0127 min-1. Conversely, there is only minimal or no electron transfer between MOF and laccase in the physical mixture state. Theoretical calculations demonstrate that the immobilization of laccase's active site and its covalent binding to the metal-organic framework surface augment the coupled system's activity, reducing the active site accessible from 27.8 to 18.1 Å. The constructed photo-enzyme coupled system successfully combines enzyme catalysis' selectivity with photocatalysis's high reactivity, providing a promising solution for solar energy use.

Nanopore-regulated in situ polymerization for synthesis of homogeneous heparan sulfate with low dispersity

The biological activities of heparan sulfate (HS) are intimately related to their molecular weights, degree and pattern of sulfation and homogeneity. The existing methods for synthesizing homogeneous sugar chains of low dispersity involve multiple steps and require stepwise isolation and purification processes. Here, we designed a mesoporous metal-organic capsule for the encapsulation of glycosyltransferase and obtained a microreactor capable of enzymatically catalyzing polymerization reactions to prepare homogeneous heparosan of low dispersity, the precursor of HS and heparin. Since the sugar chain extension occurs in the pores of the microreactor, low molecular weight heparosan can be synthesized through space-restricted catalysis. Moreover, the glycosylation co-product, uridine diphosphate (UDP), can be chelated with the exposed metal sites of the metal-organic capsule, which inhibits trans-cleavage to reduce the molecular weight dispersity. This microreactor offers the advantages of efficiency, reusability, and obviates the need for stepwise isolation and purification processes. Using the synthesized heparosan, we further successfully prepared homogeneous 6-O-sulfated HS of low dispersity with a molecular weight of approximately 6 kDa and a polydispersity index (PDI) of 1.032. Notably, the HS generated exhibited minimal anticoagulant activity, and its binding affinity to fibroblast growth factor 1 was comparable to that of low molecular weight heparins.

Catalase immobilization: Current knowledge, key insights, applications, and future prospects - A review

Catalase (CAT), a ubiquitous enzyme in all oxygen-exposed organisms, effectively decomposes hydrogen peroxide (H2O2), a harmful by-product, into water and oxygen, mitigating oxidative stress and cellular damage, safeguarding cellular organelles and tissues. Therefore, CAT plays a crucial role in maintaining cellular homeostasis and function. Owing to its pivotal role, CAT has garnered considerable interest. However, many challenges arise when used, especially in multiple practical processes. "Immobilization", a widely-used technique, can help improve enzyme properties. CAT immobilization offers numerous advantages, including enhanced stability, reusability, and facilitated downstream processing. This review presents a comprehensive overview of CAT immobilization. It starts with discussing various immobilization mechanisms, support materials, advantages, drawbacks, and factors influencing the performance of immobilized CAT. Moreover, the review explores the application of the immobilized CAT in various industries and its prospects, highlighting its essential role in diverse fields and stimulating further research and investigation. Furthermore, the review highlights some of the world's leading companies in the field of the CAT industry and their substantial potential for economic contribution. This review aims to serve as a discerning, source of information for researchers seeking a comprehensive cutting-edge overview of this rapidly evolving field and have been overwhelmed by the size of publications.

Machine Learning Optimizing Enzyme/ZIF Biocomposites for Enhanced Encapsulation Efficiency and Bioactivity

In this study, we present the first example of using a machine learning (ML)-assisted design strategy to optimize the synthesis formulation of enzyme/ZIFs (zeolitic imidazolate framework) for enhanced performance. Glucose oxidase (GOx) and horseradish peroxidase (HRP) were chosen as model enzymes, while Zn(eIM)2 (eIM = 2-ethylimidazolate) was selected as the model ZIF to test our ML-assisted workflow paradigm. Through an iterative ML-driven training-design-synthesis-measurement workflow, we efficiently discovered GOx/ZIF (G151) and HRP/ZIF (H150) with their overall performance index (OPI) values (OPI represents the product of encapsulation efficiency (E in %), retained enzymatic activity (A in %), and thermal stability (T in %)) at least 1.3 times higher than those in systematic seed data studies. Furthermore, advanced statistical methods derived from the trained random forest model qualitatively and quantitatively reveal the relationship among synthesis, structure, and performance in the enzyme/ZIF system, offering valuable guidance for future studies on enzyme/ZIFs. Overall, our proposed ML-assisted design strategy holds promise for accelerating the development of enzyme/ZIFs and other enzyme immobilization systems for biocatalysis applications and beyond, including drug delivery and sensing, among others.

Recent Advances on the Metal-Organic Frameworks-Based Biosensing Methods for Cancer Biomarkers Detection

Sensitive and selective detection of cancer biomarkers is crucial for early diagnosis and treatment of cancer, one of the most dangerous diseases in the world. Metal-organic frameworks (MOFs), a class of hybrid porous materials fabricated through the assembly of metal ions/clusters and organic ligands, have attracted increasing attention in the sensing of cancer biomarkers, due to the advantages of adjustable size, high porosity, large surface area and ease of modification. MOFs have been utilized to not only fabricate active sensing interfaces but also arouse a variety of measurable signals. Several representative analytical technologies have been applied in MOF-based biosensing strategies to ensure high detection sensitivity toward cancer biomarkers, such as fluorescence, electrochemistry, electrochemiluminescence, photochemistry and colorimetric methods. In this review, we summarized recent advances on MOFs-based biosensing strategies for the detection of cancer biomarkers in recent three years based on the categories of metal nodes, and aimed to provide valuable references for the development of innovative biosensing platform for the purpose of clinical diagnosis.

Immobilized Urease Vector System Based on the Dynamic Defect Regeneration Strategy for Efficient Urea Removal

The clearance of urea poses a formidable challenge, and its excessive accumulation can cause various renal diseases. Urease demonstrates remarkable efficacy in eliminating urea, but cannot be reused. This study aimed to develop a composite vector system comprising microcrystalline cellulose (MCC) immobilized with urease and metal-organic framework (MOF) UiO-66-NH2, denoted as MCC@UiO/U, through the dynamic defect generation strategy. By utilizing competitive coordination, effective immobilization of urease into MCC@UiO was achieved for efficient urea removal. Within 2 h, the urea removal efficiency could reach up to 1500 mg/g, surpassing an 80% clearance rate. Furthermore, an 80% clearance rate can also be attained in peritoneal dialyzate from patients. MCC@UiO/U also exhibits an exceptional bioactivity even after undergoing 5 cycles of perfusion, demonstrating remarkable stability and biocompatibility. This innovative approach and methodology provide a novel avenue and a wide range of immobilized enzyme vectors for clinical urea removal and treatment of kidney diseases, presenting immense potential for future clinical applications.

Enhancing Substrate Channeling with Multi-Enzyme Architectures in Hydrogen-Bonded Organic Frameworks

Hydrogen-bonded organic frameworks (HOF) represent an emerging category of organic structures with high crystallinity and metal-free, which are not commonly observed in alternative porous organic frameworks. These needle-like porous structure can help in stabilizing enzymes and allow transfer of molecules between enzymes participating in cascade reactions for enhanced substrate channelling. Herein, we systematically synthesized and investigated the stability of HOF at extreme conditions followed by one-pot encapsulation of single and bi-enzyme systems. Firstly, we observed HOF to be stable at pH 1 to 14 and at high temperatures (up to 115 °C). Secondly, the encapsulated glucose oxidase enzyme (GOX) showed 80 % and 90 % of its original activity at 70 °C and pH 11, respectively. Thirdly, transient time close to 0 seconds was observed for HOF encapsulated bi-enzyme cascade reaction system demonstrating a 4.25-fold improvement in catalytic activity when compared to free enzymes with enhanced substrate channelling. Our findings showcase a facile system synthesized under ambient conditions to encapsulate and stabilize enzymes at extreme conditions.

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.

A Synergetic Pore Compartmentalization and Hydrophobization Strategy for Synchronously Boosting the Stability and Activity of Enzyme

Spatial immobilization of fragile enzymes using a nanocarrier is an efficient means to design heterogeneous biocatalysts, presenting superior stability and recyclability to pristine enzymes. An immobilized enzyme, however, usually compromises its catalytic activity because of inevasible mass transfer issues and the unfavorable conformation changes in a confined environment. Here, we describe a synergetic metal-organic framework pore-engineering strategy to trap lipase (an important hydrolase), which confers lipase-boosted stability and activity simultaneously. The hierarchically porous NU-1003, featuring interconnected mesopore and micropore channels, is precisely modified by chain-adjustable fatty acids on its mesopore channel, into which lipase is trapped. The interconnected pore structure ensures efficient communication between trapped lipase and exterior media, while the fatty acid-mediated hydrophobic pore can activate the opening conformation of lipase by interfacial interaction. Such dual pore compartmentalization and hydrophobization activation effects render the catalytic center of trapped lipase highly accessible, resulting in 1.57-fold and 2.46-fold activities as native lipase on ester hydrolysis and enantioselective catalysis. In addition, the feasibility of these heterogeneous biocatalysts for kinetic resolution of enantiomer is also validated, showing much higher efficiency than native lipase.

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.

Dual-Track Multifunctional Bimetallic Metal-Organic Frameworks for Antibiotic Enrichment and Detection

The improper use and overuse of antibiotics have led to significant burdens and detrimental effects on the environment, food supply, and human health. Herein, a magnetic solid-phase extraction program and an optical immunosensor based on bimetallic Ce/Zr-UiO 66 for the detection of antibiotics are developed. A magnetic Fe3O4@SiO2@Ce/Zr-UiO 66 metal-organic framework (MOF) is prepared to extract and enrich chloramphenicol from fish, wastewater, and urine samples, and a horseradish peroxidase (HRP)-Ce/Zr-UiO 66@bovine serum protein-chloramphenicol probe is used for the sensitive detection of chloramphenicol based on the dual-effect catalysis of Ce and HRP. In this manner, the application of Ce/Zr-UiO 66 in integrating sample pretreatment and antibiotic detection is systematically investigated and the associated mechanisms are explored. It is concluded that Ce/Zr-UiO 66 is a versatile dual-track material exhibiting high enrichment efficiency (6.37 mg g-1) and high sensitivity (limit of detection of 51.3 pg mL-1) for chloramphenicol detection and serving as a multifunctional MOF for safeguarding public health and hygiene.

Metal-organic framework-based multienzyme cascade bioreactor for sensitive detection of methyl parathion

In this study, a cascade nanobioreactor was developed for the highly sensitive detection of methyl parathion (MP) in food samples. The simultaneous encapsulation of acetylcholinesterase (AChE) and choline oxidase (CHO) in a zeolitic imidazole ester backbone (ZIF-8) effectively improved the stability and cascade catalytic efficiency of the enzymes. In addition, glutathione-stabilized gold nanoclusters (GSH-AuNCs) were encapsulated in ZIF-8 by ligand self-assembly, conferring excellent fluorescence properties. Acetylcholine (ATCh) is catalyzed by a cascade of AChE/CHO@ZIF-8 as well as Fe(II) to generate hydroxyl radicals (·OH) with strong oxidizing properties. The ·OH radicals then oxidize Au(0) in GSH-AuNCs@ZIF-8 to Au(I), resulting in fluorescence quenching. MP, as an inhibitor of AChE, hinders the cascade reaction and thus restores the fluorescence emission, enabling its quantitative detection. The limit of detection of the constructed nanobioreactor for MP was 0.23 µg/L. This MOF-based cascade nanobioreactor has great potential for the detection of trace hazards.

Cascade Reactions Catalyzed by Gold Hybrid Nanoparticles Generate CO Gas Against Periodontitis in Diabetes

The treatment of diabetic periodontitis poses a significant challenge due to the presence of local inflammation characterized by excessive glucose concentration, bacterial infection, and high oxidative stress. Herein, mesoporous silica nanoparticles (MSN) are embellished with gold nanoparticles (Au NPs) and loaded with manganese carbonyl to prepare a carbon monoxide (CO) enhanced multienzyme cooperative hybrid nanoplatform (MSN-Au@CO). The Glucose-like oxidase activity of Au NPs catalyzes the oxidation of glucose to hydrogen peroxide (H2O2) and gluconic acid，and then converts H2O2 to hydroxyl radicals (•OH) by peroxidase-like activity to destroy bacteria. Moreover, CO production in response to H2O2, together with Au NPs exhibited a synergistic anti-inflammatory effect in macrophages challenged by lipopolysaccharides. The underlying mechanism can be the induction of nuclear factor erythroid 2-related factor 2 to reduce reactive oxygen species, and inhibition of nuclear factor kappa-B signaling to diminish inflammatory response. Importantly, the antibacterial and anti-inflammation effects of MSN-Au@CO are validated in diabetic rats with ligature-induced periodontitis by showing decreased periodontal bone loss with good biocompatibility. To summarize, MSN-Au@CO is fabricate to utilize glucose-activated cascade reaction to eliminate bacteria, and synergize with gas therapy to regulate the immune microenvironment, offering a potential direction for the treatment of diabetic periodontitis.

Boosted Enzyme Activity via Encapsulation within Metal-Organic Frameworks with Pores Matching Enzyme Size and Shape

A novel and versatile approach called "physical imprinting" is introduced to modulate enzyme conformation using mesoporous materials, addressing challenges in achieving improved enzyme activity and stability. Metal-organic frameworks with tailored mesopores, precisely matching enzyme size and shape, are synthesized. Remarkably, enzymes encapsulated within these customized mesopores exhibit over 1670% relative activity compared to free enzymes, maintaining outstanding efficiency even under harsh conditions such as heat, exposure to organic solvents, wide-ranging pH extremes from acidic to alkaline, and exposure to a digestion cocktail. After 18 consecutive cycles of use, the immobilized enzymes retain 80% of their initial activity. Additionally, the encapsulated enzymes exhibit a substantial increase in catalytic efficiency, with a 14.1-fold enhancement in kcat/KM compared to native enzymes. This enhancement is among the highest reported for immobilized enzymes. The improved enzyme activity and stability are corroborated by solid-state UV-vis, electron paramagnetic resonance, Fourier-transform infrared spectroscopy, and solid-state NMR spectroscopy. The findings not only offer valuable insights into the crucial role of size and shape complementarity within confined microenvironments but also establish a new pathway for developing solid carriers capable of enhancing enzyme activity and stability.

A novel laccase-like Cu-MOF for colorimetric differentiation and detection of phenolic compounds

The development of convenient, fast, and cost-effective methods for differentiating and detecting common organic pollutant phenols has become increasingly important for environmental and food safety. In this study, a copper metal-organic framework (Cu-MOF) with flower-like morphology was synthesized using 2-methylimidazole (2-MI) as ligands. The Cu-MOF was designed to mimic the natural laccase active site and proved demonstrated excellent mimicry of enzyme-like activity. Leveraging the superior properties of the constructed Cu-MOF, a colorimetric method was developed for analyzing phenolic compounds. This method exhibited a wide linear range from 0.1 to 100 μM with a low limit of detection (LOD) of 0.068 μM. Besides, by employing principal component analysis (PCA), nine kinds of phenols was successfully distinguished and identified. Moreover, the combination of smartphones with RGB profiling enabled real-time, quantitative, and high-throughput detection of phenols. Therefore, this work presents a paradigm and offers guidance for the differentiation and detection of phenolic pollutants in the environment.